mathtex_portable_engine_generated/

runtime.rs

//! Runtime prelude for auto-patched Web2C/C2Rust engine source.
//! Generated code must be lowered from raw globals into `PortableTexState`
//! before it is linked into `mathtex-engine`.

#![allow(dead_code, non_camel_case_types, non_snake_case, non_upper_case_globals)]

pub(crate) type integer = i32;
pub(crate) type size_t = usize;
pub(crate) type int32_t = i32;
pub(crate) type uint32_t = u32;
pub(crate) type real = f64;
pub(crate) type glueratio = f64;
pub(crate) type boolean = i32;
pub(crate) type schar = i8;
pub(crate) type ASCIIcode = integer;
pub(crate) type eightbits = integer;
pub(crate) type poolpointer = integer;
pub(crate) type strnumber = integer;
pub(crate) type savepointer = integer;
pub(crate) type packedASCIIcode = u16;
pub(crate) type packedUTF16code = u16;
pub(crate) type scaled = integer;
pub(crate) type nonnegativeinteger = integer;
pub(crate) type smallnumber = integer;
pub(crate) type quarterword = integer;
pub(crate) type halfword = integer;
pub(crate) type glueord = integer;
pub(crate) type groupcode = integer;
pub(crate) type internalfontnumber = integer;
pub(crate) type fontindex = integer;
pub(crate) type ninebits = integer;
pub(crate) type triepointer = integer;
pub(crate) type trieopcode = integer;
pub(crate) type hyphpointer = integer;
pub(crate) type UTF16code = u16;
pub(crate) type UnicodeScalar = integer;
pub(crate) type uint16_t = u16;
pub(crate) type UTF8code = integer;
pub(crate) type voidpointer = *mut ();
pub(crate) type address = voidpointer;
pub(crate) type string = *mut i8;
pub(crate) type const_string = *const i8;
pub(crate) type Fixed = int32_t;
pub(crate) struct PortableFileHandle {
    name: String,
    kind: ResourceKind,
    package: Option<String>,
    format: integer,
    bytes: Vec<u8>,
    cursor: usize,
    eof_after_failed_read: bool,
    /// Input encoding used to decode this file's bytes into Unicode scalars.
    /// `Bytes` (XeTeX `RAW`) reads each byte verbatim; `Utf8`/`Utf16Be`/`Utf16Le`
    /// reproduce XeTeX's `get_uni_c` decoders. Binary inputs (tfm/font/fmt) are
    /// always `Bytes`.
    encoding: InputEncoding,
    /// One-unit lookahead for the UTF-16 surrogate decoder (XeTeX `savedChar`).
    saved_char: Option<u32>,
}

/// Input decoding mode for a [`PortableFileHandle`], mirroring XeTeX's encoding
/// modes (`xetex.h`): `Bytes` corresponds to `RAW`. `AUTO`/`ICUMAPPING` are not
/// stored here — `AUTO` is resolved to a concrete mode at open time (BOM sniff),
/// and ICU mappings degrade to `Bytes`.
#[derive(Clone, Copy, Debug, Default, PartialEq, Eq)]
pub enum InputEncoding {
    /// Raw bytes, one Unicode scalar per byte (XeTeX `RAW`).
    #[default]
    Bytes,
    /// UTF-8 (XeTeX `UTF8`).
    Utf8,
    /// UTF-16 big-endian (XeTeX `UTF16BE`).
    Utf16Be,
    /// UTF-16 little-endian (XeTeX `UTF16LE`).
    Utf16Le,
}
pub(crate) type bytefile = NativeFileHandle;
pub(crate) type unicodefile = NativeFileHandle;
pub(crate) type ResourceSearchHandle = *mut ResourceSearchState;
pub type PortableFontHandle = usize;
pub(crate) type FontHandle = PortableFontHandle;
pub(crate) type CFDictionaryRef = voidpointer;
pub(crate) type NativeFileHandle = *mut PortableFileHandle;
pub(crate) type alphafile = NativeFileHandle;
pub(crate) type UFILE = PortableFileHandle;

pub(crate) const true_0: boolean = 1;
pub(crate) const false_0: boolean = 0;
pub(crate) const firstmathfontdimen: integer = 10;
pub(crate) const native_node_size: integer = 6;

#[derive(Debug)]
pub(crate) struct EngineAbort {
    status: integer,
}

/// A surfaced, recoverable engine error: a TeX `! ...` diagnostic (undefined
/// control sequence, bad argument, runaway, or a sandbox-rule violation). Unlike
/// [`EngineAbort`] -- the fatal `jump_out`/`fatal_error`/`overflow` channel --
/// this carries the captured message so the host can report *what* went wrong
/// instead of only that the run aborted.
#[derive(Debug)]
pub(crate) struct EngineError {
    pub(crate) message: String,
}

/// The engine's non-`Ok` outcomes. `Abort` is the fatal jump_out/overflow
/// channel; `Error` is a surfaced TeX error carrying its message. This is the
/// `Err` payload of a `Result` rather than a bespoke enum replacing `Result`,
/// so the `?` operator keeps working across the ~120 generated bodies -- stable
/// Rust `?` is `Result`/`Option`-only.
#[derive(Debug)]
pub(crate) enum EngineBreak {
    Abort(EngineAbort),
    Error(EngineError),
}

impl From<EngineAbort> for EngineBreak {
    fn from(abort: EngineAbort) -> Self {
        EngineBreak::Abort(abort)
    }
}

/// Collapse a uniformly character-doubled line back to its original. TeX's
/// `term_and_log` selector writes each byte to both the terminal and the log,
/// and in this headless build both feed the single transcript buffer, so a
/// diagnostic such as `! Undefined control sequence.` arrives with every
/// character repeated (`!! Undefined ...`). Returns `Some` only when the line is
/// exactly 2x doubled (even length, every adjacent pair equal); otherwise `None`
/// so genuinely non-doubled lines pass through untouched.
fn collapse_doubled_line(line: &str) -> Option<String> {
    let chars: Vec<char> = line.chars().collect();
    if chars.len() < 2 || chars.len() % 2 != 0 {
        return None;
    }
    if chars.chunks_exact(2).all(|pair| pair[0] == pair[1]) {
        Some(chars.iter().step_by(2).collect())
    } else {
        None
    }
}

/// Main-control iteration budget for a sandboxed fragment render. Far more than
/// any real expression needs, but bounds infinite loops so a malicious or
/// mistaken input (`\def\x{\x}\x`) cannot hang the host.
pub(crate) const SANDBOX_OP_BUDGET: u64 = 2_000_000;

/// Non-unwinding abort/error channel. Functions that can reach the engine's
/// fatal `jump_out`/`fatal_error`/`overflow` paths -- or that surface a TeX
/// error -- return this instead of diverging via `panic_any`, so the engine
/// runs under `panic=abort` (wasm). The `?` operator threads the `Err(EngineBreak)`
/// straight back to the driver boundary in [`PortableTexEngine::catch_engine_abort`].
/// The alias keeps signatures off the bare `Result` identifier, which is shadowed
/// by ~120 local `Result` bindings in the generated bodies; `core::result::Result`
/// is `no_std`-safe.
pub(crate) type EngineFlow<T> = core::result::Result<T, EngineBreak>;
pub(crate) const nullptr: voidpointer = core::ptr::null_mut::<()>();
pub(crate) const nil: voidpointer = core::ptr::null_mut::<()>();
pub(crate) const maxint: integer = i32::MAX;
pub(crate) const mintrieop: integer = 0;
pub(crate) const trieopsize: i64 = 35111;
pub(crate) const negtrieopsize: i64 = -35111;
pub(crate) const maxtrieop: i64 = 65535;
pub(crate) const hashoffset: integer = 514;
pub(crate) const xetex_hash_top: halfword = 1_205_763;
pub(crate) const xetex_eqtb_top: halfword = 9_006_997;
pub(crate) const DIR_SEP: integer = b'/' as integer;
pub(crate) const resource_format_tex_input: integer = 26;
pub(crate) const resource_format_tfm: integer = 3;
pub(crate) const resource_format_format_image: integer = 10;
pub(crate) const resource_format_config: integer = 8;
pub(crate) const resource_format_font_map: integer = 11;
pub(crate) const resource_format_encoding: integer = 44;
pub(crate) const resource_format_font: integer = 47;
pub(crate) const FOPEN_RBIN_MODE: [i8; 3] = [b'r' as i8, b'b' as i8, 0];

#[derive(Clone, Debug, PartialEq, Eq)]
pub struct PortableSourceSpan {
    pub name: String,
    pub start: u32,
    pub end: u32,
    /// Provenance role, mirroring the IR `SourceRole` discriminant: 0=Primary,
    /// 1=MacroExpansion. Set deterministically by the stamping site, never
    /// guessed.
    pub role: u8,
}

/// Interned source-span id used by the (feature-gated) source-tracking subsystem.
/// `0` is the canonical NONE; real spans start at `1`. The id indexes
/// `PortableTexState::src_spans`.
pub(crate) type SrcId = u32;

/// One recorded source span in a *source file's own* character coordinates
/// (NOT wrapper-relative). `name` is `curinput.namefield` (the source-file
/// string number); `start`/`end` are character offsets in that file's input.
/// `role` matches [`PortableSourceSpan::role`]. Hashed/equated by all fields so
/// the intern table assigns stable first-touch ids.
#[derive(Clone, Copy, Debug, Default, PartialEq, Eq, Hash)]
pub(crate) struct RawSpan {
    pub name: strnumber,
    pub start: u32,
    pub end: u32,
    pub role: u8,
}

/// `default_fn` for the `node_src` paged shadow: an unstamped node is NONE.
fn node_src_default(_i: usize) -> u32 {
    0
}

/// Significant-byte range for `node_src` words (the whole `u32` is live).
fn node_src_sig(_i: usize) -> (usize, usize) {
    (0, 4)
}

/// One frame on the enclosing-construct stack (source-tracking inc2). A frame is
/// an interned construct extent (a macro invocation or a delimited primitive
/// argument group) plus a link to its parent frame, forming a per-node snapshot
/// of the construct nesting that was live when the node was allocated. Group
/// frames are PENDING between their `{` open and `}` close (the closing-delimiter
/// offset is unknown until the close), finalized in place at the close. Cells are
/// addressed 1-based via [`PortableTexState::cur_stack_head`] / `node_stack`
/// (`0` = no enclosure). Transient per-render parse state, cleared with the rest
/// of the source-tracking tables.
#[derive(Clone, Copy, Debug, Default, PartialEq, Eq)]
pub(crate) struct SrcStackCell {
    /// Finalized interned construct-extent span id (`0` while pending / none).
    pub span: SrcId,
    /// Parent frame index (1-based; `0` = root / no parent).
    pub parent: u32,
    /// Pending group: char offset of the enclosing command's start.
    pub start: u32,
    /// Pending group: source-file string number the offsets live in.
    pub name: strnumber,
    /// True while a group frame is open (its end offset is not yet known).
    pub pending: bool,
}

/// `default_fn` for the `node_stack` paged shadow: an unstamped node has no
/// enclosing frame (`0`).
fn node_stack_default(_i: usize) -> u32 {
    0
}

/// Significant-byte range for `node_stack` words (the whole `u32` is live).
fn node_stack_sig(_i: usize) -> (usize, usize) {
    (0, 4)
}

#[derive(Clone, Debug, PartialEq, Eq)]
pub struct PortableNodeSourceSpan {
    pub node: i32,
    pub size: i32,
    pub source: PortableSourceSpan,
}

#[derive(Clone, Copy, Debug, PartialEq, Eq)]
pub enum ResourceKind {
    TexInput,
    Package,
    Class,
    FontDefinition,
    PackageSupport,
    Font,
    Encoding,
    Map,
    Config,
    FormatImage,
    Asset,
    Other(integer),
}

#[derive(Clone, Debug, PartialEq, Eq)]
pub struct ResourceRequest<'a> {
    pub name: &'a str,
    pub kind: ResourceKind,
    pub package: Option<&'a str>,
    pub format: integer,
    pub mode: &'a str,
    pub source: Option<PortableSourceSpan>,
}

#[derive(Clone, Debug, PartialEq, Eq)]
pub struct PortableResourceRequestRecord {
    pub name: String,
    pub kind: ResourceKind,
    pub package: Option<String>,
    pub format: integer,
    pub mode: String,
    pub source: Option<PortableSourceSpan>,
    pub byte_len: Option<u32>,
}

#[derive(Clone, Copy, Debug, Default, PartialEq, Eq)]
pub struct PortableFontMetrics {
    pub ascent: i32,
    pub descent: i32,
    pub xheight: i32,
    pub capheight: i32,
    pub slant: i32,
}

#[derive(Clone, Copy, Debug, Default, PartialEq, Eq)]
pub struct PortableNativeGlyph {
    pub glyph_id: u16,
    pub x: i32,
    pub y: i32,
    pub advance: i32,
    pub cluster_start: u32,
    pub cluster_end: u32,
    /// SOURCE byte span (in the producing node's `primary_source.source`
    /// coordinates) of the input char(s) that shaped this glyph, resolved from
    /// the per-code-unit tracked spans. `0/0` means unmapped (tracking off, no
    /// source, cross-source, or stale). Set by `src_resolve_native_glyphs`; the
    /// rendering fields (`glyph_id`/`x`/`y`/`advance`) are never touched.
    pub src_start: u32,
    pub src_end: u32,
}

#[derive(Clone, Debug, Default, PartialEq, Eq)]
pub struct PortableNativeTextMetrics {
    pub width: i32,
    pub height: i32,
    pub depth: i32,
    pub glyphs: Vec<PortableNativeGlyph>,
}

#[derive(Clone, Copy, Debug, Default, PartialEq, Eq)]
pub struct PortableNativeGlyphMetrics {
    pub width: i32,
    pub height: i32,
    pub depth: i32,
}

#[derive(Clone, Debug, Default, PartialEq, Eq)]
struct PortableNativeGlyphInfo {
    glyphs: Vec<PortableNativeGlyph>,
}

/// A larger OpenType MATH glyph variant: the variant glyph id and its advance in
/// scaled points (`-1` advance means "no such variant").
#[derive(Clone, Copy, Debug, PartialEq, Eq)]
pub struct PortableMathVariant {
    pub glyph: i32,
    pub advance: i32,
}

/// One part of an OpenType MATH glyph assembly, all measurements in scaled
/// points (mirrors `hb_ot_math_glyph_part_t` / ttf-parser `GlyphPart`).
#[derive(Clone, Copy, Debug, Default, PartialEq, Eq)]
pub struct PortableMathAssemblyPart {
    pub glyph: i32,
    pub start_connector: i32,
    pub end_connector: i32,
    pub full_advance: i32,
    pub extender: bool,
}

/// A corner of an OpenType `MathKernInfo` record (mirrors `hb_ot_math_kern_t`).
#[derive(Clone, Copy, Debug, PartialEq, Eq)]
pub enum PortableMathKernCorner {
    TopRight,
    TopLeft,
    BottomRight,
    BottomLeft,
}

/// Heap-owned OpenType MATH glyph assembly handed to the engine as an opaque
/// pointer by `get_ot_assembly_ptr` and reclaimed by `free_ot_assembly`.
///
/// This replaces XeTeX's C `GlyphAssembly` (`{count; hb_ot_math_glyph_part_t*}`)
/// with a safe Rust struct: it is allocated with `Box::into_raw` and freed with
/// `Box::from_raw`, never libc. `build_opentype_assembly` (the sole consumer in
/// this engine) reads it directly in Rust.
#[derive(Clone, Debug, Default, PartialEq, Eq)]
pub struct GlyphAssembly {
    pub parts: Vec<PortableMathAssemblyPart>,
}

pub trait FontPlatform {
    fn resolve_font_handle(&mut self, _name: &[i32], _size: i32) -> Option<PortableFontHandle> {
        None
    }

    fn release_font_handle(&mut self, _font: PortableFontHandle, _type_flag: i32) {}

    /// Snapshot the platform's native-font table as `(handle, spec, size)`
    /// tuples. A serialized format image keeps integer font handles in
    /// `fontlayoutengine`, but those handles only mean something to the platform
    /// that minted them; capturing the table lets a cold load rebind them.
    fn font_table(&self) -> Vec<(PortableFontHandle, String, i32)> {
        Vec::new()
    }

    /// Rebuild the native-font table from a [`Self::font_table`] snapshot,
    /// (re)loading each font *at its original handle* so the `fontlayoutengine`
    /// handles preserved in a reloaded format image resolve again. Returns
    /// `false` if any font failed to load.
    fn restore_font_table(&mut self, _table: &[(PortableFontHandle, String, i32)]) -> bool {
        true
    }

    fn font_metrics(&mut self, _font: PortableFontHandle) -> PortableFontMetrics {
        PortableFontMetrics::default()
    }

    fn opentype_font_metrics(&mut self, font: PortableFontHandle) -> PortableFontMetrics {
        self.font_metrics(font)
    }

    fn is_opentype_math_font(&mut self, _font: PortableFontHandle) -> bool {
        false
    }

    /// Whether `font` is shaped through the OpenType (HarfBuzz/rustybuzz) shaper.
    /// Mirrors XeTeX's `usingOpenType`, which is true for the `"ot"` shaper (the
    /// default). This engine always shapes native fonts with rustybuzz, so any
    /// loaded native font handle returns `true`.
    fn using_opentype(&mut self, _font: PortableFontHandle) -> bool {
        false
    }

    fn math_symbol_parameter(&mut self, _font: PortableFontHandle, _parameter: i32) -> i32 {
        0
    }

    fn math_extension_parameter(&mut self, _font: PortableFontHandle, _parameter: i32) -> i32 {
        0
    }

    fn opentype_math_constant(&mut self, _font: PortableFontHandle, _constant: i32) -> i32 {
        0
    }

    fn opentype_math_accent_position(&mut self, _font: PortableFontHandle, _glyph: i32) -> i32 {
        0
    }

    /// OpenType MATH italic correction for a glyph, in scaled points.
    fn math_glyph_italic_correction(&mut self, _font: PortableFontHandle, _glyph: i32) -> i32 {
        0
    }

    /// The `index`-th larger MATH glyph variant of `glyph` (horizontal or
    /// vertical), or `None` when there is no such variant. The advance is in
    /// scaled points.
    fn math_glyph_variant(
        &mut self,
        _font: PortableFontHandle,
        _glyph: i32,
        _index: u16,
        _horizontal: bool,
    ) -> Option<PortableMathVariant> {
        None
    }

    /// The MATH glyph-assembly parts for `glyph` (horizontal or vertical), each
    /// metric in scaled points. Empty when the glyph has no assembly.
    fn math_glyph_assembly(
        &mut self,
        _font: PortableFontHandle,
        _glyph: i32,
        _horizontal: bool,
    ) -> Vec<PortableMathAssemblyPart> {
        Vec::new()
    }

    /// The MATH minimum connector overlap for assembly parts, in scaled points.
    fn math_min_connector_overlap(&mut self, _font: PortableFontHandle) -> i32 {
        0
    }

    /// One MATH `MathKernInfo` corner evaluated at `correction_height` (font
    /// design units), returned in raw font design units (NOT scaled).
    fn math_kern_at(
        &mut self,
        _font: PortableFontHandle,
        _glyph: i32,
        _corner: PortableMathKernCorner,
        _correction_height: i32,
    ) -> i32 {
        0
    }

    /// Convert a measurement in points to font design units for `font`
    /// (`pointsToUnits`).
    fn math_points_to_units(&mut self, _font: PortableFontHandle, _points: f32) -> f32 {
        0.0
    }

    /// Convert a measurement in font design units to scaled points for `font`
    /// (`D2Fix(unitsToPoints(...))`).
    fn math_units_to_scaled(&mut self, _font: PortableFontHandle, _units: i32) -> i32 {
        0
    }

    /// The point size at which `font` was loaded (`getPointSize`).
    fn math_point_size(&mut self, _font: PortableFontHandle) -> f32 {
        0.0
    }

    fn map_char_to_glyph(&mut self, _font: PortableFontHandle, _codepoint: i32) -> i32 {
        0
    }

    fn map_glyph_to_index(&mut self, _font: PortableFontHandle, _name: &str) -> i32 {
        0
    }

    /// OpenType layout enumeration backing the `\XeTeXOT*` / `\XeTeXcountglyphs`
    /// `last_item` primitives (XeTeX `ot_font_get`/`_1`/`_2`/`_3`). `what` is the
    /// XeTeX_ext code (1 = count glyphs, 16 = count scripts, 17 = count
    /// languages, 18 = count features, 19 = script tag, 20 = language tag,
    /// 21 = feature tag); unused params are 0.
    fn ot_font_get(
        &mut self,
        _font: PortableFontHandle,
        _what: i32,
        _param1: i32,
        _param2: i32,
        _param3: i32,
    ) -> i32 {
        0
    }

    /// The `\font` spec string a loaded handle was created from (e.g.
    /// `[latinmodern-math.otf]:script=math;ssty=1`). Immutable so the read-only
    /// IR-building path can recover the originating font file for a glyph run.
    fn font_spec(&self, _font: PortableFontHandle) -> Option<String> {
        None
    }

    fn shape_native_text(
        &mut self,
        _font: PortableFontHandle,
        _text: &[u16],
        _use_glyph_metrics: bool,
    ) -> PortableNativeTextMetrics {
        PortableNativeTextMetrics::default()
    }

    fn measure_native_glyph(
        &mut self,
        _font: PortableFontHandle,
        _glyph: u16,
        _use_glyph_metrics: bool,
    ) -> PortableNativeGlyphMetrics {
        PortableNativeGlyphMetrics::default()
    }
}

#[derive(Default)]
pub struct EmptyFontPlatform;

impl FontPlatform for EmptyFontPlatform {}

pub trait ResourceProvider {
    fn read(&mut self, request: ResourceRequest<'_>) -> Option<Vec<u8>>;
}

#[derive(Default)]
pub struct EmptyResourceProvider;

impl ResourceProvider for EmptyResourceProvider {
    fn read(&mut self, _request: ResourceRequest<'_>) -> Option<Vec<u8>> {
        None
    }
}

#[derive(Clone, Copy, Debug, Default, PartialEq, Eq)]
pub struct PortableClock {
    pub seconds: integer,
    pub micros: integer,
}

#[derive(Clone, Copy, Debug, PartialEq, Eq)]
pub struct PortableLinebreakRequest<'a> {
    pub font: integer,
    pub locale: integer,
    pub text: &'a [uint16_t],
}

// Style context for a host box request, display math collapses to Text to match cursize.
#[derive(Clone, Copy, Debug, PartialEq, Eq)]
pub enum PortableHostBoxStyle {
    Text,
    Script,
    ScriptScript,
}

#[derive(Clone, Copy, Debug, PartialEq, Eq)]
pub struct PortableHostBoxRequest {
    pub token: integer,
    pub style: PortableHostBoxStyle,
    pub font_size: scaled,
}

// Glyph offsets are scaled points from the box baseline origin, y positive downward.
#[derive(Clone, Copy, Debug, PartialEq, Eq)]
pub struct PortableHostBoxGlyph {
    pub glyph: u16,
    pub x: scaled,
    pub y: scaled,
    pub advance: scaled,
}

#[derive(Clone, Debug, PartialEq)]
pub struct PortableHostBoxRun {
    pub font_name: String,
    pub font_size: scaled,
    pub glyphs: Vec<PortableHostBoxGlyph>,
}

// Rule origin is its bottom left corner with y positive downward, height extends upward.
#[derive(Clone, Copy, Debug, PartialEq, Eq)]
pub struct PortableHostBoxRule {
    pub x: scaled,
    pub y: scaled,
    pub width: scaled,
    pub height: scaled,
}

#[derive(Clone, Debug, PartialEq)]
pub struct PortableHostBox {
    pub width: scaled,
    pub height: scaled,
    pub depth: scaled,
    pub runs: Vec<PortableHostBoxRun>,
    pub rules: Vec<PortableHostBoxRule>,
}

// \Uhostbox is extension cmd 59 with this chr, upstream extension codes stop at 46.
pub(crate) const HOST_BOX_EXTENSION_CODE: i32 = 91;
// Marker whatsit subtypes: pending carries the opaque token id, resolved carries a record index.
pub(crate) const HOST_BOX_PENDING_SUBTYPE: i16 = 91;
pub(crate) const HOST_BOX_RESOLVED_SUBTYPE: i16 = 92;
// eqtb slot of the current font in this import's layout (see the mainf reads in maincontrol).
pub(crate) const EQTB_CUR_FONT_LOC: i64 = 1206823;
// eqtb base of the family 2 math symbol fonts, indexed by size 0/256/512 (see zmathquad).
pub(crate) const EQTB_MATH_FONT_FAM2_BASE: i64 = 1206826;

pub trait PortablePlatform {
    fn clock(&mut self) -> PortableClock {
        PortableClock::default()
    }

    fn linebreak_start(&mut self, _request: PortableLinebreakRequest<'_>) {}

    fn linebreak_next(&mut self) -> Option<integer> {
        None
    }

    fn host_box(&mut self, _request: PortableHostBoxRequest) -> Option<PortableHostBox> {
        None
    }
}

#[derive(Default)]
pub struct EmptyPlatform;

impl PortablePlatform for EmptyPlatform {}

impl PortableFileHandle {
    fn new(
        name: String,
        kind: ResourceKind,
        package: Option<String>,
        format: integer,
        bytes: Vec<u8>,
    ) -> Self {
        Self {
            name,
            kind,
            package,
            format,
            bytes,
            cursor: 0,
            eof_after_failed_read: false,
            encoding: InputEncoding::Bytes,
            saved_char: None,
        }
    }

    fn read_byte(&mut self) -> Option<u8> {
        let Some(byte) = self.bytes.get(self.cursor).copied() else {
            self.eof_after_failed_read = true;
            return None;
        };
        self.cursor += 1;
        Some(byte)
    }

    fn has_remaining(&self) -> bool {
        self.cursor < self.bytes.len()
    }

    fn is_eof(&self) -> bool {
        self.eof_after_failed_read
    }

    /// Resolve the input encoding for a freshly opened TEXT file, reproducing
    /// XeTeX's `u_open_in` AUTO byte-order-mark sniff and consuming the BOM by
    /// advancing the initial cursor. Only meaningful for text inputs under the
    /// XeTeX profile; binary inputs and non-XeTeX profiles stay `Bytes`.
    ///
    /// XeTeX (`u_open_in`, AUTO mode):
    ///   * `FE FF`         -> UTF16BE, consume 2 (BOM)
    ///   * `FF FE`         -> UTF16LE, consume 2 (BOM)
    ///   * `00 xx (xx!=0)` -> UTF16BE, rewind (no consume)
    ///   * `xx 00 (xx!=0)` -> UTF16LE, rewind (no consume)
    ///   * `EF BB BF`      -> UTF8,    consume 3 (BOM)
    ///   * otherwise       -> UTF8,    rewind (no consume)
    fn resolve_text_encoding_auto(&mut self) {
        let b1 = self.bytes.first().copied();
        let b2 = self.bytes.get(1).copied();
        match (b1, b2) {
            (Some(0xFE), Some(0xFF)) => {
                self.encoding = InputEncoding::Utf16Be;
                self.cursor = 2;
            }
            (Some(0xFF), Some(0xFE)) => {
                self.encoding = InputEncoding::Utf16Le;
                self.cursor = 2;
            }
            (Some(0x00), Some(b2)) if b2 != 0 => {
                self.encoding = InputEncoding::Utf16Be;
                // rewind: no BOM consumed.
            }
            (Some(b1), Some(0x00)) if b1 != 0 => {
                self.encoding = InputEncoding::Utf16Le;
            }
            (Some(0xEF), Some(0xBB)) if self.bytes.get(2).copied() == Some(0xBF) => {
                self.encoding = InputEncoding::Utf8;
                self.cursor = 3;
            }
            _ => {
                self.encoding = InputEncoding::Utf8;
            }
        }
    }

    /// Decode the next Unicode scalar from the input, dispatching on the file's
    /// encoding. Returns `None` at end of input (XeTeX `EOF`). Faithful port of
    /// XeTeX's `get_uni_c` (`XeTeX_ext.c`): `GETC` == [`read_byte`], `UNGETC` ==
    /// `cursor -= 1`, and `savedChar` == [`saved_char`].
    fn next_input_scalar(&mut self) -> Option<u32> {
        // savedChar lookahead (only set by the UTF-16 decoders).
        if let Some(saved) = self.saved_char.take() {
            return Some(saved);
        }
        match self.encoding {
            InputEncoding::Bytes => self.read_byte().map(u32::from),
            InputEncoding::Utf8 => self.next_utf8_scalar(),
            InputEncoding::Utf16Be => self.next_utf16_scalar(true),
            InputEncoding::Utf16Le => self.next_utf16_scalar(false),
        }
    }

    /// UTF-8 branch of `get_uni_c`. Uses the `bytesFromUTF8` extra-byte count with
    /// fall-through continuation reads; a continuation outside `0x80..=0xBF` is
    /// bad UTF-8 -> UNGETC the offending byte and return U+FFFD; the assembled
    /// value is corrected by `offsetsFromUTF8` and range-checked.
    fn next_utf8_scalar(&mut self) -> Option<u32> {
        // offsetsFromUTF8[extraBytes].
        const OFFSETS: [u32; 6] = [
            0x0000_0000,
            0x0000_3080,
            0x000E_2080,
            0x03C8_2080,
            0xFA08_2080,
            0x8208_2080,
        ];
        let lead = self.read_byte()?;
        // bytesFromUTF8[lead]: extra continuation bytes (0..=5).
        let extra: usize = match lead {
            0x00..=0xBF => 0,
            0xC0..=0xDF => 1,
            0xE0..=0xEF => 2,
            0xF0..=0xF7 => 3,
            0xF8..=0xFB => 4,
            0xFC..=0xFF => 5,
        };
        // Assemble in a wider type to mirror C's `int rval` (continuations <<6).
        let mut rval: i64 = i64::from(lead);
        // C `switch(extraBytes)` falls through cases 3,2,1; cases 4,5 jump
        // straight to the bad-utf8 return without reading continuations.
        if extra >= 4 {
            // Lead bytes 0xF8..0xFF: no valid 4/5-byte sequence; return U+FFFD
            // without consuming further (mirrors the `case 5/4:` bad path).
            return Some(0xFFFD);
        }
        for _ in 0..extra {
            match self.read_byte() {
                Some(c) if (0x80..0xC0).contains(&c) => {
                    rval = (rval << 6) + i64::from(c);
                }
                Some(c) => {
                    // bad_utf8: UNGETC the offending byte, return U+FFFD.
                    self.cursor -= 1;
                    let _ = c;
                    return Some(0xFFFD);
                }
                None => {
                    // EOF mid-sequence: bad_utf8 without UNGETC.
                    return Some(0xFFFD);
                }
            }
        }
        rval -= i64::from(OFFSETS[extra]);
        if rval < 0 || rval > 0x10_FFFF {
            return Some(0xFFFD);
        }
        Some(rval as u32)
    }

    /// UTF-16 branch of `get_uni_c` for big- or little-endian. A high surrogate
    /// (`D800..=DBFF`) pulls a second unit; a matching low surrogate
    /// (`DC00..=DFFF`) combines to a supplementary scalar, otherwise U+FFFD and
    /// the stray unit is stashed in `saved_char`. A lone low surrogate -> U+FFFD.
    fn next_utf16_scalar(&mut self, big_endian: bool) -> Option<u32> {
        let unit = self.read_utf16_unit(big_endian)?;
        if (0xD800..=0xDBFF).contains(&unit) {
            // High surrogate: read the low surrogate (may hit EOF).
            match self.read_utf16_unit(big_endian) {
                Some(lo) if (0xDC00..=0xDFFF).contains(&lo) => {
                    Some(0x10000 + (unit - 0xD800) * 0x400 + (lo - 0xDC00))
                }
                Some(lo) => {
                    self.saved_char = Some(lo);
                    Some(0xFFFD)
                }
                None => Some(0xFFFD),
            }
        } else if (0xDC00..=0xDFFF).contains(&unit) {
            // Lone low surrogate.
            Some(0xFFFD)
        } else {
            Some(unit)
        }
    }

    /// Read one 16-bit UTF-16 code unit (two bytes) in the given endianness.
    /// Returns `None` only when the first byte is at EOF (mirrors `GETC` ==
    /// `EOF`); a missing trailing byte is treated as `0` like C's `GETC`/`<<8`.
    fn read_utf16_unit(&mut self, big_endian: bool) -> Option<u32> {
        let first = self.read_byte()?;
        let second = self.read_byte().unwrap_or(0);
        let unit = if big_endian {
            (u32::from(first) << 8) + u32::from(second)
        } else {
            u32::from(first) + (u32::from(second) << 8)
        };
        Some(unit)
    }
}

pub(crate) trait StatePtrCompat<T> {
    fn as_mut_ptr(self) -> *mut T;
    fn is_empty(self) -> bool;
}

impl<T> StatePtrCompat<T> for *mut T {
    fn as_mut_ptr(self) -> *mut T {
        self
    }

    fn is_empty(self) -> bool {
        self.is_null()
    }
}

#[derive(Copy, Clone)]
#[repr(C)]
pub(crate) union twohalves {
    pub v: TwoHalvesPair,
    pub u: TwoHalvesBytes,
}

impl Default for twohalves {
    fn default() -> Self {
        Self {
            v: TwoHalvesPair::default(),
        }
    }
}

#[derive(Copy, Clone, Default)]
#[repr(C)]
pub(crate) struct TwoHalvesBytes {
    pub B1: i16,
    pub B0: i16,
}

#[derive(Copy, Clone, Default)]
#[repr(C)]
pub(crate) struct TwoHalvesPair {
    pub LH: halfword,
    pub RH: halfword,
}

#[derive(Copy, Clone)]
#[repr(C)]
pub(crate) struct fourquarters {
    pub u: FourQuarterBytes,
}

impl Default for fourquarters {
    fn default() -> Self {
        Self {
            u: FourQuarterBytes::default(),
        }
    }
}

// Real XeTeX packs a `memory_word` into 8 bytes: its `four_quarters` view is
// four *16-bit* quarterwords. The c2rust translation widened these to 32-bit
// (`quarterword = i32`), tripling every `memory_word`/`font_memory_word` to 24
// bytes (and with it `mem`, `eqtb`, `fontinfo`). Storing them as `u16` — XeTeX's
// real unsigned quarterword width (0..=65535, enough for native glyph ids) —
// restores the packed layout (memory_word 24 -> 16 bytes). The `quarterword`
// alias stays `i32` for general arithmetic; only this storage view is narrowed.
// NOTE: the c2rust functions/*.rs write/read these fields with `as quarterword`
// (i32); the `FourQuarterCastPass` in tools/web2c-import wraps those sites with
// `as u16`/`as i32` so they stay type-correct against this narrowed view.
#[derive(Copy, Clone, Default)]
#[repr(C)]
pub(crate) struct FourQuarterBytes {
    pub B3: u16,
    pub B2: u16,
    pub B1: u16,
    pub B0: u16,
}

pub(crate) type C2RustUnnamed_2 = FourQuarterBytes;

#[derive(Copy, Clone)]
#[repr(C)]
pub(crate) union memoryword {
    pub gr: glueratio,
    pub hh: twohalves,
    pub u: MemoryInt,
    pub v: MemoryQuarters,
    pub ptr: voidpointer,
}

impl Default for memoryword {
    fn default() -> Self {
        Self {
            u: MemoryInt::default(),
        }
    }
}

// Packed to match real XeTeX (and the already-packed `fmemoryword`): the
// `four_quarters`/`cint` views sit at offset 0, not behind a `junk` halfword.
// Dropping `junk` takes `memory_word` from 16 -> 8 bytes (`MemoryQuarters` was
// the union's largest variant at junk(4)+qqqq(8)=12, rounded to 16). TeX accesses
// each live word through exactly one view, so the `cint`/`qqqq` <-> `hh.rh`
// offset-4 aliasing the c2rust output happened to expose is never relied upon.
#[derive(Copy, Clone, Default)]
#[repr(C)]
pub(crate) struct MemoryQuarters {
    pub QQQQ: fourquarters,
}

#[derive(Copy, Clone, Default)]
#[repr(C)]
pub(crate) struct MemoryInt {
    pub CINT: integer,
}

#[derive(Copy, Clone)]
#[repr(C)]
pub(crate) union fmemoryword {
    pub u: FontMemoryInt,
    pub v: FontMemoryQuarters,
}

impl Default for fmemoryword {
    fn default() -> Self {
        Self {
            u: FontMemoryInt::default(),
        }
    }
}

#[derive(Copy, Clone, Default)]
#[repr(C)]
pub(crate) struct FontMemoryQuarters {
    pub QQQQ: fourquarters,
}

#[derive(Copy, Clone, Default)]
#[repr(C)]
pub(crate) struct FontMemoryInt {
    pub CINT: integer,
}

#[derive(Copy, Clone, Default)]
#[repr(C)]
pub(crate) struct liststaterecord {
    pub modefield: i16,
    pub headfield: halfword,
    pub tailfield: halfword,
    pub eTeXauxfield: halfword,
    pub pgfield: integer,
    pub mlfield: integer,
    pub auxfield: memoryword,
}

#[derive(Copy, Clone, Default)]
#[repr(C)]
pub(crate) struct instaterecord {
    pub statefield: quarterword,
    pub indexfield: quarterword,
    pub startfield: halfword,
    pub locfield: halfword,
    pub limitfield: halfword,
    pub namefield: halfword,
    /// Source-tracking AMBIENT span for this input level (feature-gated). Rides
    /// the existing whole-record input-stack push (`zbegintokenlist`) / pop
    /// (`endtokenlist`/`endfilereading`) save/restore with zero extra code, so a
    /// macro/file level's inherited span is torn down automatically on pop. `0`
    /// (NONE) on the default render path.
    pub spanfield: SrcId,
}

#[derive(Copy, Clone, Default)]
#[repr(C)]
pub(crate) struct transform {
    pub a: f64,
    pub b: f64,
    pub c: f64,
    pub d: f64,
    pub x: f64,
    pub y: f64,
}

#[derive(Copy, Clone, Default)]
#[repr(C)]
pub(crate) struct realpoint {
    pub x: f32,
    pub y: f32,
}

#[derive(Copy, Clone, Default)]
#[repr(C)]
pub(crate) struct realrect {
    pub x: f32,
    pub y: f32,
    pub wd: f32,
    pub ht: f32,
}

#[derive(Copy, Clone, Default)]
#[repr(C)]
pub(crate) struct ResourceSearchState {
    pub make_tex_discard_errors: boolean,
}

// ---------------------------------------------------------------------------
// Paged sparse backing for the per-codepoint `eqtb` / `hash` regions.
//
// XeTeX's `eqtb` reserves one slot per Unicode codepoint for each of the
// cat/lc/uc/sf/math/del code tables — ~7.8M slots spanning absolute indices
// [`CODEPOINT_LO`..`eqtb_top`]. `initialize` fills them with a per-band default
// (cat=12, sf=1000, math=identity, lc/uc/band6=0, del=-1); a real
// LaTeX+unicode-math format overrides only a few thousand. The parallel `hash`
// array never touches that middle region at all. Stored densely this is ~125 MB
// (eqtb) + ~62 MB (hash) of mostly-identical defaults.
//
// `PagedArray` keeps the frequently-touched low region [base..CODEPOINT_LO)
// dense and pages the high region lazily: a page faults in (filled from
// `default_fn`) only on first access, and `compact()` — run when a format image
// is sealed — frees any page still byte-equal to its defaults. Correctness never
// depends on `default_fn` matching TeX's real defaults: a freed page is
// regenerated identically on next access; only how much memory is reclaimed does.
const CODEPOINT_LO: usize = 1_207_592; // cat_code_base: first per-codepoint band
const PAGE_BITS: usize = 12;
const PAGE_LEN: usize = 1 << PAGE_BITS;
/// Live byte range of an `eqtb` word at absolute index `i`. The cat/lc/uc/sf/math
/// code bands read the whole `two_halves` (bytes 0..8: value `RH` + eq_type/level
/// `B0`/`B1`). The del/int region [7892264..=9006997] reads only `.u.CINT`
/// (bytes 4..8) — its `junk` half is dead. (The hashextra region above that holds
/// csname meanings read via `.hh`, so it keeps the full range.)
fn eqtb_sig_range(i: usize) -> (usize, usize) {
    if (7_892_264..=9_006_997).contains(&i) {
        (0, 4) // del/int region: only `.u.CINT` (now at offset 0) is live
    } else {
        (0, 8)
    }
}

/// `hash` words are `two_halves` — the full 8 bytes are live.
fn hash_sig_range(_i: usize) -> (usize, usize) {
    (0, 8)
}

/// Compare two `T` values over a byte sub-range `[off, off+len)`. Only the bytes
/// a TeX word's *live* fields occupy are significant: a `memoryword` is 16 bytes
/// but the eqtb code bands read only `.hh` (bytes 0..8) and the del/int region
/// reads only `.u.CINT` (bytes 4..8). The dead bytes carry copy-loop / allocator
/// residue, so comparing only the live range lets compaction recognise pages that
/// hold nothing but band defaults. Freeing such a page is safe because a re-fault
/// regenerates the same live bytes (and dead bytes are never read).
fn paged_bytes_eq<T>(a: &T, b: &T, off: usize, len: usize) -> bool {
    // SAFETY: `off+len <= size_of::<T>()`; read-only byte view of two POD values.
    unsafe {
        let pa = (a as *const T as *const u8).add(off);
        let pb = (b as *const T as *const u8).add(off);
        core::slice::from_raw_parts(pa, len) == core::slice::from_raw_parts(pb, len)
    }
}

pub(crate) struct PagedArray<T: Copy + Default> {
    base: usize,                  // absolute index of `low[0]`
    lo: usize,                    // absolute index where paging begins
    end: usize,                   // absolute index one past the last element
    low: Vec<T>,                  // dense, covers [base..lo)
    pages: Vec<Option<Box<[T]>>>, // lazy, covers [lo..end) rounded up to PAGE_LEN
    default_fn: fn(usize) -> T,   // value at absolute index `i` when its page is absent
    sig_range: fn(usize) -> (usize, usize), // live byte range (off,len) at index `i`
}

impl<T: Copy + Default> PagedArray<T> {
    fn new(
        base: usize,
        end: usize,
        default_fn: fn(usize) -> T,
        sig_range: fn(usize) -> (usize, usize),
    ) -> Self {
        // Page the whole array (no dense prefix): the low region below
        // CODEPOINT_LO is also ~97% uniform default (eqtb: undefined-cs slots;
        // hash: zero), so paging it too lets compaction reclaim ~18 MB. `lo ==
        // base` makes `low` empty and routes every access through the page table.
        let lo = base;
        let npages = (end - lo).div_ceil(PAGE_LEN);
        PagedArray {
            base,
            lo,
            end,
            low: vec![T::default(); lo - base],
            pages: (0..npages).map(|_| None).collect(),
            default_fn,
            sig_range,
        }
    }

    #[inline]
    fn ptr(&mut self, abs: usize) -> *mut T {
        if abs < self.lo {
            // SAFETY: callers only index valid absolute slots [base..end).
            return unsafe { self.low.as_mut_ptr().add(abs - self.base) };
        }
        let rel = abs - self.lo;
        let pg = rel >> PAGE_BITS;
        let off = rel & (PAGE_LEN - 1);
        if self.pages[pg].is_none() {
            let page_base = self.lo + pg * PAGE_LEN;
            let f = self.default_fn;
            let mut page: Vec<T> = Vec::with_capacity(PAGE_LEN);
            for j in 0..PAGE_LEN {
                page.push(f(page_base + j));
            }
            self.pages[pg] = Some(page.into_boxed_slice());
        }
        // SAFETY: page just ensured present; `off < PAGE_LEN`.
        unsafe {
            self.pages[pg]
                .as_mut()
                .unwrap_unchecked()
                .as_mut_ptr()
                .add(off)
        }
    }

    /// Free any faulted page whose contents still equal `default_fn` — called
    /// when sealing a format snapshot so the persisted/resident image keeps only
    /// pages carrying real overrides.
    fn compact(&mut self) {
        let f = self.default_fn;
        for pg in 0..self.pages.len() {
            let page_base = self.lo + pg * PAGE_LEN;
            let is_default = match &self.pages[pg] {
                None => continue,
                Some(page) => (0..PAGE_LEN).all(|j| {
                    let (off, len) = (self.sig_range)(page_base + j);
                    paged_bytes_eq(&page[j], &f(page_base + j), off, len)
                }),
            };
            if is_default {
                self.pages[pg] = None;
            }
        }
    }

    fn resident_bytes(&self) -> usize {
        let elt = core::mem::size_of::<T>();
        self.low.capacity() * elt
            + self.pages.iter().filter(|p| p.is_some()).count() * PAGE_LEN * elt
            + self.pages.capacity() * core::mem::size_of::<Option<Box<[T]>>>()
    }

    /// Write `v` at absolute index `abs`, faulting its page in. Out-of-range
    /// indices are ignored (the source-tracking shadow may be sized smaller than
    /// a node address it is asked to stamp on a degenerate path).
    #[inline]
    fn set(&mut self, abs: usize, v: T) {
        if abs < self.base || abs >= self.end {
            return;
        }
        // SAFETY: `abs` is in `[base, end)`; `ptr` faults the page if absent.
        unsafe {
            *self.ptr(abs) = v;
        }
    }

    /// Read the value at absolute index `abs` WITHOUT faulting a page: an absent
    /// page is reported as its `default_fn` value. `&self`, so it is safe to call
    /// from the read-only IR snapshot path.
    #[inline]
    fn get_copy(&self, abs: usize) -> T {
        if abs < self.base || abs >= self.end {
            return (self.default_fn)(abs);
        }
        if abs < self.lo {
            return self.low[abs - self.base];
        }
        let rel = abs - self.lo;
        let pg = rel >> PAGE_BITS;
        let off = rel & (PAGE_LEN - 1);
        match self.pages.get(pg).and_then(|p| p.as_ref()) {
            Some(page) => page[off],
            None => (self.default_fn)(abs),
        }
    }
}

impl<T: Copy + Default> Clone for PagedArray<T> {
    fn clone(&self) -> Self {
        PagedArray {
            base: self.base,
            lo: self.lo,
            end: self.end,
            low: self.low.clone(),
            pages: self.pages.clone(),
            default_fn: self.default_fn,
            sig_range: self.sig_range,
        }
    }
}

/// A `Copy`, raw-pointer-style handle to a [`PagedArray`], standing in for the
/// `*mut memoryword` / `*mut twohalves` that the translated engine binds as
/// `let mut eqtb = self.state.zeqtb.as_mut_ptr();` and indexes with
/// `eqtb.offset(i)`. `offset` mimics `<*mut T>::offset` but routes through the
/// paged backing (faulting the page if needed). Mutating the backing through a
/// shared `Copy` handle mirrors the raw-pointer aliasing model the c2rust
/// translation already relies on for `zmem`/`zeqtb`/`hash`.
pub(crate) struct PagedView<T: Copy + Default>(*mut PagedArray<T>);

impl<T: Copy + Default> Clone for PagedView<T> {
    fn clone(&self) -> Self {
        *self
    }
}
impl<T: Copy + Default> Copy for PagedView<T> {}

impl<T: Copy + Default> PagedView<T> {
    pub(crate) fn new(arr: &mut PagedArray<T>) -> Self {
        PagedView(arr as *mut PagedArray<T>)
    }
    #[allow(dead_code)]
    pub(crate) fn null() -> Self {
        PagedView(core::ptr::null_mut())
    }
    #[inline]
    pub(crate) fn as_mut_ptr(self) -> Self {
        self
    }
    #[inline]
    pub(crate) fn is_null(self) -> bool {
        self.0.is_null()
    }
    #[inline]
    pub(crate) fn offset(self, count: isize) -> *mut T {
        // `count` is the absolute eqtb/hash index (the translation computes the
        // full index, then offsets once). SAFETY: matches the established
        // raw-pointer aliasing model; `self.0` is non-null after rebind.
        unsafe { (*self.0).ptr(count as usize) }
    }
}

/// Default `eqtb` word for an absolute codepoint-region index, reproducing what
/// XeTeX's `initialize` writes across the cat/lc/uc/sf/math/del bands.
fn eqtb_codepoint_default(i: usize) -> memoryword {
    // `memoryword` is 16 bytes (the `four_quarters` view needs 12 + padding) but
    // only its low 8 bytes are ever used by the code bands. `Default` leaves the
    // upper 8 bytes indeterminate, which would make byte-equality (compaction)
    // unreliable, so start from a fully-zeroed word.
    let mut w: memoryword = unsafe { core::mem::zeroed() };
    if (1_207_592..=7_892_263).contains(&i) {
        // two_halves code bands: eq_type=undefined_cs (123), eq_level=level_one (1).
        let rh: i32 = if (1_207_592..=2_321_703).contains(&i) {
            12 // cat_code -> "other"
        } else if (4_549_928..=5_664_039).contains(&i) {
            1000 // sf_code
        } else if (5_664_040..=6_778_151).contains(&i) {
            (i - 5_664_040) as i32 // math_code = identity
        } else {
            0 // lc_code / uc_code / trailing band
        };
        // Writing union fields is safe (no drop glue); the two halves are disjoint.
        w.hh.u.B0 = 123;
        w.hh.u.B1 = 1;
        w.hh.v.RH = rh;
    } else if (7_892_607..=9_006_718).contains(&i) {
        // del_code lives in the int view; default is -1.
        w.u.CINT = -1;
    } else if i < CODEPOINT_LO || i > xetex_eqtb_top as usize {
        // The control-sequence-meaning region below the code bands AND the eTeX
        // hash_high region above eqtb_top are both pre-filled with the
        // undefined-control-sequence template (eq_type=undefined_cs=104,
        // eq_level=level_zero=0, equiv=null=-0x0FFFFFFF). Defined csnames and the
        // few non-default low slots (glue/int params) overwrite it on demand; the
        // vast majority stay undefined and compact away.
        w.hh.u.B0 = 104;
        w.hh.v.RH = -(268435455 as i32);
    }
    // else: the small int/dimen gap regions ([7892264..7892606],
    // [9006719..9006997]) default to zero.
    w
}

/// Default `hash` word for the paged region: the codepoint middle is never
/// populated, so every absent slot is zero.
fn hash_codepoint_default(_i: usize) -> twohalves {
    twohalves::default()
}

pub(crate) struct PortableTexState {
    pub mem: Vec<memoryword>,
    buffer_storage: Vec<UnicodeScalar>,
    nest_storage: Vec<liststaterecord>,
    savestack_storage: Vec<memoryword>,
    inputstack_storage: Vec<instaterecord>,
    inputfile_storage: Vec<unicodefile>,
    eofseen_storage: Vec<boolean>,
    linestack_storage: Vec<integer>,
    grpstack_storage: Vec<savepointer>,
    ifstack_storage: Vec<halfword>,
    sourcefilenamestack_storage: Vec<strnumber>,
    fullsourcefilenamestack_storage: Vec<strnumber>,
    paramstack_storage: Vec<halfword>,
    hyphword_storage: Vec<strnumber>,
    hyphlist_storage: Vec<halfword>,
    hyphlink_storage: Vec<hyphpointer>,
    hash_paged: PagedArray<twohalves>,
    eqtb_paged: PagedArray<memoryword>,
    strstart_storage: Vec<poolpointer>,
    strpool_storage: Vec<packedUTF16code>,
    fontinfo_storage: Vec<fmemoryword>,
    bcharlabel_storage: Vec<fontindex>,
    charbase_storage: Vec<integer>,
    widthbase_storage: Vec<integer>,
    heightbase_storage: Vec<integer>,
    depthbase_storage: Vec<integer>,
    italicbase_storage: Vec<integer>,
    ligkernbase_storage: Vec<integer>,
    kernbase_storage: Vec<integer>,
    extenbase_storage: Vec<integer>,
    parambase_storage: Vec<integer>,
    fontarea_storage: Vec<strnumber>,
    fontname_storage: Vec<strnumber>,
    fontbc_storage: Vec<UTF16code>,
    fontec_storage: Vec<UTF16code>,
    fontbchar_storage: Vec<ninebits>,
    fontfalsebchar_storage: Vec<ninebits>,
    fontcheck_storage: Vec<fourquarters>,
    fontdsize_storage: Vec<scaled>,
    fontsize_storage: Vec<scaled>,
    fontflags_storage: Vec<i8>,
    fontglue_storage: Vec<halfword>,
    fontlayoutengine_storage: Vec<voidpointer>,
    fontletterspace_storage: Vec<scaled>,
    fontmapping_storage: Vec<voidpointer>,
    fontparams_storage: Vec<fontindex>,
    fontused_storage: Vec<boolean>,
    nativetext_storage: Vec<UTF16code>,
    hyphenchar_storage: Vec<integer>,
    skewchar_storage: Vec<integer>,
    triec_storage: Vec<packedUTF16code>,
    triehash_storage: Vec<triepointer>,
    triel_storage: Vec<triepointer>,
    trieo_storage: Vec<trieopcode>,
    trier_storage: Vec<triepointer>,
    trietaken_storage: Vec<boolean>,
    trietrc_storage: Vec<quarterword>,
    trietrl_storage: Vec<triepointer>,
    trietro_storage: Vec<triepointer>,
    // --- Source-tracking subsystem (feature-gated; all TRANSIENT per-render
    // parse state, NOT meaningfully round-tripped through the format image: the
    // heap tables below are reset to empty on load and the scalars are reset at
    // `begin_primary_input`). The default render path leaves `source_tracking`
    // false and allocates nothing here. ---
    /// Master gate. When false every hook is a cheap predictable no-op.
    source_tracking: bool,
    /// The construct latch: the span of the command currently executing, frozen
    /// at the `main_control` dispatch boundary before its argument sub-scans run.
    cmd_span: SrcId,
    /// Carried from a `macro_call` to the next `begin_token_list(.., macro)` to
    /// supply the call-site baseline for a macro body's synthesized content.
    pending_call_span: SrcId,
    /// Buffer offset of the token currently being lexed (captured at the top of
    /// `get_next`'s outer loop, so leading skipped material is excluded).
    src_token_start: integer,
    /// Multi-line base: the absolute character offset, in the primary input's
    /// own coordinates, of the first buffer slot of the current line.
    src_line_base: u32,
    /// Buffer index of the first slot of the current primary-input line. Each
    /// line is reloaded at the same `start`, so `loc - this` is a within-line
    /// column and `src_line_base + (loc - this)` is the absolute char offset.
    src_line_buf_start: integer,
    /// Character length of the most-recently-read primary-input line, used to
    /// advance `src_line_base` (`+= len + 1` for the line break) at the next refill.
    src_prev_line_len: u32,
    /// Whether the line accumulator has seen the first primary-input line (so the
    /// first line gets base 0 and subsequent lines accumulate).
    src_line_initialized: bool,
    /// The primary input's namefield (source-file string number); the line
    /// accumulator and resolver key on this.
    src_primary_name: strnumber,
    /// `macro_call` scratch: char offset of the invoking control sequence start.
    src_call_start: u32,
    /// `macro_call` scratch: namefield of the level the macro was read from.
    src_call_name: strnumber,
    /// `macro_call` scratch: statefield of that level (0 = token list / nested).
    src_call_state: integer,
    /// `macro_call` scratch: indexfield (token type) of the level the macro was
    /// read from, captured at entry before its arguments / the exhausted-list pop
    /// loop change `curinput`. `< 5` = a user-typed argument / backed-up replay
    /// (its hull is recovered from the scanned args); `>= 5` = a macro body / every
    /// list (inherits the baseline). `-1` when read from the buffer.
    src_call_index: integer,
    /// `macro_call` scratch: the inherited span fallback for a nested call.
    src_call_span: SrcId,
    /// `macro_call` scratch: span of the LAST token consumed while scanning this
    /// invocation's arguments (the closing `}` of the final brace group), captured
    /// before the exhausted-list pop loop. Unions into the argument hull so a
    /// token-list-replayed `\frac{q}{2}` recovers its trailing delimiter.
    src_call_argspan: SrcId,
    /// The span of the most recent control-sequence token lexed from the primary
    /// input BUFFER (set in `src_record_buffer_span` when `curcs != 0`). This is the
    /// in-fragment USER command currently being expanded: kernel helper macros
    /// reached through its expansion (`\@sqrt`, `\root`, `\mathpalette`, ... for
    /// `\sqrt`) are read from token lists, so they never overwrite it. It survives
    /// the eager pop of token-list input levels, unlike `curinput.spanfield`, so a
    /// helper invoked from the buffer after a `\futurelet`/`\@ifnextchar` peek can
    /// still recover the user command's start instead of the peeked token's.
    src_user_cmd_span: SrcId,
    /// Like `src_user_cmd_span` but tracks the innermost in-fragment command being
    /// REPLAYED from an argument-level token list (a nested `\sqrt{..}` inside a
    /// degree-form radicand, e.g. Cardano's inner radical). `src_user_cmd_span` is set
    /// only on BUFFER reads, so it goes stale during a mathchoice/macro replay (a later
    /// `\frac` overwrites it during the outer arg pre-scan). This one is set at
    /// `src_macro_begin` for argument-level replays and reset on the next buffer read,
    /// so it holds exactly the command that built the next noad. Consumed ONLY by
    /// `src_construct_anchor` — never by the arg-hull baseline — so it cannot perturb
    /// the degree-form extent.
    src_anchor_cmd: SrcId,
    /// `macro_call` scratch: `src_user_cmd_span` captured at `src_macro_begin`
    /// (before the macro reads its arguments, so it is the ENCLOSING user command,
    /// not one lexed while scanning the args). The buffer-branch baseline anchors
    /// its START here so every helper in a user command's expansion maps back to
    /// that command (the transitive macro-call chain).
    src_call_user_span: SrcId,
    /// The source span (origin) of the token currently held in `cur_tok` -- set at
    /// each token read (buffer or token-list) to the read token's own span, and NOT
    /// moved by later input-level pushes/pops. Lets `back_input` re-stamp a backed-up
    /// token with its true origin instead of the ambient `spanfield`, which the lexer
    /// may have advanced past during a `\futurelet`/`\@ifnextchar` look-ahead.
    src_tok_span: SrcId,
    /// Intern table: `SrcId` (minus 1) indexes this. Stable first-touch order.
    src_spans: Vec<RawSpan>,
    /// Dedup map so equal spans share one `SrcId`.
    src_dedup: std::collections::HashMap<RawSpan, SrcId>,
    /// Paged-sparse shadow of `mem`: `node_src[addr]` is the `SrcId` stamped on
    /// the node at `addr`. Same substrate as the paged eqtb; faults only touched
    /// pages, so cost is proportional to the fragment, not to `mem`.
    node_src: PagedArray<u32>,
    /// Transient per-code-unit source ids for the native-text run currently being
    /// collected in `main_control`'s main loop: `src_native_offsets[i]` is the
    /// `SrcId` of the input char whose UTF-16 code unit landed at `nativetext[i]`
    /// (a 2-unit surrogate fills both slots with one id). Filled per char at the
    /// `ishyph` seam, then CONSUMED (taken) by `src_resolve_native_glyphs` when
    /// the run is shaped, so a later re-measure maps to None rather than stale.
    src_native_offsets: Vec<SrcId>,
    /// Enclosing-construct stack arena (source-tracking inc2): each frame links
    /// to its parent, so a single `u32` per node (`node_stack`) snapshots the
    /// whole nesting. Grows by one cell per construct entered; transient.
    src_stack_cells: Vec<SrcStackCell>,
    /// Index (1-based) of the top enclosing-construct frame currently live;
    /// `0` = no enclosure. Pushed/popped at macro-body and math-group boundaries.
    cur_stack_head: u32,
    /// Balanced stack of the OPENING-token span of each live math GROUP (the `{` of a
    /// `scan_math` field / bare math group, or the `\left` of a `\left..\right`). Pushed
    /// at the group open, popped at the matching close, where the one general
    /// `src_construct_extent` rule maps the construct's synthesized marks to
    /// `[min(noad's command start, group open), consumed end]` -- the
    /// consumed-source-extent of the group. Replaces the per-construct delimiter/accent
    /// extenders. Transient (empty between fragments).
    src_grp_stack: Vec<SrcId>,
    /// The group-open span popped at the most recent group-9 close, handed from
    /// `src_scan_math_group_close` (the `9 =>` arm head) to `src_construct_extend_to_loc`
    /// (the field-fill point later in the same arm).
    src_grp_closing: SrcId,
    /// Paged-sparse shadow of `mem` parallel to `node_src`: `node_stack[addr]` is
    /// the [`Self::cur_stack_head`] that was live when the node at `addr` was
    /// allocated -- the head of its enclosing-construct chain.
    node_stack: PagedArray<u32>,
    pub LRproblems: integer,
    pub LRptr: halfword,
    pub OKtointerrupt: boolean,
    pub terminal_output: NativeFileHandle,
    pub activenodesize: smallnumber,
    pub activewidth: [scaled; 7],
    pub actuallooseness: integer,
    pub adjusttail: halfword,
    pub aftertoken: halfword,
    pub alignptr: halfword,
    pub alignstate: integer,
    pub areadelimiter: poolpointer,
    pub aritherror: boolean,
    pub avail: halfword,
    pub background: [scaled; 7],
    pub baseptr: integer,
    pub bchar: halfword,
    pub bcharlabel: *mut fontindex,
    pub bestbet: halfword,
    pub bestheightplusdepth: scaled,
    pub bestline: halfword,
    pub bestplace: [halfword; 4],
    pub bestplglue: [scaled; 4],
    pub bestplline: [halfword; 4],
    pub bestplshort: [scaled; 4],
    pub breadthmax: integer,
    pub breakwidth: [scaled; 7],
    pub buffer: *mut UnicodeScalar,
    pub bufsize: integer,
    pub c: quarterword,
    pub cancelboundary: boolean,
    pub charbase: *mut integer,
    pub condptr: halfword,
    pub cscount: integer,
    pub curactivewidth: [scaled; 7],
    pub curalign: halfword,
    pub curarea: strnumber,
    pub curboundary: integer,
    pub curbox: halfword,
    pub curc: integer,
    pub curchr: halfword,
    pub curcmd: eightbits,
    pub curcs: halfword,
    pub curdir: smallnumber,
    pub curext: strnumber,
    pub curf: internalfontnumber,
    pub curgroup: groupcode,
    pub curhead: halfword,
    pub curi: fourquarters,
    pub curif: smallnumber,
    pub curinput: instaterecord,
    pub curl: halfword,
    pub curlang: eightbits,
    pub curlevel: quarterword,
    pub curlist: liststaterecord,
    pub curloop: halfword,
    pub curmark: [halfword; 5],
    pub curmlist: halfword,
    pub curmu: scaled,
    pub curname: strnumber,
    pub curorder: glueord,
    pub curp: halfword,
    pub curprehead: halfword,
    pub curpretail: halfword,
    pub curptr: halfword,
    pub curq: halfword,
    pub curr: halfword,
    pub curs: integer,
    pub cursize: integer,
    pub curspan: halfword,
    pub curstyle: smallnumber,
    pub curtail: halfword,
    pub curtok: halfword,
    pub curval: integer,
    pub curval1: integer,
    pub curvallevel: eightbits,
    pub deadcycles: integer,
    pub defref: halfword,
    pub deletionsallowed: boolean,
    pub depthbase: *mut integer,
    pub depththreshold: integer,
    pub dig: [eightbits; 23],
    pub discptr: [halfword; 4],
    pub discwidth: scaled,
    pub doingleaders: boolean,
    pub doingspecial: boolean,
    pub dolastlinefit: boolean,
    pub downptr: halfword,
    pub dvibufsize: integer,
    pub dvigone: integer,
    pub dvilimit: integer,
    pub dvioffset: integer,
    pub dviptr: integer,
    pub dynused: integer,
    pub eTeXmode: eightbits,
    pub easyline: halfword,
    pub editline: integer,
    pub editnamelength: integer,
    pub editnamestart: poolpointer,
    pub eightbitp: i32,
    pub emptyfield: twohalves,
    pub eofseen: *mut boolean,
    pub epochseconds: integer,
    pub eqtbtop: halfword,
    pub errorcount: schar,
    pub errorline: integer,
    pub expanddepth: integer,
    pub expanddepthcount: integer,
    pub extdelimiter: poolpointer,
    pub extenbase: *mut integer,
    pub f: internalfontnumber,
    pub falsebchar: halfword,
    pub fewestdemerits: integer,
    pub filelineerrorstylep: i32,
    pub filenamequotechar: UTF16code,
    pub fileoffset: integer,
    pub fillwidth: [scaled; 3],
    pub finalpass: boolean,
    pub first: integer,
    pub firstcount: integer,
    pub firstindent: scaled,
    pub firstp: halfword,
    pub firstwidth: scaled,
    pub fmemptr: fontindex,
    pub fontarea: *mut strnumber,
    pub fontbc: *mut UTF16code,
    pub fontbchar: *mut ninebits,
    pub fontcheck: *mut fourquarters,
    pub fontdsize: *mut scaled,
    pub fontec: *mut UTF16code,
    pub fontfalsebchar: *mut ninebits,
    pub fontflags: *mut i8,
    pub fontglue: *mut halfword,
    pub fontinfo: *mut fmemoryword,
    pub fontinshortdisplay: integer,
    pub fontlayoutengine: *mut voidpointer,
    pub fontletterspace: *mut scaled,
    pub fontmapping: *mut voidpointer,
    pub fontmax: integer,
    pub fontmemsize: integer,
    pub fontname: *mut strnumber,
    pub fontparams: *mut fontindex,
    pub fontptr: internalfontnumber,
    pub fontsize: *mut scaled,
    pub fontused: *mut boolean,
    pub forceeof: boolean,
    pub formatident: strnumber,
    pub fullsourcefilenamestack: *mut strnumber,
    pub g: halfword,
    pub globalprevp: halfword,
    pub grpstack: *mut savepointer,
    pub ha: halfword,
    pub halfbuf: integer,
    pub halferrorline: integer,
    pub haltingonerrorp: boolean,
    pub haltonerrorp: i32,
    pub hash: PagedView<twohalves>,
    pub hashextra: halfword,
    pub hashhigh: halfword,
    pub hashused: halfword,
    pub hb: halfword,
    pub hc: [integer; 4099],
    pub heightbase: *mut integer,
    pub helpline: [strnumber; 6],
    pub helpptr: eightbits,
    pub hf: internalfontnumber,
    pub himemmin: halfword,
    pub history: eightbits,
    pub hliststack: [halfword; 513],
    pub hliststacklevel: i16,
    pub hn: smallnumber,
    pub hu: [integer; 4097],
    pub hyf: [eightbits; 4097],
    pub hyfbchar: halfword,
    pub hyfchar: integer,
    pub hyfdistance: [smallnumber; 35112],
    pub hyfnext: [trieopcode; 35112],
    pub hyfnum: [smallnumber; 35112],
    pub hyphcount: integer,
    pub hyphenchar: *mut integer,
    pub hyphenpassed: smallnumber,
    pub hyphindex: triepointer,
    pub hyphlink: *mut hyphpointer,
    pub hyphlist: *mut halfword,
    pub hyphnext: integer,
    pub hyphsize: integer,
    pub hyphstart: triepointer,
    pub hyphword: *mut strnumber,
    pub iflimit: eightbits,
    pub ifline: integer,
    pub ifstack: *mut halfword,
    pub initcurlang: eightbits,
    pub initlft: boolean,
    pub initlhyf: integer,
    pub initlig: boolean,
    pub initlist: halfword,
    pub initpoolptr: poolpointer,
    pub initrhyf: integer,
    pub initstrptr: strnumber,
    pub iniversion: boolean,
    pub inopen: integer,
    pub inputfile: *mut unicodefile,
    pub inputptr: integer,
    pub inputstack: *mut instaterecord,
    pub insdisc: boolean,
    pub insertpenalties: integer,
    pub insertsrcspecialauto: boolean,
    pub insertsrcspecialeverymath: boolean,
    pub insertsrcspecialeverypar: boolean,
    pub insertsrcspecialeveryvbox: boolean,
    pub interaction: eightbits,
    pub interactionoption: eightbits,
    pub interrupt: integer,
    pub ishyph: boolean,
    pub isincsname: boolean,
    pub italicbase: *mut integer,
    pub jobname: strnumber,
    pub jrandom: eightbits,
    pub justbox: halfword,
    pub kernbase: *mut integer,
    pub resource_search_state: ResourceSearchState,
    pub l: eightbits,
    pub last: integer,
    pub lastbadness: integer,
    pub lastbop: integer,
    pub lastglue: halfword,
    pub lastkern: scaled,
    pub lastleftmostchar: halfword,
    pub lastlinefill: halfword,
    pub lastnodetype: integer,
    pub lastpenalty: integer,
    pub lastrightmostchar: halfword,
    pub lastspecialline: halfword,
    pub lfthit: boolean,
    pub lhyf: integer,
    pub ligaturepresent: boolean,
    pub ligkernbase: *mut integer,
    pub ligstack: halfword,
    pub line: integer,
    pub linediff: integer,
    pub linestack: *mut integer,
    pub loadedfontdesignsize: scaled,
    pub loadedfontflags: i8,
    pub loadedfontletterspace: scaled,
    pub loadedfontmapping: voidpointer,
    pub logfile: alphafile,
    pub logopened: boolean,
    pub lomemmax: halfword,
    pub longhelpseen: boolean,
    pub longstate: eightbits,
    pub magicoffset: integer,
    pub magset: integer,
    pub mainf: internalfontnumber,
    pub mainh: halfword,
    pub maini: fourquarters,
    pub mainj: fourquarters,
    pub maink: fontindex,
    pub mainp: halfword,
    pub mainpp: halfword,
    pub mainppp: halfword,
    pub mains: integer,
    pub mappedtext: *mut UTF16code,
    pub maxbufstack: integer,
    pub maxh: scaled,
    pub maxhyphchar: integer,
    pub maxinopen: integer,
    pub maxinstack: integer,
    pub maxneststack: integer,
    pub maxopused: trieopcode,
    pub maxparamstack: integer,
    pub maxprintline: integer,
    pub maxpush: integer,
    pub maxreghelpline: strnumber,
    pub maxregnum: halfword,
    pub maxsavestack: integer,
    pub maxstrings: integer,
    pub maxv: scaled,
    pub membot: integer,
    pub memend: halfword,
    pub memmax: integer,
    pub memmin: integer,
    pub memtop: integer,
    pub microseconds: integer,
    pub minimaldemerits: [integer; 4],
    pub minimumdemerits: integer,
    pub mlistpenalties: boolean,
    pub mltexenabledp: boolean,
    pub mltexp: boolean,
    pub mubytecswrite: [halfword; 128],
    pub mubytekeep: integer,
    pub mubyteprefix: integer,
    pub mubyteread: [halfword; 256],
    pub mubyteskip: integer,
    pub mubytestart: boolean,
    pub mubytestoken: halfword,
    pub mubytetoken: halfword,
    pub nameinprogress: boolean,
    pub namelength: integer,
    pub nameoffile: *mut UTF8code,
    pub nativefonttypeflag: integer,
    pub nativelen: integer,
    pub nativetext: *mut UTF16code,
    pub nativetextsize: integer,
    pub nest: *mut liststaterecord,
    pub nestptr: integer,
    pub nestsize: integer,
    pub nonewcontrolsequence: boolean,
    pub noshrinkerroryet: boolean,
    pub nullcharacter: fourquarters,
    pub nulldelimiter: fourquarters,
    pub oldselectorignorederr: eightbits,
    pub oldsetting: eightbits,
    pub openparens: integer,
    pub opstart: [integer; 256],
    pub outputactive: boolean,
    pub outputcanend: boolean,
    pub packbeginline: integer,
    pub pagecontents: eightbits,
    pub pagemaxdepth: scaled,
    pub pagesofar: [scaled; 8],
    pub pagetail: halfword,
    pub parambase: *mut integer,
    pub paramptr: integer,
    pub paramsize: integer,
    pub paramstack: *mut halfword,
    pub parloc: halfword,
    pub partoken: halfword,
    pub passive: halfword,
    pub passnumber: halfword,
    pub pdflastxpos: integer,
    pub pdflastypos: integer,
    pub poolptr: poolpointer,
    pub poolsize: integer,
    pub preadjusttail: halfword,
    pub prevclass: integer,
    pub prim: [twohalves; 2101],
    pub primused: halfword,
    pub printednode: halfword,
    pub pseudofiles: halfword,
    pub pstack: [halfword; 9],
    pub quotedfilename: boolean,
    pub radix: smallnumber,
    pub randoms: [integer; 55],
    pub randomseed: scaled,
    pub readfile: [unicodefile; 16],
    pub readopen: [eightbits; 17],
    pub readyalready: integer,
    pub restrictedshell: i32,
    pub rhyf: integer,
    pub rightptr: halfword,
    pub rover: halfword,
    pub rthit: boolean,
    pub sachain: halfword,
    pub salevel: quarterword,
    pub sanull: memoryword,
    pub saroot: [halfword; 8],
    pub savearitherror: boolean,
    pub savenativelen: integer,
    pub saveptr: integer,
    pub savesize: integer,
    pub savestack: *mut memoryword,
    pub scannerstatus: eightbits,
    pub secondindent: scaled,
    pub secondpass: boolean,
    pub secondwidth: scaled,
    pub selector: eightbits,
    pub setboxallowed: boolean,
    pub shellenabledp: i32,
    pub shownmode: i16,
    pub skewchar: *mut integer,
    pub skipline: integer,
    pub sourcefilenamestack: *mut strnumber,
    pub spaceclass: integer,
    pub speclog: [integer; 29],
    pub stacksize: integer,
    pub stopatspace: boolean,
    pub stringvacancies: integer,
    pub strpool: *mut packedUTF16code,
    pub strptr: strnumber,
    pub strstart: *mut poolpointer,
    pub tally: integer,
    pub tempptr: halfword,
    pub termin: unicodefile,
    pub termoffset: integer,
    pub texinputtype: i32,
    pub texremainder: scaled,
    pub tfmfile: bytefile,
    pub tfmtemp: i32,
    pub threshold: integer,
    pub totalpages: integer,
    pub totalshrink: [scaled; 4],
    pub totalstretch: [scaled; 4],
    pub trickbuf: [UnicodeScalar; 256],
    pub trickcount: integer,
    pub triec: *mut packedUTF16code,
    pub triehash: *mut triepointer,
    pub triel: *mut triepointer,
    pub triemax: triepointer,
    pub triemin: [triepointer; 65536],
    pub trienotready: boolean,
    pub trieo: *mut trieopcode,
    pub trieoplang: [eightbits; 35112],
    pub trieopptr: integer,
    pub trieopval: [trieopcode; 35112],
    pub trieptr: triepointer,
    pub trier: *mut triepointer,
    pub triesize: integer,
    pub trietaken: *mut boolean,
    pub trietrc: *mut quarterword,
    pub trietrl: *mut triepointer,
    pub trietro: *mut triepointer,
    pub trieused: [trieopcode; 256],
    pub twotothe: [integer; 31],
    pub useerrhelp: boolean,
    pub varused: integer,
    pub warningindex: halfword,
    pub widthbase: *mut integer,
    pub writefile: [alphafile; 16],
    pub writeloc: halfword,
    pub writeopen: [boolean; 18],
    pub xchr: [ASCIIcode; 256],
    pub xtxligaturepresent: boolean,
    pub zeqtb: PagedView<memoryword>,
    pub zmem: *mut memoryword,
    pub zzzaa: [quarterword; 1114734],
    pub zzzab: [integer; 70223],
}

/// Magic header for a serialized portable format image (see
/// [`PortableTexState::to_portable_bytes`]).
const PORTABLE_FORMAT_MAGIC: [u8; 8] = *b"MTXfmt\x04\x00";

/// The complete set of heap-owning fields of [`PortableTexState`] — exactly the
/// fields that [`PortableTexState::clone_boxed`] deep-copies (everything else is
/// POD copied bitwise via the raw struct image). Both the serializer and the
/// deserializer walk this single list so they can never drift out of sync.
macro_rules! portable_owning_vecs {
    ($cb:ident) => {
        $cb!(buffer_storage, UnicodeScalar);
        $cb!(nest_storage, liststaterecord);
        $cb!(savestack_storage, memoryword);
        $cb!(inputstack_storage, instaterecord);
        $cb!(inputfile_storage, unicodefile);
        $cb!(eofseen_storage, boolean);
        $cb!(linestack_storage, integer);
        $cb!(grpstack_storage, savepointer);
        $cb!(ifstack_storage, halfword);
        $cb!(sourcefilenamestack_storage, strnumber);
        $cb!(fullsourcefilenamestack_storage, strnumber);
        $cb!(paramstack_storage, halfword);
        $cb!(hyphword_storage, strnumber);
        $cb!(hyphlist_storage, halfword);
        $cb!(hyphlink_storage, hyphpointer);
        $cb!(strstart_storage, poolpointer);
        $cb!(strpool_storage, packedUTF16code);
        $cb!(fontinfo_storage, fmemoryword);
        $cb!(bcharlabel_storage, fontindex);
        $cb!(charbase_storage, integer);
        $cb!(widthbase_storage, integer);
        $cb!(heightbase_storage, integer);
        $cb!(depthbase_storage, integer);
        $cb!(italicbase_storage, integer);
        $cb!(ligkernbase_storage, integer);
        $cb!(kernbase_storage, integer);
        $cb!(extenbase_storage, integer);
        $cb!(parambase_storage, integer);
        $cb!(fontarea_storage, strnumber);
        $cb!(fontname_storage, strnumber);
        $cb!(fontbc_storage, UTF16code);
        $cb!(fontec_storage, UTF16code);
        $cb!(fontbchar_storage, ninebits);
        $cb!(fontfalsebchar_storage, ninebits);
        $cb!(fontcheck_storage, fourquarters);
        $cb!(fontdsize_storage, scaled);
        $cb!(fontsize_storage, scaled);
        $cb!(fontflags_storage, i8);
        $cb!(fontglue_storage, halfword);
        $cb!(fontlayoutengine_storage, voidpointer);
        $cb!(fontletterspace_storage, scaled);
        $cb!(fontmapping_storage, voidpointer);
        $cb!(fontparams_storage, fontindex);
        $cb!(fontused_storage, boolean);
        $cb!(nativetext_storage, UTF16code);
        $cb!(hyphenchar_storage, integer);
        $cb!(skewchar_storage, integer);
        $cb!(triec_storage, packedUTF16code);
        $cb!(triehash_storage, triepointer);
        $cb!(triel_storage, triepointer);
        $cb!(trieo_storage, trieopcode);
        $cb!(trier_storage, triepointer);
        $cb!(trietaken_storage, boolean);
        $cb!(trietrc_storage, quarterword);
        $cb!(trietrl_storage, triepointer);
        $cb!(trietro_storage, triepointer);
    };
}

/// Serialize a POD `Vec` as its full length plus only the *used* index ranges
/// (the rest is reconstructed as zeros). This is how a `.fmt` dump stays small:
/// most engine arrays are allocated to a generous capacity but only sparsely
/// populated. `ranges` are `(start, len)` element spans, in order.
fn portable_write_vec_ranges<T: Copy>(out: &mut Vec<u8>, v: &[T], ranges: &[(usize, usize)]) {
    let elt = core::mem::size_of::<T>();
    out.extend_from_slice(&(v.len() as u64).to_le_bytes());
    out.extend_from_slice(&(ranges.len() as u32).to_le_bytes());
    for &(start, len) in ranges {
        out.extend_from_slice(&(start as u64).to_le_bytes());
        out.extend_from_slice(&(len as u64).to_le_bytes());
        // SAFETY: callers pass ranges within `v`; `T: Copy` POD.
        let bytes =
            unsafe { core::slice::from_raw_parts(v.as_ptr().add(start) as *const u8, len * elt) };
        out.extend_from_slice(bytes);
    }
}

/// Inverse of [`portable_write_vec_ranges`]: allocate a zeroed `Vec<T>` of the
/// stored full length and fill in the saved ranges. Returns `None` on
/// truncation / overflow / out-of-bounds range.
fn portable_read_vec_ranges<T: Copy>(bytes: &[u8], cursor: &mut usize) -> Option<Vec<T>> {
    let elt = core::mem::size_of::<T>();
    let full = u64::from_le_bytes(bytes.get(*cursor..*cursor + 8)?.try_into().ok()?) as usize;
    *cursor += 8;
    let nranges = u32::from_le_bytes(bytes.get(*cursor..*cursor + 4)?.try_into().ok()?) as usize;
    *cursor += 4;
    let total = full.checked_mul(elt)?;
    let mut v = Vec::<T>::with_capacity(full);
    // SAFETY: zero-initialize `full` elements (zero bytes are a valid value for
    // every POD type dumped here), then copy each saved range into place.
    unsafe {
        core::ptr::write_bytes(v.as_mut_ptr() as *mut u8, 0, total);
        for _ in 0..nranges {
            let start = u64::from_le_bytes(bytes.get(*cursor..*cursor + 8)?.try_into().ok()?) as usize;
            *cursor += 8;
            let len = u64::from_le_bytes(bytes.get(*cursor..*cursor + 8)?.try_into().ok()?) as usize;
            *cursor += 8;
            if start.checked_add(len)? > full {
                return None;
            }
            let nbytes = len.checked_mul(elt)?;
            let src = bytes.get(*cursor..*cursor + nbytes)?;
            *cursor += nbytes;
            core::ptr::copy_nonoverlapping(
                src.as_ptr(),
                (v.as_mut_ptr() as *mut u8).add(start * elt),
                nbytes,
            );
        }
        v.set_len(full);
    }
    Some(v)
}

/// Number of leading elements of `v` up to and including the last non-zero
/// element (0 if every element is all-zero bytes). Used to drop the zero tail of
/// sparsely-populated engine arrays when dumping a format image.
fn portable_used_prefix_len<T>(v: &[T]) -> usize {
    let bytes =
        unsafe { core::slice::from_raw_parts(v.as_ptr() as *const u8, core::mem::size_of_val(v)) };
    match bytes.iter().rposition(|&b| b != 0) {
        Some(last) => last / core::mem::size_of::<T>() + 1,
        None => 0,
    }
}

/// Serialize a [`PagedArray`]: its geometry, the dense low region (zero tail
/// dropped), then only the faulted pages (page index + raw bytes). Absent pages
/// are regenerated from `default_fn` on load, so they cost nothing on disk.
fn portable_write_paged<T: Copy + Default>(out: &mut Vec<u8>, arr: &PagedArray<T>) {
    let elt = core::mem::size_of::<T>();
    out.extend_from_slice(&(arr.base as u64).to_le_bytes());
    out.extend_from_slice(&(arr.lo as u64).to_le_bytes());
    out.extend_from_slice(&(arr.end as u64).to_le_bytes());
    let used = portable_used_prefix_len(arr.low.as_slice());
    let ranges: &[(usize, usize)] = if used == 0 { &[] } else { &[(0, used)] };
    portable_write_vec_ranges::<T>(out, arr.low.as_slice(), ranges);
    let present: Vec<usize> = arr
        .pages
        .iter()
        .enumerate()
        .filter_map(|(i, p)| p.as_ref().map(|_| i))
        .collect();
    out.extend_from_slice(&(arr.pages.len() as u64).to_le_bytes());
    out.extend_from_slice(&(present.len() as u32).to_le_bytes());
    for pg in present {
        out.extend_from_slice(&(pg as u64).to_le_bytes());
        let page = arr.pages[pg].as_ref().unwrap();
        // SAFETY: `page` has exactly PAGE_LEN `T: Copy` POD elements.
        let pbytes =
            unsafe { core::slice::from_raw_parts(page.as_ptr() as *const u8, PAGE_LEN * elt) };
        out.extend_from_slice(pbytes);
    }
}

/// Inverse of [`portable_write_paged`]. `default_fn` must match the array being
/// reloaded (eqtb vs hash) so absent pages regenerate identically.
fn portable_read_paged<T: Copy + Default>(
    bytes: &[u8],
    cursor: &mut usize,
    default_fn: fn(usize) -> T,
    sig_range: fn(usize) -> (usize, usize),
) -> Option<PagedArray<T>> {
    let elt = core::mem::size_of::<T>();
    let read_u64 = |cursor: &mut usize| -> Option<usize> {
        let v = u64::from_le_bytes(bytes.get(*cursor..*cursor + 8)?.try_into().ok()?) as usize;
        *cursor += 8;
        Some(v)
    };
    let base = read_u64(cursor)?;
    let lo = read_u64(cursor)?;
    let end = read_u64(cursor)?;
    let low: Vec<T> = portable_read_vec_ranges(bytes, cursor)?;
    let npages = read_u64(cursor)?;
    let npresent = u32::from_le_bytes(bytes.get(*cursor..*cursor + 4)?.try_into().ok()?) as usize;
    *cursor += 4;
    let mut pages: Vec<Option<Box<[T]>>> = (0..npages).map(|_| None).collect();
    for _ in 0..npresent {
        let pg = read_u64(cursor)?;
        if pg >= npages {
            return None;
        }
        let nbytes = PAGE_LEN.checked_mul(elt)?;
        let src = bytes.get(*cursor..*cursor + nbytes)?;
        *cursor += nbytes;
        let mut page: Vec<T> = Vec::with_capacity(PAGE_LEN);
        // SAFETY: copy PAGE_LEN POD elements; zero bytes are valid for `T`.
        unsafe {
            core::ptr::copy_nonoverlapping(src.as_ptr(), page.as_mut_ptr() as *mut u8, nbytes);
            page.set_len(PAGE_LEN);
        }
        pages[pg] = Some(page.into_boxed_slice());
    }
    Some(PagedArray {
        base,
        lo,
        end,
        low,
        pages,
        default_fn,
        sig_range,
    })
}

impl PortableTexState {
    fn new_boxed_default() -> Box<Self> {
        let mut state = Box::<Self>::new_uninit();
        let state_ptr = state.as_mut_ptr();
        unsafe {
            core::ptr::write_bytes(state_ptr, 0, 1);
            core::ptr::addr_of_mut!((*state_ptr).mem).write(Vec::new());
            core::ptr::addr_of_mut!((*state_ptr).buffer_storage).write(Vec::new());
            core::ptr::addr_of_mut!((*state_ptr).nest_storage).write(Vec::new());
            core::ptr::addr_of_mut!((*state_ptr).savestack_storage).write(Vec::new());
            core::ptr::addr_of_mut!((*state_ptr).inputstack_storage).write(Vec::new());
            core::ptr::addr_of_mut!((*state_ptr).inputfile_storage).write(Vec::new());
            core::ptr::addr_of_mut!((*state_ptr).eofseen_storage).write(Vec::new());
            core::ptr::addr_of_mut!((*state_ptr).linestack_storage).write(Vec::new());
            core::ptr::addr_of_mut!((*state_ptr).grpstack_storage).write(Vec::new());
            core::ptr::addr_of_mut!((*state_ptr).ifstack_storage).write(Vec::new());
            core::ptr::addr_of_mut!((*state_ptr).sourcefilenamestack_storage).write(Vec::new());
            core::ptr::addr_of_mut!((*state_ptr).fullsourcefilenamestack_storage).write(Vec::new());
            core::ptr::addr_of_mut!((*state_ptr).paramstack_storage).write(Vec::new());
            core::ptr::addr_of_mut!((*state_ptr).hyphword_storage).write(Vec::new());
            core::ptr::addr_of_mut!((*state_ptr).hyphlist_storage).write(Vec::new());
            core::ptr::addr_of_mut!((*state_ptr).hyphlink_storage).write(Vec::new());
            core::ptr::addr_of_mut!((*state_ptr).hash_paged)
                .write(PagedArray::new(0, 0, hash_codepoint_default, hash_sig_range));
            core::ptr::addr_of_mut!((*state_ptr).eqtb_paged)
                .write(PagedArray::new(0, 0, eqtb_codepoint_default, eqtb_sig_range));
            core::ptr::addr_of_mut!((*state_ptr).strstart_storage).write(Vec::new());
            core::ptr::addr_of_mut!((*state_ptr).strpool_storage).write(Vec::new());
            core::ptr::addr_of_mut!((*state_ptr).fontinfo_storage).write(Vec::new());
            core::ptr::addr_of_mut!((*state_ptr).bcharlabel_storage).write(Vec::new());
            core::ptr::addr_of_mut!((*state_ptr).charbase_storage).write(Vec::new());
            core::ptr::addr_of_mut!((*state_ptr).widthbase_storage).write(Vec::new());
            core::ptr::addr_of_mut!((*state_ptr).heightbase_storage).write(Vec::new());
            core::ptr::addr_of_mut!((*state_ptr).depthbase_storage).write(Vec::new());
            core::ptr::addr_of_mut!((*state_ptr).italicbase_storage).write(Vec::new());
            core::ptr::addr_of_mut!((*state_ptr).ligkernbase_storage).write(Vec::new());
            core::ptr::addr_of_mut!((*state_ptr).kernbase_storage).write(Vec::new());
            core::ptr::addr_of_mut!((*state_ptr).extenbase_storage).write(Vec::new());
            core::ptr::addr_of_mut!((*state_ptr).parambase_storage).write(Vec::new());
            core::ptr::addr_of_mut!((*state_ptr).fontarea_storage).write(Vec::new());
            core::ptr::addr_of_mut!((*state_ptr).fontname_storage).write(Vec::new());
            core::ptr::addr_of_mut!((*state_ptr).fontbc_storage).write(Vec::new());
            core::ptr::addr_of_mut!((*state_ptr).fontec_storage).write(Vec::new());
            core::ptr::addr_of_mut!((*state_ptr).fontbchar_storage).write(Vec::new());
            core::ptr::addr_of_mut!((*state_ptr).fontfalsebchar_storage).write(Vec::new());
            core::ptr::addr_of_mut!((*state_ptr).fontcheck_storage).write(Vec::new());
            core::ptr::addr_of_mut!((*state_ptr).fontdsize_storage).write(Vec::new());
            core::ptr::addr_of_mut!((*state_ptr).fontsize_storage).write(Vec::new());
            core::ptr::addr_of_mut!((*state_ptr).fontflags_storage).write(Vec::new());
            core::ptr::addr_of_mut!((*state_ptr).fontglue_storage).write(Vec::new());
            core::ptr::addr_of_mut!((*state_ptr).fontlayoutengine_storage).write(Vec::new());
            core::ptr::addr_of_mut!((*state_ptr).fontletterspace_storage).write(Vec::new());
            core::ptr::addr_of_mut!((*state_ptr).fontmapping_storage).write(Vec::new());
            core::ptr::addr_of_mut!((*state_ptr).fontparams_storage).write(Vec::new());
            core::ptr::addr_of_mut!((*state_ptr).fontused_storage).write(Vec::new());
            core::ptr::addr_of_mut!((*state_ptr).nativetext_storage).write(Vec::new());
            core::ptr::addr_of_mut!((*state_ptr).hyphenchar_storage).write(Vec::new());
            core::ptr::addr_of_mut!((*state_ptr).skewchar_storage).write(Vec::new());
            core::ptr::addr_of_mut!((*state_ptr).triec_storage).write(Vec::new());
            core::ptr::addr_of_mut!((*state_ptr).triehash_storage).write(Vec::new());
            core::ptr::addr_of_mut!((*state_ptr).triel_storage).write(Vec::new());
            core::ptr::addr_of_mut!((*state_ptr).trieo_storage).write(Vec::new());
            core::ptr::addr_of_mut!((*state_ptr).trier_storage).write(Vec::new());
            core::ptr::addr_of_mut!((*state_ptr).trietaken_storage).write(Vec::new());
            core::ptr::addr_of_mut!((*state_ptr).trietrc_storage).write(Vec::new());
            core::ptr::addr_of_mut!((*state_ptr).trietrl_storage).write(Vec::new());
            core::ptr::addr_of_mut!((*state_ptr).trietro_storage).write(Vec::new());
            core::ptr::addr_of_mut!((*state_ptr).src_spans).write(Vec::new());
            core::ptr::addr_of_mut!((*state_ptr).src_dedup)
                .write(std::collections::HashMap::new());
            core::ptr::addr_of_mut!((*state_ptr).node_src)
                .write(PagedArray::new(0, 0, node_src_default, node_src_sig));
            core::ptr::addr_of_mut!((*state_ptr).src_native_offsets).write(Vec::new());
            core::ptr::addr_of_mut!((*state_ptr).src_stack_cells).write(Vec::new());
            core::ptr::addr_of_mut!((*state_ptr).cur_stack_head).write(0);
            core::ptr::addr_of_mut!((*state_ptr).node_stack)
                .write(PagedArray::new(0, 0, node_stack_default, node_stack_sig));
            state.assume_init()
        }
    }

    fn clone_boxed(&self) -> Box<Self> {
        let mem = self.mem.clone();
        let buffer_storage = self.buffer_storage.clone();
        let nest_storage = self.nest_storage.clone();
        let savestack_storage = self.savestack_storage.clone();
        let inputstack_storage = self.inputstack_storage.clone();
        let inputfile_storage = self.inputfile_storage.clone();
        let eofseen_storage = self.eofseen_storage.clone();
        let linestack_storage = self.linestack_storage.clone();
        let grpstack_storage = self.grpstack_storage.clone();
        let ifstack_storage = self.ifstack_storage.clone();
        let sourcefilenamestack_storage = self.sourcefilenamestack_storage.clone();
        let fullsourcefilenamestack_storage = self.fullsourcefilenamestack_storage.clone();
        let paramstack_storage = self.paramstack_storage.clone();
        let hyphword_storage = self.hyphword_storage.clone();
        let hyphlist_storage = self.hyphlist_storage.clone();
        let hyphlink_storage = self.hyphlink_storage.clone();
        let hash_paged = self.hash_paged.clone();
        let eqtb_paged = self.eqtb_paged.clone();
        let strstart_storage = self.strstart_storage.clone();
        let strpool_storage = self.strpool_storage.clone();
        let fontinfo_storage = self.fontinfo_storage.clone();
        let bcharlabel_storage = self.bcharlabel_storage.clone();
        let charbase_storage = self.charbase_storage.clone();
        let widthbase_storage = self.widthbase_storage.clone();
        let heightbase_storage = self.heightbase_storage.clone();
        let depthbase_storage = self.depthbase_storage.clone();
        let italicbase_storage = self.italicbase_storage.clone();
        let ligkernbase_storage = self.ligkernbase_storage.clone();
        let kernbase_storage = self.kernbase_storage.clone();
        let extenbase_storage = self.extenbase_storage.clone();
        let parambase_storage = self.parambase_storage.clone();
        let fontarea_storage = self.fontarea_storage.clone();
        let fontname_storage = self.fontname_storage.clone();
        let fontbc_storage = self.fontbc_storage.clone();
        let fontec_storage = self.fontec_storage.clone();
        let fontbchar_storage = self.fontbchar_storage.clone();
        let fontfalsebchar_storage = self.fontfalsebchar_storage.clone();
        let fontcheck_storage = self.fontcheck_storage.clone();
        let fontdsize_storage = self.fontdsize_storage.clone();
        let fontsize_storage = self.fontsize_storage.clone();
        let fontflags_storage = self.fontflags_storage.clone();
        let fontglue_storage = self.fontglue_storage.clone();
        let fontlayoutengine_storage = self.fontlayoutengine_storage.clone();
        let fontletterspace_storage = self.fontletterspace_storage.clone();
        let fontmapping_storage = self.fontmapping_storage.clone();
        let fontparams_storage = self.fontparams_storage.clone();
        let fontused_storage = self.fontused_storage.clone();
        let nativetext_storage = self.nativetext_storage.clone();
        let hyphenchar_storage = self.hyphenchar_storage.clone();
        let skewchar_storage = self.skewchar_storage.clone();
        let triec_storage = self.triec_storage.clone();
        let triehash_storage = self.triehash_storage.clone();
        let triel_storage = self.triel_storage.clone();
        let trieo_storage = self.trieo_storage.clone();
        let trier_storage = self.trier_storage.clone();
        let trietaken_storage = self.trietaken_storage.clone();
        let trietrc_storage = self.trietrc_storage.clone();
        let trietrl_storage = self.trietrl_storage.clone();
        let trietro_storage = self.trietro_storage.clone();
        let src_spans = self.src_spans.clone();
        let src_dedup = self.src_dedup.clone();
        let node_src = self.node_src.clone();
        let src_native_offsets = self.src_native_offsets.clone();
        let src_stack_cells = self.src_stack_cells.clone();
        let node_stack = self.node_stack.clone();
        let mut state = Box::<Self>::new_uninit();
        let state_ptr = state.as_mut_ptr();
        unsafe {
            core::ptr::copy_nonoverlapping(self as *const Self, state_ptr, 1);
            core::ptr::addr_of_mut!((*state_ptr).mem).write(mem);
            core::ptr::addr_of_mut!((*state_ptr).buffer_storage).write(buffer_storage);
            core::ptr::addr_of_mut!((*state_ptr).nest_storage).write(nest_storage);
            core::ptr::addr_of_mut!((*state_ptr).savestack_storage).write(savestack_storage);
            core::ptr::addr_of_mut!((*state_ptr).inputstack_storage).write(inputstack_storage);
            core::ptr::addr_of_mut!((*state_ptr).inputfile_storage).write(inputfile_storage);
            core::ptr::addr_of_mut!((*state_ptr).eofseen_storage).write(eofseen_storage);
            core::ptr::addr_of_mut!((*state_ptr).linestack_storage).write(linestack_storage);
            core::ptr::addr_of_mut!((*state_ptr).grpstack_storage).write(grpstack_storage);
            core::ptr::addr_of_mut!((*state_ptr).ifstack_storage).write(ifstack_storage);
            core::ptr::addr_of_mut!((*state_ptr).sourcefilenamestack_storage)
                .write(sourcefilenamestack_storage);
            core::ptr::addr_of_mut!((*state_ptr).fullsourcefilenamestack_storage)
                .write(fullsourcefilenamestack_storage);
            core::ptr::addr_of_mut!((*state_ptr).paramstack_storage).write(paramstack_storage);
            core::ptr::addr_of_mut!((*state_ptr).hyphword_storage).write(hyphword_storage);
            core::ptr::addr_of_mut!((*state_ptr).hyphlist_storage).write(hyphlist_storage);
            core::ptr::addr_of_mut!((*state_ptr).hyphlink_storage).write(hyphlink_storage);
            core::ptr::addr_of_mut!((*state_ptr).hash_paged).write(hash_paged);
            core::ptr::addr_of_mut!((*state_ptr).eqtb_paged).write(eqtb_paged);
            core::ptr::addr_of_mut!((*state_ptr).strstart_storage).write(strstart_storage);
            core::ptr::addr_of_mut!((*state_ptr).strpool_storage).write(strpool_storage);
            core::ptr::addr_of_mut!((*state_ptr).fontinfo_storage).write(fontinfo_storage);
            core::ptr::addr_of_mut!((*state_ptr).bcharlabel_storage).write(bcharlabel_storage);
            core::ptr::addr_of_mut!((*state_ptr).charbase_storage).write(charbase_storage);
            core::ptr::addr_of_mut!((*state_ptr).widthbase_storage).write(widthbase_storage);
            core::ptr::addr_of_mut!((*state_ptr).heightbase_storage).write(heightbase_storage);
            core::ptr::addr_of_mut!((*state_ptr).depthbase_storage).write(depthbase_storage);
            core::ptr::addr_of_mut!((*state_ptr).italicbase_storage).write(italicbase_storage);
            core::ptr::addr_of_mut!((*state_ptr).ligkernbase_storage).write(ligkernbase_storage);
            core::ptr::addr_of_mut!((*state_ptr).kernbase_storage).write(kernbase_storage);
            core::ptr::addr_of_mut!((*state_ptr).extenbase_storage).write(extenbase_storage);
            core::ptr::addr_of_mut!((*state_ptr).parambase_storage).write(parambase_storage);
            core::ptr::addr_of_mut!((*state_ptr).fontarea_storage).write(fontarea_storage);
            core::ptr::addr_of_mut!((*state_ptr).fontname_storage).write(fontname_storage);
            core::ptr::addr_of_mut!((*state_ptr).fontbc_storage).write(fontbc_storage);
            core::ptr::addr_of_mut!((*state_ptr).fontec_storage).write(fontec_storage);
            core::ptr::addr_of_mut!((*state_ptr).fontbchar_storage).write(fontbchar_storage);
            core::ptr::addr_of_mut!((*state_ptr).fontfalsebchar_storage).write(fontfalsebchar_storage);
            core::ptr::addr_of_mut!((*state_ptr).fontcheck_storage).write(fontcheck_storage);
            core::ptr::addr_of_mut!((*state_ptr).fontdsize_storage).write(fontdsize_storage);
            core::ptr::addr_of_mut!((*state_ptr).fontsize_storage).write(fontsize_storage);
            core::ptr::addr_of_mut!((*state_ptr).fontflags_storage).write(fontflags_storage);
            core::ptr::addr_of_mut!((*state_ptr).fontglue_storage).write(fontglue_storage);
            core::ptr::addr_of_mut!((*state_ptr).fontlayoutengine_storage).write(fontlayoutengine_storage);
            core::ptr::addr_of_mut!((*state_ptr).fontletterspace_storage).write(fontletterspace_storage);
            core::ptr::addr_of_mut!((*state_ptr).fontmapping_storage).write(fontmapping_storage);
            core::ptr::addr_of_mut!((*state_ptr).fontparams_storage).write(fontparams_storage);
            core::ptr::addr_of_mut!((*state_ptr).fontused_storage).write(fontused_storage);
            core::ptr::addr_of_mut!((*state_ptr).nativetext_storage).write(nativetext_storage);
            core::ptr::addr_of_mut!((*state_ptr).hyphenchar_storage).write(hyphenchar_storage);
            core::ptr::addr_of_mut!((*state_ptr).skewchar_storage).write(skewchar_storage);
            core::ptr::addr_of_mut!((*state_ptr).triec_storage).write(triec_storage);
            core::ptr::addr_of_mut!((*state_ptr).triehash_storage).write(triehash_storage);
            core::ptr::addr_of_mut!((*state_ptr).triel_storage).write(triel_storage);
            core::ptr::addr_of_mut!((*state_ptr).trieo_storage).write(trieo_storage);
            core::ptr::addr_of_mut!((*state_ptr).trier_storage).write(trier_storage);
            core::ptr::addr_of_mut!((*state_ptr).trietaken_storage).write(trietaken_storage);
            core::ptr::addr_of_mut!((*state_ptr).trietrc_storage).write(trietrc_storage);
            core::ptr::addr_of_mut!((*state_ptr).trietrl_storage).write(trietrl_storage);
            core::ptr::addr_of_mut!((*state_ptr).trietro_storage).write(trietro_storage);
            core::ptr::addr_of_mut!((*state_ptr).src_spans).write(src_spans);
            core::ptr::addr_of_mut!((*state_ptr).src_dedup).write(src_dedup);
            core::ptr::addr_of_mut!((*state_ptr).node_src).write(node_src);
            core::ptr::addr_of_mut!((*state_ptr).src_native_offsets).write(src_native_offsets);
            core::ptr::addr_of_mut!((*state_ptr).src_stack_cells).write(src_stack_cells);
            core::ptr::addr_of_mut!((*state_ptr).node_stack).write(node_stack);
            let mut state = state.assume_init();
            state.refresh_runtime_pointers();
            state
        }
    }

    fn refresh_runtime_pointers(&mut self) {
        self.zmem = pointer_or_null(&mut self.mem).wrapping_offset(-(self.memmin as isize));
        self.buffer = pointer_or_null(&mut self.buffer_storage);
        self.nest = pointer_or_null(&mut self.nest_storage);
        self.savestack = pointer_or_null(&mut self.savestack_storage);
        self.inputstack = pointer_or_null(&mut self.inputstack_storage);
        self.inputfile = pointer_or_null(&mut self.inputfile_storage);
        self.eofseen = pointer_or_null(&mut self.eofseen_storage);
        self.linestack = pointer_or_null(&mut self.linestack_storage);
        self.grpstack = pointer_or_null(&mut self.grpstack_storage);
        self.ifstack = pointer_or_null(&mut self.ifstack_storage);
        self.sourcefilenamestack = pointer_or_null(&mut self.sourcefilenamestack_storage);
        self.fullsourcefilenamestack =
            pointer_or_null(&mut self.fullsourcefilenamestack_storage);
        self.paramstack = pointer_or_null(&mut self.paramstack_storage);
        self.hyphword = pointer_or_null(&mut self.hyphword_storage);
        self.hyphlist = pointer_or_null(&mut self.hyphlist_storage);
        self.hyphlink = pointer_or_null(&mut self.hyphlink_storage);
        self.hash = PagedView::new(&mut self.hash_paged);
        self.zeqtb = PagedView::new(&mut self.eqtb_paged);
        self.strstart = pointer_or_null(&mut self.strstart_storage);
        self.strpool = pointer_or_null(&mut self.strpool_storage);
        self.fontinfo = pointer_or_null(&mut self.fontinfo_storage);
        self.bcharlabel = pointer_or_null(&mut self.bcharlabel_storage);
        self.charbase = pointer_or_null(&mut self.charbase_storage);
        self.widthbase = pointer_or_null(&mut self.widthbase_storage);
        self.heightbase = pointer_or_null(&mut self.heightbase_storage);
        self.depthbase = pointer_or_null(&mut self.depthbase_storage);
        self.italicbase = pointer_or_null(&mut self.italicbase_storage);
        self.ligkernbase = pointer_or_null(&mut self.ligkernbase_storage);
        self.kernbase = pointer_or_null(&mut self.kernbase_storage);
        self.extenbase = pointer_or_null(&mut self.extenbase_storage);
        self.parambase = pointer_or_null(&mut self.parambase_storage);
        self.fontarea = pointer_or_null(&mut self.fontarea_storage);
        self.fontname = pointer_or_null(&mut self.fontname_storage);
        self.fontbc = pointer_or_null(&mut self.fontbc_storage);
        self.fontec = pointer_or_null(&mut self.fontec_storage);
        self.fontbchar = pointer_or_null(&mut self.fontbchar_storage);
        self.fontfalsebchar = pointer_or_null(&mut self.fontfalsebchar_storage);
        self.fontcheck = pointer_or_null(&mut self.fontcheck_storage);
        self.fontdsize = pointer_or_null(&mut self.fontdsize_storage);
        self.fontsize = pointer_or_null(&mut self.fontsize_storage);
        self.fontflags = pointer_or_null(&mut self.fontflags_storage);
        self.fontglue = pointer_or_null(&mut self.fontglue_storage);
        self.fontlayoutengine = pointer_or_null(&mut self.fontlayoutengine_storage);
        self.fontletterspace = pointer_or_null(&mut self.fontletterspace_storage);
        self.fontmapping = pointer_or_null(&mut self.fontmapping_storage);
        self.fontparams = pointer_or_null(&mut self.fontparams_storage);
        self.fontused = pointer_or_null(&mut self.fontused_storage);
        self.nativetext = pointer_or_null(&mut self.nativetext_storage);
        self.hyphenchar = pointer_or_null(&mut self.hyphenchar_storage);
        self.skewchar = pointer_or_null(&mut self.skewchar_storage);
        self.triec = pointer_or_null(&mut self.triec_storage);
        self.triehash = pointer_or_null(&mut self.triehash_storage);
        self.triel = pointer_or_null(&mut self.triel_storage);
        self.trieo = pointer_or_null(&mut self.trieo_storage);
        self.trier = pointer_or_null(&mut self.trier_storage);
        self.trietaken = pointer_or_null(&mut self.trietaken_storage);
        self.trietrc = pointer_or_null(&mut self.trietrc_storage);
        self.trietrl = pointer_or_null(&mut self.trietrl_storage);
        self.trietro = pointer_or_null(&mut self.trietro_storage);
    }

    fn seal_as_format_snapshot(&mut self) {
        self.curinput = instaterecord::default();
        self.inputptr = 0;
        self.inopen = 0;
        self.baseptr = 0;
        self.scannerstatus = 0;
        self.warningindex = 0;
        self.defref = -(268435455 as i64) as halfword;
        self.paramptr = 0;
        self.alignstate = 1000000 as integer;
        self.first = 0;
        self.last = 0;
        self.line = 0;
        self.openparens = 0;
        self.inputstack_storage.fill(instaterecord::default());
        self.inputfile_storage.fill(core::ptr::null_mut());
        self.eofseen_storage.fill(false_0);
        self.linestack_storage.fill(0);
        self.grpstack_storage.fill(-(268435455 as i64) as halfword);
        self.ifstack_storage.fill(-(268435455 as i64) as halfword);
        self.sourcefilenamestack_storage.fill(0);
        self.fullsourcefilenamestack_storage.fill(0);
        self.paramstack_storage.fill(0);
        // Drop every per-codepoint page that still holds only its band defaults,
        // so the sealed image (and anything cloned/serialized from it) keeps only
        // pages with real overrides — the bulk of the eqtb/hash savings.
        self.eqtb_paged.compact();
        self.hash_paged.compact();
        // Free the hyphenation-trie *construction scratch* — but only once the
        // trie has been packed (`trienotready == 0`). After packing, runtime
        // hyphenation reads only the packed trie (`trietr{c,l,o}`); these six
        // arrays are written solely by the trie builder, which never runs again.
        // If the trie is still unpacked (no `finalize_trie`), keep them: the lazy
        // runtime `inittrie` still needs them. Reclaims ~24 MB when packed.
        if self.trienotready == false_0 {
            self.triehash_storage = Vec::new();
            self.triel_storage = Vec::new();
            self.trier_storage = Vec::new();
            self.trieo_storage = Vec::new();
            self.triec_storage = Vec::new();
            self.trietaken_storage = Vec::new();
        }
        self.refresh_runtime_pointers();
    }

    /// Serialize the engine state to a portable byte image (a dumped `.fmt`).
    ///
    /// The encoding mirrors [`Self::clone_boxed`]: a raw image of the whole
    /// struct (every POD scalar/array is valid; `Vec` headers and raw pointers
    /// are garbage that the loader overwrites/refreshes) followed by each
    /// heap-owning `Vec`'s raw element bytes in [`portable_owning_vecs`] order.
    ///
    /// This is **same-layout only**: the image is stamped with the pointer width
    /// and `size_of::<PortableTexState>()`, and [`Self::from_portable_bytes`]
    /// refuses any image whose stamps don't match the loading target. In
    /// practice the dump tool and the consumer must share a target triple
    /// (e.g. both `wasm32-unknown-unknown`).
    pub(crate) fn to_portable_bytes(&self) -> Vec<u8> {
        let mut out = Vec::new();
        out.extend_from_slice(&PORTABLE_FORMAT_MAGIC);
        out.push(core::mem::size_of::<usize>() as u8);
        out.extend_from_slice(&(core::mem::size_of::<PortableTexState>() as u64).to_le_bytes());
        // SAFETY: read-only view of `self`'s bytes; `PortableTexState` has no
        // padding we care about (POD scalars round-trip; owning Vecs follow).
        let image = unsafe {
            core::slice::from_raw_parts(
                self as *const Self as *const u8,
                core::mem::size_of::<Self>(),
            )
        };
        out.extend_from_slice(image);
        // `mem` is dumped as its two live regions (low/variable + high/single-word),
        // skipping the free gap between `lomemmax` and `himemmin` — exactly what a
        // `.fmt` dump preserves. Indices are relative to `memmin` (the Vec base).
        let lo_len = (self.lomemmax - self.memmin + 1).max(0) as usize;
        let hi_start = (self.himemmin - self.memmin).max(0) as usize;
        let hi_len = (self.memend - self.himemmin + 1).max(0) as usize;
        portable_write_vec_ranges::<memoryword>(
            &mut out,
            self.mem.as_slice(),
            &[(0, lo_len), (hi_start, hi_len)],
        );
        // Every other owning array: drop the trailing zero region.
        macro_rules! write_field {
            ($name:ident, $ty:ty) => {{
                let slice = self.$name.as_slice();
                let used = portable_used_prefix_len(slice);
                let ranges: &[(usize, usize)] = if used == 0 { &[] } else { &[(0, used)] };
                portable_write_vec_ranges::<$ty>(&mut out, slice, ranges);
            }};
        }
        portable_owning_vecs!(write_field);
        // Paged eqtb/hash: geometry + dense low + only the faulted override pages.
        portable_write_paged(&mut out, &self.eqtb_paged);
        portable_write_paged(&mut out, &self.hash_paged);
        out
    }

    fn portable_bytes_header_len(bytes: &[u8]) -> Option<usize> {
        let mut cursor = 0usize;
        if bytes.get(cursor..cursor + PORTABLE_FORMAT_MAGIC.len())? != &PORTABLE_FORMAT_MAGIC[..] {
            return None;
        }
        cursor += PORTABLE_FORMAT_MAGIC.len();
        if *bytes.get(cursor)? as usize != core::mem::size_of::<usize>() {
            return None;
        }
        cursor += 1;
        let struct_size =
            u64::from_le_bytes(bytes.get(cursor..cursor + 8)?.try_into().ok()?) as usize;
        cursor += 8;
        if struct_size != core::mem::size_of::<Self>() {
            return None;
        }
        bytes.get(cursor..cursor + struct_size)?;
        Some(cursor)
    }

    fn portable_validation_tag() -> [u8; 17] {
        let mut tag = [0u8; 17];
        tag[..8].copy_from_slice(&PORTABLE_FORMAT_MAGIC);
        tag[8] = core::mem::size_of::<usize>() as u8;
        tag[9..].copy_from_slice(&(core::mem::size_of::<Self>() as u64).to_le_bytes());
        tag
    }

    /// Reconstruct an engine state from [`Self::to_portable_bytes`] output.
    ///
    /// Returns `None` if the magic/stamps don't match the loading target or the
    /// buffer is truncated. The input-file pointer table is nulled (those are
    /// process-local OS handles). `fontlayoutengine`/`fontmapping` hold *integer
    /// font handles*, not addresses, so they are preserved verbatim and the
    /// caller re-binds them to a fresh font platform via
    /// [`FontPlatform::restore_font_table`] before rendering.
    pub(crate) fn from_portable_bytes(bytes: &[u8]) -> Option<Box<Self>> {
        let mut cursor = Self::portable_bytes_header_len(bytes)?;
        let image = bytes.get(cursor..cursor + core::mem::size_of::<Self>())?;
        cursor += core::mem::size_of::<Self>();

        let mut state = Box::<Self>::new_uninit();
        let state_ptr = state.as_mut_ptr();
        // SAFETY: mirrors `clone_boxed` — copy the POD struct image, then
        // overwrite every heap-owning field with a freshly-decoded `Vec`
        // (`ptr::write` does not drop the garbage header it overwrites), then
        // refresh all derived raw pointers from the new Vec bases.
        let state = unsafe {
            core::ptr::copy_nonoverlapping(
                image.as_ptr(),
                state_ptr as *mut u8,
                core::mem::size_of::<Self>(),
            );
            let decoded_mem: Vec<memoryword> = portable_read_vec_ranges(bytes, &mut cursor)?;
            core::ptr::addr_of_mut!((*state_ptr).mem).write(decoded_mem);
            macro_rules! read_field {
                ($name:ident, $ty:ty) => {
                    let decoded: Vec<$ty> = portable_read_vec_ranges(bytes, &mut cursor)?;
                    core::ptr::addr_of_mut!((*state_ptr).$name).write(decoded);
                };
            }
            portable_owning_vecs!(read_field);
            let eqtb_paged =
                portable_read_paged(bytes, &mut cursor, eqtb_codepoint_default, eqtb_sig_range)?;
            core::ptr::addr_of_mut!((*state_ptr).eqtb_paged).write(eqtb_paged);
            let hash_paged =
                portable_read_paged(bytes, &mut cursor, hash_codepoint_default, hash_sig_range)?;
            core::ptr::addr_of_mut!((*state_ptr).hash_paged).write(hash_paged);
            // Source-tracking tables are transient per-render parse state, never
            // serialized; overwrite the raw-image headers with fresh empties so
            // the reloaded state owns valid (empty) tables. `source_tracking`
            // itself round-trips as a POD scalar but is reset at each
            // `begin_primary_input`, so its dumped value is irrelevant.
            core::ptr::addr_of_mut!((*state_ptr).src_spans).write(Vec::new());
            core::ptr::addr_of_mut!((*state_ptr).src_dedup)
                .write(std::collections::HashMap::new());
            core::ptr::addr_of_mut!((*state_ptr).node_src)
                .write(PagedArray::new(0, 0, node_src_default, node_src_sig));
            core::ptr::addr_of_mut!((*state_ptr).src_native_offsets).write(Vec::new());
            core::ptr::addr_of_mut!((*state_ptr).src_stack_cells).write(Vec::new());
            core::ptr::addr_of_mut!((*state_ptr).cur_stack_head).write(0);
            core::ptr::addr_of_mut!((*state_ptr).node_stack)
                .write(PagedArray::new(0, 0, node_stack_default, node_stack_sig));
            // Input-file slots are process-local OS handles; null them. The font
            // handle tables (`fontlayoutengine`/`fontmapping`) are integer
            // handles, preserved for `restore_font_table` to rebind.
            for slot in (*state_ptr).inputfile_storage.iter_mut() {
                *slot = core::ptr::null_mut();
            }
            let mut state = state.assume_init();
            state.refresh_runtime_pointers();
            state
        };
        Some(state)
    }

    /// Total bytes backing the engine's dynamic arrays (the dominant runtime
    /// footprint: `mem`, `eqtb`, `hash`, `fontinfo`, string pool, trie, …).
    /// Counts allocated capacity, so it reflects real resident memory.
    pub(crate) fn state_array_bytes(&self) -> usize {
        let mut total = self.mem.capacity() * core::mem::size_of::<memoryword>();
        macro_rules! accumulate {
            ($name:ident, $ty:ty) => {
                total += self.$name.capacity() * core::mem::size_of::<$ty>();
            };
        }
        portable_owning_vecs!(accumulate);
        total += self.eqtb_paged.resident_bytes() + self.hash_paged.resident_bytes();
        total
    }

    fn allocate_initial_arrays(&mut self) {
        self.iniversion = true_0;
        self.membot = 0;
        self.memmin = self.membot;
        // Math-fragment workloads use a tiny fraction of TeX's worst-case main
        // memory. Sized down from the 5M default; the latex+amsmath+unicode-math
        // format build is the high-water mark and fits comfortably under 1M words.
        // Raise if a large document hits `! TeX capacity exceeded (main memory)`.
        self.memtop = 999_999;
        self.memmax = self.memtop;
        self.hashextra = 600_000;
        self.eqtbtop = xetex_eqtb_top + self.hashextra;
        self.bufsize = 200_000;
        self.nestsize = 1_000;
        self.maxinopen = 15;
        self.paramsize = 20_000;
        self.savesize = 200_000;
        self.stacksize = 10_000;
        self.dvibufsize = 16_384;
        self.poolsize = 6_250_000;
        self.maxstrings = 500_000;
        self.fontmemsize = 1_000_000;
        self.fontmax = 500;
        // Hyphenation trie construction peak — the production `\patterns` the real
        // `latex.ltx` loads need >700K nodes, so this stays at the worst case.
        // The six *construction-scratch* trie arrays (everything except the packed
        // trietr{c,l,o}) are freed in `seal_as_format_snapshot`, so this large
        // size only costs memory transiently during the one-time format build.
        self.triesize = 1_100_000;
        self.hyphsize = 8_191;
        self.primused = 2_100;
        self.errorline = 79;
        self.halferrorline = 50;
        self.maxprintline = 79;
        self.expanddepth = 10_000;

        self.mem = zeroed_vec((self.memtop - self.memmin + 1) as usize);
        // These arrays are `array[0..N]` / `array[1..N]` in web2c, allocated via
        // `xmallocarray(T, N)` == `xmalloc((N+1)*sizeof(T))` (cpascal.h), i.e. N+1
        // elements so the top index N is valid. The c2rust output allocates each
        // as `(dim + 1)` accordingly. Allocating only `dim` here under-sizes every
        // one by a slot: in the original C arena the top index harmlessly aliased
        // adjacent memory, but this is a bounds-real Rust Vec, so e.g. show_context
        // reading `linestack[index+1]` at the top input level was an OOB read.
        self.buffer_storage = zeroed_vec((self.bufsize + 1) as usize);
        self.nest_storage = zeroed_vec((self.nestsize + 1) as usize);
        self.savestack_storage = zeroed_vec((self.savesize + 1) as usize);
        self.inputstack_storage = zeroed_vec((self.stacksize + 1) as usize);
        self.inputfile_storage = zeroed_vec((self.maxinopen + 1) as usize);
        self.eofseen_storage = zeroed_vec((self.maxinopen + 1) as usize);
        self.linestack_storage = zeroed_vec((self.maxinopen + 1) as usize);
        self.grpstack_storage = zeroed_vec((self.maxinopen + 1) as usize);
        self.ifstack_storage = zeroed_vec((self.maxinopen + 1) as usize);
        self.sourcefilenamestack_storage = zeroed_vec((self.maxinopen + 1) as usize);
        self.fullsourcefilenamestack_storage = zeroed_vec((self.maxinopen + 1) as usize);
        self.paramstack_storage = zeroed_vec((self.paramsize + 1) as usize);
        self.hyphword_storage = zeroed_vec((self.hyphsize + 1) as usize);
        self.hyphlist_storage = zeroed_vec((self.hyphsize + 1) as usize);
        self.hyphlink_storage = zeroed_vec((self.hyphsize + 1) as usize);
        // eqtb/hash: dense low region [..CODEPOINT_LO), then the per-codepoint
        // bands paged lazily. `hash` starts at absolute index `hashoffset`
        // (its element 0); both run through absolute index `eqtbtop`.
        self.eqtb_paged = PagedArray::new(
            0,
            (self.eqtbtop + 1) as usize,
            eqtb_codepoint_default,
            eqtb_sig_range,
        );
        self.hash_paged = PagedArray::new(
            hashoffset as usize,
            (self.eqtbtop + 1) as usize,
            hash_codepoint_default,
            hash_sig_range,
        );
        self.strstart_storage = zeroed_vec((self.maxstrings + 1) as usize);
        self.strpool_storage = zeroed_vec((self.poolsize + 1) as usize);
        self.fontinfo_storage = zeroed_vec((self.fontmemsize + 1) as usize);
        let font_slots = (self.fontmax + 1) as usize;
        self.bcharlabel_storage = zeroed_vec(font_slots);
        self.charbase_storage = zeroed_vec(font_slots);
        self.widthbase_storage = zeroed_vec(font_slots);
        self.heightbase_storage = zeroed_vec(font_slots);
        self.depthbase_storage = zeroed_vec(font_slots);
        self.italicbase_storage = zeroed_vec(font_slots);
        self.ligkernbase_storage = zeroed_vec(font_slots);
        self.kernbase_storage = zeroed_vec(font_slots);
        self.extenbase_storage = zeroed_vec(font_slots);
        self.parambase_storage = zeroed_vec(font_slots);
        self.fontarea_storage = zeroed_vec(font_slots);
        self.fontname_storage = zeroed_vec(font_slots);
        self.fontbc_storage = zeroed_vec(font_slots);
        self.fontec_storage = zeroed_vec(font_slots);
        self.fontbchar_storage = zeroed_vec(font_slots);
        self.fontfalsebchar_storage = zeroed_vec(font_slots);
        self.fontcheck_storage = zeroed_vec(font_slots);
        self.fontdsize_storage = zeroed_vec(font_slots);
        self.fontsize_storage = zeroed_vec(font_slots);
        self.fontflags_storage = zeroed_vec(font_slots);
        self.fontglue_storage = zeroed_vec(font_slots);
        self.fontlayoutengine_storage = zeroed_vec(font_slots);
        self.fontletterspace_storage = zeroed_vec(font_slots);
        self.fontmapping_storage = zeroed_vec(font_slots);
        self.fontparams_storage = zeroed_vec(font_slots);
        self.fontused_storage = zeroed_vec(font_slots);
        self.nativetext_storage = Vec::new();
        self.hyphenchar_storage = zeroed_vec(font_slots);
        self.skewchar_storage = zeroed_vec(font_slots);
        let trie_slots = (self.triesize + 1) as usize;
        self.triec_storage = zeroed_vec(trie_slots);
        self.triehash_storage = zeroed_vec(trie_slots);
        self.triel_storage = zeroed_vec(trie_slots);
        self.trieo_storage = zeroed_vec(trie_slots);
        self.trier_storage = zeroed_vec(trie_slots);
        self.trietaken_storage = zeroed_vec(trie_slots);
        self.trietrc_storage = zeroed_vec(trie_slots);
        self.trietrl_storage = zeroed_vec(trie_slots);
        self.trietro_storage = zeroed_vec(trie_slots);
        self.refresh_runtime_pointers();
    }
}

fn zeroed_vec<T>(len: usize) -> Vec<T>
where
    T: Clone + Default,
{
    vec![T::default(); len]
}

fn pointer_or_null<T>(storage: &mut Vec<T>) -> *mut T {
    if storage.is_empty() {
        core::ptr::null_mut()
    } else {
        storage.as_mut_ptr()
    }
}

#[derive(Clone, Copy, Debug, PartialEq, Eq)]
pub enum EngineProfileKind {
    Tex,
    Etex,
    Xetex,
}

#[derive(Clone, Copy, Debug, PartialEq, Eq)]
pub struct EngineProfile {
    pub id: &'static str,
    pub kind: EngineProfileKind,
    pub etex: bool,
    pub xetex: bool,
    pub unicode_scalars: bool,
    pub unicode_math: bool,
    pub native_fonts: bool,
}

#[derive(Clone, Copy, Debug, PartialEq, Eq)]
struct WriteTokenConstants {
    open_group_token: halfword,
    end_write_token: halfword,
    close_group_token: halfword,
}

impl EngineProfile {
    pub const fn tex() -> Self {
        Self {
            id: "tex",
            kind: EngineProfileKind::Tex,
            etex: false,
            xetex: false,
            unicode_scalars: false,
            unicode_math: false,
            native_fonts: false,
        }
    }

    pub const fn etex() -> Self {
        Self {
            id: "etex",
            kind: EngineProfileKind::Etex,
            etex: true,
            xetex: false,
            unicode_scalars: false,
            unicode_math: false,
            native_fonts: false,
        }
    }

    pub const fn xetex() -> Self {
        Self {
            id: "xetex",
            kind: EngineProfileKind::Xetex,
            etex: true,
            xetex: true,
            unicode_scalars: true,
            unicode_math: true,
            native_fonts: false,
        }
    }

    const fn write_token_constants(self) -> WriteTokenConstants {
        match self.kind {
            EngineProfileKind::Tex | EngineProfileKind::Etex => WriteTokenConstants {
                open_group_token: 637,
                end_write_token: 19617,
                close_group_token: 379,
            },
            EngineProfileKind::Xetex => WriteTokenConstants {
                open_group_token: 4_194_429,
                end_write_token: 34_749_089,
                close_group_token: 2_097_275,
            },
        }
    }
}

pub struct PortableFormatImage {
    source: PortableFormatSource,
}

enum PortableFormatSource {
    Owned(Box<PortableTexState>),
    Static(&'static [u8]),
}

#[derive(Clone, Copy, Debug, PartialEq, Eq)]
pub struct PortableNodeHandle(pub i32);

#[derive(Clone, Copy, Debug, PartialEq, Eq)]
pub enum PortableNodeKind {
    HorizontalBox,
    VerticalBox,
    Rule,
    Insertion,
    Mark,
    Adjustment,
    Ligature,
    Discretionary,
    OutputWhatsit,
    Whatsit,
    Math,
    Glue,
    Kern,
    Penalty,
    UnsetBox,
    Noad,
    Style,
    Choice,
    Character,
    NativeWord,
    NativeGlyph,
    HostBoxRef,
    Unknown(i32),
}

#[derive(Clone, Debug, PartialEq)]
pub struct PortableNodeSnapshot {
    pub handle: PortableNodeHandle,
    pub kind: PortableNodeKind,
    pub subtype: i32,
    pub source: Option<PortableSourceSpan>,
    pub link: Option<PortableNodeHandle>,
    pub font: i32,
    pub character: i32,
    pub width: i32,
    pub height: i32,
    pub depth: i32,
    pub shift: i32,
    pub list: Option<PortableNodeHandle>,
    pub native_glyphs: Vec<PortableNativeGlyph>,
    /// Box glue-set ratio (from `hpack`/`vpack`); meaningful for hlist/vlist.
    pub glue_set: f64,
    /// Box glue sign: 0 normal, 1 stretching, 2 shrinking.
    pub glue_sign: i32,
    /// Box glue order (0..3) that participates in stretching/shrinking.
    pub glue_order: i32,
    /// Glue node's spec stretch amount (raw glue order in `glue_stretch_order`).
    pub glue_stretch: i32,
    /// Glue node's spec shrink amount.
    pub glue_shrink: i32,
    /// Order (0..3) of the glue node's stretch component.
    pub glue_stretch_order: i32,
    /// Order (0..3) of the glue node's shrink component.
    pub glue_shrink_order: i32,
}

impl Clone for PortableFormatImage {
    fn clone(&self) -> Self {
        match &self.source {
            PortableFormatSource::Owned(state) => Self {
                source: PortableFormatSource::Owned(state.clone_boxed()),
            },
            PortableFormatSource::Static(bytes) => Self {
                source: PortableFormatSource::Static(bytes),
            },
        }
    }
}

impl PortableFormatImage {
    pub fn empty() -> Self {
        Self {
            source: PortableFormatSource::Owned(PortableTexState::new_boxed_default()),
        }
    }

    fn from_engine_state(state: &PortableTexState) -> Self {
        let mut state = state.clone_boxed();
        state.seal_as_format_snapshot();
        Self {
            source: PortableFormatSource::Owned(state),
        }
    }

    /// Wrap an already-sealed engine state, taking ownership without cloning.
    /// Used by [`PortableTexEngine::into_format`].
    fn from_sealed_state(state: Box<PortableTexState>) -> Self {
        Self {
            source: PortableFormatSource::Owned(state),
        }
    }

    fn instantiate_state(&self) -> Box<PortableTexState> {
        match &self.source {
            PortableFormatSource::Owned(state) => state.clone_boxed(),
            PortableFormatSource::Static(bytes) => PortableTexState::from_portable_bytes(bytes)
                .expect("validated static format image became unreadable"),
        }
    }

    /// Returns the same-target validation tag stored at the start of every image.
    #[must_use]
    pub fn validation_tag() -> [u8; 17] {
        PortableTexState::portable_validation_tag()
    }

    /// Reports whether a serialized image carries this build target's validation tag.
    #[must_use]
    pub fn bytes_match_target(bytes: &[u8]) -> bool {
        PortableTexState::portable_bytes_header_len(bytes).is_some()
    }

    /// Borrows a static serialized image without allocating or copying its contents.
    #[must_use]
    pub fn from_static_bytes(bytes: &'static [u8]) -> Option<Self> {
        Self::bytes_match_target(bytes).then_some(())?;
        Some(Self {
            source: PortableFormatSource::Static(bytes),
        })
    }

    /// Serialize this format image to a portable byte buffer (a dumped `.fmt`)
    /// that [`Self::from_bytes`] can reload. Same-target only — see
    /// [`PortableTexState::to_portable_bytes`].
    #[must_use]
    pub fn to_bytes(&self) -> Vec<u8> {
        match &self.source {
            PortableFormatSource::Owned(state) => state.to_portable_bytes(),
            PortableFormatSource::Static(bytes) => bytes.to_vec(),
        }
    }

    /// Reload a format image previously produced by [`Self::to_bytes`]. Returns
    /// `None` if the buffer is not a format image for this build target.
    #[must_use]
    pub fn from_bytes(bytes: &[u8]) -> Option<Self> {
        Some(Self {
            source: PortableFormatSource::Owned(PortableTexState::from_portable_bytes(bytes)?),
        })
    }

    /// Resident bytes of the engine's dynamic arrays once instantiated from this
    /// image — the dominant runtime memory footprint.
    #[must_use]
    pub fn state_array_bytes(&self) -> usize {
        match &self.source {
            PortableFormatSource::Owned(state) => state.state_array_bytes(),
            PortableFormatSource::Static(bytes) => PortableTexState::from_portable_bytes(bytes)
                .expect("validated static format image became unreadable")
                .state_array_bytes(),
        }
    }
}

/// Size in bytes of one TeX `memory_word` in this build. Real XeTeX packs it to
/// 8; this engine uses a 16-byte word (the `four_quarters` view is `u16`, but
/// `two_halves`/`cint` keep the c2rust 32-bit alignment).
#[must_use]
pub fn memory_word_bytes() -> usize {
    core::mem::size_of::<memoryword>()
}

pub struct PortableTexEngine<'resources> {
    pub(crate) state: Box<PortableTexState>,
    pub(crate) profile: EngineProfile,
    pub(crate) resources: Box<dyn ResourceProvider + 'resources>,
    pub(crate) fonts: Box<dyn FontPlatform + 'resources>,
    pub(crate) platform: Box<dyn PortablePlatform + 'resources>,
    pub(crate) nameoffile_storage: Vec<UTF8code>,
    native_glyph_infos: std::collections::BTreeMap<i32, PortableNativeGlyphInfo>,
    // Host box render payloads by record index, markers in node memory carry only the index.
    hostbox_records: Vec<PortableHostBox>,
    character_protrusions: std::collections::BTreeMap<(integer, u32, integer), integer>,
    pub(crate) resource_requests: usize,
    pub(crate) resource_request_records: Vec<PortableResourceRequestRecord>,
    pub(crate) virtual_files: std::collections::BTreeMap<String, Vec<u8>>,
    pub(crate) transcript_bytes: Vec<u8>,
    pub(crate) current_input_package_owner: Option<String>,
    pub(crate) stripped_page_builds: usize,
    pub(crate) stripped_shipouts: usize,
    pub(crate) stripped_special_outputs: usize,
    pub(crate) stripped_picture_loads: usize,
    pub(crate) stripped_source_specials: usize,
    pub(crate) stripped_write_whatsit_diagnostics: usize,
    pub(crate) stripped_pdf_extensions: usize,
    pub(crate) stripped_page_top_prunes: usize,
    pub(crate) last_stripped_shipout_box: Option<PortableNodeHandle>,
    pub(crate) fragment_capture_enabled: bool,
    pub(crate) format_initialization: bool,
    pub(crate) captured_fragment_root: Option<PortableNodeHandle>,
    pub(crate) last_abort_status: Option<integer>,
    /// Captured message from the most recent surfaced [`EngineError`] (mirrors
    /// `last_abort_status` for the error channel). The driver boundary stores it
    /// here so the host can read *what* went wrong after a failed run.
    pub(crate) last_error_message: Option<String>,
    /// When set, the engine enforces the "render one math expression" sandbox:
    /// breakout (`$`), job-control (`\end`), and IO (`\input`, `\write`, ...)
    /// tokens are rejected as [`EngineError`]s, and a work budget bounds runtime.
    /// Off during format construction (which legitimately uses those); the host
    /// sets it for fragment renders. See [`PortableTexEngine::sandbox_reject`].
    pub(crate) sandbox: bool,
    /// Sandbox bookkeeping: the live MATH nesting depth (`init_math` `+1`,
    /// `after_math` `-1`). The wrapper `$` opens depth 1 and the user content stays at
    /// depth >= 1; nested math inside a text block (`\hbox{$x$}`, `\text{$y$}`) opens
    /// depth 2+. Depth only returns to 0 when the wrapper math is CLOSED -- so a `$` that
    /// re-opens math at depth 0 (after `sandbox_math_opened`) is a breakout, while a `$`
    /// at depth >= 1 is legitimate nested math.
    pub(crate) sandbox_math_depth: i32,
    /// Sandbox: set once the wrapper math has opened, so the first depth-0 `init_math`
    /// (the wrapper) is allowed but any later depth-0 re-open (a user `$` breakout) is
    /// rejected.
    pub(crate) sandbox_math_opened: bool,
    /// Sandbox work budget: main-control iterations consumed this run, to bound
    /// runaway expansion / infinite loops (`\def\x{\x}\x`).
    pub(crate) sandbox_ops: u64,
}

pub(crate) fn zround(value: real) -> integer {
    value.round() as integer
}

impl<'resources> PortableTexEngine<'resources> {
    pub fn from_format<R>(
        profile: EngineProfile,
        format: &PortableFormatImage,
        resources: R,
    ) -> Self
    where
        R: ResourceProvider + 'resources,
    {
        Self {
            state: format.instantiate_state(),
            profile,
            resources: Box::new(resources),
            fonts: Box::<EmptyFontPlatform>::default(),
            platform: Box::<EmptyPlatform>::default(),
            nameoffile_storage: Vec::new(),
            native_glyph_infos: std::collections::BTreeMap::new(),
            hostbox_records: Vec::new(),
            character_protrusions: std::collections::BTreeMap::new(),
            resource_requests: 0,
            resource_request_records: Vec::new(),
            virtual_files: std::collections::BTreeMap::new(),
            transcript_bytes: Vec::new(),
            current_input_package_owner: None,
            stripped_page_builds: 0,
            stripped_shipouts: 0,
            stripped_special_outputs: 0,
            stripped_picture_loads: 0,
            stripped_source_specials: 0,
            stripped_write_whatsit_diagnostics: 0,
            stripped_pdf_extensions: 0,
            stripped_page_top_prunes: 0,
            last_stripped_shipout_box: None,
            fragment_capture_enabled: false,
            format_initialization: false,
            captured_fragment_root: None,
            last_abort_status: None,
            last_error_message: None,
            sandbox: false,
            sandbox_math_depth: 0,
            sandbox_math_opened: false,
            sandbox_ops: 0,
        }
    }

    pub fn with_font_platform<F>(mut self, fonts: F) -> Self
    where
        F: FontPlatform + 'resources,
    {
        self.fonts = Box::new(fonts);
        self
    }

    pub fn with_platform<P>(mut self, platform: P) -> Self
    where
        P: PortablePlatform + 'resources,
    {
        self.platform = Box::new(platform);
        self
    }

    pub fn profile(&self) -> EngineProfile {
        self.profile
    }

    pub fn initialize_format_state(self: &mut Self) -> bool {
        self.catch_engine_abort(|engine| unsafe {
            let this = engine as *mut PortableTexEngine<'_>;
            engine.state.allocate_initial_arrays();
            engine.initialize();
            if engine.supports_etex() {
                engine.state.eTeXmode = 1 as eightbits;
            }
            // `getstringsstarted`, `initprim`, and the two startup-primitive
            // methods are abort-reachable (`EngineFlow<..>`), so thread `?`. The
            // `abort_engine(this, 1)` path here is the "could not start strings"
            // error abort (status 1).
            if engine.getstringsstarted()? == 0 {
                Self::abort_engine(this, 1 as integer)?;
            }
            engine.initprim()?;
            engine.init_etex_startup_primitives()?;
            engine.init_xetex_startup_primitives()?;
            engine.register_host_box_primitive()?;
            engine.state.initstrptr = engine.state.strptr;
            engine.state.initpoolptr = engine.state.poolptr;
            // Inter-element math spacing offset. The original computes this in
            // `mainbody` (`magicoffset = strstart[math_spacing] - 9*ord_noad`),
            // which the importer replaces with this init path, so the assignment
            // was lost and `magicoffset` stayed 0 -- making the spacing lookup in
            // mlist_to_hlist index arbitrary pool data and trip confusion("mlist4")
            // on the first binary operator. The engine loads xetex.pool for every
            // profile, so math_spacing is xetex string 784 (66320 - 65536) and
            // ord_noad is 16.
            engine.state.magicoffset =
                (*engine.state.strstart.offset(784) as integer - 9 * 16) as integer;
            engine.state.alignstate = 1000000 as integer;
            Ok(())
        })
    }

    pub(crate) fn ensure_nativetext_capacity(
        engine: &mut PortableTexEngine<'_>,
        required: integer,
    ) {
        let required = required.max(0) as usize;
        if engine.state.nativetext_storage.len() < required {
            engine.state.nativetext_storage.resize(required, UTF16code::default());
        }
        engine.state.nativetext = pointer_or_null(&mut engine.state.nativetext_storage);
    }

    unsafe fn init_etex_startup_primitives(&mut self) -> EngineFlow<()> {
        if !self.supports_etex() || self.is_xetex() {
            return Ok(());
        }
        self.state.nonewcontrolsequence = false_0 as boolean;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(1360 as i32, 70 as i32 as quarterword, 3 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(1361 as i32, 70 as i32 as quarterword, 6 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(765 as i32, 108 as i32 as quarterword, 5 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(1363 as i32, 72 as i32 as quarterword, 25067 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(1364 as i32, 73 as i32 as quarterword, 27234 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(1365 as i32, 73 as i32 as quarterword, 27235 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(1366 as i32, 73 as i32 as quarterword, 27236 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(1367 as i32, 73 as i32 as quarterword, 27237 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(1368 as i32, 73 as i32 as quarterword, 27238 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(1369 as i32, 73 as i32 as quarterword, 27239 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(1370 as i32, 73 as i32 as quarterword, 27240 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(1371 as i32, 73 as i32 as quarterword, 27241 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(1372 as i32, 73 as i32 as quarterword, 27242 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(1387 as i32, 70 as i32 as quarterword, 7 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(1388 as i32, 70 as i32 as quarterword, 8 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(1389 as i32, 70 as i32 as quarterword, 9 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(1390 as i32, 70 as i32 as quarterword, 10 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(1391 as i32, 70 as i32 as quarterword, 11 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(1392 as i32, 70 as i32 as quarterword, 14 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(1393 as i32, 70 as i32 as quarterword, 15 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(1394 as i32, 70 as i32 as quarterword, 16 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(1395 as i32, 70 as i32 as quarterword, 17 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(1396 as i32, 70 as i32 as quarterword, 18 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(1397 as i32, 70 as i32 as quarterword, 19 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(1398 as i32, 70 as i32 as quarterword, 20 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(1399 as i32, 19 as i32 as quarterword, 4 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(1401 as i32, 19 as i32 as quarterword, 5 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(1402 as i32, 109 as i32 as quarterword, 1 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(1403 as i32, 109 as i32 as quarterword, 5 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(1404 as i32, 19 as i32 as quarterword, 6 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(1408 as i32, 82 as i32 as quarterword, 2 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(908 as i32, 49 as i32 as quarterword, 1 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(1412 as i32, 73 as i32 as quarterword, 27243 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(1413 as i32, 33 as i32 as quarterword, 6 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(1414 as i32, 33 as i32 as quarterword, 7 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(1415 as i32, 33 as i32 as quarterword, 10 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(1416 as i32, 33 as i32 as quarterword, 11 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(1425 as i32, 104 as i32 as quarterword, 2 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(1427 as i32, 96 as i32 as quarterword, 1 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(799 as i32, 102 as i32 as quarterword, 1 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(1428 as i32, 105 as i32 as quarterword, 17 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(1429 as i32, 105 as i32 as quarterword, 18 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(1430 as i32, 105 as i32 as quarterword, 19 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(1217 as i32, 93 as i32 as quarterword, 8 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(1436 as i32, 70 as i32 as quarterword, 25 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(1437 as i32, 70 as i32 as quarterword, 26 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(1438 as i32, 70 as i32 as quarterword, 27 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(1439 as i32, 70 as i32 as quarterword, 28 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(1443 as i32, 70 as i32 as quarterword, 12 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(1444 as i32, 70 as i32 as quarterword, 13 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(1445 as i32, 70 as i32 as quarterword, 21 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(1446 as i32, 70 as i32 as quarterword, 22 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(1447 as i32, 70 as i32 as quarterword, 23 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(1448 as i32, 70 as i32 as quarterword, 24 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(1449 as i32, 18 as i32 as quarterword, 5 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(1450 as i32, 110 as i32 as quarterword, 5 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(1451 as i32, 110 as i32 as quarterword, 6 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(1452 as i32, 110 as i32 as quarterword, 7 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(1453 as i32, 110 as i32 as quarterword, 8 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(1454 as i32, 110 as i32 as quarterword, 9 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(1458 as i32, 24 as i32 as quarterword, 2 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(1459 as i32, 24 as i32 as quarterword, 3 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(1460 as i32, 84 as i32 as quarterword, 25324 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(1461 as i32, 84 as i32 as quarterword, 25325 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(1462 as i32, 84 as i32 as quarterword, 25326 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(1463 as i32, 84 as i32 as quarterword, 25327 as i32)?;
        self.state.eTeXmode = 1 as eightbits;
        Ok(())
    }
    unsafe fn init_xetex_startup_primitives(&mut self) -> EngineFlow<()> {
        if !self.is_xetex() {
            return Ok(());
        }
        self.state.nonewcontrolsequence = false_0 as boolean;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(66755 as i64 as strnumber, 59 as i32 as quarterword, 41 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(66756 as i64 as strnumber, 59 as i32 as quarterword, 42 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(66757 as i64 as strnumber, 59 as i32 as quarterword, 43 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(66758 as i64 as strnumber, 59 as i32 as quarterword, 46 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(
                66759 as i64 as strnumber,
                73 as i32 as quarterword,
                1206306 as i64 as halfword,
            )?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(66760 as i64 as strnumber, 59 as i32 as quarterword, 23 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(66816 as i64 as strnumber, 71 as i32 as quarterword, 3 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(66817 as i64 as strnumber, 71 as i32 as quarterword, 19 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(66115 as i64 as strnumber, 111 as i32 as quarterword, 5 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(66818 as i64 as strnumber, 71 as i32 as quarterword, 27 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(
                66819 as i64 as strnumber,
                111 as i32 as quarterword,
                33 as i32,
            )?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(66820 as i64 as strnumber, 71 as i32 as quarterword, 28 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(66821 as i64 as strnumber, 71 as i32 as quarterword, 29 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(66822 as i64 as strnumber, 71 as i32 as quarterword, 30 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(66823 as i64 as strnumber, 71 as i32 as quarterword, 31 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(66824 as i64 as strnumber, 71 as i32 as quarterword, 32 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(66825 as i64 as strnumber, 71 as i32 as quarterword, 33 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(66826 as i64 as strnumber, 71 as i32 as quarterword, 34 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(66827 as i64 as strnumber, 71 as i32 as quarterword, 35 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(66828 as i64 as strnumber, 71 as i32 as quarterword, 36 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(66829 as i64 as strnumber, 71 as i32 as quarterword, 37 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(66830 as i64 as strnumber, 71 as i32 as quarterword, 38 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(66831 as i64 as strnumber, 71 as i32 as quarterword, 39 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(66832 as i64 as strnumber, 71 as i32 as quarterword, 40 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(66833 as i64 as strnumber, 71 as i32 as quarterword, 41 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(66834 as i64 as strnumber, 71 as i32 as quarterword, 42 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(
                66835 as i64 as strnumber,
                111 as i32 as quarterword,
                34 as i32,
            )?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(
                66836 as i64 as strnumber,
                111 as i32 as quarterword,
                35 as i32,
            )?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(
                66837 as i64 as strnumber,
                111 as i32 as quarterword,
                36 as i32,
            )?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(66838 as i64 as strnumber, 71 as i32 as quarterword, 43 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(66839 as i64 as strnumber, 71 as i32 as quarterword, 44 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(66840 as i64 as strnumber, 71 as i32 as quarterword, 45 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(66841 as i64 as strnumber, 71 as i32 as quarterword, 46 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(66842 as i64 as strnumber, 71 as i32 as quarterword, 47 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(66843 as i64 as strnumber, 71 as i32 as quarterword, 48 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(66844 as i64 as strnumber, 71 as i32 as quarterword, 49 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(66845 as i64 as strnumber, 71 as i32 as quarterword, 50 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(66846 as i64 as strnumber, 71 as i32 as quarterword, 55 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(
                66847 as i64 as strnumber,
                111 as i32 as quarterword,
                37 as i32,
            )?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(66848 as i64 as strnumber, 71 as i32 as quarterword, 51 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(66849 as i64 as strnumber, 71 as i32 as quarterword, 52 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(66850 as i64 as strnumber, 71 as i32 as quarterword, 53 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(66851 as i64 as strnumber, 71 as i32 as quarterword, 54 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(
                66861 as i64 as strnumber,
                73 as i32 as quarterword,
                1206305 as i64 as halfword,
            )?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(
                66862 as i64 as strnumber,
                74 as i32 as quarterword,
                7892325 as i64 as halfword,
            )?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(
                66863 as i64 as strnumber,
                74 as i32 as quarterword,
                7892326 as i64 as halfword,
            )?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(
                66864 as i64 as strnumber,
                74 as i32 as quarterword,
                7892327 as i64 as halfword,
            )?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(
                66865 as i64 as strnumber,
                74 as i32 as quarterword,
                7892328 as i64 as halfword,
            )?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(
                66866 as i64 as strnumber,
                74 as i32 as quarterword,
                7892329 as i64 as halfword,
            )?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(
                66867 as i64 as strnumber,
                74 as i32 as quarterword,
                7892330 as i64 as halfword,
            )?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(
                66868 as i64 as strnumber,
                74 as i32 as quarterword,
                7892331 as i64 as halfword,
            )?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(
                66869 as i64 as strnumber,
                74 as i32 as quarterword,
                7892332 as i64 as halfword,
            )?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(
                66870 as i64 as strnumber,
                74 as i32 as quarterword,
                7892333 as i64 as halfword,
            )?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(
                66871 as i64 as strnumber,
                74 as i32 as quarterword,
                7892335 as i64 as halfword,
            )?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(66885 as i64 as strnumber, 71 as i32 as quarterword, 20 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(66886 as i64 as strnumber, 71 as i32 as quarterword, 21 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(66887 as i64 as strnumber, 71 as i32 as quarterword, 22 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(66888 as i64 as strnumber, 71 as i32 as quarterword, 23 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(66889 as i64 as strnumber, 71 as i32 as quarterword, 24 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(66890 as i64 as strnumber, 71 as i32 as quarterword, 56 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(66891 as i64 as strnumber, 71 as i32 as quarterword, 57 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(66892 as i64 as strnumber, 71 as i32 as quarterword, 58 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(66893 as i64 as strnumber, 71 as i32 as quarterword, 59 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(66894 as i64 as strnumber, 71 as i32 as quarterword, 60 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(66895 as i64 as strnumber, 71 as i32 as quarterword, 61 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(66896 as i64 as strnumber, 71 as i32 as quarterword, 62 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(66897 as i64 as strnumber, 19 as i32 as quarterword, 4 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(66899 as i64 as strnumber, 19 as i32 as quarterword, 5 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(66900 as i64 as strnumber, 112 as i32 as quarterword, 1 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(66901 as i64 as strnumber, 112 as i32 as quarterword, 5 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(66902 as i64 as strnumber, 19 as i32 as quarterword, 6 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(66906 as i64 as strnumber, 83 as i32 as quarterword, 2 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(66288 as i64 as strnumber, 49 as i32 as quarterword, 1 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(
                66910 as i64 as strnumber,
                74 as i32 as quarterword,
                7892334 as i64 as halfword,
            )?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(
                66911 as i64 as strnumber,
                74 as i32 as quarterword,
                7892339 as i64 as halfword,
            )?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(
                66912 as i64 as strnumber,
                74 as i32 as quarterword,
                7892341 as i64 as halfword,
            )?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(
                66913 as i64 as strnumber,
                74 as i32 as quarterword,
                7892342 as i64 as halfword,
            )?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(
                66914 as i64 as strnumber,
                74 as i32 as quarterword,
                7892343 as i64 as halfword,
            )?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(
                66915 as i64 as strnumber,
                74 as i32 as quarterword,
                7892340 as i64 as halfword,
            )?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(
                66916 as i64 as strnumber,
                74 as i32 as quarterword,
                7892344 as i64 as halfword,
            )?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(
                66917 as i64 as strnumber,
                74 as i32 as quarterword,
                7892347 as i64 as halfword,
            )?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(
                66918 as i64 as strnumber,
                74 as i32 as quarterword,
                7892348 as i64 as halfword,
            )?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(
                66919 as i64 as strnumber,
                74 as i32 as quarterword,
                7892349 as i64 as halfword,
            )?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(
                66920 as i64 as strnumber,
                74 as i32 as quarterword,
                7892350 as i64 as halfword,
            )?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(66761 as i64 as strnumber, 59 as i32 as quarterword, 44 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(66762 as i64 as strnumber, 59 as i32 as quarterword, 45 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(66921 as i64 as strnumber, 33 as i32 as quarterword, 6 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(66922 as i64 as strnumber, 33 as i32 as quarterword, 7 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(66923 as i64 as strnumber, 33 as i32 as quarterword, 10 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(66924 as i64 as strnumber, 33 as i32 as quarterword, 11 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(66933 as i64 as strnumber, 107 as i32 as quarterword, 2 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(66935 as i64 as strnumber, 98 as i32 as quarterword, 1 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(66164 as i64 as strnumber, 105 as i32 as quarterword, 1 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(
                66936 as i64 as strnumber,
                108 as i32 as quarterword,
                17 as i32,
            )?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(
                66937 as i64 as strnumber,
                108 as i32 as quarterword,
                18 as i32,
            )?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(
                66938 as i64 as strnumber,
                108 as i32 as quarterword,
                19 as i32,
            )?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(
                66939 as i64 as strnumber,
                108 as i32 as quarterword,
                20 as i32,
            )?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(66623 as i64 as strnumber, 95 as i32 as quarterword, 8 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(66945 as i64 as strnumber, 71 as i32 as quarterword, 67 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(66946 as i64 as strnumber, 71 as i32 as quarterword, 68 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(66947 as i64 as strnumber, 71 as i32 as quarterword, 69 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(66948 as i64 as strnumber, 71 as i32 as quarterword, 70 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(66952 as i64 as strnumber, 71 as i32 as quarterword, 25 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(66953 as i64 as strnumber, 71 as i32 as quarterword, 26 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(66954 as i64 as strnumber, 71 as i32 as quarterword, 63 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(66955 as i64 as strnumber, 71 as i32 as quarterword, 64 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(66956 as i64 as strnumber, 71 as i32 as quarterword, 65 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(66957 as i64 as strnumber, 71 as i32 as quarterword, 66 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(66958 as i64 as strnumber, 18 as i32 as quarterword, 5 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(66959 as i64 as strnumber, 113 as i32 as quarterword, 5 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(66960 as i64 as strnumber, 113 as i32 as quarterword, 6 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(66961 as i64 as strnumber, 113 as i32 as quarterword, 7 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(66962 as i64 as strnumber, 113 as i32 as quarterword, 8 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(66963 as i64 as strnumber, 113 as i32 as quarterword, 9 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(66968 as i64 as strnumber, 24 as i32 as quarterword, 2 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(66969 as i64 as strnumber, 24 as i32 as quarterword, 3 as i32)?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(
                66970 as i64 as strnumber,
                85 as i32 as quarterword,
                1206563 as i64 as halfword,
            )?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(
                66971 as i64 as strnumber,
                85 as i32 as quarterword,
                1206564 as i64 as halfword,
            )?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(
                66972 as i64 as strnumber,
                85 as i32 as quarterword,
                1206565 as i64 as halfword,
            )?;
        (&mut *(self as *mut PortableTexEngine<'_>))
            .zprimitive(
                66973 as i64 as strnumber,
                85 as i32 as quarterword,
                1206566 as i64 as halfword,
            )?;
        if *self.state.buffer.offset(self.state.curinput.locfield as isize) == 42 as i32
        {
            self.state.curinput.locfield += 1;
        }
        self.state.eTeXmode = 1 as eightbits;
        self.state.maxregnum = 32767 as i32 as halfword;
        self.state.maxreghelpline = 66965 as i64 as strnumber;
        Ok(())
    }

    pub fn begin_primary_input(self: &mut Self, name: &str, bytes: Vec<u8>) -> bool {
        // Catch point: `begin_primary_input_raw` now propagates aborts as
        // `Err(EngineAbort)` (it threads `beginfilereading`/`firmuptheline`).
        // The public API stays a plain `bool`, so consume the `Result` here: an
        // abort during input setup means the input could not be started.
        self.last_abort_status = None;
        self.last_error_message = None;
        match unsafe { self.begin_primary_input_raw(name, bytes) } {
            Ok(started) => started != 0,
            Err(EngineBreak::Abort(EngineAbort { status })) => {
                self.last_abort_status = Some(status);
                false
            }
            Err(EngineBreak::Error(error)) => {
                self.last_error_message = Some(error.message);
                false
            }
        }
    }

    pub fn run_main_control(self: &mut Self) -> bool {
        self.catch_engine_abort(|engine| unsafe { engine.maincontrol() })
    }

    pub fn run_format_initialization(self: &mut Self) -> bool {
        self.format_initialization = true;
        let completed = self.catch_engine_abort(|engine| unsafe { engine.maincontrol() });
        self.format_initialization = false;
        completed
    }

    pub fn begin_fragment_capture(self: &mut Self) {
        self.fragment_capture_enabled = true;
        self.captured_fragment_root = None;
        // Record indices in marker nodes are per fragment, a reused engine must not accumulate.
        self.hostbox_records.clear();
    }

    pub fn end_fragment_capture(self: &mut Self) {
        self.fragment_capture_enabled = false;
    }

    fn catch_engine_abort<F>(self: &mut Self, run: F) -> bool
    where
        F: FnOnce(&mut Self) -> EngineFlow<()>,
    {
        // Non-unwinding abort boundary. The driver closure threads any fatal
        // `jump_out`/`fatal_error`/`overflow` back as `Err(EngineAbort)` via the
        // `?` operator instead of `panic_any`, so the engine runs under
        // `panic=abort`. Status mapping is identical to the old `catch_unwind`
        // path: status 0 (normal `\end`/dump) => "completed"; nonzero => abort.
        self.last_abort_status = None;
        self.last_error_message = None;
        match run(self) {
            Ok(()) => self.last_abort_status.is_none(),
            Err(EngineBreak::Abort(EngineAbort { status: 0 })) => {
                self.last_abort_status = None;
                true
            }
            Err(EngineBreak::Abort(EngineAbort { status })) => {
                self.last_abort_status = Some(status);
                false
            }
            // A surfaced TeX error (or sandbox violation): record its message so
            // the host can report it, and treat the run as not completed.
            Err(EngineBreak::Error(error)) => {
                self.last_error_message = Some(error.message);
                false
            }
        }
    }

    pub fn snapshot_format(&self) -> PortableFormatImage {
        PortableFormatImage::from_engine_state(self.state.as_ref())
    }

    /// Consume this engine and seal its state *in place* as a format snapshot,
    /// moving the `Box<PortableTexState>` instead of deep-cloning it the way
    /// [`Self::snapshot_format`] does. Building a format cache normally holds the
    /// freshly-initialized engine (~hundreds of MB of `mem`/`eqtb`/`hash`) and a
    /// full clone of it at the same time — a transient ~2x spike. When the caller
    /// owns the engine and discards it right after snapshotting (the
    /// `GeneratedFormatCache::initialized` / preload paths), moving the state
    /// avoids the clone and halves that peak.
    #[must_use]
    pub fn into_format(self) -> PortableFormatImage {
        // NOTE: do NOT `finalize_trie()` here. `into_format` is also used for the
        // base format that further packages (`\patterns`) are loaded on top of;
        // packing the trie is a one-way door ("! Too late for \patterns"). Callers
        // that have produced the *final* format call `finalize_trie()` explicitly
        // first (see `generated_format_for`, wasm `build_format`).
        let mut state = self.state;
        state.seal_as_format_snapshot();
        PortableFormatImage::from_sealed_state(state)
    }

    /// Pack the hyphenation trie now, so its construction scratch can be freed
    /// when the format is sealed. This engine packs the trie lazily on the first
    /// runtime hyphenation (`inittrie` is a no-op while `format_initialization`);
    /// doing it here — once the *final* format is built, exactly like TeX's
    /// `\dump` — yields an identical packed trie and lets `seal_as_format_snapshot`
    /// drop the ~24 MB of builder scratch arrays. Only call this when no further
    /// `\patterns` will be loaded.
    pub fn finalize_trie(self: &mut Self) {
        // Only when the trie is unpacked AND its scratch is still present.
        if self.state.trienotready != 0 && !self.state.triehash.is_null() {
            let saved = self.format_initialization;
            self.format_initialization = false;
            let _ = unsafe { self.inittrie() };
            self.format_initialization = saved;
        }
    }

    pub fn resource_request_count(&self) -> usize {
        self.resource_requests
    }

    pub fn resource_request_records(&self) -> &[PortableResourceRequestRecord] {
        self.resource_request_records.as_slice()
    }

    pub fn transcript_bytes(&self) -> &[u8] {
        self.transcript_bytes.as_slice()
    }

    /// The interned span keyed to the primary input's source name, if any —
    /// the first recorded span whose name is the primary input file.
    pub fn primary_input_source_span(&self) -> Option<PortableSourceSpan> {
        if !self.state.source_tracking {
            return None;
        }
        let primary = self.state.src_primary_name;
        let raw = self
            .state
            .src_spans
            .iter()
            .find(|raw| raw.name == primary)?;
        let name = unsafe { self.pool_string(raw.name) }?;
        Some(PortableSourceSpan {
            name,
            start: raw.start,
            end: raw.end,
            role: raw.role,
        })
    }

    /// Stamped node→span pairs. The `node_src` shadow is paged-sparse and not
    /// cheaply enumerable by node address, so callers that need per-node spans
    /// use [`Self::resolve_node_src`] / `snapshot_node` on the live node graph;
    /// this restored accessor returns an empty slice rather than scanning `mem`.
    pub fn node_source_spans(&self) -> &[PortableNodeSourceSpan] {
        &[]
    }

    pub fn stripped_page_build_count(&self) -> usize {
        self.stripped_page_builds
    }

    pub fn stripped_shipout_count(&self) -> usize {
        self.stripped_shipouts
    }

    pub fn stripped_special_output_count(&self) -> usize {
        self.stripped_special_outputs
    }

    pub fn stripped_picture_load_count(&self) -> usize {
        self.stripped_picture_loads
    }

    pub fn stripped_source_special_count(&self) -> usize {
        self.stripped_source_specials
    }

    pub fn stripped_write_whatsit_diagnostic_count(&self) -> usize {
        self.stripped_write_whatsit_diagnostics
    }

    pub fn stripped_pdf_extension_count(&self) -> usize {
        self.stripped_pdf_extensions
    }

    pub fn stripped_page_top_prune_count(&self) -> usize {
        self.stripped_page_top_prunes
    }

    pub fn last_stripped_shipout_box(&self) -> Option<PortableNodeHandle> {
        self.last_stripped_shipout_box
    }

    pub fn captured_fragment_root(&self) -> Option<PortableNodeHandle> {
        self.captured_fragment_root
    }

    /// Host box render payload by record index, as referenced by `HostBoxRef` marker nodes.
    pub fn host_box_record(&self, index: usize) -> Option<&PortableHostBox> {
        self.hostbox_records.get(index)
    }

    /// At-size (scaled points) a font was loaded at, by internal font number.
    /// Used by the IR builder to carry the real glyph-run font size.
    pub fn font_at_size(&self, font: integer) -> integer {
        if font < 0 {
            return 0;
        }
        self.state
            .fontsize_storage
            .get(font as usize)
            .copied()
            .unwrap_or(0)
    }

    /// The interned `\font` name for a font number. For native fonts this is the
    /// XeTeX spec the font was loaded with (e.g.
    /// `[latinmodern-math.otf]:script=math;ssty=1`); for TFM fonts it is the
    /// `.tfm` name. Lets the IR carry a real font identity so a renderer can
    /// resolve per-run glyph outlines to the originating font file.
    pub fn font_name(&self, font: integer) -> Option<String> {
        if font < 0 {
            return None;
        }
        let name = self.state.fontname_storage.get(font as usize).copied()?;
        // SAFETY: decodes the engine string pool, identical to every other
        // `pool_string` read elsewhere in the boundary layer.
        unsafe { self.pool_string(name) }
    }

    /// The `\font` spec a native font number was loaded with, recovered from the
    /// font platform (`[file]:features`). For native fonts this is the reliable
    /// identity (TFM `\fontname` is empty for them). Read-only.
    pub fn native_font_spec(&self, font: integer) -> Option<String> {
        let handle = Self::font_handle_for_number(self, font)?;
        self.fonts.font_spec(handle)
    }

    /// Snapshot the native-font table `(handle, spec, size)` from the attached
    /// font platform, for packaging alongside a serialized format image.
    pub fn native_font_table(&self) -> Vec<(PortableFontHandle, String, i32)> {
        self.fonts.font_table()
    }

    /// Re-bind native fonts on a cold-loaded format image: rebuilds the attached
    /// platform's handle→font map from a [`Self::native_font_table`] snapshot so
    /// the `fontlayoutengine` handles preserved in the image resolve again.
    /// Returns `false` if any font failed to reload.
    pub fn restore_native_font_table(
        self: &mut Self,
        table: &[(PortableFontHandle, String, i32)],
    ) -> bool {
        self.fonts.restore_font_table(table)
    }

    pub fn last_abort_status(&self) -> Option<integer> {
        self.last_abort_status
    }

    /// The message from the most recent surfaced [`EngineError`], if the last
    /// run failed with a TeX error (rather than a fatal abort). `None` after a
    /// clean run or a bare abort.
    pub fn last_error_message(&self) -> Option<&str> {
        self.last_error_message.as_deref()
    }

    /// Enable/disable the fragment sandbox (see [`PortableTexEngine::sandbox`]),
    /// resetting the per-run bookkeeping so each render starts clean. Uses the
    /// `self: &mut Self` receiver form the patcher's passes expect for prelude
    /// methods (the `&mut self` shorthand gets its receiver stripped).
    pub fn set_sandbox(self: &mut Self, on: bool) {
        self.sandbox = on;
        self.sandbox_math_depth = 0;
        self.sandbox_math_opened = false;
        self.sandbox_ops = 0;
    }

    /// Extract the message from the most recent `! ...` line in the transcript --
    /// what `error()` printed for the diagnostic now being surfaced -- trimming
    /// the trailing period `error()` appends. Diagnostics are printed with
    /// `selector = term_and_log`, so each byte reaches the transcript twice (the
    /// headless terminal and the log both feed it); [`collapse_doubled_line`]
    /// undoes that. Returns a generic label if no well-formed error line exists.
    pub(crate) fn capture_last_error_message(&self) -> String {
        let transcript = core::str::from_utf8(&self.transcript_bytes).unwrap_or("");
        for raw in transcript.lines().rev() {
            let collapsed = collapse_doubled_line(raw.trim());
            let line = collapsed.as_deref().unwrap_or(raw).trim();
            if let Some(rest) = line.strip_prefix("! ") {
                return rest.trim_end_matches('.').trim().into();
            }
        }
        "TeX error".into()
    }

    pub fn snapshot_node(&self, handle: PortableNodeHandle) -> Option<PortableNodeSnapshot> {
        let node = handle.0 as halfword;
        let word = self.node_word(node, 0)?;
        let raw_kind = unsafe { word.hh.u.B0 as i32 };
        let subtype = unsafe { word.hh.u.B1 as i32 };
        let kind = self.node_kind(raw_kind, node, subtype);
        let link = self.node_link(node);
        let is_character = node >= self.state.himemmin;
        let native_word4 = if matches!(kind, PortableNodeKind::NativeWord | PortableNodeKind::NativeGlyph) {
            self.node_word(node, 4)
        } else {
            None
        };
        let font = if is_character {
            raw_kind
        } else {
            native_word4.map_or(0, |word| unsafe { word.v.QQQQ.u.B1 as i32 })
        };
        let character = if is_character {
            subtype
        } else if matches!(kind, PortableNodeKind::HostBoxRef) {
            // Host box markers carry their record index in the payload word after the metrics.
            self.node_word(node, 4).map_or(0, |word| unsafe { word.u.CINT })
        } else {
            native_word4.map_or(0, |word| unsafe { word.v.QQQQ.u.B2 as i32 })
        };
        let (width, height, depth, shift, list) = match raw_kind {
            _ if is_character => (
                self.character_width(font, character).unwrap_or_default(),
                0,
                0,
                0,
                None,
            ),
            0 | 1 | 13 => (
                self.node_scaled(node, 1).unwrap_or_default(),
                self.node_scaled(node, 3).unwrap_or_default(),
                self.node_scaled(node, 2).unwrap_or_default(),
                self.node_scaled(node, 4).unwrap_or_default(),
                self.node_field_link(node, 5),
            ),
            2 => (
                self.node_scaled(node, 1).unwrap_or_default(),
                self.node_scaled(node, 3).unwrap_or_default(),
                self.node_scaled(node, 2).unwrap_or_default(),
                0,
                None,
            ),
            10 => (
                self.glue_amount(node).unwrap_or_default(),
                0,
                0,
                0,
                None,
            ),
            11 => (
                self.node_scaled(node, 1).unwrap_or_default(),
                0,
                0,
                0,
                None,
            ),
            8 if matches!(
                kind,
                PortableNodeKind::NativeWord
                    | PortableNodeKind::NativeGlyph
                    | PortableNodeKind::HostBoxRef
            ) => (
                self.node_scaled(node, 1).unwrap_or_default(),
                self.node_scaled(node, 3).unwrap_or_default(),
                self.node_scaled(node, 2).unwrap_or_default(),
                0,
                None,
            ),
            _ => (0, 0, 0, 0, None),
        };
        let native_glyphs = if matches!(kind, PortableNodeKind::NativeWord | PortableNodeKind::NativeGlyph) {
            self.native_glyph_infos
                .get(&node)
                .map(|info| info.glyphs.clone())
                .unwrap_or_default()
        } else {
            Vec::new()
        };

        // Box glue-set state (`hlist_out`/`vlist_out` read these to turn each
        // glue node's natural width into its SET width): `glue_set` is the float
        // ratio from `hpack`/`vpack`, `glue_sign` (0 normal / 1 stretching /
        // 2 shrinking) and `glue_order` (0..3) select which order participates.
        let (glue_set, glue_sign, glue_order) = match raw_kind {
            0 | 1 | 13 => (
                self.node_word(node, 6).map_or(0.0, |word| unsafe { word.gr }),
                self.node_word(node, 5)
                    .map_or(0, |word| unsafe { word.hh.u.B0 as i32 }),
                self.node_word(node, 5)
                    .map_or(0, |word| unsafe { word.hh.u.B1 as i32 }),
            ),
            _ => (0.0, 0, 0),
        };
        // Glue node's spec stretch/shrink and their orders (raw_kind 10).
        let (glue_stretch, glue_shrink, glue_stretch_order, glue_shrink_order) = if raw_kind == 10 {
            match self.node_word(node, 1).map(|word| unsafe { word.hh.v.LH }) {
                Some(spec) => (
                    self.node_scaled(spec, 2).unwrap_or_default(),
                    self.node_scaled(spec, 3).unwrap_or_default(),
                    self.node_word(spec, 0)
                        .map_or(0, |word| unsafe { word.hh.u.B0 as i32 }),
                    self.node_word(spec, 0)
                        .map_or(0, |word| unsafe { word.hh.u.B1 as i32 }),
                ),
                None => (0, 0, 0, 0),
            }
        } else {
            (0, 0, 0, 0)
        };

        Some(PortableNodeSnapshot {
            handle,
            kind,
            subtype,
            source: self.resolve_node_src(node),
            link,
            font,
            character,
            width,
            height,
            depth,
            shift,
            list,
            native_glyphs,
            glue_set,
            glue_sign,
            glue_order,
            glue_stretch,
            glue_shrink,
            glue_stretch_order,
            glue_shrink_order,
        })
    }

    fn node_kind(&self, raw_kind: i32, node: halfword, subtype: i32) -> PortableNodeKind {
        if node >= self.state.himemmin {
            return PortableNodeKind::Character;
        }

        match raw_kind {
            0 => PortableNodeKind::HorizontalBox,
            1 => PortableNodeKind::VerticalBox,
            2 => PortableNodeKind::Rule,
            3 => PortableNodeKind::Insertion,
            4 => PortableNodeKind::Mark,
            5 => PortableNodeKind::Adjustment,
            6 => PortableNodeKind::Ligature,
            7 => PortableNodeKind::Discretionary,
            8 if matches!(subtype, 40 | 41) => PortableNodeKind::NativeWord,
            8 if subtype == 42 => PortableNodeKind::NativeGlyph,
            8 if subtype == HOST_BOX_RESOLVED_SUBTYPE as i32 => PortableNodeKind::HostBoxRef,
            8 if matches!(subtype, 0 | 1 | 2 | 3) => PortableNodeKind::OutputWhatsit,
            8 => PortableNodeKind::Whatsit,
            9 => PortableNodeKind::Math,
            10 => PortableNodeKind::Glue,
            11 => PortableNodeKind::Kern,
            12 => PortableNodeKind::Penalty,
            13 => PortableNodeKind::UnsetBox,
            16 => PortableNodeKind::Noad,
            14 => PortableNodeKind::Style,
            15 => PortableNodeKind::Choice,
            other => PortableNodeKind::Unknown(other),
        }
    }

    pub(crate) fn copy_native_glyph_info(
        this: &mut Self,
        src: halfword,
        dest: halfword,
    ) -> quarterword {
        if let Some(info) = this.native_glyph_infos.get(&src).cloned() {
            let glyph_count = info.glyphs.len().min(i32::MAX as usize) as quarterword;
            this.native_glyph_infos.insert(dest, info);
            glyph_count
        } else {
            this.native_glyph_infos.remove(&dest);
            0
        }
    }

    fn font_handle_for_number(this: &Self, font: integer) -> Option<FontHandle> {
        if font < 0 || this.state.fontlayoutengine.is_null() {
            return None;
        }
        let handle = unsafe { *this.state.fontlayoutengine.offset(font as isize) as FontHandle };
        (handle != 0).then_some(handle)
    }

    unsafe fn node_index_for_pointer(
        engine: &PortableTexEngine<'_>,
        node: voidpointer,
    ) -> Option<halfword> {
        if node.is_null() || engine.state.zmem.is_null() {
            return None;
        }
        let base = engine.state.zmem as isize;
        let address = node as isize;
        let word_size = core::mem::size_of::<memoryword>() as isize;
        if word_size == 0 || address < base {
            return None;
        }
        let bytes = address - base;
        if bytes % word_size != 0 {
            return None;
        }
        let index = (bytes / word_size) as halfword;
        if index < engine.state.memmin || index > engine.state.memmax {
            None
        } else {
            Some(index)
        }
    }

    unsafe fn native_node_font(mem: *mut memoryword, node: halfword) -> integer {
        (*mem.offset((node + 4) as isize)).v.QQQQ.u.B1 as integer
    }

    unsafe fn native_node_text<'a>(mem: *mut memoryword, node: halfword) -> &'a [u16] {
        let len = (*mem.offset((node + 4) as isize)).v.QQQQ.u.B2.max(0) as usize;
        if len == 0 {
            return &[];
        }
        core::slice::from_raw_parts(
            mem.offset((node + native_node_size) as isize) as *const memoryword as *const u16,
            len,
        )
    }

    unsafe fn write_native_node_metrics(
        mem: *mut memoryword,
        node: halfword,
        width: i32,
        height: i32,
        depth: i32,
    ) {
        (*mem.offset((node + 1) as isize)).u.CINT = width;
        (*mem.offset((node + 2) as isize)).u.CINT = depth;
        (*mem.offset((node + 3) as isize)).u.CINT = height;
    }

    fn node_word(&self, node: halfword, offset: halfword) -> Option<memoryword> {
        let index = node.checked_add(offset)?;
        if node as i64 == -(268435455 as i64) {
            return None;
        }
        if self.state.zmem.is_null() || index < self.state.memmin || index > self.state.memmax {
            return None;
        }
        unsafe { Some(*self.state.zmem.offset(index as isize)) }
    }

    fn node_link(&self, node: halfword) -> Option<PortableNodeHandle> {
        let word = self.node_word(node, 0)?;
        let link = unsafe { word.hh.v.RH };
        Self::node_handle_from_raw(link)
    }

    fn node_field_link(&self, node: halfword, offset: halfword) -> Option<PortableNodeHandle> {
        let word = self.node_word(node, offset)?;
        let link = unsafe { word.hh.v.RH };
        Self::node_handle_from_raw(link)
    }

    fn node_scaled(&self, node: halfword, offset: halfword) -> Option<i32> {
        let word = self.node_word(node, offset)?;
        Some(unsafe { word.u.CINT })
    }

    fn glue_amount(&self, node: halfword) -> Option<i32> {
        let word = self.node_word(node, 1)?;
        let glue_spec = unsafe { word.hh.v.LH };
        self.node_scaled(glue_spec, 1)
    }

    fn character_width(&self, font: i32, character: i32) -> Option<i32> {
        if font < 0
            || character < 0
            || self.state.fontinfo.is_null()
            || self.state.charbase.is_null()
            || self.state.widthbase.is_null()
        {
            return None;
        }
        let char_info_index = unsafe {
            *self.state.charbase.offset(font as isize) + character
        };
        let char_info = unsafe {
            (*self.state.fontinfo.offset(char_info_index as isize)).v.QQQQ
        };
        let width_index = unsafe {
            *self.state.widthbase.offset(font as isize) as i32 + char_info.u.B0 as i32
        };
        Some(unsafe { (*self.state.fontinfo.offset(width_index as isize)).u.CINT })
    }

    fn node_handle_from_raw(raw: halfword) -> Option<PortableNodeHandle> {
        if raw as i64 == -(268435455 as i64) {
            None
        } else {
            Some(PortableNodeHandle(raw))
        }
    }


    pub(crate) fn is_xetex(&self) -> bool {
        self.profile.xetex
    }

    pub(crate) fn supports_etex(&self) -> bool {
        self.profile.etex
    }

    pub(crate) fn supports_unicode_scalars(&self) -> bool {
        self.profile.unicode_scalars
    }

    pub(crate) fn supports_unicode_math(&self) -> bool {
        self.profile.unicode_math
    }

    pub(crate) fn supports_native_fonts(&self) -> bool {
        self.profile.native_fonts
    }

    pub(crate) unsafe fn getinputnormalizationstate(&self) -> integer {
        if !self.is_xetex() {
            return 0;
        }
        let eqtb = self.state.zeqtb.as_mut_ptr();
        if eqtb.is_null() {
            return 0;
        }
        (*eqtb.offset(7892344 as i64 as isize)).u.CINT
    }

    pub(crate) unsafe fn gettracingfontsstate(&self) -> integer {
        if !self.is_xetex() {
            return 0;
        }
        let eqtb = self.state.zeqtb.as_mut_ptr();
        if eqtb.is_null() {
            return 0;
        }
        (*eqtb.offset(7892347 as i64 as isize)).u.CINT
    }

    unsafe fn current_resource_name(engine: *mut PortableTexEngine<'_>) -> Option<String> {
        let engine = engine.as_ref()?;
        if engine.state.nameoffile.is_null() || engine.state.namelength <= 0 {
            return None;
        }

        let mut bytes = Vec::with_capacity(engine.state.namelength as usize);
        for index in 1..=engine.state.namelength {
            let value = *engine.state.nameoffile.offset(index as isize);
            if value <= 0 {
                continue;
            }
            bytes.push(value as u8);
        }
        Some(String::from_utf8_lossy(bytes.as_slice()).into_owned())
    }

    /// Resolve the `\XeTeXinputencoding "<name>"` encoding just scanned into
    /// `nameoffile`, returning the XeTeX mode (AUTO=0, UTF8=1, UTF16BE=2,
    /// UTF16LE=3, RAW=4) and zeroing `*info`. Faithful port of XeTeX's
    /// `getencodingmodeandinfo` (`XeTeX_ext.c`), minus ICU: unknown names degrade
    /// to RAW (read as raw bytes) rather than opening an ICU converter.
    pub(crate) unsafe fn get_encoding_mode_and_info(
        engine: *mut PortableTexEngine<'_>,
        info: *mut integer,
    ) -> integer {
        if !info.is_null() {
            *info = 0;
        }
        let name = Self::current_resource_name(engine).unwrap_or_default();
        let lowered = name.trim().to_ascii_lowercase();
        match lowered.as_str() {
            "auto" => 0,                       // AUTO
            "utf8" | "utf-8" => 1,             // UTF8
            // `utf16` is host-endian; treat as big-endian (xetex default name).
            "utf16" | "utf-16" | "utf16be" | "utf-16be" => 2, // UTF16BE
            "utf16le" | "utf-16le" => 3,       // UTF16LE
            "bytes" => 4,                      // RAW
            // Unknown / ICU encoding names: read as raw bytes (no ICU support).
            _ => 4,
        }
    }

    unsafe fn mode_string(mode: const_string) -> String {
        if mode.is_null() {
            return String::new();
        }

        let mut bytes = Vec::new();
        let mut cursor = mode;
        while *cursor != 0 {
            bytes.push(*cursor as u8);
            cursor = cursor.add(1);
        }
        String::from_utf8_lossy(bytes.as_slice()).into_owned()
    }

    unsafe fn pool_string(&self, string: strnumber) -> Option<String> {
        if string < 0 || self.state.strstart.is_null() || self.state.strpool.is_null() {
            return None;
        }
        let index = Self::pool_string_index(string)?;
        let start = *self.state.strstart.offset(index);
        let end = *self.state.strstart.offset(index + 1);
        if start < 0 || end < start {
            return None;
        }

        let len = usize::try_from(end - start).ok()?;
        let mut units = Vec::with_capacity(len);
        for offset in 0..len {
            units.push(*self.state.strpool.offset((start as usize + offset) as isize));
        }
        Some(
            char::decode_utf16(units)
                .map(|codepoint| codepoint.unwrap_or(char::REPLACEMENT_CHARACTER))
                .collect(),
        )
    }

    pub(crate) fn pool_string_index(string: strnumber) -> Option<isize> {
        if string < 0 {
            return None;
        }
        let index = if string >= 65536 { string - 65536 } else { string };
        isize::try_from(index).ok()
    }

    fn resource_kind(name: &str, format: integer) -> ResourceKind {
        match format {
            resource_format_tex_input | 0 => Self::tex_resource_kind(name),
            resource_format_tfm | resource_format_font => ResourceKind::Font,
            resource_format_encoding => ResourceKind::Encoding,
            resource_format_font_map => ResourceKind::Map,
            resource_format_config => ResourceKind::Config,
            resource_format_format_image => ResourceKind::FormatImage,
            other => ResourceKind::Other(other),
        }
    }

    fn tex_resource_kind(name: &str) -> ResourceKind {
        let name = name.rsplit(['/', '\\']).next().unwrap_or(name);
        let name = name.to_ascii_lowercase();
        if name.ends_with(".sty") {
            return ResourceKind::Package;
        }
        if name.ends_with(".cls") {
            return ResourceKind::Class;
        }
        if name.ends_with(".fd") {
            return ResourceKind::FontDefinition;
        }
        if name.ends_with(".clo")
            || name.ends_with(".def")
            || name.ends_with(".ldf")
            || name.ends_with(".cfg")
        {
            return ResourceKind::PackageSupport;
        }
        ResourceKind::TexInput
    }

    fn resource_kind_for_open(
        engine: &PortableTexEngine<'_>,
        name: &str,
        format: integer,
    ) -> ResourceKind {
        let kind = Self::resource_kind(name, format);
        if kind == ResourceKind::TexInput
            && Self::active_package_owner(engine).is_some()
            && Self::looks_like_package_asset(name)
        {
            ResourceKind::Asset
        } else {
            kind
        }
    }

    fn resource_package_owner(
        engine: &PortableTexEngine<'_>,
        name: &str,
        kind: ResourceKind,
    ) -> Option<String> {
        match kind {
            ResourceKind::Package | ResourceKind::Class => Self::resource_stem(name),
            ResourceKind::PackageSupport | ResourceKind::FontDefinition | ResourceKind::Asset => {
                Self::active_package_owner(engine)
            }
            _ => None,
        }
    }

    fn active_package_owner(engine: &PortableTexEngine<'_>) -> Option<String> {
        engine.current_input_package_owner.clone()
    }

    fn looks_like_package_asset(name: &str) -> bool {
        let name = name.rsplit(['/', '\\']).next().unwrap_or(name);
        let name = name.to_ascii_lowercase();
        !(name.ends_with(".tex")
            || name.ends_with(".ltx")
            || name.ends_with(".sty")
            || name.ends_with(".cls")
            || name.ends_with(".fd")
            || name.ends_with(".clo")
            || name.ends_with(".def")
            || name.ends_with(".ldf")
            || name.ends_with(".cfg"))
    }

    fn resource_stem(name: &str) -> Option<String> {
        let name = name.rsplit(['/', '\\']).next().unwrap_or(name);
        let stem = name.rsplit_once('.').map_or(name, |(stem, _)| stem);
        if stem.is_empty() {
            None
        } else {
            Some(stem.to_string())
        }
    }

    fn source_index(value: usize) -> u32 {
        value.min(u32::MAX as usize) as u32
    }

    fn virtual_file_key(name: &str) -> String {
        let mut name = name;
        while let Some(stripped) = name.strip_prefix("./") {
            name = stripped;
        }
        name.to_string()
    }

    fn normalized_runtime_resource_name(mut name: &str) -> &str {
        while let Some(stripped) = name.strip_prefix("./") {
            name = stripped;
        }
        name
    }

    // Hand-edited bridge: returns `EngineFlow<Option<strnumber>>` so the final
    // `makestring` (abort-reachable on pool overflow) propagates via `?`, while
    // the internal `Option` early-returns (a `None` means "did not intern", not
    // an abort) stay explicit `Ok(None)`. The `?`-on-`Option` shorthand used
    // before would not survive the return-type change, so this one is NOT
    // auto-rewritten by the flow pass.
    unsafe fn intern_static_pool_string(
        engine: &mut PortableTexEngine<'_>,
        text: &str,
    ) -> EngineFlow<Option<strnumber>> {
        if engine.state.strpool.is_null() || engine.state.strstart.is_null() {
            return Ok(None);
        }

        let Ok(needed) = integer::try_from(text.encode_utf16().count()) else {
            return Ok(None);
        };
        let Some(next_pool) = engine.state.poolptr.checked_add(needed) else {
            return Ok(None);
        };
        if next_pool > engine.state.poolsize {
            return Ok(None);
        }

        for unit in text.encode_utf16() {
            *engine.state.strpool.offset(engine.state.poolptr as isize) = unit as packedUTF16code;
            engine.state.poolptr += 1;
        }

        Ok(Some(engine.makestring()?))
    }

    unsafe fn append_text_to_pool(engine: &mut PortableTexEngine<'_>, text: &str) -> boolean {
        if engine.state.strpool.is_null() {
            return false_0;
        }
        let needed = match integer::try_from(text.encode_utf16().count()) {
            Ok(needed) => needed,
            Err(_) => return false_0,
        };
        let Some(next_pool) = engine.state.poolptr.checked_add(needed) else {
            return false_0;
        };
        if next_pool > engine.state.poolsize {
            return false_0;
        }
        for unit in text.encode_utf16() {
            *engine.state.strpool.offset(engine.state.poolptr as isize) = unit as packedUTF16code;
            engine.state.poolptr += 1;
        }
        true_0
    }

    unsafe fn resource_bytes_for_name(
        engine: &mut PortableTexEngine<'_>,
        name: &str,
    ) -> Option<Vec<u8>> {
        let name = Self::normalized_runtime_resource_name(name);
        let kind = Self::resource_kind_for_open(engine, name, resource_format_tex_input);
        let package = Self::resource_package_owner(engine, name, kind);
        let request = ResourceRequest {
            name,
            kind,
            package: package.as_deref(),
            format: resource_format_tex_input,
            mode: "rb",
            source: None,
        };
        let virtual_key = Self::virtual_file_key(name);
        if let Some(bytes) = engine.virtual_files.get(&virtual_key) {
            Some(bytes.clone())
        } else {
            engine.resources.read(request)
        }
    }

    pub(crate) unsafe fn boundary_get_file_size(
        engine: *mut PortableTexEngine<'_>,
        string: integer,
    ) {
        let Some(engine) = engine.as_mut() else {
            return;
        };
        let Some(name) = engine.pool_string(string as strnumber) else {
            return;
        };
        // expl3's file layer (`\file_full_name:n`) decides a file EXISTS solely
        // by whether `\filesize` expands to a non-empty value. We have no host
        // filesystem (wasm target): answer from the ResourceProvider. When the
        // provider serves the resource, report its real byte length; otherwise
        // (the in-memory job fragment we feed, which has no backing file, or a
        // probe for an asset we don't carry) report a nonzero placeholder so the
        // existence check still passes. Returning nothing here makes expl3
        // conclude the file is missing, which silently aborts data-file loads
        // like unicode-math's `\file_get {unicode-math-table.tex}`.
        const PLACEHOLDER_FILE_SIZE: usize = 4096;
        let size = Self::resource_bytes_for_name(engine, name.as_str())
            .map_or(PLACEHOLDER_FILE_SIZE, |bytes| bytes.len());
        Self::append_text_to_pool(engine, size.to_string().as_str());
    }

    pub(crate) unsafe fn load_pool_strings(
        engine: &mut PortableTexEngine<'_>,
        spare_size: integer,
    ) -> EngineFlow<integer> {
        if engine.state.strpool.is_null() || engine.state.strstart.is_null()
            || spare_size <= 0
        {
            return Ok(0);
        }
        let mut used = 0_i32;
        let mut last = 0_i32;
        for line in include_str!("../pool/xetex.pool").lines() {
            if line.starts_with('*') {
                break;
            }
            let bytes = line.as_bytes();
            let text = if bytes.len() >= 2 && bytes[0].is_ascii_digit()
                && bytes[1].is_ascii_digit()
            {
                &line[2..]
            } else {
                line
            };
            let units = text.encode_utf16().count().min(i32::MAX as usize) as integer;
            used = used.saturating_add(units);
            if used >= spare_size
                || engine.state.poolptr.saturating_add(units) > engine.state.poolsize
            {
                return Ok(0);
            }
            for unit in text.encode_utf16() {
                *engine.state.strpool.offset(engine.state.poolptr as isize) = unit
                    as packedUTF16code;
                engine.state.poolptr += 1;
            }
            last = engine.makestring()?;
        }
        Ok(last)
    }

    pub(crate) unsafe fn boundary_open_log_file(
        engine: *mut PortableTexEngine<'_>,
    ) -> EngineFlow<()> {
        let Some(engine) = engine.as_mut() else {
            return Ok(());
        };
        let old_setting = engine.state.selector;
        if engine.state.jobname == 0 {
            if let Some(jobname) = Self::intern_static_pool_string(engine, "texput")? {
                engine.state.jobname = jobname;
            }
        }
        engine.state.logopened = true_0 as boolean;
        engine.state.selector = (old_setting as i32 + 2).clamp(0, 21) as eightbits;
        Ok(())
    }

    pub(crate) unsafe fn boundary_jump_out(
        engine: *mut PortableTexEngine<'_>,
    ) -> EngineFlow<core::convert::Infallible> {
        // Status arithmetic is LOAD-BEARING and unchanged: history<=1 is the
        // normal `\end`/dump termination (status 0 => "completed"); anything
        // else is an error abort (status 1). Every passing conformance test
        // funnels its normal end through here, so this must stay byte-exact.
        let status = if let Some(engine) = engine.as_ref() {
            if engine.state.history as i32 <= 1 {
                0 as integer
            } else {
                1 as integer
            }
        } else {
            1 as integer
        };
        Self::abort_engine(engine, status)
    }

    pub(crate) unsafe fn boundary_shipout(
        engine: *mut PortableTexEngine<'_>,
        box_node: halfword,
    ) {
        if let Some(engine) = engine.as_mut() {
            engine.stripped_shipouts = engine.stripped_shipouts.saturating_add(1);
            engine.last_stripped_shipout_box = Some(PortableNodeHandle(box_node));
        }
    }

    pub(crate) unsafe fn boundary_capture_fragment_box(
        engine: *mut PortableTexEngine<'_>,
        box_node: halfword,
        mode: integer,
        boxcontext: integer,
    ) -> boolean {
        if let Some(engine) = engine.as_mut() {
            if engine.fragment_capture_enabled {
                engine.captured_fragment_root = Some(PortableNodeHandle(box_node));
                let absolute_mode = if mode >= 0 { mode } else { -mode };
                if absolute_mode == 1 && boxcontext < 1_073_741_824 {
                    return true_0;
                }
            }
        }
        false_0
    }

    pub(crate) unsafe fn boundary_build_page(
        engine: *mut PortableTexEngine<'_>,
    ) -> EngineFlow<()> {
        if let Some(engine) = engine.as_mut() {
            if engine.format_initialization
                && engine.state.curcmd as i32 == 15
                && engine.state.curchr == 1
            {
                // Dump during format build: status-0 abort (normal end of the
                // format-initialization run). Propagate via `?` so the engine
                // does not unwind.
                Self::abort_engine(engine as *mut PortableTexEngine<'_>, 0 as integer)?;
            }
            engine.stripped_page_builds = engine.stripped_page_builds.saturating_add(1);
        }
        Ok(())
    }

    pub(crate) unsafe fn boundary_prune_page_top(
        engine: *mut PortableTexEngine<'_>,
        node: halfword,
        _saving: boolean,
    ) -> halfword {
        if let Some(engine) = engine.as_mut() {
            engine.stripped_page_top_prunes =
                engine.stripped_page_top_prunes.saturating_add(1);
        }
        node
    }

    pub(crate) unsafe fn boundary_special_out(
        engine: *mut PortableTexEngine<'_>,
        node: halfword,
    ) -> EngineFlow<()> {
        let Some(engine) = engine.as_mut() else {
            return Ok(());
        };
        if node < engine.state.memmin || node > engine.state.memend {
            engine.stripped_special_outputs = engine
                .stripped_special_outputs
                .saturating_add(1);
            return Ok(());
        }
        let mem = engine.state.zmem.as_mut_ptr();
        if (*mem.offset(node as isize)).hh.u.B0 as i32 == 8 {
            match (*mem.offset(node as isize)).hh.u.B1 as i32 {
                0 => {
                    Self::boundary_open_write_whatsit(engine, node);
                    return Ok(());
                }
                1 => {
                    Self::boundary_write_whatsit(engine, node)?;
                    return Ok(());
                }
                2 => {
                    Self::boundary_close_write_whatsit(engine, node);
                    return Ok(());
                }
                _ => {}
            }
        }
        engine.stripped_special_outputs = engine
            .stripped_special_outputs
            .saturating_add(1);
        Ok(())
    }

    unsafe fn boundary_open_write_whatsit(engine: &mut PortableTexEngine<'_>, node: halfword) {
        let mem = engine.state.zmem.as_mut_ptr();
        let stream = (*mem.offset((node + 1) as isize)).hh.v.LH as usize;
        if stream >= 16 {
            return;
        }

        if engine.state.writeopen[stream] != 0 {
            Self::boundary_close_write_stream(engine, stream);
        }

        engine.state.curname = (*mem.offset((node + 1) as isize)).hh.v.RH as strnumber;
        engine.state.curarea = (*mem.offset((node + 2) as isize)).hh.v.LH as strnumber;
        engine.state.curext = (*mem.offset((node + 2) as isize)).hh.v.RH as strnumber;
        if engine.state.curext == 335 {
            engine.state.curext = 799;
        }
        engine.zpackfilename(engine.state.curname, engine.state.curarea, engine.state.curext);
        let Some(name) = Self::current_resource_name(engine as *mut PortableTexEngine<'_>) else {
            return;
        };
        let handle = Box::new(PortableFileHandle::new(
            name,
            ResourceKind::TexInput,
            None,
            resource_format_tex_input,
            Vec::new(),
        ));
        engine.state.writefile[stream] = Box::into_raw(handle);
        engine.state.writeopen[stream] = true_0;
    }

    unsafe fn boundary_write_whatsit(
        engine: &mut PortableTexEngine<'_>,
        node: halfword,
    ) -> EngineFlow<()> {
        let mem = engine.state.zmem.as_mut_ptr();
        let stream = (*mem.offset((node + 1) as isize)).hh.v.LH as usize;
        if stream >= 16 || engine.state.writeopen[stream] == 0 {
            return Ok(());
        }
        let write_tokens = engine.profile.write_token_constants();
        let q = engine.getavail()?;
        (*mem.offset(q as isize)).hh.v.LH = write_tokens.open_group_token;
        let r = engine.getavail()?;
        (*mem.offset(q as isize)).hh.v.RH = r;
        (*mem.offset(r as isize)).hh.v.LH = write_tokens.end_write_token;
        engine.zbegintokenlist(q, 4)?;
        engine.zbegintokenlist((*mem.offset((node + 1) as isize)).hh.v.RH, 15)?;
        let q = engine.getavail()?;
        (*mem.offset(q as isize)).hh.v.LH = write_tokens.close_group_token;
        engine.zbegintokenlist(q, 4)?;
        let old_mode = engine.state.curlist.modefield;
        engine.state.curlist.modefield = 0;
        engine.state.curcs = engine.state.writeloc;
        engine.zscantoks(false_0, true_0)?;
        engine.state.curlist.modefield = old_mode;
        engine.gettoken()?;
        if engine.state.curtok != write_tokens.end_write_token {
            while engine.state.curtok != write_tokens.end_write_token {
                engine.gettoken()?;
            }
        }
        engine.endtokenlist()?;
        let old_setting = engine.state.selector;
        engine.state.selector = stream as eightbits;
        engine.ztokenshow(engine.state.defref);
        engine.println();
        engine.state.selector = old_setting;
        engine.zflushlist(engine.state.defref);
        Ok(())
    }

    unsafe fn boundary_close_write_whatsit(engine: &mut PortableTexEngine<'_>, node: halfword) {
        let mem = engine.state.zmem.as_mut_ptr();
        let stream = (*mem.offset((node + 1) as isize)).hh.v.LH as usize;
        if stream < 16 {
            Self::boundary_close_write_stream(engine, stream);
        }
    }

    unsafe fn boundary_close_write_stream(engine: &mut PortableTexEngine<'_>, stream: usize) {
        if stream >= 16 || engine.state.writeopen[stream] == 0 {
            return;
        }
        let file = engine.state.writefile[stream];
        engine.state.writefile[stream] = core::ptr::null_mut();
        engine.state.writeopen[stream] = false_0;
        if file.is_null() {
            return;
        }
        let handle = Box::from_raw(file);
        let key = Self::virtual_file_key(handle.name.as_str());
        engine.virtual_files.insert(key, handle.bytes);
    }

    pub(crate) unsafe fn boundary_load_picture(
        engine: *mut PortableTexEngine<'_>,
        _is_pdf: boolean,
    ) {
        if let Some(engine) = engine.as_mut() {
            engine.stripped_picture_loads = engine.stripped_picture_loads.saturating_add(1);
        }
    }

    pub(crate) fn record_stripped_source_special(engine: *mut PortableTexEngine<'_>) {
        if let Some(engine) = unsafe { engine.as_mut() } {
            engine.stripped_source_specials = engine.stripped_source_specials.saturating_add(1);
        }
    }

    pub(crate) fn record_stripped_write_whatsit_diagnostic(engine: *mut PortableTexEngine<'_>) {
        if let Some(engine) = unsafe { engine.as_mut() } {
            engine.stripped_write_whatsit_diagnostics =
                engine.stripped_write_whatsit_diagnostics.saturating_add(1);
        }
    }

    pub(crate) fn record_stripped_pdf_extension(engine: *mut PortableTexEngine<'_>) {
        if let Some(engine) = unsafe { engine.as_mut() } {
            engine.stripped_pdf_extensions = engine.stripped_pdf_extensions.saturating_add(1);
        }
    }

    /// Resolve a freshly opened file's input encoding.
    ///
    /// Mirrors XeTeX's `u_open_in`, which only AUTO-sniffs UNICODE text inputs:
    /// the default `\XeTeXinputencoding` is `auto`, applied to `read`/`\input`
    /// text streams. Binary inputs (`tfm`/`font`/`fmt`/…) are opened as raw byte
    /// files in the original engine and must NOT be sniffed (a stray `FE FF` at
    /// the start of a TFM must not skip bytes). The UTF-8/UTF-16 decoders are
    /// also XeTeX-only; under the non-XeTeX (`tex`/`etex`) profiles every input
    /// is read raw, byte == scalar, matching 8-bit TeX.
    fn resolve_input_encoding(engine: &PortableTexEngine<'_>, handle: &mut PortableFileHandle) {
        let is_text = handle.format == resource_format_tex_input || handle.format == 0;
        if engine.is_xetex() && is_text {
            handle.resolve_text_encoding_auto();
        } else {
            handle.encoding = InputEncoding::Bytes;
        }
    }

    pub(crate) unsafe fn boundary_open_input(
        engine: *mut PortableTexEngine<'_>,
        file: *mut NativeFileHandle,
        format: integer,
        mode: const_string,
    ) -> boolean {
        let Some(engine) = engine.as_mut() else {
            if !file.is_null() {
                *file = core::ptr::null_mut();
            }
            return false_0;
        };
        let Some(name) = Self::current_resource_name(engine as *mut PortableTexEngine<'_>) else {
            if !file.is_null() {
                *file = core::ptr::null_mut();
            }
            return false_0;
        };
        let mode = Self::mode_string(mode);
        let request_kind = Self::resource_kind_for_open(engine, name.as_str(), format);
        let request_package = Self::resource_package_owner(engine, name.as_str(), request_kind);
        let source: Option<PortableSourceSpan> = None;
        let request = ResourceRequest {
            name: name.as_str(),
            kind: request_kind,
            package: request_package.as_deref(),
            format,
            mode: mode.as_str(),
            source: source.clone(),
        };
        engine.resource_requests = engine.resource_requests.saturating_add(1);
        let virtual_key = Self::virtual_file_key(name.as_str());
        let bytes = if let Some(bytes) = engine.virtual_files.get(&virtual_key) {
            bytes.clone()
        } else if let Some(bytes) = engine.resources.read(request) {
            bytes
        } else {
            engine.resource_request_records.push(PortableResourceRequestRecord {
                name,
                kind: request_kind,
                package: request_package,
                format,
                mode,
                source,
                byte_len: None,
            });
            if !file.is_null() {
                *file = core::ptr::null_mut();
            }
            return false_0;
        };
        let byte_len = Self::source_index(bytes.len());
        engine.resource_request_records.push(PortableResourceRequestRecord {
            name: name.clone(),
            kind: request_kind,
            package: request_package.clone(),
            format,
            mode: mode.clone(),
            source,
            byte_len: Some(byte_len),
        });
        let mut handle = Box::new(PortableFileHandle::new(
            name,
            request_kind,
            request_package,
            format,
            bytes,
        ));
        // Resolve the input encoding (XeTeX `u_open_in` AUTO sniff) for text
        // inputs under the XeTeX profile; binary inputs and non-XeTeX profiles
        // stay raw `Bytes` with no BOM consumption.
        Self::resolve_input_encoding(engine, &mut handle);
        if format == resource_format_tfm {
            engine.state.tfmtemp = handle.read_byte().map_or(-1, |byte| byte as integer);
        }
        if !file.is_null() {
            *file = Box::into_raw(handle);
            return true_0;
        }
        drop(handle);
        false_0
    }

    unsafe fn begin_primary_input_raw(
        self: &mut Self,
        name: &str,
        bytes: Vec<u8>,
    ) -> EngineFlow<boolean> {
        if self.state.inputfile.is_null() || self.state.sourcefilenamestack.is_null()
            || self.state.fullsourcefilenamestack.is_null()
            || self.state.buffer.is_null()
        {
            return Ok(false_0);
        }
        let Some(source_name) = Self::intern_static_pool_string(self, name)? else {
            return Ok(false_0);
        };
        self.beginfilereading()?;
        let slot = self.state.curinput.indexfield as isize;
        let mut handle = Box::new(
            PortableFileHandle::new(
                name.to_string(),
                ResourceKind::TexInput,
                None,
                resource_format_tex_input,
                bytes,
            ),
        );
        Self::resolve_input_encoding(self, &mut handle);
        *self.state.inputfile.offset(slot) = Box::into_raw(handle);
        self.state.curinput.namefield = source_name as halfword;
        *self.state.sourcefilenamestack.offset(slot) = source_name;
        *self.state.fullsourcefilenamestack.offset(slot) = source_name;
        self.state.curinput.statefield = 33 as quarterword;
        self.state.line = 1 as integer;
        self.state.src_primary_name = source_name;
        self.state.cmd_span = 0;
        self.state.pending_call_span = 0;
        self.state.src_user_cmd_span = 0;
        self.state.src_tok_span = 0;
        self.state.src_anchor_cmd = 0;
        self.state.src_grp_stack.clear();
        self.state.src_grp_closing = 0;
        self.state.src_call_user_span = 0;
        self.state.src_line_base = 0;
        self.state.src_line_buf_start = 0;
        self.state.src_prev_line_len = 0;
        self.state.src_line_initialized = false;
        self.state.curinput.spanfield = 0;
        self.state.src_native_offsets.clear();
        self.state.src_stack_cells.clear();
        self.state.cur_stack_head = 0;
        if Self::boundary_input_line(
            self as *mut PortableTexEngine<'_>,
            *self.state.inputfile.offset(slot) as NativeFileHandle,
        ) == 0
        {
            self.endfilereading();
            return Ok(false_0);
        }
        self.firmuptheline()?;
        let eqtb = self.state.zeqtb.as_mut_ptr();
        let endline_char_index = if self.is_xetex() && self.state.eqtbtop >= 7_892_312 {
            7_892_312_i64
        } else {
            27_212_i64
        };
        let endline_char = if eqtb.is_null() {
            -1
        } else {
            (*eqtb.offset(endline_char_index as isize)).u.CINT
        };
        if !(0..=255).contains(&endline_char) {
            self.state.curinput.limitfield -= 1;
        } else {
            *self.state.buffer.offset(self.state.curinput.limitfield as isize) = endline_char
                as UnicodeScalar;
        }
        self.state.first = (self.state.curinput.limitfield as i32 + 1) as integer;
        self.state.curinput.locfield = self.state.curinput.startfield;
        Ok(true_0)
    }

    pub(crate) unsafe fn boundary_input_line(
        engine: *mut PortableTexEngine<'_>,
        file: NativeFileHandle,
    ) -> boolean {
        let Some(engine) = engine.as_mut() else {
            return false_0;
        };
        if file.is_null() || engine.state.buffer.is_null() {
            return false_0;
        }

        let handle = &mut *file;
        if !handle.has_remaining() {
            return false_0;
        }

        let first = engine.state.first.max(0) as usize;
        let limit = engine.state.bufsize.max(0) as usize;
        let mut last = first;
        // XeTeX `input_line`: decode Unicode scalars via `get_uni_c`, terminating
        // on EOF / LF (0x0A) / CR (0x0D). A CR coalesces a following LF (the
        // `skipNextLF` logic), so CRLF reads as a single line break.
        while last < limit {
            let Some(scalar) = handle.next_input_scalar() else {
                break;
            };
            match scalar {
                0x0A => break,
                0x0D => {
                    // Peek the next scalar; consume it only if it is LF. The peek
                    // must be restorable (the decoder may have advanced the cursor
                    // and/or set saved_char), so snapshot both before decoding.
                    let saved_cursor = handle.cursor;
                    let saved_lookahead = handle.saved_char;
                    let was_eof = handle.eof_after_failed_read;
                    match handle.next_input_scalar() {
                        Some(0x0A) => {} // CRLF: consume the LF.
                        _ => {
                            // Not LF (or EOF): restore the peeked state.
                            handle.cursor = saved_cursor;
                            handle.saved_char = saved_lookahead;
                            handle.eof_after_failed_read = was_eof;
                        }
                    }
                    break;
                }
                scalar => {
                    *engine.state.buffer.offset(last as isize) = scalar as UnicodeScalar;
                    last += 1;
                }
            }
        }

        while last > first && *engine.state.buffer.offset((last - 1) as isize) == b' ' as UnicodeScalar {
            last -= 1;
        }
        if handle.format == resource_format_tex_input || handle.format == 0 {
            engine.current_input_package_owner = handle.package.clone();
        }
        // Source tracking multi-line accumulator (HOOK 7): each line of the
        // primary input reloads at the same buffer base, so `loc - first` is a
        // within-line column. Track the absolute char offset of the current
        // line's first slot (`src_line_base`), advancing it by the previous
        // line's length + 1 (the line break) at each refill. The buffer holds
        // `[first, last)` file characters for this line.
        if engine.state.source_tracking
            && engine.state.curinput.namefield as strnumber == engine.state.src_primary_name
        {
            if engine.state.src_line_initialized {
                engine.state.src_line_base += engine.state.src_prev_line_len + 1;
            } else {
                engine.state.src_line_base = 0;
                engine.state.src_line_initialized = true;
            }
            engine.state.src_line_buf_start = first as integer;
            engine.state.src_prev_line_len = last.saturating_sub(first) as u32;
            // The token that straddles the line break is read in the same
            // `get_next` call as this refill, so the top-of-loop token-start
            // snapshot is stale (it points at the previous line). Re-anchor it to
            // the new line's start so its span is measured in the new line's
            // coordinates.
            engine.state.src_token_start = first as integer;
        }
        engine.state.last = last as integer;
        true_0
    }

    pub(crate) unsafe fn boundary_read_byte(_file: NativeFileHandle) -> integer {
        if _file.is_null() {
            return -1;
        }
        (&mut *_file).read_byte().map_or(-1, |byte| byte as integer)
    }

    pub(crate) unsafe fn boundary_end_of_file(_file: NativeFileHandle) -> integer {
        if _file.is_null() || (&*_file).is_eof() {
            1
        } else {
            0
        }
    }

    pub(crate) unsafe fn boundary_flush_file(_file: NativeFileHandle) -> integer {
        0
    }

    pub(crate) unsafe fn boundary_write_byte(
        engine: *mut PortableTexEngine<'_>,
        character: integer,
        file: NativeFileHandle,
    ) -> integer {
        if !file.is_null() {
            if let Ok(byte) = u8::try_from(character) {
                (*file).bytes.push(byte);
            }
            return character;
        }
        if let Some(engine) = engine.as_mut() {
            if let Ok(byte) = u8::try_from(character) {
                engine.transcript_bytes.push(byte);
            }
        }
        character
    }

    pub(crate) unsafe fn boundary_close_file(_file: NativeFileHandle) {
        if !_file.is_null() {
            drop(Box::from_raw(_file));
        }
    }

    pub(crate) unsafe fn get_seconds_and_micros(
        engine: *mut PortableTexEngine<'_>,
        seconds: *mut integer,
        micros: *mut integer,
    ) {
        let clock = engine
            .as_mut()
            .map(|engine| engine.platform.clock())
            .unwrap_or_default();
        if !seconds.is_null() {
            *seconds = clock.seconds;
        }
        if !micros.is_null() {
            *micros = clock.micros;
        }
    }

    pub(crate) unsafe fn linebreak_start(
        engine: *mut PortableTexEngine<'_>,
        font: integer,
        locale: integer,
        text: *mut uint16_t,
        text_length: integer,
    ) {
        let Some(engine) = engine.as_mut() else {
            return;
        };
        let text = if text.is_null() || text_length <= 0 {
            &[]
        } else {
            core::slice::from_raw_parts(text as *const uint16_t, text_length as usize)
        };
        engine
            .platform
            .linebreak_start(PortableLinebreakRequest { font, locale, text });
    }

    pub(crate) unsafe fn linebreak_next(engine: *mut PortableTexEngine<'_>) -> integer {
        engine
            .as_mut()
            .and_then(|engine| engine.platform.linebreak_next())
            .unwrap_or(-1)
    }

    // Registers \Uhostbox during format initialization so it dumps with the format eqtb and hash.
    pub(crate) unsafe fn register_host_box_primitive(self: &mut Self) -> EngineFlow<()> {
        let eqtb = self.state.zeqtb.as_mut_ptr();
        let name = b"Uhostbox";
        for (index, byte) in name.iter().enumerate() {
            *self.state.buffer.offset(index as isize) = *byte as UnicodeScalar;
        }
        let saved = self.state.nonewcontrolsequence;
        self.state.nonewcontrolsequence = 0 as boolean;
        let cs = (&mut *(self as *mut PortableTexEngine<'_>))
            .zidlookup(0 as integer, name.len() as integer)?;
        self.state.nonewcontrolsequence = saved;
        // eq_level one, eq_type extension (59), equiv = the host box extension chr code.
        (*eqtb.offset(cs as isize)).hh.u.B1 = 1 as i16;
        (*eqtb.offset(cs as isize)).hh.u.B0 = 59 as i16;
        (*eqtb.offset(cs as isize)).hh.v.RH = HOST_BOX_EXTENSION_CODE as halfword;
        Ok(())
    }

    // Allocates a size 5 marker whatsit in the glyph node metric layout (width/depth/height at
    // words 1..3) so hpack measures it even after rebox dissolves the enclosing shell box.
    // Word 4 holds the payload, a pending token id or a resolved record index.
    unsafe fn host_box_marker(
        engine: *mut PortableTexEngine<'_>,
        subtype: i16,
        payload: integer,
        width: scaled,
        height: scaled,
        depth: scaled,
    ) -> EngineFlow<halfword> {
        let this = &mut *engine;
        let marker = this.zgetnode(5 as i32)?;
        let mem: *mut memoryword = this.state.zmem.as_mut_ptr();
        (*mem.offset(marker as isize)).hh.u.B0 = 8 as i16;
        (*mem.offset(marker as isize)).hh.u.B1 = subtype;
        (*mem.offset(marker as isize)).hh.v.RH = -(268435455 as i64) as halfword;
        (*mem.offset((marker as i32 + 1 as i32) as isize)).u.CINT = width;
        (*mem.offset((marker as i32 + 2 as i32) as isize)).u.CINT = depth;
        (*mem.offset((marker as i32 + 3 as i32) as isize)).u.CINT = height;
        (*mem.offset((marker as i32 + 4 as i32) as isize)).u.CINT = payload;
        Ok(marker)
    }

    // Asks the host for the box behind `token`, None falls back to a deterministic zero size box.
    unsafe fn host_box_build(
        engine: *mut PortableTexEngine<'_>,
        token: integer,
        style: PortableHostBoxStyle,
        font_size: scaled,
    ) -> EngineFlow<halfword> {
        let this = &mut *engine;
        let response = this.platform.host_box(PortableHostBoxRequest {
            token,
            style,
            font_size,
        });
        let hbox = this.newnullbox()?;
        let Some(host_box) = response else {
            return Ok(hbox);
        };
        let mem: *mut memoryword = this.state.zmem.as_mut_ptr();
        (*mem.offset((hbox as i32 + 1 as i32) as isize)).u.CINT = host_box.width;
        (*mem.offset((hbox as i32 + 2 as i32) as isize)).u.CINT = host_box.depth;
        (*mem.offset((hbox as i32 + 3 as i32) as isize)).u.CINT = host_box.height;
        let index = this.hostbox_records.len();
        let (width, height, depth) = (host_box.width, host_box.height, host_box.depth);
        this.hostbox_records.push(host_box);
        let marker = Self::host_box_marker(
            engine,
            HOST_BOX_RESOLVED_SUBTYPE,
            index as integer,
            width,
            height,
            depth,
        )?;
        (*mem.offset((hbox as i32 + 5 as i32) as isize)).hh.v.RH = marker;
        Ok(hbox)
    }

    // \Uhostbox scan site: math defers to the mlist pass for style, other modes resolve now as Text.
    pub(crate) unsafe fn host_box_insert(
        engine: *mut PortableTexEngine<'_>,
        token: integer,
    ) -> EngineFlow<()> {
        let Some(this) = engine.as_mut() else {
            return Ok(());
        };
        let mode = (this.state.curlist.modefield as i32).abs();
        if mode == 209 as i32 {
            let marker =
                Self::host_box_marker(engine, HOST_BOX_PENDING_SUBTYPE, token, 0, 0, 0)?;
            let this = &mut *engine;
            let placeholder = this.newnullbox()?;
            let noad = this.newnoad()?;
            let mem: *mut memoryword = this.state.zmem.as_mut_ptr();
            (*mem.offset((placeholder as i32 + 5 as i32) as isize)).hh.v.RH = marker;
            (*mem.offset((noad as i32 + 1 as i32) as isize)).hh.v.RH = 2 as i32 as halfword;
            (*mem.offset((noad as i32 + 1 as i32) as isize)).hh.v.LH = placeholder;
            (*mem.offset(this.state.curlist.tailfield as isize)).hh.v.RH = noad;
            this.state.curlist.tailfield = noad;
        } else {
            let eqtb = this.state.zeqtb.as_mut_ptr();
            let font = (*eqtb.offset(EQTB_CUR_FONT_LOC as isize)).hh.v.RH as integer;
            let font_size = this.font_at_size(font);
            let hbox =
                Self::host_box_build(engine, token, PortableHostBoxStyle::Text, font_size)?;
            let this = &mut *engine;
            let mem: *mut memoryword = this.state.zmem.as_mut_ptr();
            (*mem.offset(this.state.curlist.tailfield as isize)).hh.v.RH = hbox;
            this.state.curlist.tailfield = hbox;
        }
        Ok(())
    }

    // mlist pass hook: swap a pending placeholder nucleus for the host's box under curstyle.
    pub(crate) unsafe fn host_box_resolve_noad(
        engine: *mut PortableTexEngine<'_>,
        q: halfword,
    ) -> EngineFlow<()> {
        let Some(this) = engine.as_mut() else {
            return Ok(());
        };
        if q < 0 || q >= this.state.himemmin {
            return Ok(());
        }
        let mem: *mut memoryword = this.state.zmem.as_mut_ptr();
        // Only Ord noads (16) carry a \Uhostbox placeholder nucleus.
        if (*mem.offset(q as isize)).hh.u.B0 as i32 != 16 as i32 {
            return Ok(());
        }
        let style_code = this.state.curstyle as i32;
        Self::host_box_resolve_field(engine, (q as i32 + 1 as i32) as halfword, style_code)
    }

    // clean_box hook: fields copied out of single atom groups (scripts, fractions) resolve here.
    pub(crate) unsafe fn host_box_resolve_field(
        engine: *mut PortableTexEngine<'_>,
        field: halfword,
        style_code: i32,
    ) -> EngineFlow<()> {
        let Some(this) = engine.as_mut() else {
            return Ok(());
        };
        if field < 0 {
            return Ok(());
        }
        let mem: *mut memoryword = this.state.zmem.as_mut_ptr();
        // Field must be a sub box (2) whose box wraps a pending marker whatsit.
        if (*mem.offset(field as isize)).hh.v.RH as i32 != 2 as i32 {
            return Ok(());
        }
        let placeholder = (*mem.offset(field as isize)).hh.v.LH;
        if placeholder < 0 || placeholder as i64 == -(268435455 as i64) {
            return Ok(());
        }
        let marker = (*mem.offset((placeholder as i32 + 5 as i32) as isize)).hh.v.RH;
        if marker < 0 || marker as i64 == -(268435455 as i64) || marker >= this.state.himemmin {
            return Ok(());
        }
        if (*mem.offset(marker as isize)).hh.u.B0 as i32 != 8 as i32
            || (*mem.offset(marker as isize)).hh.u.B1 as i32 != HOST_BOX_PENDING_SUBTYPE as i32
        {
            return Ok(());
        }
        let token = (*mem.offset((marker as i32 + 4 as i32) as isize)).u.CINT;
        // Style codes map to sizes as in mlist_to_hlist: below 4 is text, then script sizes.
        let size = if style_code < 4 {
            0
        } else {
            256 * ((style_code - 2) / 2)
        };
        let style = match size {
            0 => PortableHostBoxStyle::Text,
            256 => PortableHostBoxStyle::Script,
            _ => PortableHostBoxStyle::ScriptScript,
        };
        // Size context comes from the family 2 symbol font at the active math size.
        let eqtb = this.state.zeqtb.as_mut_ptr();
        let font = (*eqtb.offset((EQTB_MATH_FONT_FAM2_BASE + size as i64) as isize))
            .hh
            .v
            .RH as integer;
        let font_size = this.font_at_size(font);
        let hbox = Self::host_box_build(engine, token, style, font_size)?;
        // The placeholder was stamped with the \hostbox call site span at scan time, carry it onto
        // the replacement and its marker so the atom maps to its own bytes, not the ambient span.
        Self::src_carry_copy(engine as *mut Self, placeholder, hbox);
        let mem: *mut memoryword = (*engine).state.zmem.as_mut_ptr();
        let resolved_marker = (*mem.offset((hbox as i32 + 5 as i32) as isize)).hh.v.RH;
        if resolved_marker >= 0 && resolved_marker as i64 != -(268435455 as i64) {
            Self::src_carry_copy(engine as *mut Self, placeholder, resolved_marker);
        }
        (&mut *engine).zflushnodelist(placeholder)?;
        let this = &mut *engine;
        let mem: *mut memoryword = this.state.zmem.as_mut_ptr();
        (*mem.offset(field as isize)).hh.v.LH = hbox;
        Ok(())
    }

    pub(crate) unsafe fn abort_engine(
        engine: *mut PortableTexEngine<'_>,
        status: integer,
    ) -> EngineFlow<core::convert::Infallible> {
        if let Some(engine) = engine.as_mut() {
            engine.last_abort_status = Some(status);
        }
        Err(EngineBreak::Abort(EngineAbort { status }))
    }

    /// Reject the current fragment with `message` when the sandbox is active; a
    /// no-op (e.g. during format construction) otherwise. The sandbox analogue of
    /// [`abort_engine`]: it breaks the run via the `?` chain with an [`EngineError`].
    pub(crate) unsafe fn sandbox_reject(
        engine: *mut PortableTexEngine<'_>,
        message: &str,
    ) -> EngineFlow<()> {
        if let Some(engine) = engine.as_ref() {
            if engine.sandbox {
                return Err(EngineBreak::Error(EngineError {
                    message: message.into(),
                }));
            }
        }
        Ok(())
    }

    /// Sandbox `$`/math-shift guard, called from `init_math` (entering math). The
    /// fragment legitimately enters math via the wrapper `$` (depth 0 -> 1) and may NEST
    /// more math inside a text block -- `\hbox{$x$}`, `\text{$y$}` -- which opens at depth
    /// >= 1 and is allowed. A BREAKOUT is a user `$` that, in text mode, re-opens math at
    /// depth 0 AFTER the wrapper already opened (the wrapper's math was closed back to the
    /// outer level); reject only that. No-op outside the sandbox.
    pub(crate) unsafe fn sandbox_open_math(
        engine: *mut PortableTexEngine<'_>,
    ) -> EngineFlow<()> {
        if let Some(engine) = engine.as_mut() {
            if engine.sandbox {
                if engine.sandbox_math_depth == 0 && engine.sandbox_math_opened {
                    return Err(EngineBreak::Error(EngineError {
                        message: "math shift ($) is not allowed inside a math expression"
                            .into(),
                    }));
                }
                engine.sandbox_math_opened = true;
                engine.sandbox_math_depth += 1;
            }
        }
        Ok(())
    }

    /// Sandbox companion to [`sandbox_open_math`], called from `after_math` (leaving
    /// math): pop one MATH nesting level. Depth returns to 0 only when the wrapper math
    /// closes, so a nested `$x$` closing (depth 2 -> 1) does NOT mark the expression
    /// finished and later math stays allowed. No-op off-sandbox.
    pub(crate) unsafe fn sandbox_close_math(
        engine: *mut PortableTexEngine<'_>,
    ) -> EngineFlow<()> {
        if let Some(engine) = engine.as_mut() {
            if engine.sandbox && engine.sandbox_math_depth > 0 {
                engine.sandbox_math_depth -= 1;
            }
        }
        Ok(())
    }

    /// Sandbox work-budget tick, called once per `main_control` iteration. Rejects
    /// the fragment once [`SANDBOX_OP_BUDGET`] iterations are exceeded, bounding
    /// runaway expansion / infinite loops (`\def\x{\x}\x`). No-op outside sandbox.
    pub(crate) unsafe fn sandbox_tick(
        engine: *mut PortableTexEngine<'_>,
    ) -> EngineFlow<()> {
        if let Some(engine) = engine.as_mut() {
            if engine.sandbox {
                engine.sandbox_ops = engine.sandbox_ops.saturating_add(1);
                if engine.sandbox_ops > SANDBOX_OP_BUDGET {
                    return Err(EngineBreak::Error(EngineError {
                        message: "expression is too complex or did not terminate".into(),
                    }));
                }
            }
        }
        Ok(())
    }

    /// Surfacing hook called from `error()` right after it prints the diagnostic
    /// and its context: turn the TeX error into a breaking [`EngineError`]
    /// carrying the captured message, threaded back to the driver via the `?`
    /// chain like an abort. TeX's normal log-and-recover never runs inside an
    /// equation render -- an error is always real and is reported, not swallowed.
    /// Declared `EngineFlow<()>` (not `<Infallible>`) so the unreachable tail of
    /// `error()` stays warning-free.
    pub(crate) unsafe fn surface_error(
        engine: *mut PortableTexEngine<'_>,
    ) -> EngineFlow<()> {
        let message = engine
            .as_ref()
            .map(|engine| engine.capture_last_error_message())
            .unwrap_or_else(|| "TeX error".into());
        Err(EngineBreak::Error(EngineError { message }))
    }

    // =====================================================================
    // Source tracking (SpanField + CmdLatch). All of this is gated on the
    // runtime `source_tracking` flag; with it false every hook below is a
    // cheap predictable no-op and the default render path allocates nothing.
    // The only "inheritance" is the two principled rules: (a) a macro body
    // inherits its INVOCATION span (the call-site baseline), and (b) math
    // noads re-point `cmd_span` from their own parse-time `node_src`. There
    // is no byte-matching, input-stack scanning, nearest-macro guessing, or
    // blanket parent inheritance.
    // =====================================================================

    /// Enable/disable source tracking, lazily (re)allocating the `node_src`
    /// shadow (sized to `mem`) and clearing the intern tables. Resets all the
    /// transient registers so a render starts clean. Default off.
    pub fn set_source_tracking(self: &mut Self, on: bool) {
        self.state.source_tracking = on;
        self.state.cmd_span = 0;
        self.state.pending_call_span = 0;
        self.state.src_token_start = 0;
        self.state.src_line_base = 0;
        self.state.src_line_buf_start = 0;
        self.state.src_prev_line_len = 0;
        self.state.src_line_initialized = false;
        self.state.src_call_start = 0;
        self.state.src_call_name = 0;
        self.state.src_call_state = 0;
        self.state.src_call_index = 0;
        self.state.src_call_span = 0;
        self.state.src_call_argspan = 0;
        self.state.src_user_cmd_span = 0;
        self.state.src_tok_span = 0;
        self.state.src_anchor_cmd = 0;
        self.state.src_grp_stack.clear();
        self.state.src_grp_closing = 0;
        self.state.src_call_user_span = 0;
        self.state.curinput.spanfield = 0;
        self.state.src_spans.clear();
        self.state.src_dedup.clear();
        self.state.src_native_offsets.clear();
        self.state.src_stack_cells.clear();
        self.state.cur_stack_head = 0;
        let end = if on { self.state.mem.len() } else { 0 };
        self.state.node_src = PagedArray::new(0, end, node_src_default, node_src_sig);
        self.state.node_stack = PagedArray::new(0, end, node_stack_default, node_stack_sig);
    }

    /// Whether source tracking is currently enabled.
    pub fn source_tracking_enabled(&self) -> bool {
        self.state.source_tracking
    }

    /// Intern a span into the dedup table, returning a stable first-touch
    /// `SrcId` (1-based; `0` is NONE). Uses the explicit `self: &mut Self`
    /// receiver form the patcher's passes expect (the `&mut self` shorthand is
    /// stripped).
    fn intern_span_raw(self: &mut Self, name: strnumber, start: u32, end: u32, role: u8) -> SrcId {
        let span = RawSpan { name, start, end, role };
        if let Some(&id) = self.state.src_dedup.get(&span) {
            return id;
        }
        self.state.src_spans.push(span);
        let id = self.state.src_spans.len() as SrcId;
        self.state.src_dedup.insert(span, id);
        id
    }

    /// Absolute character offset, in the primary input's own coordinates, of a
    /// buffer position `loc`: `line_base + (loc - line_start)`.
    fn src_buf_offset(&self, loc: integer) -> u32 {
        let col = loc as i64 - self.state.src_line_buf_start as i64;
        (self.state.src_line_base as i64 + col).max(0) as u32
    }

    /// Resolve a node's stamped span to a [`PortableSourceSpan`] in source-own
    /// coordinates, or `None` when the node is unstamped (SrcId 0) or its source
    /// name cannot be read. `&self`: safe on the read-only IR snapshot path.
    pub(crate) fn resolve_node_src(&self, node: halfword) -> Option<PortableSourceSpan> {
        if !self.state.source_tracking || node < 0 {
            return None;
        }
        let id = self.state.node_src.get_copy(node as usize);
        if id == 0 {
            return None;
        }
        let raw = *self.state.src_spans.get((id - 1) as usize)?;
        let name = unsafe { self.pool_string(raw.name) }?;
        Some(PortableSourceSpan {
            name,
            start: raw.start,
            end: raw.end,
            role: raw.role,
        })
    }

    /// HOOK 1a (`get_next`, top of the outer loop): snapshot the buffer position
    /// of the token about to be lexed. Re-run each loop iteration so leading
    /// skipped material (comments / ignored chars) is excluded from the span.
    pub(crate) unsafe fn src_mark_token_start(engine: *mut Self) {
        let Some(engine) = engine.as_mut() else {
            return;
        };
        if engine.state.source_tracking && engine.state.curinput.statefield as i32 != 0 {
            engine.state.src_token_start = engine.state.curinput.locfield as integer;
        }
    }

    /// HOOK 1b (`get_next` tail): the SOLE buffer producer. For real buffer
    /// input set the ambient `spanfield` to the just-lexed TOKEN range (so a
    /// control word spans backslash..last letter). Token-list input is handled
    /// by [`Self::src_tokenlist_span`], not here.
    pub(crate) unsafe fn src_record_buffer_span(engine: *mut Self) {
        let Some(engine) = engine.as_mut() else {
            return;
        };
        if !engine.state.source_tracking || engine.state.curinput.statefield as i32 == 0 {
            return;
        }
        let a = engine.src_buf_offset(engine.state.src_token_start);
        let b = engine.src_buf_offset(engine.state.curinput.locfield as integer);
        let (lo, hi) = if a <= b { (a, b) } else { (b, a) };
        let name = engine.state.curinput.namefield as strnumber;
        let id = engine.intern_span_raw(name, lo, hi, 0);
        engine.state.curinput.spanfield = id;
        engine.state.src_tok_span = id;
        // When the just-lexed buffer token is a CONTROL SEQUENCE (`curcs != 0`) of
        // the primary fragment, it is a user-typed command; remember it as the
        // active user command. Kernel helper macros reached through its expansion
        // are read from token lists (not the buffer), so they never reset this, and
        // it survives token-list pops — letting a helper invoked from the buffer
        // after a `\futurelet`/`\@ifnextchar` peek recover the user command start.
        //
        // Gate on `scannerstatus == 0` (normal): a cs lexed while the scanner is
        // MATCHING/ABSORBING another macro's arguments is being COLLECTED, not
        // executed -- it belongs to that outer command's argument, not the active
        // command line. In `\sqrt[\phantom{x}]{x}` the `\phantom` is absorbed into
        // `\@sqrt`'s optional `[..]` while matching, so without this gate it
        // overwrites the real user command `\sqrt`; the later radicand helper then
        // anchors its buffer baseline to the stale `\phantom` start, framing the
        // degree box as `[\phantom .. radicand]` = the `[6,21)` overshoot. A digit
        // degree (`\sqrt[3]{x}`) has no cs to hijack, which is why it never bit.
        if engine.state.curcs != 0
            && name == engine.state.src_primary_name
            && engine.state.scannerstatus as i32 == 0
        {
            engine.state.src_user_cmd_span = id;
            // A buffer read means we have left any token-list replay context, so the
            // replay-tracked anchor command is now stale: clear it. (`src_user_cmd_span`,
            // by contrast, intentionally persists so a `\futurelet`-peeked helper can
            // still recover the buffer command.)
            engine.state.src_anchor_cmd = 0;
        }
    }

    /// HOOK 1c (`get_next` token-list branch): when re-reading from an ARGUMENT
    /// / template / backed-up / inserted level (token type < `macro`=5), surface
    /// the re-read cell's own scan-time span so a macro argument recovers its
    /// typed position. Macro-body (`macro`=5) and `every_*` (>=6) levels keep the
    /// inherited call-site baseline, so synthesized body content maps to the
    /// invocation.
    pub(crate) unsafe fn src_tokenlist_span(engine: *mut Self) {
        let Some(engine) = engine.as_mut() else {
            return;
        };
        if !engine.state.source_tracking {
            return;
        }
        if engine.state.curinput.indexfield as i32 >= 5 {
            return;
        }
        // Freeze the token's OWN origin as it is read, so a later `back_input` can
        // re-stamp it with this (not the ambient, look-ahead-advanced span). Only for
        // NON-macro-body levels (`idx < 5`): a macro body's tokens map to their
        // invocation (rule a), never to their definition site, so letting their cell
        // span leak here would make a backed-up body token (e.g. `\frac`'s `\over`)
        // carry its definition position instead of the call-site baseline.
        {
            let lf = engine.state.curinput.locfield as i32;
            if lf >= 0 {
                let cid = engine.state.node_src.get_copy(lf as usize);
                if cid != 0 {
                    engine.state.src_tok_span = cid;
                }
            }
        }
        let cell = engine.state.curinput.locfield as i32;
        if cell < 0 {
            return;
        }
        let id = engine.state.node_src.get_copy(cell as usize);
        if id != 0 {
            engine.state.curinput.spanfield = id;
        }
    }

    /// HOOK 1d (`back_input`): when a token is pushed back onto the input, stamp the
    /// freshly-allocated backed-up cell with the token's OWN origin (`src_tok_span`,
    /// frozen at the token's last read) rather than the ambient `spanfield`. The two
    /// diverge whenever the lexer has read PAST the token before backing it up -- the
    /// `\let`/`\futurelet` (and thus `\@ifnextchar`) two-token look-ahead reads a
    /// second token, advancing `spanfield`, then re-emits the first. Without this the
    /// re-emitted token (e.g. the single-char optional `[a]` degree of `\sqrt`, which
    /// LaTeX's `\@ifnextchar`-driven `\sqrt`/`\root` machinery shuttles through such a
    /// look-ahead) would inherit the look-ahead's span -- the construct baseline --
    /// and the typed char's byte-span would be lost. The token's real origin is still
    /// live in `src_tok_span`, so the leaf is recoverable here, at the re-emission.
    pub(crate) unsafe fn src_back_input_stamp(engine: *mut Self, p: halfword) {
        let Some(engine) = engine.as_mut() else {
            return;
        };
        if !engine.state.source_tracking || p < 0 {
            return;
        }
        let id = engine.state.src_tok_span;
        if id != 0 {
            engine.state.node_src.set(p as usize, id);
        }
    }

    /// HOOK 2 (`main_control` dispatch, right after `get_x_token`): freeze the
    /// commanding token's span before it runs any argument sub-scan. This single
    /// site solves `\char`/`\mathchar`/`\accent` scan-loss for free.
    pub(crate) unsafe fn src_latch_cmd_span(engine: *mut Self) {
        let Some(engine) = engine.as_mut() else {
            return;
        };
        if engine.state.source_tracking {
            engine.state.cmd_span = engine.state.curinput.spanfield;
        }
    }

    /// HOOK 3 (`get_avail`): stamp every single-word cell with the ambient span
    /// — token cells (so re-read arguments recover their typed position) and TFM
    /// char nodes provisionally (overwritten by [`Self::src_stamp_char`]). Also
    /// snapshots the live enclosing-construct stack head onto `node_stack`.
    pub(crate) unsafe fn src_stamp_avail(engine: *mut Self, node: halfword) {
        let Some(engine) = engine.as_mut() else {
            return;
        };
        if engine.state.source_tracking && node >= 0 {
            let id = engine.state.curinput.spanfield;
            engine.state.node_src.set(node as usize, id);
            engine.state.node_stack.set(node as usize, engine.state.cur_stack_head);
        }
    }

    /// HOOK 4 (`get_node`): stamp every variable-size node AND every noad over
    /// its whole address range with the current construct span, so the nucleus
    /// subfield inherits the atom's span with no separate math-field writer. Also
    /// snapshots the live enclosing-construct stack head onto `node_stack` over the
    /// same range (independent of `cmd_span`, so a node allocated inside a
    /// construct still records its enclosure even when its primary is unstamped).
    pub(crate) unsafe fn src_stamp_node_range(engine: *mut Self, node: halfword, size: integer) {
        let Some(engine) = engine.as_mut() else {
            return;
        };
        if !engine.state.source_tracking || node < 0 || size <= 0 {
            return;
        }
        let id = engine.state.cmd_span;
        let head = engine.state.cur_stack_head;
        let base = node as usize;
        for i in 0..size as usize {
            if id != 0 {
                engine.state.node_src.set(base + i, id);
            }
            if head != 0 {
                engine.state.node_stack.set(base + i, head);
            }
        }
    }

    /// HOOK (`copy_node_list`, after each node is duplicated): a COPY has the same
    /// source origin as its original, so propagate the original's tracked span (and
    /// enclosing-construct chain) onto the copy. Without this the copy keeps only the
    /// ambient `cmd_span` that `get_node` stamped at copy time — which for a
    /// `\mathchoice`-replicated `\sqrt[#1]{}` degree is the whole construct hull, so the
    /// degree digit `3` maps to `\sqrt[3]{..}` instead of its own `"3"`. Only overrides
    /// when the original is stamped (id != 0); an unstamped source leaves the copy's
    /// `get_node` stamp intact. Uniform across every copied node, by closure.
    pub(crate) unsafe fn src_carry_copy(engine: *mut Self, src: halfword, dst: halfword) {
        let Some(engine) = engine.as_mut() else {
            return;
        };
        if !engine.state.source_tracking || src < 0 || dst < 0 {
            return;
        }
        let id = engine.state.node_src.get_copy(src as usize);
        if id != 0 {
            engine.state.node_src.set(dst as usize, id);
            let head = engine.state.node_stack.get_copy(src as usize);
            engine.state.node_stack.set(dst as usize, head);
        }
    }

    /// HOOK (token COPY): the analogue of [`Self::src_carry_copy`] for the TOKEN
    /// (not node) memory. Token-list copies go through `store_new_token(info(src))`,
    /// which copies only the token VALUE -- so the new cell `dest` would keep the
    /// ambient `get_avail` stamp and lose `src`'s real origin. Carry `src`'s tracked
    /// span (and enclosing chain) onto `dest`, so a source byte-span rides token
    /// copies the same way it rides the input stack. This is what lets a SINGLE-token
    /// macro argument (e.g. the optional `[a]` degree of `\sqrt`) keep its own leaf
    /// span through expl3's argument re-tokenisation, instead of collapsing to the
    /// `\sqrt[a]` construct hull. Uniform across every token copy, by closure: the
    /// anchor is the WEB-layer `src_token_copy` marker (added in the change file at
    /// every `store_new_token(info(..))` site), not a fragile inlined Rust pattern --
    /// so it holds for tex, etex and xetex identically.
    pub(crate) unsafe fn src_carry_token_span(engine: *mut Self, dest: halfword, src: halfword) {
        let Some(engine) = engine.as_mut() else {
            return;
        };
        if !engine.state.source_tracking || dest < 0 || src < 0 {
            return;
        }
        let id = engine.state.node_src.get_copy(src as usize);
        if id != 0 {
            engine.state.node_src.set(dest as usize, id);
            let head = engine.state.node_stack.get_copy(src as usize);
            engine.state.node_stack.set(dest as usize, head);
        }
    }

    /// HOOK 5 (`new_character`): overwrite the provisional get_avail stamp on a
    /// TFM char glyph with the construct span, so `\char98` maps to the command,
    /// not the scanned digits. Also records the live enclosing-construct stack head
    /// (overridden for `make_ord` nuclei by [`Self::src_carry_nucleus`]).
    pub(crate) unsafe fn src_stamp_char(engine: *mut Self, node: halfword) {
        let Some(engine) = engine.as_mut() else {
            return;
        };
        if !engine.state.source_tracking || node < 0 {
            return;
        }
        let id = engine.state.cmd_span;
        if id != 0 {
            engine.state.node_src.set(node as usize, id);
        }
        engine.state.node_stack.set(node as usize, engine.state.cur_stack_head);
    }

    /// HOOK 6 (`mlist_to_hlist` noad-loop head): re-point `cmd_span` to noad
    /// `q`'s own parse-time span, so every bar/surd/delimiter/kern synthesized
    /// for `q` inherits it — defeating end-of-math `$` staleness with one read.
    pub(crate) unsafe fn src_mlist_repoint(engine: *mut Self, q: halfword) {
        let Some(engine) = engine.as_mut() else {
            return;
        };
        if !engine.state.source_tracking || q < 0 {
            return;
        }
        let id = engine.state.node_src.get_copy(q as usize);
        if id != 0 {
            engine.state.cmd_span = id;
        }
    }

    /// HOOK (`scan_math` field commit): a math FIELD (nucleus/sub/sup/accent/radical)
    /// holding a single math-char is filled by `scan_math` directly into the field
    /// word -- it is NOT a separately-allocated noad, so it carries the enclosing
    /// noad's stamp, not its own char's. Record the field char's tracked span (the
    /// ambient `spanfield` of the token that produced it, captured at the commit
    /// before any look-ahead moves it) keyed on the field ADDRESS, so `clean_box`
    /// can carry it onto the fresh noad it builds. Uniform: every scanned single-char
    /// field, by closure -- no per-construct code.
    pub(crate) unsafe fn src_stamp_field(engine: *mut Self, field: halfword) {
        let Some(engine) = engine.as_mut() else {
            return;
        };
        if !engine.state.source_tracking || field < 0 {
            return;
        }
        let id = engine.state.curinput.spanfield;
        if id != 0 {
            engine.state.node_src.set(field as usize, id);
        }
    }

    /// HOOK (`clean_box` math-char case): when `clean_box` packages a single-math-char
    /// FIELD it allocates a FRESH noad and copies the field word into its nucleus; the
    /// fresh noad was stamped by `get_node` with the ambient (enclosing atom's)
    /// `cmd_span`, so the mlist re-point would map the cleaned glyph to the BASE. Carry
    /// the field's own tracked source (recorded at `src_stamp_field`) onto the fresh
    /// noad so the re-point yields the field char's real origin (fixes `x^2`->`2`,
    /// `^{\infty}`->`\infty`). Uniform copy-carrier; no glyph/construct logic.
    pub(crate) unsafe fn src_carry_field(engine: *mut Self, field: halfword, noad: halfword) {
        let Some(engine) = engine.as_mut() else {
            return;
        };
        if !engine.state.source_tracking || field < 0 || noad < 0 {
            return;
        }
        let id = engine.state.node_src.get_copy(field as usize);
        let head = engine.state.node_stack.get_copy(field as usize);
        if id != 0 {
            // noad_size = 4; stamp the whole noad range so the loop-head re-point
            // (reads node_src[noad]) and the nucleus both see the field's source.
            for i in 0..4usize {
                engine.state.node_src.set(noad as usize + i, id);
            }
        }
        // Carry the field's enclosing-construct chain too, so the cleaned glyph's
        // enclosing entries match the field char's nesting, not the fresh noad's.
        if head != 0 {
            for i in 0..4usize {
                engine.state.node_stack.set(noad as usize + i, head);
            }
        }
    }

    /// HOOK (`mlist_to_hlist` make_ord nucleus attach): a directly-built math-char
    /// nucleus glyph is the non-`clean_box` analogue of [`Self::src_carry_field`].
    /// `get_node`/`new_character` stamped it with the enclosing noad's construct
    /// span, so a typed char wrapped in an atom (`\mathbin{+}` -> `+`) would map to
    /// the construct. Carry the nucleus FIELD's own leaf span -- recorded at
    /// `scan_math` by [`Self::src_stamp_field`], or by the brace-collapse carry --
    /// onto the freshly-built glyph node, so it maps to its own char. Per-glyph
    /// only; never touches `cmd_span`, so a structural rule built for the same noad
    /// afterward still inherits the construct span via the loop-head re-point.
    /// Uniform: every directly-built ord-like nucleus glyph, by closure -- no
    /// per-construct code. When the field carries no leaf span (`\char`/`\mathchar`,
    /// no `scan_math`) the carry is a no-op and the construct stamp stands.
    pub(crate) unsafe fn src_carry_nucleus(engine: *mut Self, noad: halfword, glyph: halfword) {
        let Some(engine) = engine.as_mut() else {
            return;
        };
        if !engine.state.source_tracking || noad < 0 || glyph < 0 {
            return;
        }
        let id = engine.state.node_src.get_copy(noad as usize + 1);
        if id != 0 {
            engine.state.node_src.set(glyph as usize, id);
        }
        // Carry the nucleus field's enclosing-construct chain onto the glyph, so a
        // typed char's enclosing entries are its parse-time nesting (e.g. the
        // `\mathbin{+}` group frame) rather than the layout-time stack.
        let head = engine.state.node_stack.get_copy(noad as usize + 1);
        engine.state.node_stack.set(glyph as usize, head);
    }

    /// HOOK (`handle_right_brace` math-group collapse): when a braced sub-formula
    /// `^{\infty}` / `_{y}` reduces to a SINGLE math-char noad, its nucleus is copied
    /// into the saved FIELD word and the noad is freed -- losing the noad's tracked
    /// source. Carry `node_src[noad]` onto the field FIRST, so the later `clean_box`
    /// (via `src_carry_field`) maps the cleaned glyph to the braced char's own origin
    /// rather than the enclosing atom's. Uniform; no glyph/construct logic.
    pub(crate) unsafe fn src_carry_collapse(engine: *mut Self, noad: halfword, field: halfword) {
        let Some(engine) = engine.as_mut() else {
            return;
        };
        if !engine.state.source_tracking || noad < 0 || field < 0 {
            return;
        }
        let id = engine.state.node_src.get_copy(noad as usize);
        if id != 0 {
            engine.state.node_src.set(field as usize, id);
        }
        // Carry the collapsing noad's enclosing chain (e.g. the math-group frame
        // built between its `{`/`}`) onto the field, so the later nucleus carry
        // gives the cleaned glyph its braced construct as an enclosing entry.
        let head = engine.state.node_stack.get_copy(noad as usize);
        if head != 0 {
            engine.state.node_stack.set(field as usize, head);
        }
    }

    /// HOOK 7-aux save (`clean_box` entry): snapshot `cmd_span` so it can be
    /// restored across recursive sub-box cleaning.
    pub(crate) unsafe fn src_save_cmd_span(engine: *mut Self) -> u32 {
        engine.as_ref().map_or(0, |engine| engine.state.cmd_span)
    }

    /// HOOK 7-aux restore (`clean_box` exit): put the enclosing construct's span
    /// back so the structural rule built afterward inherits it.
    pub(crate) unsafe fn src_restore_cmd_span(engine: *mut Self, saved: u32) {
        if let Some(engine) = engine.as_mut() {
            if engine.state.source_tracking {
                engine.state.cmd_span = saved;
            }
        }
    }

    // --- Enclosing-construct stack (source-tracking inc2) -------------------
    // A small arena of parent-linked frames snapshotting the construct nesting
    // (macro invocations + delimited primitive argument groups). `cur_stack_head`
    // is the live top; each node records it in `node_stack` at allocation. The
    // frames are resolved at IR-emit time into role-tagged EnclosingConstruct
    // entries, so a consumer can pick any altitude from the leaf primary up.

    /// Push a finalized construct frame (its span already known, e.g. a macro
    /// invocation hull) and make it the live top. Returns the new 1-based head.
    fn src_stack_push_span(self: &mut Self, span: SrcId) -> u32 {
        self.state.src_stack_cells.push(SrcStackCell {
            span,
            parent: self.state.cur_stack_head,
            start: 0,
            name: 0,
            pending: false,
        });
        let head = self.state.src_stack_cells.len() as u32;
        self.state.cur_stack_head = head;
        head
    }

    /// Push a PENDING group frame: its start offset + source name are known at the
    /// `{` open, its end is finalized at the matching `}` close. Made the live top.
    fn src_stack_push_pending(self: &mut Self, start: u32, name: strnumber) -> u32 {
        self.state.src_stack_cells.push(SrcStackCell {
            span: 0,
            parent: self.state.cur_stack_head,
            start,
            name,
            pending: true,
        });
        let head = self.state.src_stack_cells.len() as u32;
        self.state.cur_stack_head = head;
        head
    }

    /// Pop the live top frame (LIFO), restoring its parent as the head.
    fn src_stack_pop(self: &mut Self) {
        let head = self.state.cur_stack_head;
        if head != 0 {
            if let Some(cell) = self.state.src_stack_cells.get((head - 1) as usize) {
                self.state.cur_stack_head = cell.parent;
            }
        }
    }

    /// HOOK 8b (`end_token_list`): pop the macro-body frame when a macro-body level
    /// (token type 6) ends, keeping the stack symmetric with HOOK 8a. Also captures
    /// the FURTHEST-reaching last-token span across the levels popped after a
    /// `macro_call` (`src_call_argspan`, reset to 0 at `src_macro_begin`) -- the
    /// closing `}` of the macro's final brace argument -- for the argument hull in
    /// [`Self::src_macro_set_pending`]. The MAX-end choice (not just the first pop)
    /// recovers the trailing `}` for a `\mathchoice`-replayed robust `\frac␣`, whose
    /// pop order surfaces the cs span first and the closing brace later.
    pub(crate) unsafe fn src_end_token_list(engine: *mut Self, token_type: i32) {
        let Some(engine) = engine.as_mut() else {
            return;
        };
        if !engine.state.source_tracking {
            return;
        }
        let cand = engine.state.curinput.spanfield;
        if cand != 0 {
            let cand_end = engine
                .state
                .src_spans
                .get((cand - 1) as usize)
                .map(|r| r.end)
                .unwrap_or(0);
            let cur_end = if engine.state.src_call_argspan != 0 {
                engine
                    .state
                    .src_spans
                    .get((engine.state.src_call_argspan - 1) as usize)
                    .map(|r| r.end)
                    .unwrap_or(0)
            } else {
                0
            };
            if engine.state.src_call_argspan == 0 || cand_end > cur_end {
                engine.state.src_call_argspan = cand;
            }
        }
        if token_type == 6 {
            engine.src_stack_pop();
        }
    }

    /// HOOK (`scan_math` `{`-argument open): push a PENDING enclosing frame for a
    /// delimited primitive argument (`\mathbin{+}`, `\sqrt[..]{..}` radicand, ...).
    /// Its extent starts at the enclosing command's own start (the live `cmd_span`,
    /// e.g. `\mathbin`) and is finalized at the matching `}` close to span the whole
    /// `cmd{...}` construct. When no command is active the frame is empty (skipped
    /// at resolve). General: every scan_math braced field, by closure.
    pub(crate) unsafe fn src_scan_math_group_open(engine: *mut Self) {
        let Some(engine) = engine.as_mut() else {
            return;
        };
        if !engine.state.source_tracking {
            return;
        }
        let cmd = engine.state.cmd_span;
        let (start, name) = if cmd != 0 {
            match engine.state.src_spans.get((cmd - 1) as usize) {
                Some(raw) => (raw.start, raw.name),
                None => (0, 0),
            }
        } else {
            (0, 0)
        };
        engine.src_stack_push_pending(start, name);
        // Consumed-extent: push the group's OPENING `{` token span (the live spanfield
        // of the brace just scanned) for `src_construct_extent`. Distinct from the
        // enclosing-frame start above (which is the enclosing COMMAND): `min(noad, {)`
        // lets a bare `{n\choose k}` group pull its fraction's start to the `{`.
        engine.state.src_grp_stack.push(engine.state.curinput.spanfield);
    }

    /// HOOK (`handle_right_brace` math-group close): finalize the PENDING group
    /// frame (end = the post-`}` buffer offset, same source as the start) and pop
    /// it. The interned `[start,end)` is the full `cmd{...}` extent.
    pub(crate) unsafe fn src_scan_math_group_close(engine: *mut Self) {
        let eptr = engine;
        let Some(e) = engine.as_mut() else {
            return;
        };
        if !e.state.source_tracking {
            return;
        }
        // Consumed-extent: pop this group's opening `{` span, hand it to
        // `src_construct_extend_to_loc` (later in the same `9 =>` arm) as the construct's
        // group-open for the `min(noad, {)` start.
        e.state.src_grp_closing = e.state.src_grp_stack.pop().unwrap_or(0);
        let grp = e.state.src_grp_closing;
        // A `\over`/`\atop`/`\choose` in this group leaves the in-progress generalized
        // fraction noad in `curlist.auxfield` (still set here, before `fin_mlist`). Apply
        // the SAME group consumed-extent to it so its bar / `\atopwithdelims` delimiters
        // map to the whole `{..\choose..}` group -- the one rule reaches the fraction too.
        let aux = e.state.curlist.auxfield.u.CINT;
        let frac = if aux > 0 && aux != -(268435455 as i32) { aux } else { -1 };
        if e.state.cur_stack_head != 0 {
            let idx = (e.state.cur_stack_head - 1) as usize;
            if let Some(cell) = e.state.src_stack_cells.get(idx).copied() {
                // Only finalize a still-pending group frame whose source matches the live
                // buffer; otherwise just pop (defensive against any non-group top).
                if cell.pending
                    && cell.name != 0
                    && cell.name == e.state.curinput.namefield as strnumber
                {
                    let end = e.src_buf_offset(e.state.curinput.locfield as integer);
                    let (lo, hi) = if cell.start <= end {
                        (cell.start, end)
                    } else {
                        (end, cell.start)
                    };
                    let id = e.intern_span_raw(cell.name, lo, hi, 1);
                    if let Some(c) = e.state.src_stack_cells.get_mut(idx) {
                        c.span = id;
                        c.pending = false;
                    }
                }
                e.state.cur_stack_head = cell.parent;
            }
        }
        if frac >= 0 {
            Self::src_construct_extent(eptr, frac, grp);
        }
    }

    /// HOOK (`math_radical` / `math_ac`, right after the construct noad is
    /// allocated): anchor its source START to the in-fragment USER command. The
    /// noad was just stamped by `get_node` with the ambient `cmd_span`, which for a
    /// `\@ifnextchar`-peeked construct (`\sqrt{y}` -> `\sqrtsign` dispatched while
    /// the buffer `spanfield` still points at the peeked `{`) is the radicand brace,
    /// not the command. The noad is allocated BEFORE its field is scanned, so the
    /// live `src_user_cmd_span` is exactly the command the user typed (no inner
    /// construct lexed yet). Pull the START left to it (same source, only leftward),
    /// keeping the end; the matching `src_construct_extend_to_loc` then grows the end
    /// past the field. Uniform: every mark-synthesizing construct primitive, by
    /// closure -- no per-construct code, no heuristic (the command<->noad link is
    /// the tracked user-command register, not source adjacency).
    pub(crate) unsafe fn src_construct_anchor(engine: *mut Self) {
        let Some(engine) = engine.as_mut() else {
            return;
        };
        if !engine.state.source_tracking {
            return;
        }
        let noad = engine.state.curlist.tailfield as i32;
        if noad < 0 {
            return;
        }
        let id = engine.state.node_src.get_copy(noad as usize);
        if id == 0 {
            return;
        }
        let Some(raw) = engine.state.src_spans.get((id - 1) as usize).copied() else {
            return;
        };
        // Prefer the replay-aware anchor command (set while a NESTED construct was
        // replayed from a token list); fall back to the buffer user command ONLY when
        // the anchor is absent or from a different source. `src_anchor_cmd` is reset
        // on every buffer read, so it never leaks across sibling constructs.
        //
        // The anchor and the fallback are NOT interchangeable candidates to pick
        // whichever "wins" a leftward-pull check: a valid, same-source anchor means
        // this noad IS the replayed nested construct, so the buffer user command (the
        // OUTER construct enclosing the replay, e.g. Cardano's outer `\sqrt[3]{..}`)
        // must never be consulted for it -- not even as a fallback -- regardless of
        // whether the anchor itself happens to already equal the noad's own start (no
        // pull needed: the noad is already correctly anchored to itself, not to the
        // buffer command of note). Only ever pulls the START leftward.
        let anchor = (engine.state.src_anchor_cmd != 0)
            .then(|| engine.state.src_spans.get((engine.state.src_anchor_cmd - 1) as usize).copied())
            .flatten()
            .filter(|u| u.name == raw.name);
        let chosen = match anchor {
            Some(u) => {
                if u.start < raw.start {
                    Some(u)
                } else {
                    None
                }
            }
            None => (engine.state.src_user_cmd_span != 0)
                .then(|| engine.state.src_spans.get((engine.state.src_user_cmd_span - 1) as usize).copied())
                .flatten()
                .filter(|u| u.name == raw.name && u.start < raw.start),
        };
        let Some(u) = chosen else {
            return;
        };
        let newid = engine.intern_span_raw(raw.name, u.start, raw.end, raw.role);
        engine.state.node_src.set(noad as usize, newid);
    }

    /// HOOK (`handle_right_brace` math-group close, after the nucleus field is
    /// filled): the spec's "extend to loc at noad commit" half of the construct
    /// rule. A construct primitive (`\radical`, `\mathaccent`, hence `\sqrt{y}`,
    /// `\hat{x}`, bare `\radical..{y}`) scans its nucleus `{..}` AFTER its command:
    /// `scan_math` RETURNS at the opening `{` and the field is filled only when the
    /// group closes here, so the noad stamped at allocation covers only the command.
    /// Extend the construct noad's source END to the post-`}` buffer loc, giving the
    /// surd/vinculum/accent the FULL `cmd{..}` extent. The START (the latched
    /// command) is kept, so this is pure right-extension; the nucleus field span is
    /// never touched, so the radicand glyph keeps its own char. A token-list-replayed
    /// nucleus (a NESTED `\sqrt{..}`'s radicand inside a degree-form outer) has a mem-ptr
    /// loc, so the end comes from the just-closed `}` token's own span instead of the
    /// buffer loc. Uniform across every construct whose nucleus is its `+1` field, by
    /// closure -- no per-construct code.
    pub(crate) unsafe fn src_construct_extend_to_loc(engine: *mut Self) {
        let e = match engine.as_ref() {
            Some(e) => e,
            None => return,
        };
        if !e.state.source_tracking {
            return;
        }
        // Only the construct's OWN nucleus (its `+1` field): a sub/superscript field
        // (`+2`/`+3`) closing must not extend the base atom.
        let field = (*e
            .state
            .savestack
            .offset((e.state.saveptr as i32 + 0 as i32) as isize))
            .u
            .CINT;
        let noad = e.state.curlist.tailfield as i32;
        let grp = e.state.src_grp_closing;
        if noad < 0 || field != noad + 1 {
            return;
        }
        Self::src_construct_extent(engine, noad, grp);
    }

    /// THE general construct-extent rule (replaces the per-construct delimiter/accent/
    /// nucleus extenders). Map a construct noad's SYNTHESIZED marks (radical surd +
    /// vinculum, fraction bar/delimiters, accent glyph, `\left/\right` delimiters) to the
    /// construct's full CONSUMED-SOURCE extent `[min(noad command start, group open),
    /// consumed end]`:
    /// - `group_open` = the opening-token span of the construct's group (`{` of a
    ///   `scan_math` field / bare math group, or `\left`), from `src_grp_stack`. `min`
    ///   keeps a PREFIX command's earlier start (`\sqrt{x}` -> `\sqrt`) and pulls an
    ///   ENCLOSING group's start to the bracket (`\left(..\right)`, `{n\choose k}`). `0`
    ///   means no group (END-only: an unbraced `\dot q`).
    /// - END = the live post-close buffer loc, or, when the close is replayed from a token
    ///   list (a nested construct), the just-closed token's OWN interned span end.
    /// Pure extension of `node_src[noad]`; the nucleus FIELD / leaf spans are never
    /// touched, so content chars keep their own origin. One rule, no per-construct code.
    pub(crate) unsafe fn src_construct_extent(engine: *mut Self, noad: halfword, group_open: SrcId) {
        let Some(engine) = engine.as_mut() else {
            return;
        };
        if !engine.state.source_tracking || noad < 0 {
            return;
        }
        let id = engine.state.node_src.get_copy(noad as usize);
        if id == 0 {
            return;
        }
        let Some(raw) = engine.state.src_spans.get((id - 1) as usize).copied() else {
            return;
        };
        let (end, name) = if engine.state.curinput.statefield as i32 != 0 {
            (
                engine.src_buf_offset(engine.state.curinput.locfield as integer),
                engine.state.curinput.namefield as strnumber,
            )
        } else {
            let sid = engine.state.curinput.spanfield;
            if sid == 0 {
                return;
            }
            let Some(braw) = engine.state.src_spans.get((sid - 1) as usize).copied() else {
                return;
            };
            (braw.end, braw.name)
        };
        if raw.name != name {
            return;
        }
        let end = end.max(raw.end);
        let mut start = raw.start;
        if group_open != 0 {
            if let Some(g) = engine.state.src_spans.get((group_open - 1) as usize).copied() {
                if g.name == name && g.start < start {
                    start = g.start;
                }
            }
        }
        if start == raw.start && end == raw.end {
            return;
        }
        let newid = engine.intern_span_raw(name, start, end, raw.role);
        engine.state.node_src.set(noad as usize, newid);
    }

    /// HOOK (`math_left_right`, after `scan_delimiter`): drive the GENERAL extent for a
    /// `\left..\right` group, which is NOT a `scan_math` `{}` field so does not pass
    /// through `src_scan_math_group_*`. `\left` (t==30) pushes its command span as the
    /// group open; `\right` (t==31) pops it and applies `src_construct_extent` to the
    /// right delimiter noad `p` (from which `make_left_right` builds BOTH delimiter
    /// glyphs), giving them the whole `[\left, )]` extent through the same one rule.
    pub(crate) unsafe fn src_leftright(engine: *mut Self, p: halfword, t: integer) {
        let Some(eng) = engine.as_mut() else {
            return;
        };
        if !eng.state.source_tracking {
            return;
        }
        if t == 30 as i32 {
            let cmd = eng.state.cmd_span;
            eng.state.src_grp_stack.push(cmd);
        } else if t == 31 as i32 {
            let open = eng.state.src_grp_stack.pop().unwrap_or(0);
            Self::src_construct_extent(engine, p, open);
        }
    }

    /// Resolve a node's enclosing-construct chain (innermost first) to display
    /// spans, gated to the node's own source and to frames that strictly enclose
    /// the node's primary range (a real enclosing construct contains the node),
    /// with consecutive duplicates and the primary-equal innermost frame dropped.
    /// `&self`: safe on the read-only IR snapshot path. Empty when tracking off.
    /// Consumed by the IR builder to emit role-tagged EnclosingConstruct entries.
    pub fn node_enclosing_spans(&self, handle: PortableNodeHandle) -> Vec<PortableSourceSpan> {
        let node = handle.0 as halfword;
        let mut out: Vec<PortableSourceSpan> = Vec::new();
        if !self.state.source_tracking || node < 0 {
            return out;
        }
        let primary = self.resolve_node_src(node);
        let mut head = self.state.node_stack.get_copy(node as usize);
        let mut guard = 0u32;
        while head != 0 {
            guard += 1;
            if guard > 4096 {
                break;
            }
            let Some(cell) = self.state.src_stack_cells.get((head - 1) as usize) else {
                break;
            };
            let parent = cell.parent;
            let span_id = cell.span;
            head = parent;
            if span_id == 0 {
                continue;
            }
            let Some(raw) = self.state.src_spans.get((span_id - 1) as usize) else {
                continue;
            };
            let Some(name) = (unsafe { self.pool_string(raw.name) }) else {
                continue;
            };
            if let Some(p) = primary.as_ref() {
                // Same-source + containment: an enclosing construct's range must
                // contain the node's primary range; drop the frame equal to it.
                if name != p.name || raw.start > p.start || raw.end < p.end {
                    continue;
                }
                if raw.start == p.start && raw.end == p.end {
                    continue;
                }
            }
            if let Some(last) = out.last() {
                if last.name == name && last.start == raw.start && last.end == raw.end {
                    continue;
                }
            }
            out.push(PortableSourceSpan {
                name,
                start: raw.start,
                end: raw.end,
                role: 1,
            });
        }
        out
    }

    /// HOOK 8 (`begin_token_list`, after the input-stack push): set the new
    /// level's BASELINE. A macro body (`t == macro`) adopts the call-site span
    /// captured at `macro_call`; every other level keeps the parent's span (the
    /// generated push already copied it into `curinput`, so that is free).
    pub(crate) unsafe fn src_begin_token_list(engine: *mut Self, t: quarterword) {
        let Some(engine) = engine.as_mut() else {
            return;
        };
        if !engine.state.source_tracking {
            return;
        }
        // `macro` token type is 6 in this build's (XeTeX) numbering.
        if t as i32 == 6 {
            let call = engine.state.pending_call_span;
            if call != 0 {
                engine.state.curinput.spanfield = call;
            }
            engine.state.pending_call_span = 0;
            // HOOK 8a: push this macro invocation as an enclosing-construct frame
            // (popped at the matching end_token_list, HOOK 8b). Nodes the body
            // allocates record it on `node_stack`.
            engine.src_stack_push_span(call);
        }
    }

    /// HOOK 12a (`\let`/`\futurelet` 2-token look-ahead, `prefixed_command`
    /// case `let` with `n != normal`, right after `q := cur_tok`): capture
    /// token A's (the first peeked token, held in `q`) OWN origin, frozen in
    /// `src_tok_span` by the `get_token` that just read it.
    ///
    /// tex.web: `get_token; q:=cur_tok; get_token; back_input; cur_tok:=q;
    /// back_input;`. The SECOND `get_token` (reading token B) overwrites
    /// `src_tok_span` with B's own origin; `q := cur_tok`/`cur_tok := q` are
    /// plain register copies that never re-freeze it. So without this capture
    /// (paired with [`Self::src_restore_tok_span`] right before the SECOND
    /// `back_input`), that `back_input` -- which re-emits token A -- fires
    /// with `src_tok_span` still pointing at B, stamping A's backed-up cell
    /// with B's origin instead of its own. `\@ifnextchar` (built on
    /// `\futurelet`) hits this in `\@tabularcr`'s `array`/`tabular`
    /// row-boundary check and in `\sqrt`'s degree scan, where token A is the
    /// token right after the command (e.g. the `{` of a degree-less
    /// `\sqrt{..}`) and B is unrelated look-ahead content.
    pub(crate) unsafe fn src_capture_tok_span(engine: *mut Self) -> u32 {
        engine.as_ref().map_or(0, |engine| engine.state.src_tok_span)
    }

    /// HOOK 12b: the restore half of [`Self::src_capture_tok_span`].
    pub(crate) unsafe fn src_restore_tok_span(engine: *mut Self, saved: u32) {
        if let Some(engine) = engine.as_mut() {
            if engine.state.source_tracking {
                engine.state.src_tok_span = saved;
            }
        }
    }

    /// HOOK 9a (`macro_call` entry): stash the invoking control sequence's
    /// origin so [`Self::src_macro_set_pending`] can build the whole-invocation
    /// span after the arguments are scanned.
    pub(crate) unsafe fn src_macro_begin(engine: *mut Self) {
        let Some(engine) = engine.as_mut() else {
            return;
        };
        if !engine.state.source_tracking {
            return;
        }
        let span = engine.state.curinput.spanfield;
        engine.state.src_call_span = span;
        engine.state.src_call_state = engine.state.curinput.statefield as integer;
        engine.state.src_call_index = engine.state.curinput.indexfield as integer;
        engine.state.src_call_name = engine.state.curinput.namefield as strnumber;
        engine.state.src_call_argspan = 0;
        // Capture the enclosing user command NOW (before this macro reads its
        // arguments, so a construct lexed while scanning the args does not become
        // the anchor). The buffer-branch baseline anchors its START here.
        engine.state.src_call_user_span = engine.state.src_user_cmd_span;
        engine.state.src_call_start = if span != 0 {
            engine
                .state
                .src_spans
                .get((span - 1) as usize)
                .map(|s| s.start)
                .unwrap_or(0)
        } else {
            0
        };
        // A macro whose cs was REPLAYED at PARAMETER level (`state == 0 && index < 3`,
        // span in the user fragment) is genuinely user-typed ARGUMENT content — e.g. a
        // nested `\sqrt{..}` replayed inside a degree-form radicand. Record it as the
        // anchor command (consumed ONLY by `src_construct_anchor`, never the arg-hull).
        // The gate is `< 3` (parameter/template levels) rather than `< 5`
        // (backed_up/inserted too): this hook only needs to see the macro CALL itself
        // (e.g. the inner `\sqrt`), which is read at parameter level; widening it to
        // also match backed_up/inserted reads (e.g. a `\futurelet`-peeked helper token)
        // would let unrelated look-ahead plumbing overwrite a real anchor. Macro BODIES
        // (index 6) are excluded for the usual definition-vs-invocation-site reason.
        if engine.state.src_call_state == 0 && engine.state.src_call_index < 3 && span != 0 {
            if let Some(raw) = engine.state.src_spans.get((span - 1) as usize).copied() {
                if raw.name == engine.state.src_primary_name {
                    engine.state.src_anchor_cmd = span;
                }
            }
        }
    }

    /// Convex hull (same source) of the invoking cs token span (`src_call_span`),
    /// the scanned argument token spans (`pstack[0..n]`, each a token list walked to
    /// its end), and the last consumed argument span (`src_call_argspan`, the final
    /// `}`). Returns the interned role-1 hull, or `0` if nothing was found. This is
    /// the `\frac{q}{2}` -> "\frac{q}{2}" recovery for a token-list-replayed macro,
    /// gated to the cs token's OWN source (not the replay level's `namefield`).
    unsafe fn src_arg_hull(self: &mut Self, n: integer) -> SrcId {
        let mut lo = u32::MAX;
        let mut hi = 0u32;
        let mut found = false;
        let mut name: strnumber = self.state.src_primary_name;
        if self.state.src_call_span != 0 {
            if let Some(raw) = self
                .state
                .src_spans
                .get((self.state.src_call_span - 1) as usize)
            {
                name = raw.name;
                lo = raw.start;
                hi = raw.end;
                found = true;
            }
        }
        // Forward-only gate: when seeded from a known command span, only union args
        // that fall AT OR AFTER the command start (the macro's own `cmd{..}` region).
        // This keeps `\def\foo{\frac{1}{2}}\foo` mapping its bar to "\foo": the inner
        // `\frac`'s args sit at the `\def` site, BEFORE the `\foo` invocation the bar
        // inherited, so they are excluded rather than merged into a span straddling
        // the definition and the call. When there is no command span (a library
        // helper), the gate is open (`0`) and the first arg seeds the hull.
        let cmd_start = if found { lo } else { 0 };
        let zmem = self.state.zmem;
        let lo_b = self.state.memmin;
        let hi_b = self.state.memmax;
        for i in 0..n.max(0) {
            let mut p = self.state.pstack[i as usize];
            let mut guard = 0i32;
            while p >= lo_b && p <= hi_b && p as i64 != -(268435455 as i64) {
                guard += 1;
                if guard > 100000 {
                    break;
                }
                let id = self.state.node_src.get_copy(p as usize);
                if id != 0 {
                    if let Some(raw) = self.state.src_spans.get((id - 1) as usize) {
                        if raw.name == name && raw.start >= cmd_start {
                            if found {
                                lo = lo.min(raw.start);
                                hi = hi.max(raw.end);
                            } else {
                                lo = raw.start;
                                hi = raw.end;
                                found = true;
                            }
                        }
                    }
                }
                p = (*zmem.offset(p as isize)).hh.v.RH;
            }
        }
        // Extend to the last consumed argument token (the closing `}` of the final
        // brace group) so the construct includes its trailing delimiter. Two tracked
        // sources: `src_call_argspan` (captured at the first `end_token_list` pop)
        // and the live `curinput.spanfield` (the last token read while matching the
        // args). The latter recovers the trailing `}` for a `\mathchoice`-replayed
        // robust `\frac␣` where the pop-order leaves `src_call_argspan` stale.
        for cand in [self.state.src_call_argspan, self.state.curinput.spanfield] {
            if cand == 0 {
                continue;
            }
            if let Some(raw) = self.state.src_spans.get((cand - 1) as usize) {
                if raw.name == name && raw.start >= cmd_start {
                    if found {
                        lo = lo.min(raw.start);
                        hi = hi.max(raw.end);
                    } else {
                        lo = raw.start;
                        hi = raw.end;
                        found = true;
                    }
                }
            }
        }
        if found && hi > lo {
            self.intern_span_raw(name, lo, hi, 1)
        } else {
            0
        }
    }

    /// HOOK 9b (`macro_call`, right before the body `begin_token_list`): publish
    /// the call-site span the body level will inherit, LEVEL-TYPED by where the
    /// invoking control sequence was read from (captured at `src_macro_begin`,
    /// before the exhausted-list pop loop perturbs `curinput`):
    ///
    /// * Genuine macro ARGUMENT replay (entry token type `parameter` = 0, e.g. a
    ///   `\frac{q}{2}` typed inside another macro's `{...}` or replayed by
    ///   `\mathchoice`): the buffer `loc` has popped past this invocation, so its
    ///   `[cs,loc)` would overshoot into the enclosing macro. Recover the extent as
    ///   the same-source convex hull of the cs token and the scanned argument token
    ///   spans (`pstack[0..n]`) -> the user's own `\frac{q}{2}`, not `\frac`.
    /// * Otherwise CURRENT buffer (`statefield != 0`, the common direct call and the
    ///   backed-up math-probe whose args were scanned from the buffer): the whole
    ///   `[cs_start, loc)` invocation (loc past the args) -> `\frac{a}{b}`.
    /// * Otherwise a still-live token list (a macro body / every-list): the
    ///   inherited baseline, so body-internal calls collapse to the outer
    ///   invocation (`\def\foo{\frac..}\foo` -> `\foo`).
    pub(crate) unsafe fn src_macro_set_pending(engine: *mut Self, n: integer) {
        let Some(engine) = engine.as_mut() else {
            return;
        };
        if !engine.state.source_tracking {
            return;
        }
        if engine.state.src_call_index == 0 && engine.state.src_call_span == 0 {
            // A LIBRARY HELPER macro -- one with no in-fragment cs span, e.g. `\@sqrt`
            // invoked by `\sqrt`, or `\root`/`\mathchoice` machinery -- is NOT a user
            // construct. Its in-fragment ARGUMENTS (`[3]{x}`) are the OUTER command's
            // args, not a new construct boundary. So it must NOT establish a new
            // baseline from those args (which is why the surd was landing on `[3]{x}`);
            // inherit the parent baseline (the transitively-propagated user command,
            // e.g. `\sqrt`) by leaving the level to inherit on push. The arg CONTENT
            // (3, x) still keeps its own cell spans. Only a USER macro (in-fragment cs,
            // handled below) defines its own `[cs..args]` hull.
            engine.state.pending_call_span = 0;
        } else if engine.state.src_call_index == 0 {
            // ARGUMENT / backed-up replay (`\frac{q}{2}` typed inside another macro's
            // `{..}`): recover its own `[cs..args]` hull from the scanned args.
            let hull = engine.src_arg_hull(n);
            engine.state.pending_call_span = if hull != 0 {
                hull
            } else {
                engine.state.src_call_span
            };
        } else if engine.state.curinput.statefield as i32 != 0 {
            // BUFFER invocation: the whole `[cmd_start, loc)` extent (loc is past the
            // args). Anchor the START to the ENCLOSING USER COMMAND (captured at
            // `src_macro_begin`), not this macro's own `src_call_span`: a kernel
            // helper reached through a user command's expansion (e.g. `\@sqrt`,
            // `\root`, `\mathpalette` for `\sqrt[3]{x}`) is invoked from the buffer
            // with a borrowed cs span (the `\@ifnextchar` peeked `[`), which would
            // drop the `\sqrt` origin. The user command's start transitively anchors
            // every helper to the command the user typed. For a directly-typed user
            // macro the user command IS this macro, so the start is unchanged.
            let end = engine.src_buf_offset(engine.state.curinput.locfield as integer);
            let name = engine.state.curinput.namefield as strnumber;
            let mut start = engine.state.src_call_start.min(end);
            let user = engine.state.src_call_user_span;
            if user != 0 {
                if let Some(raw) = engine.state.src_spans.get((user - 1) as usize) {
                    if raw.name == name && raw.start <= start {
                        start = raw.start;
                    }
                }
            }
            let id = engine.intern_span_raw(name, start, end, 1);
            engine.state.pending_call_span = id;
        } else if n > 0 {
            // TOKEN-LIST macro BODY (`index >= 5`) that consumed args. The inherited
            // baseline is the user invocation that produced this body (`\frac` ->
            // `\protect\frac␣`: `\frac␣`'s baseline is the user's `\frac`). UNION it
            // with the macro's OWN trailing args so a `\frac{q}{2}` the user typed as
            // a `\mathchoice`-replayed radicand recovers "\frac{q}{2}". `src_arg_hull`
            // only unions args that fall AFTER the command start (the macro's own
            // `cmd{..}` region), so a `\def\foo{\frac{1}{2}}\foo` body -- whose inner
            // `\frac` args precede the `\foo` invocation -- excludes them and keeps
            // the bar -> "\foo". The join is the command and its OWN tracked args
            // (the macro-call chain), never an unrelated adjacent range.
            let hull = engine.src_arg_hull(n);
            engine.state.pending_call_span = if hull != 0 {
                hull
            } else {
                engine.state.src_call_span
            };
        } else {
            engine.state.pending_call_span = engine.state.src_call_span;
        }
    }

    /// HOOK 11 (`main_control` main loop, the `is_hyph` seam): record the source
    /// span of the input char just appended to `nativetext`, one entry per UTF-16
    /// code unit (a surrogate-pair char fills both units with the same id). This
    /// runs once per collected char while `curinput.spanfield` still points at it.
    /// The run begins when `nativelen` was 0 before this char (`prev == 0`), so the
    /// table self-resets at the head of each run without a second anchor; a later
    /// re-measure of an unrelated run is caught by the length guard in
    /// [`Self::src_resolve_native_glyphs`]. No-op when tracking off.
    pub(crate) unsafe fn src_native_run_push(engine: *mut Self) {
        let Some(engine) = engine.as_mut() else {
            return;
        };
        if !engine.state.source_tracking {
            return;
        }
        let nativelen = engine.state.nativelen.max(0) as usize;
        // The engine appends 2 UTF-16 units for a supplementary scalar, else 1
        // (mirrors the `curchr > 65535` branch just above this seam).
        let units = if engine.state.curchr as i64 > 65535 { 2 } else { 1 };
        let prev = nativelen.saturating_sub(units);
        if prev == 0 {
            engine.state.src_native_offsets.clear();
        }
        // Trim any stale overshoot (defensive; cleared at `prev == 0`), then fill
        // this char's units with its tracked span id.
        if engine.state.src_native_offsets.len() > prev {
            engine.state.src_native_offsets.truncate(prev);
        }
        let id = engine.state.curinput.spanfield;
        while engine.state.src_native_offsets.len() < nativelen {
            engine.state.src_native_offsets.push(id);
        }
    }

    /// Map each shaped glyph of a native run to the EXACT source span of the input
    /// char(s) under its shaper cluster, setting `src_start`/`src_end` (in the
    /// node's `primary_source.source` coordinates). The shaper reports each glyph's
    /// `cluster_start` as a UTF-8 BYTE offset into `String::from_utf16_lossy(text)`
    /// (the engine hands the shaper UTF-16 `nativetext`, the adapter converts to a
    /// Rust `&str`, and rustybuzz clusters are UTF-8 byte indices). This rebuilds
    /// that string, maps each UTF-8 byte to its char's tracked span via a UTF-16
    /// code-unit cursor aligned with `src_native_offsets`, then for each glyph
    /// unions the (same-source) spans across its cluster's byte extent — the extent
    /// being `[cluster_start, next distinct cluster_start)`, so a ligature glyph
    /// covers the contiguous union of its source chars. CONSUME-ONCE: the offsets
    /// table is taken here, so a re-measure (reconstituted/hyphenated run, or an
    /// unrelated node) finds it empty and leaves clusters unmapped rather than
    /// mis-mapping. Zero heuristics: no text==source linear assumption — every span
    /// comes from a per-char tracked id. No-op when tracking off.
    pub(crate) unsafe fn src_resolve_native_glyphs(
        engine: *mut Self,
        node: halfword,
        text: &[u16],
        glyphs: &mut [PortableNativeGlyph],
    ) {
        let Some(engine) = engine.as_mut() else {
            return;
        };
        if !engine.state.source_tracking {
            return;
        }
        let offsets = core::mem::take(&mut engine.state.src_native_offsets);
        // Only resolve our freshly-collected run: the per-code-unit table must
        // exactly cover this node's text. Any mismatch => leave glyphs unmapped.
        if text.is_empty() || offsets.len() != text.len() {
            return;
        }
        if node < 0 {
            return;
        }
        // The cluster span lives in the node's source coordinates, so only chars
        // from the node's own source file may contribute (no cross-source span).
        let node_id = engine.state.node_src.get_copy(node as usize);
        if node_id == 0 {
            return;
        }
        let node_name = match engine.state.src_spans.get((node_id - 1) as usize) {
            Some(raw) => raw.name,
            None => return,
        };
        // Rebuild the exact UTF-8 string the shaper saw and tag each byte with the
        // source id of the char it belongs to (UTF-16 cursor aligns to `offsets`).
        // The shaper reports `cluster_start` as a UTF-8 BYTE offset into this
        // string (verified empirically: a supplementary-plane run char lands its
        // following glyph at the UTF-8 byte offset, not the UTF-16 code-unit one).
        let s = String::from_utf16_lossy(text);
        let n = s.len();
        let mut byte_src = vec![0u32; n];
        let mut u16i = 0usize;
        for (b, ch) in s.char_indices() {
            let id = offsets.get(u16i).copied().unwrap_or(0);
            let upper = (b + ch.len_utf8()).min(n);
            for slot in byte_src.iter_mut().take(upper).skip(b) {
                *slot = id;
            }
            u16i += ch.len_utf16();
        }
        for gi in 0..glyphs.len() {
            let cs = (glyphs[gi].cluster_start as usize).min(n);
            // Monotone (LTR) clusters: this cluster ends at the next strictly
            // greater `cluster_start`, else at end-of-text. Glyphs sharing `cs`
            // (a decomposed char) resolve to the same char span.
            let mut ce = n;
            for g2 in glyphs.iter() {
                let c2 = (g2.cluster_start as usize).min(n);
                if c2 > cs && c2 < ce {
                    ce = c2;
                }
            }
            let mut lo = u32::MAX;
            let mut hi = 0u32;
            let mut found = false;
            for &id in byte_src.iter().take(ce).skip(cs) {
                if id == 0 {
                    continue;
                }
                let Some(raw) = engine.state.src_spans.get((id - 1) as usize) else {
                    continue;
                };
                if raw.name != node_name {
                    continue;
                }
                lo = lo.min(raw.start);
                hi = hi.max(raw.end);
                found = true;
            }
            if found && hi > lo {
                glyphs[gi].src_start = lo;
                glyphs[gi].src_end = hi;
            }
        }
    }

    /// All interned spans, resolved to display form. Restored from the stubbed
    /// `&[]`: exposes the populated table for inspection / tests.
    pub fn input_source_spans(&self) -> Vec<PortableSourceSpan> {
        self.state
            .src_spans
            .iter()
            .filter_map(|raw| {
                let name = unsafe { self.pool_string(raw.name) }?;
                Some(PortableSourceSpan {
                    name,
                    start: raw.start,
                    end: raw.end,
                    role: raw.role,
                })
            })
            .collect()
    }

    pub(crate) unsafe fn resolve_font_handle(
        engine: *mut PortableTexEngine<'_>,
        name: *mut ASCIIcode,
        size: integer,
    ) -> FontHandle {
        let Some(engine) = engine.as_mut() else {
            return 0;
        };
        let name_len = engine.state.namelength.max(0) as usize;
        let name = if name.is_null() || name_len == 0 {
            &[]
        } else {
            core::slice::from_raw_parts(name as *const i32, name_len)
        };
        engine.fonts.resolve_font_handle(name, size).unwrap_or(0)
    }

    pub(crate) unsafe fn measure_font_metrics(
        engine: *mut PortableTexEngine<'_>,
        font: FontHandle,
        ascent: *mut integer,
        descent: *mut integer,
        xheight: *mut integer,
        capheight: *mut integer,
        slant: *mut integer,
    ) {
        let metrics = engine
            .as_mut()
            .map(|engine| engine.fonts.font_metrics(font))
            .unwrap_or_default();
        if !ascent.is_null() {
            *ascent = metrics.ascent;
        }
        if !descent.is_null() {
            *descent = metrics.descent;
        }
        if !xheight.is_null() {
            *xheight = metrics.xheight;
        }
        if !capheight.is_null() {
            *capheight = metrics.capheight;
        }
        if !slant.is_null() {
            *slant = metrics.slant;
        }
    }

    pub(crate) unsafe fn get_native_mathsy_parameter(
        engine: *mut PortableTexEngine<'resources>,
        font: integer,
        param: integer,
    ) -> integer {
        let Some(engine) = engine.as_mut() else {
            return 0;
        };
        let Some(font_handle) = Self::font_handle_for_number(engine, font) else {
            return 0;
        };
        engine.fonts.math_symbol_parameter(font_handle, param)
    }

    pub(crate) unsafe fn get_native_mathex_parameter(
        engine: *mut PortableTexEngine<'resources>,
        font: integer,
        param: integer,
    ) -> integer {
        let Some(engine) = engine.as_mut() else {
            return 0;
        };
        let Some(font_handle) = Self::font_handle_for_number(engine, font) else {
            return 0;
        };
        engine.fonts.math_extension_parameter(font_handle, param)
    }

    /// Italic correction for a native OpenType-math glyph, in scaled points.
    ///
    /// Mirrors XeTeX's `get_ot_math_ital_corr` (`XeTeXOTMath.cpp`): it reads the
    /// glyph's `MathItalicsCorrectionInfo` value and scales it through the same
    /// `unitsToPoints` + `D2Fix` path as every other font metric. The math list
    /// builder (`mlist_to_hlist`) appends a `\kern` of this size after an ord
    /// glyph when there is no following subscript, so a correct nonzero value
    /// produces the exact italic-correction kern real XeTeX emits.
    pub(crate) unsafe fn get_ot_math_ital_corr(
        engine: *mut PortableTexEngine<'resources>,
        font: integer,
        glyph: integer,
    ) -> integer {
        let Some(engine) = engine.as_mut() else {
            return 0;
        };
        let Some(font_handle) = Self::font_handle_for_number(engine, font) else {
            return 0;
        };
        engine.fonts.math_glyph_italic_correction(font_handle, glyph)
    }

    /// The `v`-th larger MATH glyph variant of `g` (horizontal or vertical),
    /// writing its scaled advance to `*adv`. Mirrors XeTeX's
    /// `get_ot_math_variant`: returns the glyph unchanged with `*adv = -1` when
    /// there is no such variant.
    pub(crate) unsafe fn get_ot_math_variant(
        engine: *mut PortableTexEngine<'resources>,
        f_0: integer,
        g_0: integer,
        v: integer,
        adv: *mut integer,
        horiz: integer,
    ) -> integer {
        if !adv.is_null() {
            *adv = -1;
        }
        let Some(engine) = engine.as_mut() else {
            return g_0;
        };
        let Some(font_handle) = Self::font_handle_for_number(engine, f_0) else {
            return g_0;
        };
        let index = u16::try_from(v).unwrap_or(u16::MAX);
        match engine
            .fonts
            .math_glyph_variant(font_handle, g_0, index, horiz != 0)
        {
            Some(variant) => {
                if !adv.is_null() {
                    *adv = variant.advance;
                }
                variant.glyph
            }
            None => g_0,
        }
    }

    /// Build a heap-owned [`GlyphAssembly`] for the stretchable glyph `g` and
    /// hand ownership to the engine as a `void*` (reclaimed by
    /// [`free_ot_assembly`]). Returns null when there is no assembly. Mirrors
    /// XeTeX's `get_ot_assembly_ptr`, but allocates a safe Rust struct with
    /// `Box::into_raw` instead of a libc C struct.
    pub(crate) unsafe fn get_ot_assembly_ptr(
        engine: *mut PortableTexEngine<'resources>,
        f_0: integer,
        g_0: integer,
        horiz: integer,
    ) -> voidpointer {
        let Some(engine) = engine.as_mut() else {
            return nullptr;
        };
        let Some(font_handle) = Self::font_handle_for_number(engine, f_0) else {
            return nullptr;
        };
        let parts = engine
            .fonts
            .math_glyph_assembly(font_handle, g_0, horiz != 0);
        if parts.is_empty() {
            return nullptr;
        }
        let assembly = Box::new(GlyphAssembly { parts });
        Box::into_raw(assembly) as voidpointer
    }

    /// Minimum connector overlap between assembly parts for font `f`, in scaled
    /// points (`ot_min_connector_overlap`).
    pub(crate) unsafe fn ot_min_connector_overlap(
        engine: *mut PortableTexEngine<'resources>,
        f_0: integer,
    ) -> integer {
        let Some(engine) = engine.as_mut() else {
            return 0;
        };
        let Some(font_handle) = Self::font_handle_for_number(engine, f_0) else {
            return 0;
        };
        engine.fonts.math_min_connector_overlap(font_handle)
    }

    /// MATH glyph height (scaled points) via the font platform.
    unsafe fn math_glyph_height(
        engine: &mut PortableTexEngine<'resources>,
        f_0: integer,
        g_0: integer,
    ) -> scaled {
        let Some(font_handle) = Self::font_handle_for_number(engine, f_0) else {
            return 0;
        };
        let Ok(glyph) = u16::try_from(g_0) else {
            return 0;
        };
        engine.fonts.measure_native_glyph(font_handle, glyph, true).height
    }

    /// MATH glyph depth (scaled points) via the font platform.
    unsafe fn math_glyph_depth(
        engine: &mut PortableTexEngine<'resources>,
        f_0: integer,
        g_0: integer,
    ) -> scaled {
        let Some(font_handle) = Self::font_handle_for_number(engine, f_0) else {
            return 0;
        };
        let Ok(glyph) = u16::try_from(g_0) else {
            return 0;
        };
        engine.fonts.measure_native_glyph(font_handle, glyph, true).depth
    }

    /// Evaluate one MATH kern corner of glyph `g` at `correction_height` (font
    /// design units), in raw font units, via the font platform.
    unsafe fn math_kern_at(
        engine: &mut PortableTexEngine<'resources>,
        f_0: integer,
        g_0: integer,
        height: integer,
        corner: PortableMathKernCorner,
    ) -> integer {
        let Some(font_handle) = Self::font_handle_for_number(engine, f_0) else {
            return 0;
        };
        engine.fonts.math_kern_at(font_handle, g_0, corner, height)
    }

    /// Superscript/subscript cut-in kerning between base glyph `g` in font `f`
    /// and script glyph `sg` in font `sf`. Faithful port of XeTeX's
    /// `get_ot_math_kern` (`XeTeXOTMath.cpp`): all intermediate arithmetic runs
    /// in base-glyph units with a `scale_factor = sf_size / f_size`, the "max not
    /// min" corner choice is preserved, and the result is scaled to scaled points
    /// through the same `unitsToPoints` + `D2Fix` path.
    pub(crate) unsafe fn get_ot_math_kern(
        engine: *mut PortableTexEngine<'resources>,
        f_0: integer,
        g_0: integer,
        sf: integer,
        sg: integer,
        cmd: integer,
        shift_scaled: integer,
    ) -> integer {
        const SUP_CMD: integer = 0;
        const SUB_CMD: integer = 1;
        let Some(engine) = engine.as_mut() else {
            return 0;
        };
        let Some(font_handle) = Self::font_handle_for_number(engine, f_0) else {
            return 0;
        };
        let Some(sfont_handle) = Self::font_handle_for_number(engine, sf) else {
            return 0;
        };

        // Glyph height/depth in points (sp -> pt) for the base and script glyphs.
        let g_height_pt = Self::math_glyph_height(engine, f_0, g_0) as f32 / 65536.0;
        let g_depth_pt = Self::math_glyph_depth(engine, f_0, g_0) as f32 / 65536.0;
        let sg_height_pt = Self::math_glyph_height(engine, sf, sg) as f32 / 65536.0;
        let sg_depth_pt = Self::math_glyph_depth(engine, sf, sg) as f32 / 65536.0;

        // Convert everything to base-glyph units.
        let g_height = engine.fonts.math_points_to_units(font_handle, g_height_pt) as integer;
        let g_depth = engine.fonts.math_points_to_units(font_handle, g_depth_pt) as integer;
        let sg_height = engine
            .fonts
            .math_points_to_units(sfont_handle, sg_height_pt) as integer;
        let sg_depth = engine
            .fonts
            .math_points_to_units(sfont_handle, sg_depth_pt) as integer;
        let shift_pt = shift_scaled as f32 / 65536.0;
        let shift = engine.fonts.math_points_to_units(font_handle, shift_pt) as integer;

        let f_size = engine.fonts.math_point_size(font_handle);
        let sf_size = engine.fonts.math_point_size(sfont_handle);
        if f_size == 0.0 {
            return 0;
        }
        let scale_factor = sf_size / f_size;

        let mut rval: integer;
        if cmd == SUP_CMD {
            let kern = Self::math_kern_at(
                engine,
                f_0,
                g_0,
                shift - (scale_factor * sg_depth as f32) as integer,
                PortableMathKernCorner::TopRight,
            );
            let skern =
                Self::math_kern_at(engine, sf, sg, -sg_depth, PortableMathKernCorner::BottomLeft);
            let top_kern = kern + (scale_factor * skern as f32) as integer;

            let kern =
                Self::math_kern_at(engine, f_0, g_0, g_height, PortableMathKernCorner::TopRight);
            let skern = Self::math_kern_at(
                engine,
                sf,
                sg,
                ((g_height - shift) as f32 / scale_factor) as integer,
                PortableMathKernCorner::BottomLeft,
            );
            let bot_kern = kern + (scale_factor * skern as f32) as integer;

            rval = if top_kern > bot_kern { top_kern } else { bot_kern };
        } else if cmd == SUB_CMD {
            let kern = Self::math_kern_at(
                engine,
                f_0,
                g_0,
                (scale_factor * sg_height as f32) as integer - shift,
                PortableMathKernCorner::BottomRight,
            );
            let skern =
                Self::math_kern_at(engine, sf, sg, sg_height, PortableMathKernCorner::TopLeft);
            let top_kern = kern + (scale_factor * skern as f32) as integer;

            let kern =
                Self::math_kern_at(engine, f_0, g_0, -g_depth, PortableMathKernCorner::BottomRight);
            let skern = Self::math_kern_at(
                engine,
                sf,
                sg,
                ((shift - g_depth) as f32 / scale_factor) as integer,
                PortableMathKernCorner::TopLeft,
            );
            let bot_kern = kern + (scale_factor * skern as f32) as integer;

            rval = if top_kern > bot_kern { top_kern } else { bot_kern };
        } else {
            return 0;
        }

        rval = engine.fonts.math_units_to_scaled(font_handle, rval);
        rval
    }

    pub(crate) unsafe fn get_native_word_cp(
        engine: *mut PortableTexEngine<'resources>,
        node: voidpointer,
        side: integer,
    ) -> integer {
        let Some(engine) = engine.as_mut() else {
            return 0;
        };
        let Some(node_index) = Self::node_index_for_pointer(engine, node) else {
            return 0;
        };
        let Some(info) = engine.native_glyph_infos.get(&node_index) else {
            return 0;
        };
        let glyph = if side == 0 {
            info.glyphs.first()
        } else {
            info.glyphs.last()
        };
        let Some(glyph) = glyph else {
            return 0;
        };
        let font = Self::native_node_font(engine.state.zmem, node_index);
        Self::character_protrusion(engine, font, u32::from(glyph.glyph_id), side)
    }

    pub(crate) unsafe fn get_native_glyph(
        engine: *mut PortableTexEngine<'resources>,
        node: voidpointer,
        index: u32,
    ) -> uint16_t {
        let Some(engine) = engine.as_mut() else {
            return 0;
        };
        let Some(node_index) = Self::node_index_for_pointer(engine, node) else {
            return 0;
        };
        engine
            .native_glyph_infos
            .get(&node_index)
            .and_then(|info| info.glyphs.get(index as usize))
            .map_or(0, |glyph| glyph.glyph_id)
    }

    pub(crate) unsafe fn get_character_protrusion(
        engine: *mut PortableTexEngine<'_>,
        font: integer,
        code: u32,
        side: integer,
    ) -> integer {
        engine
            .as_mut()
            .map_or(0, |engine| Self::character_protrusion(engine, font, code, side))
    }

    pub(crate) fn character_protrusion(
        engine: &PortableTexEngine<'_>,
        font: integer,
        code: u32,
        side: integer,
    ) -> integer {
        engine
            .character_protrusions
            .get(&(font, code, side))
            .copied()
            .unwrap_or(0)
    }

    pub(crate) fn set_character_protrusion(
        engine: &mut PortableTexEngine<'_>,
        font: integer,
        code: u32,
        side: integer,
        value: integer,
    ) {
        let key = (font, code, side);
        if value == 0 {
            engine.character_protrusions.remove(&key);
        } else {
            engine.character_protrusions.insert(key, value);
        }
    }

    pub(crate) unsafe fn get_opentype_math_constant(
        engine: *mut PortableTexEngine<'resources>,
        font: integer,
        constant: integer,
    ) -> integer {
        let Some(engine) = engine.as_mut() else {
            return 0;
        };
        let Some(font_handle) = Self::font_handle_for_number(engine, font) else {
            return 0;
        };
        engine.fonts.opentype_math_constant(font_handle, constant)
    }

    pub(crate) unsafe fn get_opentype_math_accent_position(
        engine: *mut PortableTexEngine<'resources>,
        font: integer,
        glyph: integer,
    ) -> integer {
        let Some(engine) = engine.as_mut() else {
            return 0;
        };
        let Some(font_handle) = Self::font_handle_for_number(engine, font) else {
            return 0;
        };
        engine.fonts.opentype_math_accent_position(font_handle, glyph)
    }

    pub(crate) unsafe fn map_char_to_glyph(
        engine: *mut PortableTexEngine<'resources>,
        font: integer,
        ch: integer,
    ) -> integer {
        let Some(engine) = engine.as_mut() else {
            return 0;
        };
        let Some(font_handle) = Self::font_handle_for_number(engine, font) else {
            return 0;
        };
        engine.fonts.map_char_to_glyph(font_handle, ch)
    }

    pub(crate) unsafe fn map_glyph_to_index(
        engine: *mut PortableTexEngine<'resources>,
        font: integer,
    ) -> integer {
        let Some(engine) = engine.as_mut() else {
            return 0;
        };
        let Some(font_handle) = Self::font_handle_for_number(engine, font) else {
            return 0;
        };
        let Some(name) = engine.pool_string(engine.state.curname) else {
            return 0;
        };
        engine.fonts.map_glyph_to_index(font_handle, name.as_str())
    }

    /// Boundary for the `\XeTeXOT*` / `\XeTeXcountglyphs` `last_item` primitives.
    /// Resolves the font number to a platform handle (mirroring
    /// `map_char_to_glyph`) and dispatches to the font platform's OpenType
    /// layout enumeration. Replaces the old `otfontget*` no-op stubs.
    pub(crate) unsafe fn ot_font_get(
        engine: *mut PortableTexEngine<'resources>,
        what: integer,
        font: integer,
        param1: integer,
        param2: integer,
        param3: integer,
    ) -> integer {
        let Some(engine) = engine.as_mut() else {
            return 0;
        };
        let Some(font_handle) = Self::font_handle_for_number(engine, font) else {
            return 0;
        };
        engine
            .fonts
            .ot_font_get(font_handle, what, param1, param2, param3)
    }

    pub(crate) unsafe fn is_opentype_math_font(
        engine: *mut PortableTexEngine<'_>,
        font: FontHandle,
    ) -> boolean {
        engine
            .as_mut()
            .map(|engine| engine.fonts.is_opentype_math_font(font) as boolean)
            .unwrap_or(false_0)
    }

    pub(crate) unsafe fn using_opentype(
        engine: *mut PortableTexEngine<'_>,
        font: FontHandle,
    ) -> boolean {
        engine
            .as_mut()
            .map(|engine| engine.fonts.using_opentype(font) as boolean)
            .unwrap_or(false_0)
    }

    pub(crate) unsafe fn release_font_engine(
        engine: *mut PortableTexEngine<'_>,
        font: FontHandle,
        type_flag: integer,
    ) {
        if let Some(engine) = engine.as_mut() {
            engine.fonts.release_font_handle(font, type_flag);
        }
    }

    pub(crate) unsafe fn measure_opentype_font_metrics(
        engine: *mut PortableTexEngine<'_>,
        font: FontHandle,
        ascent: *mut integer,
        descent: *mut integer,
        xheight: *mut integer,
        capheight: *mut integer,
        slant: *mut integer,
    ) {
        let metrics = engine
            .as_mut()
            .map(|engine| engine.fonts.opentype_font_metrics(font))
            .unwrap_or_default();
        if !ascent.is_null() {
            *ascent = metrics.ascent;
        }
        if !descent.is_null() {
            *descent = metrics.descent;
        }
        if !xheight.is_null() {
            *xheight = metrics.xheight;
        }
        if !capheight.is_null() {
            *capheight = metrics.capheight;
        }
        if !slant.is_null() {
            *slant = metrics.slant;
        }
    }

    pub(crate) unsafe fn measure_native_node(
        engine: *mut PortableTexEngine<'resources>,
        node: voidpointer,
        use_glyph_metrics: integer,
    ) {
        let Some(engine) = engine.as_mut() else {
            return;
        };
        let Some(node_index) = Self::node_index_for_pointer(engine, node) else {
            return;
        };
        let mem = engine.state.zmem;
        let font_number = Self::native_node_font(mem, node_index);
        let Some(font_handle) = Self::font_handle_for_number(engine, font_number) else {
            return;
        };
        let text = Self::native_node_text(mem, node_index);
        let mut metrics =
            engine
                .fonts
                .shape_native_text(font_handle, text, use_glyph_metrics != 0);
        // Source tracking: map each shaped glyph back to the EXACT source span of
        // the input char(s) that produced its shaper cluster, via the per-code-unit
        // ids collected during the main-loop run (no-op when tracking off).
        Self::src_resolve_native_glyphs(
            engine as *mut PortableTexEngine<'resources>,
            node_index,
            text,
            metrics.glyphs.as_mut_slice(),
        );
        Self::write_native_node_metrics(
            mem,
            node_index,
            metrics.width,
            metrics.height,
            metrics.depth,
        );
        (*mem.offset((node_index + 4) as isize)).v.QQQQ.u.B3 =
            (metrics.glyphs.len().min(i32::MAX as usize) as quarterword) as u16;
        (*mem.offset((node_index + 5) as isize)).ptr = nullptr;
        engine.native_glyph_infos.insert(
            node_index,
            PortableNativeGlyphInfo {
                glyphs: metrics.glyphs,
            },
        );
    }

    pub(crate) unsafe fn measure_native_glyph(
        engine: *mut PortableTexEngine<'resources>,
        node: voidpointer,
        use_glyph_metrics: integer,
    ) {
        let Some(engine) = engine.as_mut() else {
            return;
        };
        let Some(node_index) = Self::node_index_for_pointer(engine, node) else {
            return;
        };
        let mem = engine.state.zmem;
        let font_number = Self::native_node_font(mem, node_index);
        let Some(font_handle) = Self::font_handle_for_number(engine, font_number) else {
            return;
        };
        let glyph = (*mem.offset((node_index + 4) as isize)).v.QQQQ.u.B2 as u16;
        let metrics = engine
            .fonts
            .measure_native_glyph(font_handle, glyph, use_glyph_metrics != 0);
        Self::write_native_node_metrics(
            mem,
            node_index,
            metrics.width,
            metrics.height,
            metrics.depth,
        );
        (*mem.offset((node_index + 4) as isize)).v.QQQQ.u.B3 = (1 as quarterword) as u16;
        // NOTE: a `glyph_node` is allocated with `glyph_node_size = 5` words
        // (indices 0..=4), but XeTeX's `native_glyph_info_ptr` macro lives at word
        // `node + 5` -- one past this node. In the original C engine that word
        // aliases adjacent `mem`, which is tolerated; here `mem` is a bounds-real
        // Rust array and writing `node + 5` corrupts the *next* node (it crashed
        // `var_delimiter`, which builds a single-glyph delimiter box this way).
        // The glyph info this field would point at is held authoritatively in the
        // engine-side `native_glyph_infos` map (keyed by node index) and the raw
        // `node + 5` word is never dereferenced anywhere, so the write is omitted.
        engine.native_glyph_infos.insert(
            node_index,
            PortableNativeGlyphInfo {
                glyphs: Vec::from([PortableNativeGlyph {
                    glyph_id: glyph,
                    x: 0,
                    y: 0,
                    advance: metrics.width,
                    cluster_start: 0,
                    cluster_end: 0,
                    src_start: 0,
                    src_end: 0,
                }]),
            },
        );
    }

    pub(crate) unsafe fn znotaatfonterror(
        self: &mut Self,
        cmd: integer,
        c_0: integer,
        f_0: integer,
    ) -> EngineFlow<()> {
        self.znototfonterror(cmd, c_0, f_0)?;
        Ok(())
    }

    pub(crate) unsafe fn znotaatgrfonterror(
        self: &mut Self,
        cmd: integer,
        c_0: integer,
        f_0: integer,
    ) -> EngineFlow<()> {
        self.znototfonterror(cmd, c_0, f_0)?;
        Ok(())
    }

    /// Append a native glyph for `(f_0, g_0)` to the end of box `b`, growing the
    /// box height/depth (hlist) or width (vlist). Port of XeTeX's
    /// `stack_glyph_into_box` (`xetex.web`). The glyph node is `glyph_node_size`
    /// (5) words, measured through `measure_native_glyph`.
    unsafe fn stack_glyph_into_box(
        self: &mut Self,
        b: halfword,
        f_0: internalfontnumber,
        g_0: integer,
    ) -> EngineFlow<()> {
        let mem: *mut memoryword = self.state.zmem.as_mut_ptr();
        const NULL: halfword = -(268435455 as i64) as halfword;
        let p = (&mut *(self as *mut PortableTexEngine<'_>)).zgetnode(5)?;
        (*mem.offset(p as isize)).hh.u.B0 = 8;
        (*mem.offset(p as isize)).hh.u.B1 = 42;
        (*mem.offset((p + 4) as isize)).v.QQQQ.u.B1 = (f_0 as quarterword) as u16;
        (*mem.offset((p + 4) as isize)).v.QQQQ.u.B2 = (g_0 as quarterword) as u16;
        Self::measure_native_glyph(
            self as *mut PortableTexEngine<'resources>,
            mem.offset(p as isize) as *mut memoryword as *mut (),
            1,
        );
        Ok(
            if (*mem.offset(b as isize)).hh.u.B0 as i32 == 0 {
                let mut q = (*mem.offset((b + 5) as isize)).hh.v.RH;
                if q == NULL {
                    (*mem.offset((b + 5) as isize)).hh.v.RH = p;
                } else {
                    while (*mem.offset(q as isize)).hh.v.RH != NULL {
                        q = (*mem.offset(q as isize)).hh.v.RH;
                    }
                    (*mem.offset(q as isize)).hh.v.RH = p;
                    if (*mem.offset((b + 3) as isize)).u.CINT
                        < (*mem.offset((p + 3) as isize)).u.CINT
                    {
                        (*mem.offset((b + 3) as isize)).u.CINT = (*mem
                            .offset((p + 3) as isize))
                            .u
                            .CINT;
                    }
                    if (*mem.offset((b + 2) as isize)).u.CINT
                        < (*mem.offset((p + 2) as isize)).u.CINT
                    {
                        (*mem.offset((b + 2) as isize)).u.CINT = (*mem
                            .offset((p + 2) as isize))
                            .u
                            .CINT;
                    }
                }
            } else {
                (*mem.offset(p as isize)).hh.v.RH = (*mem.offset((b + 5) as isize))
                    .hh
                    .v
                    .RH;
                (*mem.offset((b + 5) as isize)).hh.v.RH = p;
                (*mem.offset((b + 3) as isize)).u.CINT = (*mem.offset((p + 3) as isize))
                    .u
                    .CINT;
                if (*mem.offset((b + 1) as isize)).u.CINT
                    < (*mem.offset((p + 1) as isize)).u.CINT
                {
                    (*mem.offset((b + 1) as isize)).u.CINT = (*mem
                        .offset((p + 1) as isize))
                        .u
                        .CINT;
                }
            },
        )
    }

    /// Append a glue node with natural width `min` and stretch `max - min` to box
    /// `b`. Port of XeTeX's `stack_glue_into_box` (`xetex.web`).
    unsafe fn stack_glue_into_box(
        self: &mut Self,
        b: halfword,
        min: scaled,
        max: scaled,
    ) -> EngineFlow<()> {
        let mem: *mut memoryword = self.state.zmem.as_mut_ptr();
        const NULL: halfword = -(268435455 as i64) as halfword;
        const ZERO_GLUE: halfword = 0;
        let q = (&mut *(self as *mut PortableTexEngine<'_>)).znewspec(ZERO_GLUE)?;
        (*mem.offset((q + 1) as isize)).u.CINT = min;
        (*mem.offset((q + 2) as isize)).u.CINT = max - min;
        let p = (&mut *(self as *mut PortableTexEngine<'_>)).znewglue(q)?;
        Ok(
            if (*mem.offset(b as isize)).hh.u.B0 as i32 == 0 {
                let mut r = (*mem.offset((b + 5) as isize)).hh.v.RH;
                if r == NULL {
                    (*mem.offset((b + 5) as isize)).hh.v.RH = p;
                } else {
                    while (*mem.offset(r as isize)).hh.v.RH != NULL {
                        r = (*mem.offset(r as isize)).hh.v.RH;
                    }
                    (*mem.offset(r as isize)).hh.v.RH = p;
                }
            } else {
                (*mem.offset(p as isize)).hh.v.RH = (*mem.offset((b + 5) as isize))
                    .hh
                    .v
                    .RH;
                (*mem.offset((b + 5) as isize)).hh.v.RH = p;
                (*mem.offset((b + 3) as isize)).u.CINT = (*mem.offset((p + 3) as isize))
                    .u
                    .CINT;
                (*mem.offset((b + 1) as isize)).u.CINT = (*mem.offset((p + 1) as isize))
                    .u
                    .CINT;
            },
        )
    }

    /// Build a box (height/width at least `s`) for the stretchable glyph assembly
    /// `assembly` in font `f_0`, stacking parts with overlap glue. Faithful port
    /// of XeTeX's `build_opentype_assembly` (`xetex.web`), reading parts from the
    /// heap-owned [`GlyphAssembly`] handed out by `get_ot_assembly_ptr`.
    pub(crate) unsafe fn zbuildopentypeassembly(
        self: &mut Self,
        f_0: internalfontnumber,
        assembly: voidpointer,
        s: scaled,
        horiz_flag: integer,
    ) -> EngineFlow<halfword> {
        let mem: *mut memoryword = self.state.zmem.as_mut_ptr();
        let horiz = horiz_flag != 0;
        let b = (&mut *(self as *mut PortableTexEngine<'_>)).newnullbox()?;
        (*mem.offset(b as isize)).hh.u.B0 = if horiz { 0 } else { 1 };
        let parts: &[PortableMathAssemblyPart] = if assembly.is_null() {
            &[]
        } else {
            &(*(assembly as *const GlyphAssembly)).parts
        };
        let part_count = parts.len();
        let min_o = Self::ot_min_connector_overlap(
            self as *mut PortableTexEngine<'resources>,
            f_0 as i32,
        );
        let mut n: integer = -1;
        let mut no_extenders = true;
        loop {
            n += 1;
            let mut s_max: scaled = 0;
            let mut prev_o: scaled = 0;
            for part in parts.iter() {
                if part.extender {
                    no_extenders = false;
                    for _ in 0..n {
                        let mut o = part.start_connector;
                        if min_o < o {
                            o = min_o;
                        }
                        if prev_o < o {
                            o = prev_o;
                        }
                        s_max = s_max - o + part.full_advance;
                        prev_o = part.end_connector;
                    }
                } else {
                    let mut o = part.start_connector;
                    if min_o < o {
                        o = min_o;
                    }
                    if prev_o < o {
                        o = prev_o;
                    }
                    s_max = s_max - o + part.full_advance;
                    prev_o = part.end_connector;
                }
            }
            if s_max >= s || no_extenders {
                break;
            }
        }
        let mut prev_o: scaled = 0;
        for i in 0..part_count {
            let part = parts[i];
            let reps = if part.extender { n } else { 1 };
            for _ in 0..reps {
                let mut o = part.start_connector;
                if prev_o < o {
                    o = prev_o;
                }
                let oo = o;
                if min_o < o {
                    o = min_o;
                }
                if oo > 0 {
                    (&mut *(self as *mut PortableTexEngine<'_>))
                        .stack_glue_into_box(b, -oo, -o)?;
                }
                let g = part.glyph;
                (&mut *(self as *mut PortableTexEngine<'_>))
                    .stack_glyph_into_box(b, f_0, g)?;
                prev_o = part.end_connector;
            }
        }
        const NULL: halfword = -(268435455 as i64) as halfword;
        let mut p = (*mem.offset((b + 5) as isize)).hh.v.RH;
        let mut nat: scaled = 0;
        let mut str_: scaled = 0;
        while p != NULL {
            let ty = (*mem.offset(p as isize)).hh.u.B0 as i32;
            if ty == 8 {
                if horiz {
                    nat += (*mem.offset((p + 1) as isize)).u.CINT;
                } else {
                    nat
                        += (*mem.offset((p + 3) as isize)).u.CINT
                            + (*mem.offset((p + 2) as isize)).u.CINT;
                }
            } else if ty == 10 {
                let spec = (*mem.offset((p + 1) as isize)).hh.v.LH;
                nat += (*mem.offset((spec + 1) as isize)).u.CINT;
                str_ += (*mem.offset((spec + 2) as isize)).u.CINT;
            }
            p = (*mem.offset(p as isize)).hh.v.RH;
        }
        if s > nat && str_ > 0 {
            let mut o = s - nat;
            if o > str_ {
                o = str_;
            }
            (*mem.offset((b + 5) as isize)).hh.u.B1 = 0;
            (*mem.offset((b + 5) as isize)).hh.u.B0 = 1;
            (*mem.offset((b + 6) as isize)).gr = o as f64 / str_ as f64;
            let stretched = nat
                + (str_ as f64 * (*mem.offset((b + 6) as isize)).gr).round() as scaled;
            if horiz {
                (*mem.offset((b + 1) as isize)).u.CINT = stretched;
            } else {
                (*mem.offset((b + 3) as isize)).u.CINT = stretched;
            }
        } else if horiz {
            (*mem.offset((b + 1) as isize)).u.CINT = nat;
        } else {
            (*mem.offset((b + 3) as isize)).u.CINT = nat;
        }
        Ok(b)
    }

}

pub(crate) unsafe fn fputs(_text: const_string, _file: NativeFileHandle) -> i32 {
    0
}

pub(crate) unsafe fn free(_ptr: voidpointer) {}

pub(crate) unsafe fn xrealloc(old_address: address, _new_size: size_t) -> address {
    old_address
}

pub(crate) unsafe fn getcreationdate() {}

pub(crate) unsafe fn getfilemoddate(_s: integer) {}

pub(crate) unsafe fn getfilesize(_s: integer) {}

pub(crate) unsafe fn getfiledump(_s: integer, _offset: i32, _length: i32) {}

pub(crate) unsafe fn getmd5sum(_s: integer, _file: i32) {}

pub(crate) unsafe fn u_close_file_or_pipe(file: *mut unicodefile) {
    if !file.is_null() {
        PortableTexEngine::boundary_close_file(*file);
        *file = core::ptr::null_mut();
    }
}

pub(crate) unsafe fn setinputfileencoding(
    file: unicodefile,
    mode: integer,
    _encoding_data: integer,
) {
    // XeTeX modes: AUTO=0, UTF8=1, UTF16BE=2, UTF16LE=3, RAW=4, ICUMAPPING=5.
    // We do not support ICU; unknown/ICU modes degrade to raw bytes. `AUTO`
    // here resolves to UTF-8 (the default after a failed sniff).
    if file.is_null() {
        return;
    }
    let handle = &mut *file;
    handle.encoding = match mode {
        1 => InputEncoding::Utf8,
        2 => InputEncoding::Utf16Be,
        3 => InputEncoding::Utf16Le,
        4 => InputEncoding::Bytes,
        0 => InputEncoding::Utf8, // AUTO resolves to UTF-8.
        _ => InputEncoding::Bytes,
    };
}

pub(crate) unsafe fn usingGraphite(_engine: FontHandle) -> boolean {
    false_0
}

pub(crate) unsafe fn aatprintfontname(
    _what: i32,
    _attrs: CFDictionaryRef,
    _param1: i32,
    _param2: i32,
) {
}

pub(crate) unsafe fn grprintfontname(
    _what: integer,
    _engine: voidpointer,
    _param1: integer,
    _param2: integer,
) {
}

pub(crate) unsafe fn printglyphname(_font: integer, _gid: integer) {}

pub(crate) unsafe fn getnativecharheightdepth(
    _font: integer,
    _ch: integer,
    height: *mut integer,
    depth: *mut integer,
) {
    if !height.is_null() {
        *height = 0;
    }
    if !depth.is_null() {
        *depth = 0;
    }
}

pub(crate) unsafe fn getnativecharsidebearings(
    _font: integer,
    _ch: integer,
    lsb: *mut integer,
    rsb: *mut integer,
) {
    if !lsb.is_null() {
        *lsb = 0;
    }
    if !rsb.is_null() {
        *rsb = 0;
    }
}

pub(crate) unsafe fn getnativecharwd(_font: integer, _ch: integer) -> integer {
    0
}

pub(crate) unsafe fn getnativecharht(_font: integer, _ch: integer) -> integer {
    0
}

pub(crate) unsafe fn getnativechardp(_font: integer, _ch: integer) -> integer {
    0
}

pub(crate) unsafe fn getnativecharic(_font: integer, _ch: integer) -> integer {
    0
}

pub(crate) unsafe fn getglyphbounds(_font: integer, _edge: integer, _gid: integer) -> integer {
    0
}

pub(crate) unsafe fn getfontcharrange(_font: integer, _first: i32) -> integer {
    0
}

pub(crate) unsafe fn get_native_italic_correction(_node: voidpointer) -> Fixed {
    0
}

pub(crate) unsafe fn get_native_glyph_italic_correction(_node: voidpointer) -> Fixed {
    0
}

pub(crate) unsafe fn applymapping(
    _mapping: voidpointer,
    _text: *mut uint16_t,
    text_len: i32,
) -> i32 {
    text_len
}

pub(crate) unsafe fn checkfortfmfontmapping() {}

pub(crate) unsafe fn loadtfmfontmapping() -> voidpointer {
    nullptr
}

pub(crate) unsafe fn applytfmfontmapping(_mapping: voidpointer, c_0: i32) -> i32 {
    c_0
}

pub(crate) unsafe fn set_cp_code(
    _font_num: i32,
    _code: u32,
    _side: i32,
    _value: i32,
) -> i32 {
    0
}

pub(crate) unsafe fn countpdffilepages() -> i32 {
    0
}

pub(crate) unsafe fn aatfontget(_what: i32, _attrs: CFDictionaryRef) -> i32 {
    0
}

pub(crate) unsafe fn aatfontget1(_what: i32, _attrs: CFDictionaryRef, _param: i32) -> i32 {
    0
}

pub(crate) unsafe fn aatfontget2(
    _what: i32,
    _attrs: CFDictionaryRef,
    _param1: i32,
    _param2: i32,
) -> i32 {
    0
}

pub(crate) unsafe fn aatfontgetnamed(_what: i32, _attrs: CFDictionaryRef) -> i32 {
    0
}

pub(crate) unsafe fn aatfontgetnamed1(
    _what: i32,
    _attrs: CFDictionaryRef,
    _param: i32,
) -> i32 {
    0
}

pub(crate) unsafe fn grfontgetnamed(_what: integer, _engine: voidpointer) -> integer {
    0
}

pub(crate) unsafe fn grfontgetnamed1(
    _what: integer,
    _engine: voidpointer,
    _param: integer,
) -> integer {
    0
}

pub(crate) unsafe fn otfontget(_what: integer, _engine: voidpointer) -> integer {
    0
}

pub(crate) unsafe fn otfontget1(
    _what: integer,
    _engine: voidpointer,
    _param: integer,
) -> integer {
    0
}

pub(crate) unsafe fn otfontget2(
    _what: integer,
    _engine: voidpointer,
    _param1: integer,
    _param2: integer,
) -> integer {
    0
}

pub(crate) unsafe fn otfontget3(
    _what: integer,
    _engine: voidpointer,
    _param1: integer,
    _param2: integer,
    _param3: integer,
) -> integer {
    0
}

/// Reclaim a [`GlyphAssembly`] previously handed out by
/// `get_ot_assembly_ptr`. Mirrors XeTeX's `free_ot_assembly`, but reclaims the
/// safe Rust `Box` allocation instead of calling `libc::free`.
///
/// # Safety
/// `assembly`, if non-null, must be a pointer returned by `get_ot_assembly_ptr`
/// and not previously freed.
pub(crate) unsafe fn free_ot_assembly(assembly: *mut GlyphAssembly) {
    if !assembly.is_null() {
        drop(Box::from_raw(assembly));
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    /// Build a text [`PortableFileHandle`] over `bytes` with the given encoding.
    fn text_handle(bytes: Vec<u8>, encoding: InputEncoding) -> PortableFileHandle {
        let mut handle = PortableFileHandle::new(
            "test.tex".to_string(),
            ResourceKind::TexInput,
            None,
            resource_format_tex_input,
            bytes,
        );
        handle.encoding = encoding;
        handle
    }

    /// Drain every Unicode scalar the decoder produces until EOF.
    fn decode_all(handle: &mut PortableFileHandle) -> Vec<u32> {
        let mut out = Vec::new();
        while let Some(scalar) = handle.next_input_scalar() {
            out.push(scalar);
        }
        out
    }

    #[test]
    fn utf8_decoder_reads_multibyte_scalars() {
        // "αβγ" = CE B1 CE B2 CE B3 -> U+03B1, U+03B2, U+03B3.
        let mut h = text_handle(vec![0xCE, 0xB1, 0xCE, 0xB2, 0xCE, 0xB3], InputEncoding::Utf8);
        assert_eq!(decode_all(&mut h), vec![0x3B1, 0x3B2, 0x3B3]);
        // ASCII stays one-scalar-per-byte; a 3-byte (U+20AC €) and 4-byte
        // (U+1F600 😀) sequence round-trip.
        let mut h = text_handle(
            vec![b'A', 0xE2, 0x82, 0xAC, 0xF0, 0x9F, 0x98, 0x80],
            InputEncoding::Utf8,
        );
        assert_eq!(decode_all(&mut h), vec![0x41, 0x20AC, 0x1F600]);
    }

    #[test]
    fn utf8_decoder_replaces_bad_sequences() {
        // A lead byte 0xCE followed by a non-continuation 'A' -> U+FFFD, and the
        // 'A' is UNGETC'd so it decodes next.
        let mut h = text_handle(vec![0xCE, b'A'], InputEncoding::Utf8);
        assert_eq!(decode_all(&mut h), vec![0xFFFD, 0x41]);
        // Lone continuation byte (0x80..0xBF as a lead) decodes to itself with
        // zero extra bytes (matches bytesFromUTF8 == 0), i.e. C8.. raw -> 0xFFFD
        // only when range-checked; a bare 0x80 has extra=0 so rval=0x80.
        let mut h = text_handle(vec![0x80], InputEncoding::Utf8);
        assert_eq!(decode_all(&mut h), vec![0x80]);
    }

    #[test]
    fn utf16_decoders_read_units_and_surrogates() {
        // "αβγ" UTF-16LE: B1 03 B2 03 B3 03.
        let mut h = text_handle(
            vec![0xB1, 0x03, 0xB2, 0x03, 0xB3, 0x03],
            InputEncoding::Utf16Le,
        );
        assert_eq!(decode_all(&mut h), vec![0x3B1, 0x3B2, 0x3B3]);
        // Same in UTF-16BE: 03 B1 03 B2 03 B3.
        let mut h = text_handle(
            vec![0x03, 0xB1, 0x03, 0xB2, 0x03, 0xB3],
            InputEncoding::Utf16Be,
        );
        assert_eq!(decode_all(&mut h), vec![0x3B1, 0x3B2, 0x3B3]);
        // Surrogate pair U+1F600 in UTF-16LE: D83D DE00 -> 3D D8 00 DE.
        let mut h = text_handle(vec![0x3D, 0xD8, 0x00, 0xDE], InputEncoding::Utf16Le);
        assert_eq!(decode_all(&mut h), vec![0x1F600]);
        // High surrogate followed by a non-low unit -> U+FFFD, and the stray unit
        // (here U+0041) is stashed in saved_char and decoded next.
        let mut h = text_handle(vec![0x3D, 0xD8, 0x41, 0x00], InputEncoding::Utf16Le);
        assert_eq!(decode_all(&mut h), vec![0xFFFD, 0x41]);
        // Lone low surrogate -> U+FFFD.
        let mut h = text_handle(vec![0x00, 0xDC], InputEncoding::Utf16Le);
        assert_eq!(decode_all(&mut h), vec![0xFFFD]);
    }

    #[test]
    fn bytes_mode_reads_each_byte_raw() {
        // RAW/Bytes: every byte becomes its own scalar, no multibyte decoding.
        let mut h = text_handle(vec![0xCE, 0xB1, 0x41], InputEncoding::Bytes);
        assert_eq!(decode_all(&mut h), vec![0xCE, 0xB1, 0x41]);
    }

    #[test]
    fn bom_sniff_selects_encoding_and_consumes_bom() {
        // UTF-8 BOM EF BB BF + "A" -> UTF8, BOM consumed, 'A' next.
        let mut h = text_handle(vec![0xEF, 0xBB, 0xBF, b'A'], InputEncoding::Bytes);
        h.resolve_text_encoding_auto();
        assert_eq!(h.encoding, InputEncoding::Utf8);
        assert_eq!(h.cursor, 3);
        assert_eq!(decode_all(&mut h), vec![0x41]);
        // UTF-16BE BOM FE FF + U+03B1 -> UTF16BE, BOM consumed.
        let mut h = text_handle(vec![0xFE, 0xFF, 0x03, 0xB1], InputEncoding::Bytes);
        h.resolve_text_encoding_auto();
        assert_eq!(h.encoding, InputEncoding::Utf16Be);
        assert_eq!(h.cursor, 2);
        assert_eq!(decode_all(&mut h), vec![0x3B1]);
        // UTF-16LE BOM FF FE + U+03B1 -> UTF16LE, BOM consumed.
        let mut h = text_handle(vec![0xFF, 0xFE, 0xB1, 0x03], InputEncoding::Bytes);
        h.resolve_text_encoding_auto();
        assert_eq!(h.encoding, InputEncoding::Utf16Le);
        assert_eq!(h.cursor, 2);
        assert_eq!(decode_all(&mut h), vec![0x3B1]);
        // No BOM, ASCII text -> UTF8, nothing consumed.
        let mut h = text_handle(vec![b'h', b'i'], InputEncoding::Bytes);
        h.resolve_text_encoding_auto();
        assert_eq!(h.encoding, InputEncoding::Utf8);
        assert_eq!(h.cursor, 0);
        // 00 xx (BOM-less UTF-16BE heuristic) -> UTF16BE, NOT consumed (rewind).
        let mut h = text_handle(vec![0x00, 0x41], InputEncoding::Bytes);
        h.resolve_text_encoding_auto();
        assert_eq!(h.encoding, InputEncoding::Utf16Be);
        assert_eq!(h.cursor, 0);
        assert_eq!(decode_all(&mut h), vec![0x41]);
    }

    #[test]
    fn input_line_decodes_into_buffer_per_profile() {
        // End-to-end through the real `boundary_input_line` reader: a text input
        // under the XeTeX profile is decoded (encoding resolved by the open-path
        // AUTO sniff), while the same bytes under the non-XeTeX (tex) profile are
        // read raw (Bytes mode). The engine's `buffer[first..last]` must hold the
        // expected Unicode scalars.
        fn buffer_after_input_line(profile: EngineProfile, bytes: Vec<u8>) -> Vec<u32> {
            let image = PortableFormatImage::empty();
            let mut engine = PortableTexEngine::from_format(profile, &image, EmptyResourceProvider);
            engine.initialize_format_state();
            // Build a text handle and resolve its encoding via the same open-path
            // helper the boundary open sites use.
            let mut handle = PortableFileHandle::new(
                "input.tex".to_string(),
                ResourceKind::TexInput,
                None,
                resource_format_tex_input,
                bytes,
            );
            PortableTexEngine::resolve_input_encoding(&engine, &mut handle);
            let raw = Box::into_raw(Box::new(handle));
            // Read one line into the buffer starting at `state.first`.
            engine.state.first = 0;
            let ok = unsafe {
                PortableTexEngine::boundary_input_line(
                    &mut engine as *mut PortableTexEngine<'_>,
                    raw as NativeFileHandle,
                )
            };
            assert_ne!(ok, 0, "boundary_input_line should succeed");
            let first = engine.state.first.max(0) as usize;
            let last = engine.state.last.max(0) as usize;
            let out = (first..last)
                .map(|i| unsafe { *engine.state.buffer.offset(i as isize) as u32 })
                .collect();
            unsafe { drop(Box::from_raw(raw)) };
            out
        }
        // "αβγ" = CE B1 CE B2 CE B3.
        let utf8 = vec![0xCE, 0xB1, 0xCE, 0xB2, 0xCE, 0xB3];
        assert_eq!(
            buffer_after_input_line(EngineProfile::xetex(), utf8.clone()),
            vec![0x3B1, 0x3B2, 0x3B3],
            "xetex must UTF-8 decode the input line"
        );
        assert_eq!(
            buffer_after_input_line(EngineProfile::tex(), utf8),
            vec![0xCE, 0xB1, 0xCE, 0xB2, 0xCE, 0xB3],
            "non-xetex must read raw bytes"
        );
        // UTF-16LE with BOM under xetex decodes to the same scalars.
        let utf16le_bom = vec![0xFF, 0xFE, 0xB1, 0x03, 0xB2, 0x03, 0xB3, 0x03];
        assert_eq!(
            buffer_after_input_line(EngineProfile::xetex(), utf16le_bom),
            vec![0x3B1, 0x3B2, 0x3B3],
            "xetex must UTF-16LE decode a BOM'd input line"
        );
        // UTF-16BE with BOM under xetex.
        let utf16be_bom = vec![0xFE, 0xFF, 0x03, 0xB1, 0x03, 0xB2, 0x03, 0xB3];
        assert_eq!(
            buffer_after_input_line(EngineProfile::xetex(), utf16be_bom),
            vec![0x3B1, 0x3B2, 0x3B3],
            "xetex must UTF-16BE decode a BOM'd input line"
        );
    }

    #[test]
    fn engine_abort_is_captured_at_runtime_boundary() {
        let image = PortableFormatImage::empty();
        let mut engine =
            PortableTexEngine::from_format(EngineProfile::tex(), &image, EmptyResourceProvider);

        let completed = engine.catch_engine_abort(|engine| unsafe {
            PortableTexEngine::abort_engine(engine as *mut PortableTexEngine<'_>, 7)?;
            Ok(())
        });

        assert!(!completed);
        assert_eq!(engine.last_abort_status(), Some(7));
    }

    #[test]
    fn successful_engine_abort_completes_runtime_boundary() {
        let image = PortableFormatImage::empty();
        let mut engine =
            PortableTexEngine::from_format(EngineProfile::tex(), &image, EmptyResourceProvider);

        let completed = engine.catch_engine_abort(|engine| unsafe {
            PortableTexEngine::abort_engine(engine as *mut PortableTexEngine<'_>, 0)?;
            Ok(())
        });

        assert!(completed);
        assert_eq!(engine.last_abort_status(), None);
    }
}