Module ir 

LayoutTreeIR — canonical, deterministic intermediate representation of XFA layout state.

This module is part of M1 (Observability Foundation). It exists so that XFA fidelity debugging can reason about a stable, snapshottable tree of layout decisions instead of comparing rasterised PDFs page by page.

Design constraints

• No new dependencies. All types are plain Rust; the canonical-JSON serializer in canonical_json is hand-rolled and uses only std.
• Deterministic by construction. The IR has no HashMap/HashSet, no Instant::now, no RNG, and no process-id leakage. Children are ordered by an explicit Vec. Object keys in the JSON output are emitted alphabetically. Floats are formatted with fixed precision.
• Off by default. Constructing an IR is opt-in: the engine never builds one unless a caller asks for it. There is no global state.
• Stable schema. SCHEMA_VERSION is part of the JSON output. Field additions bump the version; field renames bump the major (when we ever ship a v2). v1 is intentionally minimal.

Out of scope (M1 v1)

• Population from a real XFA pipeline. v1 ships the data types, a deterministic serializer, and a synthetic-fixture snapshot harness. Wiring the engine to populate LayoutTreeIR from a real flatten_xfa_to_pdf call is deferred to a follow-up.
• Renderer state, font tables, PDF object refs. The IR sits before rasterisation; it captures what the engine decided, not what was drawn.

Re-exports

pub use version::SCHEMA_VERSION;

Modules

canonical_json

Canonical, deterministic JSON output for crate::ir::LayoutTreeIR.

version

Schema version for the LayoutTreeIR.

Structs

LayoutNode

One node in the layout tree IR.

LayoutNodeId

Deterministic identifier for a layout node, derived from its position in the tree (sequence of child indices from the root).

LayoutTreeIR

Top-level IR document.

Enums

FieldKindIR

Field-specific kind tag for nodes whose NodeKind is Field.

NodeKind

Kind of a layout node in the IR.

OverflowState

Overflow / split state of a node at IR-capture time.

PresenceIR

Visibility/presence state.