BREP_render 0.12.0

//! PMI — the engine half of the PMI workbench: the document's `pmi` block
//! (checkpointed edits + re-run, like `wire_harness_ops`), the ACTIVE view
//! (applied camera / visibility / wireframe / explode poses, restored
//! exactly on deactivate), annotation CRUD, the coalesced label drag, and the
//! reference picker's PMI flavour.
//!
//! Persisted vs engine memory: the `pmi` block (views, annotations, label
//! positions) lives in the document and rides its undo stack; WHICH view is
//! active and WHICH annotation's form is open are engine memory — a mode,
//! not model state — so a rerun, a save or an undo never churns on them.
//!
//! A label drag is the one high-frequency PMI edit: it writes the block with
//! a coalesced checkpoint (`pmi:label:{id}` — one undo step per drag) and
//! NEVER re-runs the history: the cached report's label position is patched
//! locally and the overlay re-baked. Every other mutation (a view capture,
//! an annotation add / edit / remove) is its own undo step followed by a
//! re-run, whose tail re-resolves the annotations.

use super::*;
use brep_kernel::{
    PmiAnnotation, PmiCamera, PmiDisplay, PmiGeometry, PmiProjection, PmiReport, PmiState,
    PmiStatus, PmiView,
};
use crate::view::Projection;

/// The modeling state remembered while the PMI workbench is active.
#[derive(Debug, Clone)]
pub struct PmiModelingSnapshot {
    pub camera_json: String,
    pub hidden: Vec<String>,
    pub wireframe: bool,
}

/// A patch the panel applies to one view's name / display state.
#[derive(Debug, Default, Clone, PartialEq)]
pub struct PmiViewPatch {
    pub name: Option<String>,
    pub text_size_pt: Option<f64>,
    pub wireframe: Option<bool>,
    pub hidden: Option<Vec<String>>,
    pub section: Option<Option<brep_kernel::feature_pipeline::pmi::PmiSection>>,
}

/// The **PMI view** dialog's schema — what a view's own form edits: its name,
/// the text size its labels draw at and whether it shows the model in
/// wireframe, plus the two re-capture actions its row menu also offers. Shaped
/// like every other object schema so the shared form view draws it;
/// [`EngineState::pmi_update_view`] applies what it edits.
pub fn pmi_view_schema() -> serde_json::Value {
    serde_json::json!({
        "type": "pmiView",
        "shortName": "VIEW",
        "longName": "PMI view",
        "inputParamsSchema": {
            "name": { "type": "string", "label": "Name", "default_value": "View 1" },
            "textSizePt": { "type": "number", "label": "Text size (pt)", "default_value": brep_kernel::PmiDisplay::default().text_size_pt },
            "wireframe": { "type": "boolean", "label": "Wireframe", "default_value": false },
            "sectionEnabled": { "type": "boolean", "label": "Section view", "default_value": false },
            "sectionAxis": { "type": "options", "label": "Section normal", "options": ["View", "X", "Y", "Z", "Plane"], "default_value": "View" },
            "sectionPlane": {
                "type": "reference_selection", "label": "Section plane", "selectionFilter": ["FACE", "PLANE"], "multiple": false,
                "minSelections": 0, "maxSelections": 1, "default_value": null,
                "hint": "A planar face, datum plane or sketch plane to cut on (Section normal: Plane); the offset moves the cut along its normal"
            },
            "sectionOffset": { "type": "number", "label": "Section offset (mm)", "default_value": 0.0 },
            "sectionFlip": { "type": "boolean", "label": "Reverse section", "default_value": false },
            "halfAxis": {
                "type": "options", "label": "Half section", "options": ["None", "View", "X", "Y", "Z"], "default_value": "None",
                "hint": "A second plane through the section's origin: material is removed only where both planes remove it (a quarter cut away)"
            },
            "halfOffset": { "type": "number", "label": "Half section offset (mm)", "default_value": 0.0 },
            "halfFlip": { "type": "boolean", "label": "Reverse half section", "default_value": false },
            "sectionExclude": {
                "type": "reference_selection", "label": "Not cut", "selectionFilter": ["SOLID", "COMPONENT"], "multiple": true,
                "minSelections": 0, "maxSelections": 64, "default_value": [],
                "hint": "Solids or components the section leaves whole, such as shafts and fasteners"
            },
            "updateCamera": { "type": "button", "label": "Update camera from the viewport" },
            "hideSelected": { "type": "button", "label": "Hide the selected bodies in this view" }
        }
    })
}

/// The further planes a view's section edit asks for: a whole `sectionPlanes`
/// list replaces them, then the form's `half*` rows set (or, `None`, drop)
/// the first; what neither names is kept. A frozen `View` normal is kept for
/// a plane that stays `View`.
fn section_planes_from(
    params: &serde_json::Value,
    prior: Option<&brep_kernel::feature_pipeline::pmi::PmiSection>,
) -> Result<Vec<brep_kernel::feature_pipeline::pmi::PmiSectionPlane>, String> {
    use brep_kernel::feature_pipeline::pmi::PmiSectionPlane;
    let prior_planes = prior.map(|s| s.planes.clone()).unwrap_or_default();
    let valid = |plane: &PmiSectionPlane| ["View", "X", "Y", "Z"].contains(&plane.axis.as_str()) && plane.offset.is_finite();
    let mut planes = match params.get("sectionPlanes") {
        Some(serde_json::Value::Null) => Vec::new(),
        Some(list) => {
            let planes: Vec<PmiSectionPlane> = serde_json::from_value(list.clone()).map_err(|e| format!("invalid section planes: {e}"))?;
            if !planes.iter().all(valid) {
                return Err("invalid section plane".into());
            }
            planes
        }
        None => prior_planes,
    };
    if let Some(axis) = params.get("halfAxis").and_then(serde_json::Value::as_str) {
        if axis == "None" {
            if !planes.is_empty() {
                planes.remove(0);
            }
        } else {
            let before = planes.first();
            let plane = PmiSectionPlane {
                axis: axis.to_string(),
                offset: params.get("halfOffset").and_then(serde_json::Value::as_f64).or(before.map(|p| p.offset)).unwrap_or(0.),
                flip: params.get("halfFlip").and_then(serde_json::Value::as_bool).or(before.map(|p| p.flip)).unwrap_or(false),
                normal: before.filter(|p| p.axis == axis).and_then(|p| p.normal),
            };
            if !valid(&plane) {
                return Err("invalid section plane".into());
            }
            match planes.first_mut() {
                Some(first) => *first = plane,
                None => planes.push(plane),
            }
        }
    }
    // A View plane with no normal takes the captured direction in `freeze`.
    Ok(planes)
}

/// A view's current values in [`pmi_view_schema`]'s shape — the form's seed.
pub fn pmi_view_params(view: &brep_kernel::PmiView) -> serde_json::Value {
    serde_json::json!({
        "name": view.name,
        "textSizePt": view.display.text_size_pt,
        "wireframe": view.display.wireframe,
        "sectionEnabled": view.display.section.is_some(),
        "sectionAxis": view.display.section.as_ref().map(|s| s.axis.as_str()).unwrap_or("View"),
        "sectionOffset": view.display.section.as_ref().map(|s| s.offset).unwrap_or(0.),
        "sectionFlip": view.display.section.as_ref().is_some_and(|s| s.flip),
        "sectionPlane": view.display.section.as_ref().and_then(|s| s.plane.as_deref()).unwrap_or(""),
        "sectionExclude": view.display.section.as_ref().map(|s| s.exclude.clone()).unwrap_or_default(),
        "halfAxis": view.display.section.as_ref().and_then(|s| s.planes.first()).map(|p| p.axis.as_str()).unwrap_or("None"),
        "halfOffset": view.display.section.as_ref().and_then(|s| s.planes.first()).map(|p| p.offset).unwrap_or(0.),
        "halfFlip": view.display.section.as_ref().and_then(|s| s.planes.first()).is_some_and(|p| p.flip),
    })
}

/// `{solid}@x,y,z` in WORLD coordinates (the PMI vertex-ref convention).
pub fn world_vertex_ref(solid: &str, position: [f64; 3]) -> String {
    let trim = |v: f64| {
        let rounded = (v * 1e9).round() / 1e9;
        let trimmed = crate::formatting::compact_decimal(rounded, 9);
        if trimmed == "-0" || trimmed.is_empty() { "0".to_string() } else { trimmed }
    };
    format!("{solid}@{},{},{}", trim(position[0]), trim(position[1]), trim(position[2]))
}

impl EngineState {
    // --- read surface ------------------------------------------------------

    /// The document's `pmi` block as typed state (the default — no views —
    /// when the document carries none).
    pub fn pmi_state(&self) -> PmiState {
        self.history
            .pmi_block()
            .and_then(|block| serde_json::from_value(block.clone()).ok())
            .unwrap_or_default()
    }

    /// [`Self::pmi_state`] parsed once per history revision and shared: what
    /// a frame reads (an animation frame's section check and overlay), where
    /// parsing the whole block each time cost ~14 ms a parse on a 500-step
    /// view.
    pub fn pmi_state_shared(&self) -> std::rc::Rc<PmiState> {
        let revision = self.history.revision();
        if let Some((at, state)) = self.pmi_state_cache.borrow().as_ref() {
            if *at == revision {
                return state.clone();
            }
        }
        let state = std::rc::Rc::new(self.pmi_state());
        *self.pmi_state_cache.borrow_mut() = Some((revision, state.clone()));
        state
    }

    /// The PMI report of the last APPLIED run.
    pub fn pmi_report(&self) -> Option<&PmiReport> {
        self.pmi_report.as_ref()
    }

    pub fn pmi_active_view(&self) -> Option<&str> {
        self.pmi_active_view.as_deref()
    }

    pub fn pmi_open_annotation(&self) -> Option<&str> {
        self.pmi_open_annotation.as_deref()
    }

    /// The view whose dialog the PMI pane shows, if one is open.
    pub fn pmi_open_view(&self) -> Option<&str> {
        self.pmi_open_view.as_deref()
    }

    /// How many PMI dialogs — annotation or view — this engine has OPENED. The
    /// app's dialog door reads it beside the open subject so a re-open of the
    /// dialog already open is still an open (the id alone does not move).
    /// Monotonic and never reset; a CLOSE does not count.
    pub fn pmi_dialog_opens(&self) -> u64 {
        self.pmi_dialog_opens
    }

    /// **The PMI half of the dialog door's counter.** Open `id`'s form and
    /// count the open. EVERY path that opens an annotation form goes through
    /// here — the panel's `+`, its row Edit and double-click, the viewport
    /// label double click, the automation add — so the door has one signal to watch
    /// and a re-open of the same annotation still reads as an open. Assigning
    /// `pmi_open_annotation = Some(..)` anywhere else is the bug this exists to
    /// prevent: the form would open with its pane still behind another tab.
    ///
    /// An open annotation is the selected one too — the dialog is about it —
    /// and it replaces an open VIEW dialog, since the pane shows one dialog.
    fn open_pmi_annotation(&mut self, id: String) {
        self.pmi_open_view = None;
        self.pmi_selected_view = None;
        self.pmi_selected_annotation = Some(id.clone());
        self.pmi_open_annotation = Some(id);
        self.pmi_dialog_opens = self.pmi_dialog_opens.wrapping_add(1);
    }

    /// The view half of [`Self::open_pmi_annotation`]: open view `id`'s dialog,
    /// closing an open annotation's, select the view and count the open.
    fn open_pmi_view(&mut self, id: String) {
        self.pmi_open_annotation = None;
        if self.pmi_selected_annotation.take().is_some() {
            self.refresh_pmi_overlay();
        }
        self.pmi_selected_view = Some(id.clone());
        self.pmi_open_view = Some(id);
        self.pmi_dialog_opens = self.pmi_dialog_opens.wrapping_add(1);
    }

    /// The annotation selected in the PMI tree (or opened), while it exists.
    /// Asked every frame (the tree's highlight), so it reads the shared parse.
    pub fn pmi_selected_annotation(&self) -> Option<&str> {
        let id = self.pmi_selected_annotation.as_deref()?;
        self.pmi_state_shared().find_annotation(id).is_some().then_some(id)
    }

    /// The view selected in the PMI tree (or opened), while it exists.
    pub fn pmi_selected_view(&self) -> Option<&str> {
        let id = self.pmi_selected_view.as_deref()?;
        self.pmi_state_shared().find_view(id).is_some().then_some(id)
    }

    /// Whether the PMI workbench remembered a modeling state (it is "entered").
    pub fn pmi_workbench_entered(&self) -> bool {
        self.pmi_modeling.is_some()
    }

    /// The `__brepPmi` verifier global: the block, the report, the active
    /// view, the open annotation and the datum letters, as one object.
    pub fn pmi_state_json(&self) -> String {
        self.pmi_state_value().to_string()
    }

    /// [`Self::pmi_state_json`] as a JSON value.
    pub fn pmi_state_value(&self) -> serde_json::Value {
        let state = self.pmi_state();
        serde_json::json!({
            "views": state.views,
            "idCounter": state.id_counter,
            "activeView": self.pmi_active_view,
            "openAnnotation": self.pmi_open_annotation,
            "openView": self.pmi_open_view,
            "selectedAnnotation": self.pmi_selected_annotation(),
            "selectedView": self.pmi_selected_view(),
            "entered": self.pmi_modeling.is_some(),
            "datums": state.datum_letters(),
            "report": self.pmi_report,
        })
    }

    // --- block writes --------------------------------------------------------

    /// Write `state` as the document's block (checkpointed) and re-run the
    /// history so the tail resolves it. An empty block is removed so a part
    /// that never had PMI saves byte-identically.
    pub(super) fn write_pmi_state(&mut self, state: PmiState) -> String {
        let block = if state.is_empty() { None } else { serde_json::to_value(&state).ok() };
        self.history.set_pmi_block(block, None);
        self.rerun_history()
    }

    // --- views ---------------------------------------------------------------

    /// The current camera as a snapshot.
    pub(super) fn snapshot_camera(&self) -> PmiCamera {
        let camera = &self.camera;
        PmiCamera {
            eye: camera.eye,
            target: camera.target,
            up: camera.up,
            projection: match camera.projection {
                Projection::Orthographic { half_height } => PmiProjection::Orthographic { half_height },
                Projection::Perspective { fov_y_deg } => PmiProjection::Perspective { fov_y_deg },
            },
            viewport: [camera.width, camera.height],
        }
    }

    /// The names of the solids currently hidden in the scene.
    fn hidden_solid_names(&self) -> Vec<String> {
        // A committed sketch's visibility is its own (`hidden_sketches`),
        // never a view's: a sketch name is no solid a hide step resolves.
        self.scene
            .solids()
            .iter()
            .filter(|solid| !solid.visible && !solid.is_sketch)
            .map(|solid| solid.name.clone())
            .collect()
    }

    /// Capture a view: the current camera, hidden objects (its baseline hide
    /// step) and wireframe setting, named `name` (or `View N`). The new view
    /// becomes active.
    pub fn pmi_capture_view(&mut self, name: Option<&str>) -> String {
        let mut state = self.pmi_state();
        let id = state.next_id("VIEW");
        let name = name
            .map(str::trim)
            .filter(|n| !n.is_empty())
            .map(String::from)
            .unwrap_or_else(|| format!("View {}", state.views.len() + 1));
        // The capture reads the MODELING state: if another view is active its
        // applied state is what is on screen, so deactivate first (restores)
        // — a view captures what the user set up, not another view's snapshot.
        let was_active = self.pmi_active_view.is_some();
        if was_active {
            self.pmi_deactivate_view();
        }
        self.pmi_remember_modeling();
        state.views.push(PmiView {
            id: id.clone(),
            name,
            camera: Some(self.snapshot_camera()),
            display: PmiDisplay::new(12.0, self.settings.wireframe, None),
            annotations: Vec::new(),
        });
        state.set_view_baseline(&id, &self.hidden_solid_names());
        self.write_pmi_state(state);
        let _ = self.pmi_activate_view(&id);
        id
    }

    pub fn pmi_rename_view(&mut self, id: &str, name: &str) -> Result<(), String> {
        let mut state = self.pmi_state();
        let view = state.find_view_mut(id).ok_or_else(|| format!("no PMI view '{id}'"))?;
        let name = name.trim();
        if name.is_empty() {
            return Err("a view needs a name".into());
        }
        view.name = name.to_string();
        self.write_pmi_state(state);
        Ok(())
    }

    /// Delete a view (and its annotations). An active view deactivates first.
    pub fn pmi_delete_view(&mut self, id: &str) -> Result<(), String> {
        let mut state = self.pmi_state();
        let before = state.views.len();
        if self.pmi_active_view.as_deref() == Some(id) {
            self.pmi_deactivate_view();
        }
        state.views.retain(|view| view.id != id);
        if state.views.len() == before {
            return Err(format!("no PMI view '{id}'"));
        }
        if let Some(open) = &self.pmi_open_annotation {
            if state.find_annotation(open).is_none() {
                self.pmi_open_annotation = None;
            }
        }
        if self.pmi_open_view.as_deref() == Some(id) {
            self.pmi_open_view = None;
        }
        self.write_pmi_state(state);
        Ok(())
    }

    /// Re-capture a view's camera from the current camera (the explicit
    /// Update Camera action — orbiting never rewrites a snapshot silently).
    pub fn pmi_update_view_camera(&mut self, id: &str) -> Result<(), String> {
        // A step's view: the capture is the step's author camera, kept
        // through the step edits that regenerate a generated one. The step
        // stays shown as the user had it (the capture rebuilds the views,
        // which puts every view away).
        if let Some(step) = self.instructions_step_of_view(id) {
            let shown = self.instructions_shown_step().as_deref() == Some(step.as_str());
            self.instructions_capture_camera(&step)?;
            if shown {
                self.instructions_show_step(&step)?;
            }
            return Ok(());
        }
        let mut state = self.pmi_state();
        let camera = self.snapshot_camera();
        let view = state.find_view_mut(id).ok_or_else(|| format!("no PMI view '{id}'"))?;
        // A section saved before its plane was stored is anchored on the OLD
        // camera first, so the cut stays where it was.
        if let Some(section) = view.display.section.as_mut() {
            section.freeze(view.camera.as_ref());
        }
        view.camera = Some(camera);
        self.write_pmi_state(state);
        Ok(())
    }

    /// Hide the selection in view `view_id` (the active view when `None`) as
    /// a new **hide step** — a `hide` annotation naming the selected
    /// components (whole placements, a part inside a sub-assembly by its
    /// occurrence path, as an explode step names them) and any other
    /// selected solids — tracked, listed, edited and undone like an explode
    /// step. The step's form opens. Refused with nothing selected.
    pub fn pmi_hide_selected(&mut self, view_id: Option<&str>) -> Result<String, String> {
        let mut targets = self.selected_occurrences();
        for solid in &self.emphasis.selected_solids {
            if !targets.iter().any(|target| brep_kernel::entry_names_solid(target, solid)) {
                targets.push(solid.clone());
            }
        }
        if targets.is_empty() {
            return Err("select the solids or components to hide".into());
        }
        let params = serde_json::json!({ "targets": targets }).to_string();
        self.pmi_add_annotation(view_id, "hide", &params)
    }

    /// Patch a view's name / display state. The active view re-applies.
    pub fn pmi_set_view_display(&mut self, id: &str, patch: &PmiViewPatch) -> Result<(), String> {
        self.patch_pmi_view(id, patch, None)
    }

    /// Apply an edited **PMI view** form ([`pmi_view_schema`]'s params). Only
    /// the fields that differ from the view are written, and a run of edits to
    /// one view is ONE undo step — the form writes on every keystroke of the
    /// name, the way an annotation's form does.
    pub fn pmi_update_view(&mut self, id: &str, params_json: &str) -> Result<(), String> {
        let params: serde_json::Value =
            serde_json::from_str(params_json).map_err(|error| format!("view params: {error}"))?;
        let state = self.pmi_state();
        let view = state.find_view(id).ok_or_else(|| format!("no PMI view '{id}'"))?;
        let name = params
            .get("name")
            .and_then(serde_json::Value::as_str)
            .filter(|name| *name != view.name)
            .map(String::from);
        let text_size_pt = params
            .get("textSizePt")
            .and_then(serde_json::Value::as_f64)
            .filter(|size| *size != view.display.text_size_pt);
        let wireframe = params
            .get("wireframe")
            .and_then(serde_json::Value::as_bool)
            .filter(|on| *on != view.display.wireframe);
        let section = if params.get("sectionEnabled").is_some() {
            let section = if params["sectionEnabled"].as_bool().unwrap_or(false) {
                let axis = params["sectionAxis"].as_str().unwrap_or("View");
                let offset = params["sectionOffset"].as_f64().unwrap_or(0.);
                if !["View", "X", "Y", "Z", "Plane"].contains(&axis) || !offset.is_finite() { return Err("invalid section plane".into()); }
                // The plane keeps the anchor it was set on: a re-captured
                // camera must not move the cut. A newly chosen View axis takes
                // the captured direction.
                let prior = view.display.section.as_ref();
                let mut section = brep_kernel::feature_pipeline::pmi::PmiSection {
                    axis: axis.into(),
                    offset,
                    flip: params["sectionFlip"].as_bool().unwrap_or(false),
                    origin: prior.and_then(|s| s.origin),
                    normal: prior.filter(|s| s.axis == axis).and_then(|s| s.normal),
                    // The picked face or plane (`Plane`): the run resolves it.
                    plane: match params.get("sectionPlane") {
                        Some(serde_json::Value::String(name)) => Some(name.trim().to_string()).filter(|name| !name.is_empty()),
                        Some(serde_json::Value::Null) => None,
                        _ => prior.and_then(|s| s.plane.clone()),
                    },
                    exclude: match params.get("sectionExclude") {
                        Some(serde_json::Value::Array(names)) => names
                            .iter()
                            .filter_map(serde_json::Value::as_str)
                            .map(|name| name.trim().to_string())
                            .filter(|name| !name.is_empty())
                            .collect(),
                        Some(serde_json::Value::Null) => Vec::new(),
                        _ => prior.map(|s| s.exclude.clone()).unwrap_or_default(),
                    },
                    planes: section_planes_from(&params, prior)?,
                };
                section.freeze(view.camera.as_ref());
                Some(section)
            } else { None };
            (section != view.display.section).then_some(section)
        } else { None };
        if name.is_none() && text_size_pt.is_none() && wireframe.is_none() && section.is_none() {
            return Ok(());
        }
        let patch = PmiViewPatch { name, text_size_pt, wireframe, hidden: None, section };
        self.patch_pmi_view(id, &patch, Some(&format!("pmi:view:{id}")))
    }

    /// Set view `id`'s section the way its form's section rows do, as ONE
    /// undo step: `enabled` turns it on or off, and each field left `None`
    /// keeps what the section has (or the form's default: `View`, offset 0,
    /// not reversed, no plane, nothing left whole, no further planes).
    /// `planes` replaces the further planes (a half or corner cut away;
    /// empty: none). The plane is anchored as the form anchors it
    /// ([`Self::pmi_update_view`]).
    #[allow(clippy::too_many_arguments)]
    pub fn pmi_set_view_section(
        &mut self,
        id: &str,
        enabled: bool,
        axis: Option<&str>,
        offset: Option<f64>,
        flip: Option<bool>,
        plane: Option<&str>,
        exclude: Option<Vec<String>>,
        planes: Option<Vec<brep_kernel::feature_pipeline::pmi::PmiSectionPlane>>,
    ) -> Result<(), String> {
        let state = self.pmi_state();
        let view = state.find_view(id).ok_or_else(|| format!("no PMI view '{id}'"))?;
        let prior = view.display.section.as_ref();
        // A plane named with no axis cuts on that plane, as picking one in
        // the form does.
        let axis = axis.or_else(|| plane.filter(|plane| !plane.trim().is_empty()).map(|_| "Plane"));
        let mut params = serde_json::json!({
            "sectionEnabled": enabled,
            "sectionAxis": axis.map(str::to_string).or_else(|| prior.map(|s| s.axis.clone())).unwrap_or_else(|| "View".into()),
            "sectionOffset": offset.or_else(|| prior.map(|s| s.offset)).unwrap_or(0.),
            "sectionFlip": flip.or_else(|| prior.map(|s| s.flip)).unwrap_or(false),
        });
        if let Some(plane) = plane {
            params["sectionPlane"] = plane.into();
        }
        if let Some(exclude) = exclude {
            params["sectionExclude"] = exclude.into();
        }
        if let Some(planes) = planes {
            params["sectionPlanes"] = serde_json::to_value(planes).map_err(|e| e.to_string())?;
        }
        self.history.break_coalescing();
        let result = self.pmi_update_view(id, &params.to_string());
        self.history.break_coalescing();
        result
    }

    /// Open view `id`'s dialog (`None` closes it). Opening activates the view,
    /// as opening one of its annotations does: the dialog describes what is on
    /// screen. An id that names no view opens nothing and counts nothing.
    pub fn pmi_set_view_open(&mut self, id: Option<&str>) {
        match id {
            Some(id) => {
                if self.pmi_state().find_view(id).is_none() {
                    return;
                }
                if self.pmi_active_view.as_deref() != Some(id) {
                    let _ = self.pmi_activate_view(id);
                }
                self.open_pmi_view(id.to_string());
            }
            None => self.pmi_open_view = None,
        }
        self.refresh_pmi_overlay();
    }

    fn patch_pmi_view(&mut self, id: &str, patch: &PmiViewPatch, coalesce_key: Option<&str>) -> Result<(), String> {
        let mut state = self.pmi_state();
        let view = state.find_view_mut(id).ok_or_else(|| format!("no PMI view '{id}'"))?;
        if let Some(name) = &patch.name {
            let name = name.trim();
            if name.is_empty() {
                return Err("a view needs a name".into());
            }
            view.name = name.to_string();
        }
        if let Some(size) = patch.text_size_pt {
            view.display.text_size_pt = brep_kernel::clamp_text_size(size);
        }
        if let Some(wireframe) = patch.wireframe {
            view.display.wireframe = wireframe;
        }
        if let Some(section) = &patch.section { view.display.section = section.clone(); }
        if let Some(hidden) = &patch.hidden {
            let solids = self.view_hideable_names();
            state.set_view_hidden(id, hidden, &solids);
        }
        let view = state.find_view(id).expect("patched above").clone();
        let block = if state.is_empty() { None } else { serde_json::to_value(&state).ok() };
        self.history.set_pmi_block(block, coalesce_key);
        self.rerun_history();
        if self.pmi_active_view.as_deref() == Some(id) {
            self.apply_view_display(&view);
        }
        Ok(())
    }

    /// The scene's solid names a view's hide step can name (committed
    /// sketches excluded: their visibility is `hidden_sketches`).
    fn view_hideable_names(&self) -> Vec<String> {
        self.scene.solids().iter().filter(|solid| !solid.is_sketch).map(|solid| solid.name.clone()).collect()
    }

    /// **A viewport hide or show while a view is active is an edit of that
    /// view** (one undo step): hiding adds a hide step naming what was not
    /// hidden yet, showing drops the names from its hide steps (a hidden
    /// component keeps its other solids hidden). The view then re-applies,
    /// so leaving and re-entering it shows the same thing, and its sheets,
    /// 3D PDF and report agree. Names that are no scene solid are ignored.
    /// False when nothing changed.
    pub(crate) fn pmi_record_visibility(&mut self, view_id: &str, names: &[String], visible: bool) -> bool {
        let solids = self.view_hideable_names();
        let names: Vec<String> = names.iter().filter(|name| solids.contains(name)).cloned().collect();
        if names.is_empty() {
            return false;
        }
        let mut state = self.pmi_state();
        let changed = if visible {
            state.show_in_view(view_id, &names, &solids)
        } else {
            state.hide_in_view(view_id, &names).is_some()
        };
        if !changed {
            return false;
        }
        let Some(view) = state.find_view(view_id).cloned() else { return false };
        self.write_pmi_state(state);
        if self.pmi_active_view.as_deref() == Some(view_id) {
            self.apply_view_display(&view);
            self.refresh_pmi_overlay();
        }
        true
    }

    /// Remember the modeling state: what is on screen while NO view is
    /// active is the modeling state (hiding a body in the workbench before
    /// capturing is a modeling change, not a view's), so it is re-snapshotted
    /// whenever an activation starts from no active view; while a view is
    /// active the snapshot is kept (switching views restores to it).
    fn pmi_remember_modeling(&mut self) {
        if self.pmi_active_view.is_none() || self.pmi_modeling.is_none() {
            self.pmi_modeling = Some(PmiModelingSnapshot {
                camera_json: self.camera_state_json(),
                hidden: self.hidden_solid_names(),
                wireframe: self.settings.wireframe,
            });
        }
    }

    /// Entering the PMI workbench: remember the modeling camera, visibility
    /// and wireframe so a view activation can be undone exactly.
    pub fn pmi_enter_workbench(&mut self) {
        self.pmi_remember_modeling();
    }

    /// Leaving the PMI workbench: deactivate the view (restoring the modeling
    /// state), close its dialogs, and forget the snapshot. An open SHEET is
    /// not this workbench's to close — sheets are the Drawing workbench's, and
    /// the shell closes the paper when a workbench hides the Sheets pane.
    pub fn pmi_leave_workbench(&mut self) {
        self.pmi_deactivate_view();
        self.pmi_modeling = None;
        self.pmi_open_annotation = None;
        self.pmi_open_view = None;
        self.refresh_pmi_overlay();
    }

    /// Apply a view's visibility and wireframe: a solid is hidden when the
    /// view `hides` it — its captured baseline or one of its hide steps
    /// (`PmiView::hides`, by name, so a step just added, edited, removed or
    /// undone takes effect without waiting on a run).
    fn apply_view_display(&mut self, view: &PmiView) {
        let display = &view.display;
        let names: Vec<String> = self.scene.solids().iter().map(|s| s.name.clone()).collect();
        for name in names {
            let hidden = view.hides(&name);
            if let Some(original) = self.pmi_explode_originals.get_mut(&name).filter(|original| original.visible == hidden) {
                original.visible = !hidden;
                self.pmi_unposed_visibility += 1;
            }
            if hidden {
                // Hidden by the view: restoring the section must not show it.
                self.pmi_section_hidden.retain(|hidden| *hidden != name);
                self.scene.set_visible(&name, false);
            } else if !self.pmi_section_hidden.contains(&name) {
                // A solid the section removes whole stays hidden.
                self.scene.set_visible(&name, true);
            }
        }
        if self.settings.wireframe != display.wireframe {
            self.settings.wireframe = display.wireframe;
            self.settings_generation = self.settings_generation.wrapping_add(1);
        }
        self.dirty = true;
    }

    /// Activate a view: apply its camera (refit to the live viewport), hidden
    /// names, wireframe and explode poses; its annotations become the drawn
    /// and editable set.
    pub fn pmi_activate_view(&mut self, id: &str) -> Result<(), String> {
        let state = self.pmi_state();
        let view = state.find_view(id).ok_or_else(|| format!("no PMI view '{id}'"))?.clone();
        if self.pmi_active_view.as_deref() != Some(id) {
            // Switching views keeps the snapshot: deactivating restores the
            // modeling state, and the new view starts from it.
            let keep = self.pmi_active_view.is_some();
            self.pmi_deactivate_view();
            if !keep {
                self.pmi_remember_modeling();
            }
        }
        if self.pmi_modeling.is_none() {
            self.pmi_remember_modeling();
        }
        if self.pmi_active_view.as_deref() != Some(id) {
            // A view activated afresh shows every explode step at full.
            self.explode_playback = Default::default();
        }
        self.pmi_active_view = Some(id.to_string());
        if let Some(camera) = &view.camera {
            let (kind, scale) = match camera.projection {
                PmiProjection::Orthographic { half_height } => ("orthographic", half_height),
                PmiProjection::Perspective { fov_y_deg } => ("perspective", fov_y_deg),
            };
            let json = serde_json::json!({
                "kind": kind, "eye": camera.eye, "target": camera.target, "up": camera.up, "scale": scale,
            })
            .to_string();
            let _ = self.apply_camera_state_json(&json);
            self.controls_sync_after_camera_apply();
        }
        self.apply_view_display(&view);
        self.pmi_apply_explode();
        self.instructions_refresh_ghosts();
        if let Some(open) = &self.pmi_open_annotation {
            if !view.annotations.iter().any(|a| a.id() == open) {
                self.pmi_open_annotation = None;
            }
        }
        self.refresh_pmi_overlay();
        Ok(())
    }

    /// Deactivate the active view: restore the explode poses, the modeling
    /// visibility, wireframe and camera. A no-op without an active view.
    pub fn pmi_deactivate_view(&mut self) {
        if self.pmi_active_view.take().is_none() {
            return;
        }
        // Instructions' ghosts go before the modeling visibility comes back.
        self.instructions_refresh_ghosts();
        if self.pmi_state().find_annotation(&self.transform_armed_feature()).is_some() { self.disarm_transform(); }
        self.pmi_restore_explode();
        if let Some(snapshot) = self.pmi_modeling.clone() {
            let names: Vec<String> = self.scene.solids().iter().map(|s| s.name.clone()).collect();
            for name in names {
                let visible = !snapshot.hidden.contains(&name);
                self.scene.set_visible(&name, visible);
            }
            if self.settings.wireframe != snapshot.wireframe {
                self.settings.wireframe = snapshot.wireframe;
                self.settings_generation = self.settings_generation.wrapping_add(1);
            }
            let _ = self.apply_camera_state_json(&snapshot.camera_json);
            self.controls_sync_after_camera_apply();
        }
        self.pmi_open_annotation = None;
        self.dirty = true;
        self.refresh_pmi_overlay();
    }

    /// Keep the arcball controls in step with a camera written wholesale.
    pub(super) fn controls_sync_after_camera_apply(&mut self) {
        // The controls read the camera each frame (orbit deltas are applied
        // onto `self.camera`), so writing the camera is enough; a fresh depth
        // fit happens on the next render. Nothing else to sync.
        self.dirty = true;
    }

    // --- explode (display-only poses) -----------------------------------------

    /// Pose the active view's explode targets on the CURRENT displays,
    /// keeping the un-posed copies for the restore.
    pub(crate) fn pmi_apply_explode(&mut self) {
        let Some(active) = self.pmi_active_view.clone() else {
            self.pmi_restore_explode();
            return;
        };
        let report = self.pmi_report.as_ref().and_then(|report| report.view(&active));
        let state = self.pmi_state_shared();
        let view = state.find_view(&active);
        // Every plane of the section: material goes only where all remove it.
        let planes = view.map(|v| v.section_planes_in(report)).unwrap_or_default();
        let section = (!planes.is_empty()).then_some(());
        let exclude = view.and_then(|v| v.display.section.clone());
        let poses: Vec<(Vec<String>, [f64; 3], [f64; 3], [f64; 3], [f64; 3])> = report
            .map(|view| {
                view.annotations
                    .iter()
                    .filter(|row| row.enabled && row.status == PmiStatus::Ok)
                    .filter(|row| matches!(row.geometry, PmiGeometry::Explode { .. }))
                    .enumerate()
                    // Each step at its playback fraction (`exploded_ops`; 1 unless animating).
                    .filter_map(|(step, row)| match super::exploded_ops::explode_at(&row.geometry, self.explode_fraction(step)) {
                        PmiGeometry::Explode { solids, translate, rotate_deg, scale, center, .. } => {
                            Some((solids, translate, rotate_deg, scale, center))
                        }
                        _ => None,
                    })
                    .collect()
            })
            .unwrap_or_default();
        // An instructions step's insertion: its arrowed parts on their way home.
        let mut poses = poses;
        poses.extend(self.instructions_insertion_poses());
        if section.is_none() && self.pmi_section_hidden.is_empty() && !self.pmi_explode_originals.is_empty() {
            // Posed again (an animation frame): a display already posed is
            // reset from its original's geometry, copied into the buffers it
            // holds, rather than restored and cloned whole again (every frame,
            // every moving solid: ~500 on a deep l500 view). A section changes
            // the meshes themselves, so a sectioned view takes the full way.
            let wanted: std::collections::HashSet<&String> = poses.iter().flat_map(|pose| pose.0.iter()).collect();
            let stale: Vec<String> = self.pmi_explode_originals.keys().filter(|name| !wanted.contains(name)).cloned().collect();
            for name in stale {
                if let (Some(original), Some(display)) = (self.pmi_explode_originals.remove(&name), self.scene.solid_mut(&name)) {
                    *display = original;
                }
            }
            for name in wanted {
                match self.pmi_explode_originals.get(name) {
                    Some(original) => {
                        if let Some(display) = self.scene.solid_mut(name) {
                            reset_posed_geometry(display, original);
                        }
                    }
                    None => {
                        if let Some(display) = self.scene.solid(name) {
                            self.pmi_explode_originals.insert(name.clone(), display.clone());
                        }
                    }
                }
            }
        } else {
            self.pmi_restore_explode();
            for (solids, ..) in &poses {
                for name in solids {
                    let Some(display) = self.scene.solid(name) else { continue };
                    self.pmi_explode_originals.entry(name.clone()).or_insert_with(|| display.clone());
                }
            }
        }
        for (solids, translate, rotate_deg, scale, center) in poses {
            for name in solids {
                if let Some(display) = self.scene.solid_mut(&name) {
                    transform_display(display, center, translate, rotate_deg, scale);
                }
            }
        }
        if section.is_some() {
            use super::pmi_section::{side_of_all, Side};
            // A solid wholly on the kept side is left exactly as it is (no
            // copy, no new revision: the GPU keeps its buffers); one wholly
            // removed is hidden, which keeps its revision too, and its
            // un-hidden original is kept so sheets and the 3D PDF still draw
            // it. Only what the plane crosses is clipped, capped and
            // re-uploaded.
            // A solid the section excludes (a shaft, a fastener) stays whole.
            let names: Vec<(String, Side)> = self
                .scene
                .solids()
                .iter()
                .map(|s| (s.name.clone(), if exclude.as_ref().is_some_and(|cut| cut.excludes(&s.name)) { Side::Kept } else { side_of_all(s, &planes) }))
                .collect();
            for (name, side) in names {
                match side {
                    Side::Kept => {}
                    Side::Removed => {
                        if let Some(display) = self.scene.solid(&name).filter(|display| display.visible) {
                            self.pmi_explode_originals.entry(name.clone()).or_insert_with(|| display.clone());
                            self.scene.set_visible(&name, false);
                            self.pmi_section_hidden.push(name);
                        }
                    }
                    Side::Cut => {
                        if let Some(display) = self.scene.solid(&name) { self.pmi_explode_originals.entry(name.clone()).or_insert_with(|| display.clone()); }
                        if let Some(display) = self.scene.solid_mut(&name) { super::pmi_section::clip_display_all(display, &planes); }
                    }
                }
            }
        }
        if !self.pmi_explode_originals.is_empty() || !self.pmi_section_hidden.is_empty() {
            self.dirty = true;
        }
    }

    /// Put every exploded display back exactly.
    pub(crate) fn pmi_restore_explode(&mut self) {
        for name in std::mem::take(&mut self.pmi_section_hidden) {
            self.scene.set_visible(&name, true);
        }
        let originals = std::mem::take(&mut self.pmi_explode_originals);
        for (name, original) in originals {
            if let Some(display) = self.scene.solid_mut(&name) {
                *display = original;
            }
        }
        self.dirty = true;
    }

    /// Post-apply tail (`finish_apply`): the displays are fresh, so re-pose
    /// the active view's explode targets and re-bake the overlay.
    pub(crate) fn pmi_after_apply(&mut self) {
        // The fresh report resolved every balloon's head from its stored bubble.
        self.pmi_balloon_stale = None;
        // Normally already un-posed by `apply_run_output` (before the scene
        // reconcile); the parse-error branch of a rerun reaches here with the
        // poses still applied, so restore rather than forget them.
        self.pmi_restore_explode();
        if let Some(active) = self.pmi_active_view.clone() {
            // A view that vanished (undo of its capture) deactivates.
            let view = self.pmi_state().find_view(&active).cloned();
            match view {
                None => {
                    self.pmi_active_view = None;
                    self.pmi_open_annotation = None;
                }
                Some(view) => {
                    // The view's hide steps may have changed with this run
                    // (added, edited, removed, suppressed, undone): the
                    // displays take the view's visibility again, then its poses.
                    self.apply_view_display(&view);
                    self.pmi_apply_explode();
                }
            }
        }
        self.instructions_refresh_ghosts();
        if let Some(open) = &self.pmi_open_annotation {
            if self.pmi_state().find_annotation(open).is_none() {
                self.pmi_open_annotation = None;
            }
        }
        // A view dialog whose view went away (undo of its capture) closes.
        if let Some(open) = &self.pmi_open_view {
            if self.pmi_state().find_view(open).is_none() {
                self.pmi_open_view = None;
            }
        }
        self.refresh_pmi_overlay();
    }

    // --- annotations -----------------------------------------------------------

    /// Add an annotation of `type_id` to view `view_id` (the active view when
    /// `None`) with `params_json` (the schema params; `id` is minted). A datum
    /// with no letter gets the next unused one. Returns the id; the new
    /// annotation's form opens.
    pub fn pmi_add_annotation(
        &mut self,
        view_id: Option<&str>,
        type_id: &str,
        params_json: &str,
    ) -> Result<String, String> {
        let def = brep_kernel::pmi_type(type_id).ok_or_else(|| format!("unknown PMI annotation type '{type_id}'"))?;
        let mut state = self.pmi_state();
        let view_id = view_id
            .map(String::from)
            .or_else(|| self.pmi_active_view.clone())
            .ok_or_else(|| "no active PMI view — capture or activate a view first".to_string())?;
        let id = state.next_id(def.short_name);
        let mut params: serde_json::Value = serde_json::from_str(params_json).unwrap_or_else(|_| serde_json::json!({}));
        if !params.is_object() {
            params = serde_json::json!({});
        }
        // Schema defaults under the given params.
        let schema = (def.schema)();
        if let (Some(fields), Some(object)) = (
            schema.get("inputParamsSchema").and_then(serde_json::Value::as_object),
            params.as_object_mut(),
        ) {
            for (key, spec) in fields {
                if !object.contains_key(key) {
                    if let Some(default) = spec.get("default_value") {
                        if !default.is_null() {
                            object.insert(key.clone(), default.clone());
                        }
                    }
                }
            }
            object.insert("id".into(), serde_json::Value::String(id.clone()));
            if type_id == "datum" {
                let letter = object.get("letter").and_then(serde_json::Value::as_str).unwrap_or("").trim().to_string();
                if letter.is_empty() {
                    if let Some(next) = state.next_datum_letter() {
                        object.insert("letter".into(), serde_json::Value::String(next));
                    }
                }
            }
        }
        let view = state.find_view_mut(&view_id).ok_or_else(|| format!("no PMI view '{view_id}'"))?;
        view.annotations.push(PmiAnnotation {
            plugin_replay: None,
            persistent_data: serde_json::Value::Null,
            kind: type_id.to_string(),
            enabled: true,
            params,
            label_world: None,
        });
        self.open_pmi_annotation(id.clone());
        self.write_pmi_state(state);
        Ok(id)
    }

    /// Replace an annotation's params (a form edit). Re-runs.
    pub fn pmi_update_annotation(&mut self, id: &str, params_json: &str) -> Result<(), String> {
        if self.pmi_state().find_annotation(id).is_some_and(|(_, a)| a.kind.contains('/')) {
            let params = serde_json::from_str(params_json).map_err(|e| format!("annotation params: {e}"))?;
            return self.plugin_update_annotation(id, params).map(|_| ());
        }
        self.pmi_update_annotation_no_rerun(id, params_json)?;
        self.rerun_history();
        Ok(())
    }

    /// The fold half of [`Self::pmi_update_annotation`] (checkpointed, no
    /// re-run) — the reference picker's commit uses it before its shared
    /// end tail re-runs.
    pub(crate) fn pmi_update_annotation_no_rerun(&mut self, id: &str, params_json: &str) -> Result<(), String> {
        let mut state = self.pmi_state();
        let annotation = state.find_annotation_mut(id).ok_or_else(|| format!("no PMI annotation '{id}'"))?;
        if annotation.kind.contains('/') {
            return Err("plugin annotation edits require the worker transaction path".into());
        }
        let mut params: serde_json::Value =
            serde_json::from_str(params_json).map_err(|error| format!("annotation params: {error}"))?;
        if let Some(object) = params.as_object_mut() {
            object.insert("id".into(), serde_json::Value::String(id.to_string()));
        }
        annotation.params = params;
        let block = serde_json::to_value(&state).ok();
        self.history.set_pmi_block(block, Some(&format!("pmi:params:{id}")));
        Ok(())
    }

    pub fn pmi_remove_annotation(&mut self, id: &str) -> Result<(), String> {
        if self.pmi_state().find_annotation(id).is_some_and(|(_, a)| a.kind.contains('/')) {
            return self.plugin_delete_annotation(id).map(|_| ());
        }
        let mut state = self.pmi_state();
        let Some((view_index, index)) = state.locate_annotation(id) else {
            return Err(format!("no PMI annotation '{id}'"));
        };
        state.views[view_index].annotations.remove(index);
        if self.pmi_open_annotation.as_deref() == Some(id) {
            self.pmi_open_annotation = None;
        }
        self.write_pmi_state(state);
        Ok(())
    }

    pub fn pmi_set_annotation_enabled(&mut self, id: &str, enabled: bool) -> Result<(), String> {
        if self.pmi_state().find_annotation(id).is_some_and(|(_, a)| a.kind.contains('/')) {
            return self.plugin_set_annotation_enabled(id, enabled).map(|_| ());
        }
        let mut state = self.pmi_state();
        let annotation = state.find_annotation_mut(id).ok_or_else(|| format!("no PMI annotation '{id}'"))?;
        if annotation.enabled == enabled {
            return Ok(());
        }
        annotation.enabled = enabled;
        self.write_pmi_state(state);
        Ok(())
    }

    /// Move an annotation to `index` within its view.
    pub fn pmi_move_annotation(&mut self, id: &str, index: usize) -> Result<(), String> {
        let mut state = self.pmi_state();
        let Some((view_index, from)) = state.locate_annotation(id) else {
            return Err(format!("no PMI annotation '{id}'"));
        };
        let annotations = &mut state.views[view_index].annotations;
        let annotation = annotations.remove(from);
        let to = index.min(annotations.len());
        annotations.insert(to, annotation);
        self.write_pmi_state(state);
        Ok(())
    }

    /// Move an annotation to another view (append).
    pub fn pmi_move_annotation_to_view(&mut self, id: &str, view_id: &str) -> Result<(), String> {
        let mut state = self.pmi_state();
        let Some((view_index, from)) = state.locate_annotation(id) else {
            return Err(format!("no PMI annotation '{id}'"));
        };
        if state.find_view(view_id).is_none() {
            return Err(format!("no PMI view '{view_id}'"));
        }
        let annotation = state.views[view_index].annotations.remove(from);
        state.find_view_mut(view_id).expect("checked").annotations.push(annotation);
        self.write_pmi_state(state);
        Ok(())
    }

    /// Open one annotation's form (engine memory; `None` closes). Opening an
    /// annotation of another view activates that view. An open COUNTS
    /// (`Self::open_pmi_annotation`) — including a re-open of the annotation
    /// already open, which is a viewport label double click on the form the user
    /// cannot see; an id that resolves to no annotation opens nothing and
    /// counts nothing.
    pub fn pmi_set_annotation_open(&mut self, id: Option<&str>) {
        match id {
            Some(id) => {
                let state = self.pmi_state();
                if let Some((view, _)) = state.find_annotation(id) {
                    let view_id = view.id.clone();
                    if self.pmi_active_view.as_deref() != Some(view_id.as_str()) {
                        let _ = self.pmi_activate_view(&view_id);
                    }
                    self.open_pmi_annotation(id.to_string());
                }
            }
            None => {
                if self.pmi_open_annotation.as_deref() == Some(self.transform_armed_feature().as_str()) { self.disarm_transform(); }
                self.pmi_open_annotation = None;
            },
        }
        self.refresh_pmi_overlay();
    }

    // --- labels -----------------------------------------------------------------

    /// Move an annotation's label (world). Coalesced per annotation into ONE
    /// undo step, and NEVER a re-run: the cached report is patched in place
    /// and the overlay re-baked. A balloon's arrow head is re-derived from
    /// the moved bubble (`Self::pmi_reproject_balloon_head`).
    pub fn pmi_set_label_world(&mut self, id: &str, world: [f64; 3]) -> Result<(), String> {
        let mut state = self.pmi_state();
        let annotation = state.find_annotation_mut(id).ok_or_else(|| format!("no PMI annotation '{id}'"))?;
        annotation.label_world = Some(world);
        let block = serde_json::to_value(&state).ok();
        self.history.set_pmi_block(block, Some(&format!("pmi:label:{id}")));
        if let Some(report) = self.pmi_report.as_mut() {
            if let Some(row) = report.annotation_mut(id) {
                row.label_world = world;
                if let PmiGeometry::Note { position } = &mut row.geometry {
                    *position = world;
                }
            }
        }
        self.pmi_reproject_balloon_head(id);
        self.refresh_pmi_overlay();
        Ok(())
    }

    /// Re-derive a balloon's arrow head from its row's bubble through the
    /// recipe the kernel put on its leader (the same projection the resolver
    /// ran, on the exact-solid clones the scene holds), and patch the cached
    /// report. The head is derived, never stored, so no document edit and no
    /// run: the next run resolves the same head from the stored bubble. A
    /// solid the scene does not hold yet is asked of the runner; the head is
    /// re-derived when the reply lands ([`Self::pmi_refresh_stale_balloon`]),
    /// which for the Inline runner is before this returns. Any other
    /// annotation is left alone.
    pub(crate) fn pmi_reproject_balloon_head(&mut self, id: &str) {
        if let Some(missing) = self.pmi_balloon_head_now(id) {
            self.pmi_balloon_stale = Some(id.to_string());
            self.request_exact_solids(missing.iter().map(String::as_str));
            self.pmi_refresh_stale_balloon();
        }
    }

    /// Retry the balloon whose re-projection waited on a topology reply.
    pub(crate) fn pmi_refresh_stale_balloon(&mut self) {
        let Some(id) = self.pmi_balloon_stale.take() else {
            return;
        };
        if self.pmi_balloon_head_now(&id).is_some() {
            // Still waiting (a background runner's reply is on its way).
            self.pmi_balloon_stale = Some(id);
        } else {
            self.refresh_pmi_overlay();
        }
    }

    /// One re-projection attempt: `None` when done (or not a balloon), else
    /// the occurrence solids the scene does not hold.
    pub(super) fn pmi_balloon_head_now(&mut self, id: &str) -> Option<Vec<String>> {
        let (mut anchor, bubble) = self
            .pmi_report
            .as_ref()
            .and_then(|report| report.annotation(id))
            .and_then(|row| match &row.geometry {
                PmiGeometry::Leader { balloon: true, anchor: Some(anchor), .. } => Some((anchor.clone(), row.label_world)),
                _ => None,
            })?;
        anchor.camera = Some(self.snapshot_camera());
        let mut missing = Vec::new();
        let head = brep_kernel::pmi_balloon_head(&anchor, bubble, |name| self.scene.exact_solid(name), &mut missing);
        if !missing.is_empty() {
            return Some(missing);
        }
        // A fixed (vertex) anchor answers `None`: the head never moves. A
        // projection error keeps the kernel's head rather than a wrong one.
        if let Ok(Some(head)) = head {
            if let Some(row) = self.pmi_report.as_mut().and_then(|report| report.annotation_mut(id)) {
                if let PmiGeometry::Leader { targets, anchor: recipe, .. } = &mut row.geometry {
                    *recipe = Some(anchor);
                    if let Some(first) = targets.first_mut() {
                        *first = head;
                    }
                }
            }
        }
        None
    }

    /// Drag an annotation's label to the pointer: the new position is where
    /// the pick ray crosses the plane through the current label perpendicular
    /// to the viewing direction (so a drag never changes the label's depth).
    pub fn pmi_label_drag_to(&mut self, id: &str, x: f64, y: f64) {
        // Part-way through explode playback the chip is drawn where its body
        // is now: the drag runs there, and is stored back in the run's frame.
        let playback = self.explode_playback_poses();
        let Some((current, plane)) = self
            .pmi_report
            .as_ref()
            .and_then(|r| r.annotation(id))
            .map(|r| (playback.as_ref().map_or(r.label_world, |poses| poses.shown(r, r.label_world)), r.plane))
        else {
            return;
        };
        let ray = self.camera.pick_ray(x, y);
        // In a picked annotation plane the label stays ON that plane; a
        // view-aligned label moves in the view-parallel plane through its
        // current position.
        let plane = plane.unwrap_or_else(|| {
            let (_, _, view) = self.camera.basis();
            brep_kernel::PmiPlane {
                origin: current,
                normal: view,
                x_axis: [0.0; 3],
            }
        });
        let Some(world) = plane.hit(ray.origin, ray.dir) else {
            return;
        };
        let world = match (&playback, self.pmi_report.as_ref().and_then(|r| r.annotation(id))) {
            (Some(poses), Some(row)) => poses.full(row, world),
            _ => world,
        };
        let _ = self.pmi_set_label_world(id, world);
    }

    /// A label drag ended: the next drag is a fresh undo step.
    pub fn pmi_label_drag_end(&mut self) {
        self.history.break_coalescing();
    }

    /// Hover a label: highlight the annotation's referenced geometry.
    pub fn pmi_hover(&mut self, id: &str) {
        self.pmi_label_hover_active = true;
        if self.pmi_hovered.as_deref() == Some(id) {
            return;
        }
        let references: Vec<String> = self
            .pmi_report
            .as_ref()
            .and_then(|report| report.annotation(id))
            .map(|row| row.references.clone())
            .unwrap_or_default();
        let mut solids: Vec<String> = Vec::new();
        let mut faces: Vec<String> = Vec::new();
        let mut edges: Vec<String> = Vec::new();
        for reference in &references {
            if let Some(at) = reference.find('@') {
                solids.push(reference[..at].to_string());
            } else if self.scene_has_face(reference) {
                faces.push(reference.clone());
            } else if self.scene_has_edge(reference) {
                edges.push(reference.clone());
            } else if self.scene.solid(reference).is_some() {
                solids.push(reference.clone());
            } else {
                let prefix = format!("{reference}:");
                solids.extend(self.scene.solids().iter().filter(|s| s.name.starts_with(&prefix)).map(|s| s.name.clone()));
            }
        }
        self.clear_hover();
        self.emphasis.hovered_solids.extend(solids);
        self.emphasis.hovered_faces.extend(faces);
        self.emphasis.hovered_edges.extend(edges);
        self.emphasis.generation = self.emphasis.generation.wrapping_add(1);
        self.pmi_hovered = Some(id.to_string());
        self.dirty = true;
    }

    pub fn pmi_hover_end(&mut self) {
        if self.pmi_hovered.take().is_some() {
            self.clear_hover();
            self.dirty = true;
        }
    }

    /// Consume the one-frame "a PMI label is hovering elements" flag (the
    /// viewport's scene-hover pass yields while set).
    pub fn take_pmi_label_hover(&mut self) -> bool {
        std::mem::take(&mut self.pmi_label_hover_active)
    }

    /// A label was clicked: SELECT that annotation, as its tree row's single
    /// click does — the label carries the accent and nothing opens.
    pub fn pmi_label_clicked(&mut self, id: &str) {
        self.pmi_select_annotation(id);
    }

    /// A label was double-clicked: open that annotation's form, as its tree
    /// row's double click does.
    pub fn pmi_label_double_clicked(&mut self, id: &str) {
        self.pmi_set_annotation_open(Some(id));
    }

    /// SELECT an annotation without opening it — the PMI tree's single click.
    /// Its view activates when it is not the active one, as opening does, so
    /// the selected label is on screen to carry the selection accent. Returns
    /// false, changing nothing, for an id that names no annotation.
    pub fn pmi_select_annotation(&mut self, id: &str) -> bool {
        let state = self.pmi_state();
        let Some((view, _)) = state.find_annotation(id) else {
            return false;
        };
        if self.pmi_active_view.as_deref() != Some(view.id.as_str()) {
            let _ = self.pmi_activate_view(&view.id);
        }
        self.pmi_selected_view = None;
        self.pmi_selected_annotation = Some(id.to_string());
        self.refresh_pmi_overlay();
        true
    }

    /// SELECT a view without activating it — the PMI tree's single click on a
    /// view row. The camera, visibility and wireframe stay as they are: a
    /// double click (which opens the view's dialog) or the row's On toggle is
    /// what activates. A selected annotation gives up the selection. Returns
    /// false, changing nothing, for an id that names no view.
    pub fn pmi_select_view(&mut self, id: &str) -> bool {
        if self.pmi_state().find_view(id).is_none() {
            return false;
        }
        if self.pmi_selected_annotation.take().is_some() {
            self.refresh_pmi_overlay();
        }
        self.pmi_selected_view = Some(id.to_string());
        self.dirty = true;
        true
    }

    // --- reference picker ---------------------------------------------------------

    /// Enter reference-selection mode for annotation `id`'s field at `path`.
    pub fn begin_ref_select_for_pmi(
        &mut self,
        id: &str,
        path: Vec<String>,
        label: String,
        filter: Vec<String>,
        multiple: bool,
        seed_names: Vec<String>,
    ) {
        let restore_index = self.history.rollback();
        self.selection_filter = SelectionFilter::from_ref_filter(&filter);
        self.ref_select = Some(RefSelectState {
            feature_id: id.to_string(),
            path,
            label,
            filter,
            multiple,
            names: seed_names,
            restore_index,
            target: RefSelectTarget::Pmi,
            picks: 0,
            claimed: false,
            finish_requested: false,
        });
        self.sync_ref_select_emphasis();
    }

    // --- explode editing before the pick commits ------------------------------

    /// The names an open explode step is about to move: the reference pick
    /// running on its `targets` field while one runs (the picker holds the
    /// part until Done commits it), else the step's committed targets.
    fn explode_target_names(&self, id: &str, annotation: &PmiAnnotation) -> Vec<String> {
        if let Some(field) = self.ref_select_field() {
            if field.target == RefSelectTarget::Pmi && field.subject == id && field.path == ["targets"] {
                return field.names;
            }
        }
        annotation.references("targets")
    }

    /// The world bbox centre of the scene solids `names` name: a solid by its
    /// name, a component by every solid inside it (`ACOMP2` → `ACOMP2:…`).
    /// `None` when none of them is in the scene.
    fn scene_names_center(&self, names: &[String]) -> Option<[f64; 3]> {
        let mut low = [f64::INFINITY; 3];
        let mut high = [f64::NEG_INFINITY; 3];
        let mut any = false;
        for name in names {
            let prefix = format!("{name}:");
            for solid in self.scene.solids() {
                if solid.name == *name || solid.name.starts_with(&prefix) {
                    for axis in 0..3 {
                        low[axis] = low[axis].min(solid.bbox.min[axis]);
                        high[axis] = high[axis].max(solid.bbox.max[axis]);
                    }
                    any = true;
                }
            }
        }
        any.then(|| std::array::from_fn(|axis| (low[axis] + high[axis]) * 0.5))
    }

    /// Where an open explode step's gizmo stands BEFORE the kernel has laid
    /// the step out — the owner (2026-10-26) picked a part for a new explode
    /// and saw no transform controls: a reference pick commits at Done, and
    /// until then the step had nothing to stand on. This is the centre of
    /// what the step is about to move (the running pick's names, else its
    /// committed targets), the same bbox centre the kernel's layout uses.
    /// `None` with nothing to move yet, or when the step is not in the
    /// active view. Once the run lays the step out, the report's centre is
    /// the one the gizmo and a drag use.
    pub(super) fn pmi_explode_live_center(&self, id: &str) -> Option<[f64; 3]> {
        let state = self.pmi_state_shared();
        let (view, annotation) = state.find_annotation(id)?;
        if annotation.kind != "explode" || self.pmi_active_view.as_deref() != Some(view.id.as_str()) {
            return None;
        }
        let names = self.explode_target_names(id, annotation);
        self.scene_names_center(&names)
    }

    /// Commit a finished PMI ref-select into the annotation's params (fold
    /// only — the caller's shared tail re-runs).
    pub(crate) fn pmi_commit_refs(&mut self, id: &str, path: &[String], names: &[String], multiple: bool) {
        if self.pmi_state().find_view(id).is_some() {
            match path.first().map(String::as_str) {
                Some("sectionExclude") => self.pmi_commit_section_exclude(id, names),
                _ => self.pmi_commit_section_plane(id, names.first().map(String::as_str).unwrap_or("")),
            }
            self.history.break_coalescing();
            return;
        }
        let state = self.pmi_state();
        let Some((_, annotation)) = state.find_annotation(id) else {
            self.push_notice(format!("unknown PMI annotation '{id}'"));
            return;
        };
        let mut params = annotation.params.clone();
        let value = if multiple {
            serde_json::Value::Array(names.iter().cloned().map(serde_json::Value::String).collect())
        } else {
            serde_json::Value::String(names.first().cloned().unwrap_or_default())
        };
        super::selection_ux::set_json_at(&mut params, path, value);
        if let Err(error) = self.pmi_update_annotation_no_rerun(id, &params.to_string()) {
            self.push_notice(format!("PMI update failed: {error}"));
        }
        // A pick is a discrete change (it ends with Finish): the next edit of
        // the same annotation's params is its own undo step, so picking an
        // anchor and then clearing it in the form undo one at a time.
        self.history.break_coalescing();
    }

    /// Commit a view form's **Section plane** pick (fold only, like
    /// [`Self::pmi_commit_refs`]): picking a face or plane makes the section
    /// cut on it — the section turns on with the `Plane` normal.
    fn pmi_commit_section_plane(&mut self, id: &str, name: &str) {
        let mut state = self.pmi_state();
        let Some(view) = state.find_view_mut(id) else { return };
        let section = view.display.section.get_or_insert_with(|| brep_kernel::feature_pipeline::pmi::PmiSection {
            axis: "Plane".into(),
            offset: 0.,
            flip: false,
            origin: None,
            normal: None,
            plane: None,
            exclude: Vec::new(),
            planes: Vec::new(),
        });
        section.axis = "Plane".into();
        section.plane = Some(name.trim().to_string()).filter(|name| !name.is_empty());
        section.freeze(None);
        let block = serde_json::to_value(&state).ok();
        // Its own undo step, not folded into the form's edits before it.
        self.history.break_coalescing();
        self.history.set_pmi_block(block, Some(&format!("pmi:view:{id}")));
    }

    /// Commit a view form's **Not cut** picks (fold only, like
    /// [`Self::pmi_commit_section_plane`]): the solids and components the
    /// section leaves whole. Nothing to commit on a view without a section.
    fn pmi_commit_section_exclude(&mut self, id: &str, names: &[String]) {
        let mut state = self.pmi_state();
        let Some(section) = state.find_view_mut(id).and_then(|view| view.display.section.as_mut()) else { return };
        section.exclude = names.iter().map(|name| name.trim().to_string()).filter(|name| !name.is_empty()).collect();
        let block = serde_json::to_value(&state).ok();
        self.history.break_coalescing();
        self.history.set_pmi_block(block, Some(&format!("pmi:view:{id}")));
    }

    // --- import -------------------------------------------------------------------

    /// Merge a file's lifted PMI (`read_step_pmi`) into the document beside
    /// the import that added its geometry: views append with fresh ids, the
    /// import's undo checkpoint covers both (no second checkpoint).
    pub(crate) fn pmi_merge_imported(&mut self, lifted: PmiState) {
        let mut state = self.pmi_state();
        for view in lifted.views {
            let id = state.next_id("VIEW");
            let mut annotations = Vec::with_capacity(view.annotations.len());
            for mut annotation in view.annotations {
                let prefix = brep_kernel::pmi_type(&annotation.kind).map(|def| def.short_name).unwrap_or("PMI");
                let fresh = state.next_id(prefix);
                if let Some(object) = annotation.params.as_object_mut() {
                    object.insert("id".into(), serde_json::Value::String(fresh));
                }
                annotations.push(annotation);
            }
            state.views.push(PmiView {
                id,
                name: view.name,
                camera: view.camera,
                display: view.display,
                annotations,
            });
        }
        let block = serde_json::to_value(&state).ok();
        self.history.set_pmi_block_no_undo(block);
        self.rerun_history();
    }
}

/// Pose a display in place: `p' = R((p − c) ∘ s) + c + t` on the mesh, the
/// edge polylines and the vertices; normals rotate; the bbox is rebuilt.
/// `p ↦ R((p − c) ∘ s) + c + t` as a column-major 4×4, its rotation read off
/// the very rotation the vertices are turned by.
fn pose_matrix(center: [f64; 3], translate: [f64; 3], rotate: &dyn Fn([f64; 3]) -> [f64; 3], scale: [f64; 3]) -> [f32; 16] {
    let columns = [rotate([1.0, 0.0, 0.0]), rotate([0.0, 1.0, 0.0]), rotate([0.0, 0.0, 1.0])];
    let linear: [[f64; 3]; 3] = std::array::from_fn(|j| columns[j].map(|v| v * scale[j]));
    let shifted: [f64; 3] = std::array::from_fn(|i| center[i] + translate[i] - (0..3).map(|j| linear[j][i] * center[j]).sum::<f64>());
    let mut m = [0.0f32; 16];
    for j in 0..3 {
        for i in 0..3 {
            m[j * 4 + i] = linear[j][i] as f32;
        }
    }
    m[12] = shifted[0] as f32;
    m[13] = shifted[1] as f32;
    m[14] = shifted[2] as f32;
    m[15] = 1.0;
    m
}

/// `a · b`, column-major 4×4.
use crate::view::mat4_mul_column_major as mat4_mul;

/// Put a posed display's geometry back to its original's, copying into the
/// buffers it already holds: what a pose moves (positions, normals, edge
/// polylines, vertices, the box) and the revisions it set.
fn reset_posed_geometry(display: &mut crate::scene::SolidDisplay, original: &crate::scene::SolidDisplay) {
    display.mesh.positions.clone_from(&original.mesh.positions);
    display.mesh.normals.clone_from(&original.mesh.normals);
    if display.edges.len() == original.edges.len() {
        for (edge, from) in display.edges.iter_mut().zip(&original.edges) {
            edge.polyline.clone_from(&from.polyline);
        }
    } else {
        display.edges.clone_from(&original.edges);
    }
    display.vertices.clone_from(&original.vertices);
    display.bbox = original.bbox;
    display.revision = original.revision;
    display.shape_revision = original.shape_revision;
    display.pose = original.pose;
}

pub(super) fn transform_display(
    display: &mut crate::scene::SolidDisplay,
    center: [f64; 3],
    translate: [f64; 3],
    rotate_deg: [f64; 3],
    scale: [f64; 3],
) {
    // The same mesh posed: the renderer rewrites its positions in the buffers
    // it holds (`sync_scene`'s pose path) instead of rebuilding the solid on
    // every frame an exploded view animates (l500: p95 81 ms a frame). A
    // section clip, which changes the mesh, resets this itself.
    // The kernel's explode rotation is in degrees (as every `rotationEuler`;
    // its balloon anchors convert the same way); the rotation takes radians.
    let rotate_rad = rotate_deg.map(f64::to_radians);
    let rotate = |v: [f64; 3]| super::rotate_euler_xyz_f64(v, rotate_rad);
    // The pose as a matrix over the shape's own geometry: this one, composed
    // with any pose already on it. A display moved some other way (a drag)
    // has no shape geometry to compose over, and keeps none.
    let step = pose_matrix(center, translate, &rotate, scale);
    display.pose = if display.shape_revision == 0 {
        Some(step)
    } else {
        display.pose.map(|before| mat4_mul(&step, &before))
    };
    if display.shape_revision == 0 {
        display.shape_revision = display.revision;
    }
    display.revision = crate::scene::next_revision();
    let pose = |p: [f64; 3]| -> [f64; 3] {
        let local = [(p[0] - center[0]) * scale[0], (p[1] - center[1]) * scale[1], (p[2] - center[2]) * scale[2]];
        let rotated = rotate(local);
        [rotated[0] + center[0] + translate[0], rotated[1] + center[1] + translate[1], rotated[2] + center[2] + translate[2]]
    };
    let mut bbox = crate::camera::Aabb::empty();
    for position in &mut display.mesh.positions {
        let posed = pose([position[0] as f64, position[1] as f64, position[2] as f64]);
        *position = [posed[0] as f32, posed[1] as f32, posed[2] as f32];
        bbox.expand(posed);
    }
    for normal in &mut display.mesh.normals {
        let rotated = rotate(std::array::from_fn(|i| normal[i] as f64 / scale[i]));
        let length = rotated.iter().map(|v| v * v).sum::<f64>().sqrt().max(1e-20);
        *normal = rotated.map(|v| (v / length) as f32);
    }
    for edge in &mut display.edges {
        for point in &mut edge.polyline {
            let posed = pose([point[0] as f64, point[1] as f64, point[2] as f64]);
            *point = [posed[0] as f32, posed[1] as f32, posed[2] as f32];
            bbox.expand(posed);
        }
    }
    for vertex in &mut display.vertices {
        vertex.position = pose(vertex.position);
        bbox.expand(vertex.position);
    }
    if !bbox.is_empty() {
        display.bbox = bbox;
    }
}