BREP_render 0.2.1

use super::*;
use serde_json::Value;

// ===========================================================================
// Assembly surface (Wave-3 lane F) — the engine-state altitude the app's
// assembly panels program against.
//
// # Where the kernel assembly session LIVES (the main-side sync pattern)
//
// The kernel's assembly session (constraint state + scene clone, installed by
// the `execute_history` tail) is THREAD-LOCAL to whichever thread ran the
// history. The DISPLAY run happens on the runner (native thread / wasm
// worker), so the main thread's session would be cold. Following the repo's
// established pattern for main-side kernel-state needs (`export_step_text`,
// `flat_pattern_target_handle`, `consumed_feature_names` all re-execute the
// history main-side against the warm incremental cache), [`sync_assembly`]
// runs `brep_kernel::execute_history` ON THE MAIN THREAD after every applied
// display run — a cache-hit replay for unchanged features — which installs a
// fresh main-side session, surfaces the scene's ComponentRecords, and folds
// the solved state back into the document (the pose-authority contract).
// Componentless documents skip ALL of it (`history_has_assembly` gates).
//
// SEAM (integrator): a runner-protocol extension could move the assembly ABI
// off-thread later; until then the first sync after opening a heavy assembly
// re-executes cold on the UI thread (wasm: a one-time stall).
//
// # The per-mutation lifecycle (spec §6)
//
// Every constraint mutation: (1) ensure the main-side session is current,
// (2) call the kernel mutation ABI (which auto-solves the session), (3) FOLD
// the session back into the document (`assembly_apply_document_json` → adopt,
// checkpointed = undoable), (4) when `settings.assembly_auto_solve` is on,
// re-run the history through the display runner so the viewport re-poses.
// With auto-solve off, step 4 waits for the manual Solve button.
// ===========================================================================

/// What a component-insert names: an EXISTING parts-library entry (skip the
/// store read — just add an instance) or a NEW part payload to hand to
/// `add_part_to_library` (which dedups by sourceKey+signature and returns the
/// EFFECTIVE entry name the instance must reference).
pub enum ComponentInsert<'a> {
    Existing {
        part_name: &'a str,
    },
    New {
        name: &'a str,
        source_key: &'a str,
        source_signature: &'a str,
        document_json: &'a str,
    },
}

/// A STABLE content signature of a document: a sorted-key JSON walk hashed
/// with the (fixed-key, cross-process-deterministic) std SipHash. The ONE
/// signature fn, at the ENGINE altitude so app-side and engine-side writers
/// share one copy: the app's insert flow (`panels::file`), the edit-in-place
/// Finish (`panels::assembly_edit::refresh_library_entry`) and the
/// update-components comparison (`panels::update_components`) all write/compare
/// a parts-library `sourceSignature` with THIS function — a freshly inserted,
/// unchanged part must always compare up-to-date, which a second copy would
/// break the moment either drifted.
/// (Distinct from the kernel's `parts_library::stable_json_hash`, which is an
/// in-memory `doc_hash` for the per-feature fingerprint hook.)
pub fn document_signature(doc_json: &str) -> String {
    use std::hash::{Hash, Hasher};
    fn walk(value: &serde_json::Value, hasher: &mut impl Hasher) {
        match value {
            serde_json::Value::Null => 0u8.hash(hasher),
            serde_json::Value::Bool(flag) => {
                1u8.hash(hasher);
                flag.hash(hasher);
            }
            serde_json::Value::Number(number) => {
                2u8.hash(hasher);
                number.to_string().hash(hasher);
            }
            serde_json::Value::String(text) => {
                3u8.hash(hasher);
                text.hash(hasher);
            }
            serde_json::Value::Array(items) => {
                4u8.hash(hasher);
                for item in items {
                    walk(item, hasher);
                }
            }
            serde_json::Value::Object(map) => {
                5u8.hash(hasher);
                let mut keys: Vec<&String> = map.keys().collect();
                keys.sort();
                for key in keys {
                    key.hash(hasher);
                    walk(&map[key], hasher);
                }
            }
        }
    }
    let mut hasher = std::collections::hash_map::DefaultHasher::new();
    match serde_json::from_str::<serde_json::Value>(doc_json) {
        Ok(value) => walk(&value, &mut hasher),
        Err(_) => doc_json.hash(&mut hasher),
    }
    format!("{:016x}", hasher.finish())
}

/// Stringify a kernel ABI error. The kernel exports return `JsValue` errors
/// (wasm-bindgen, built from plain strings); this crate does not depend on
/// wasm-bindgen directly, so stringify generically via `Debug` — for a
/// string-payload `JsValue` that is the message (quoted), which is all the
/// notice/status lanes need.
fn js_err<E: std::fmt::Debug>(error: E) -> String {
    format!("{error:?}")
}

/// Rigid inverse `[Rᵀ | −Rᵀ·t]` of a component pose — used to express a picked
/// WORLD point in COMPONENT-LOCAL coordinates (the vertex-ref contract).
fn rigid_inverse_point(transform: &brep_kernel::AffineTransform, world: [f64; 3]) -> [f64; 3] {
    let m = &transform.elements;
    let d = [world[0] - m[3], world[1] - m[7], world[2] - m[11]];
    [
        m[0] * d[0] + m[4] * d[1] + m[8] * d[2],
        m[1] * d[0] + m[5] * d[1] + m[9] * d[2],
        m[2] * d[0] + m[6] * d[1] + m[10] * d[2],
    ]
}

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

    /// Whether the current document is an ASSEMBLY document: any ACOMP-typed
    /// feature, or a present `assembly` constraint block. Componentless
    /// documents skip every main-side sync (zero cost for modeling files).
    pub fn history_has_assembly(&self) -> bool {
        let has_acomp = (0..self.history.len()).any(|index| {
            matches!(
                self.history.feature_type(index).as_deref(),
                Some("ACOMP") | Some("ASSEMBLY COMPONENT")
            )
        });
        has_acomp
            || self
                .history
                .assembly_block()
                .map(|block| !block.is_null())
                .unwrap_or(false)
    }

    /// The scene's component records (deterministic id order) as of the last
    /// [`sync_assembly`] — the Assembly Structure tree's projection source.
    /// A VIEW over the scene, never an owning structure.
    pub fn assembly_components(&self) -> &[brep_kernel::ComponentRecord] {
        &self.assembly_components
    }

    /// Make sure the main-side assembly session + component projection are
    /// current with the last APPLIED display run. Cheap no-op when already
    /// synced (or for componentless documents). Panels call this at frame
    /// start; the post-run tail (`finish_apply`) also syncs eagerly.
    pub fn ensure_assembly_synced(&mut self) {
        if self.assembly_synced_generation == Some(self.applied_generation) {
            return;
        }
        self.sync_assembly();
    }

    /// The per-constraint status rows (`[{id, type, enabled, open, status,
    /// message, satisfied, error}]`) from the main-side session.
    pub fn assembly_statuses_value(&mut self) -> Value {
        self.ensure_assembly_synced();
        serde_json::from_str(&brep_kernel::assembly_statuses_json())
            .unwrap_or_else(|_| Value::Array(Vec::new()))
    }

    /// The current `assembly` block (post-solve): `{constraints, idCounter}`.
    pub fn assembly_state_value(&mut self) -> Value {
        self.ensure_assembly_synced();
        serde_json::from_str(&brep_kernel::assembly_state_json()).unwrap_or(Value::Null)
    }

    /// The last solve's DOF/diagnostics summary (`{ok, dof, rank, redundant,
    /// …}` — `movedSolids` may be absent; tolerate it).
    pub fn assembly_dof_value(&mut self) -> Value {
        self.ensure_assembly_synced();
        serde_json::from_str(&brep_kernel::assembly_dof_json()).unwrap_or(Value::Null)
    }

    /// Per-constraint overlay rows (world anchors/directions/status/value) —
    /// the constraints panel reads the evaluated value/unit for the
    /// distance/angle label suffix; lane G's viewport graphics read the rest.
    pub fn assembly_overlay_value(&mut self) -> Value {
        self.ensure_assembly_synced();
        serde_json::from_str(&brep_kernel::assembly_overlay_json())
            .unwrap_or_else(|_| Value::Array(Vec::new()))
    }

    /// The parts-library entry names currently resident (insert-flow "existing
    /// entries first" list). Main-side store — seeded by document ingest on
    /// sync and grown by [`insert_component`].
    pub fn parts_library_names(&mut self) -> Vec<String> {
        if self.history_has_assembly() {
            self.ensure_assembly_synced();
        }
        serde_json::from_str::<Value>(&brep_kernel::parts_library_json())
            .ok()
            .and_then(|value| {
                value
                    .as_object()
                    .map(|map| map.keys().cloned().collect::<Vec<_>>())
            })
            .unwrap_or_default()
    }

    // --- the sync + fold (pose-authority contract) --------------------------

    /// Re-execute the rolled-to history MAIN-SIDE (warm-cache replay), fold
    /// the resulting ComponentRecords into [`Self::assembly_components`], fold
    /// the post-solve session state + poses back into the document (silent
    /// adopt — solver write-back is not a user edit), and refresh the
    /// document's `partsLibrary` block from the kernel store (post-GC; SAVE
    /// must serialize the store, never echo a loaded block). Componentless
    /// documents just clear the projection.
    pub(crate) fn sync_assembly(&mut self) {
        if !self.history_has_assembly() {
            self.assembly_components.clear();
            // No ACOMP references left ⇒ any partsLibrary block is orphaned
            // payload (the kernel GCs the store the same way at the end of
            // every run) — drop it so deleting the last instance never leaves
            // a dangling entry in the saved document.
            self.history
                .set_parts_library(Value::Object(serde_json::Map::new()));
            self.assembly_synced_generation = Some(self.applied_generation);
            return;
        }
        let request: brep_kernel::HistoryRequest =
            match serde_json::from_value(self.history.prefix_request()) {
                Ok(request) => request,
                Err(_) => return, // unparseable mid-edit document — retry next frame
            };
        let result = brep_kernel::execute_history(&request);

        // Fold the per-feature component side-channel exactly like
        // SceneMap::apply: removals unmap by id, additions insert in order
        // (BTreeMap ⇒ deterministic id order for the tree/BOM).
        let mut components: std::collections::BTreeMap<String, brep_kernel::ComponentRecord> =
            std::collections::BTreeMap::new();
        for feature in &result.results {
            for removed in &feature.removed {
                components.remove(removed);
            }
            for record in &feature.components {
                components.insert(record.id.clone(), record.clone());
            }
        }
        self.assembly_components = components.into_values().collect();

        // Fold the session (solved constraint state + poses/isFixed) into the
        // document — the pose-authority write-back, silent (not a user edit).
        self.apply_assembly_fold(false);

        // SAVE-side contract: the document's partsLibrary block mirrors the
        // kernel store (heals + GC included). Fingerprint-neutral: snapshots
        // are excluded from the ACOMP content hash.
        // Read the revision AFTER the run above: its ACOMP self-heal and orphan
        // GC are library mutations, and they bump it. Serializing the store
        // costs the whole embedded part payload, so do it only when the library
        // actually moved — in the steady state (edit, roll, re-solve) it does
        // not, and this is a single integer compare.
        let revision = brep_kernel::parts_library_revision();
        if self.parts_library_block_revision != Some(revision)
            || !self.history.parts_library_mirrors_store()
        {
            if let Ok(library) = serde_json::from_str::<Value>(&brep_kernel::parts_library_json()) {
                self.history.set_parts_library(library);
                self.parts_library_block_revision = Some(revision);
            }
        }
        self.assembly_synced_generation = Some(self.applied_generation);
    }

    /// Run the document fold: `assembly_apply_document_json(document)` →
    /// adopt the returned document (assembly block replaced; solved poses +
    /// isFixed folded into features by `inputParams.id`). `checkpoint` = true
    /// for USER mutations (undoable), false for the silent post-run fold.
    /// A missing session (no run yet) is tolerated silently.
    fn apply_assembly_fold(&mut self, checkpoint: bool) {
        // The fold only rewrites the `assembly` block and per-feature
        // `inputParams` — it never reads `partsLibrary` — so hand it the
        // document WITHOUT the library. Otherwise every edit serialized,
        // parsed and re-serialized the whole embedded part payload three times
        // over for nothing. `adopt_document` keeps the field when the adopted
        // document carries no block, so the library survives the round trip.
        let document = self.history.request_json_without_parts_library();
        match brep_kernel::assembly_apply_document_json(&document) {
            Ok(folded) => {
                let adopted = if checkpoint {
                    self.history.adopt_document_checkpointed(&folded)
                } else {
                    self.history.adopt_document(&folded)
                };
                if let Err(error) = adopted {
                    self.push_notice(format!("assembly fold failed: {error}"));
                }
            }
            Err(_) => {} // no session yet (fresh document before its first run)
        }
    }

    /// Shared tail of every USER constraint mutation: fold (checkpointed) and,
    /// when auto-solve is on, re-run the display history so the viewport
    /// re-poses (changed ACOMP transforms dirty their fingerprints → those
    /// instances re-execute + re-tessellate; the runner's tail re-solves).
    fn after_constraint_mutation(&mut self) {
        self.apply_assembly_fold(true);
        if self.settings.assembly_auto_solve {
            self.rerun_history();
        } else {
            self.dirty = true;
        }
    }

    // --- constraint mutations (kernel ABI + fold + optional rerun) ----------

    /// Add a constraint (`params_json` = inputParams; the kernel mints the id
    /// from the type's short name when absent). Returns the minted id.
    pub fn assembly_add_constraint(
        &mut self,
        constraint_type: &str,
        params_json: &str,
    ) -> Result<String, String> {
        self.ensure_assembly_synced();
        let reply =
            brep_kernel::assembly_add_constraint_json(constraint_type, params_json).map_err(js_err)?;
        self.after_constraint_mutation();
        let id = serde_json::from_str::<Value>(&reply)
            .ok()
            .and_then(|value| value.get("id").and_then(|id| id.as_str()).map(String::from))
            .unwrap_or_default();
        Ok(id)
    }

    /// Replace a constraint's `inputParams` (the dialog commit).
    pub fn assembly_update_constraint(&mut self, id: &str, params_json: &str) -> Result<(), String> {
        self.ensure_assembly_synced();
        brep_kernel::assembly_update_constraint_json(id, params_json).map_err(js_err)?;
        self.after_constraint_mutation();
        Ok(())
    }

    /// Update WITHOUT the rerun tail — for callers whose own continuation
    /// re-runs anyway (the ref-select Finish, whose `end_ref_select` reruns).
    /// Still folds (checkpointed) so the document is current before that run.
    pub(crate) fn assembly_update_constraint_no_rerun(
        &mut self,
        id: &str,
        params_json: &str,
    ) -> Result<(), String> {
        self.ensure_assembly_synced();
        brep_kernel::assembly_update_constraint_json(id, params_json).map_err(js_err)?;
        self.apply_assembly_fold(true);
        Ok(())
    }

    /// Delete a constraint.
    pub fn assembly_remove_constraint(&mut self, id: &str) -> Result<(), String> {
        self.ensure_assembly_synced();
        brep_kernel::assembly_remove_constraint_json(id).map_err(js_err)?;
        self.after_constraint_mutation();
        Ok(())
    }

    /// Enable/disable a constraint (the row checkbox).
    pub fn assembly_set_constraint_enabled(&mut self, id: &str, enabled: bool) -> Result<(), String> {
        self.ensure_assembly_synced();
        brep_kernel::assembly_set_constraint_enabled_json(id, enabled).map_err(js_err)?;
        self.after_constraint_mutation();
        Ok(())
    }

    /// Persist WHICH constraint has its dialog open (view state — SILENT fold,
    /// no solve, no rerun, no undo entry). ACCORDION: at most ONE constraint is
    /// open — opening one first closes every other inside the same silent fold,
    /// so the panel toggle, the context bar's add-from-selection, and a viewport
    /// label click all converge on a single open constraint. The constraints
    /// PANEL reads this flag as its mode: open one and its form replaces the
    /// tree (`panels::assembly_constraints`), which is why every one of those
    /// surfaces opens the dialog without knowing the panel exists.
    pub fn assembly_set_constraint_open(&mut self, id: &str, open: bool) -> Result<(), String> {
        self.ensure_assembly_synced();
        if open {
            let others: Vec<String> =
                serde_json::from_str::<Value>(&brep_kernel::assembly_state_json())
                    .ok()
                    .and_then(|state| {
                        state.get("constraints").and_then(|l| l.as_array()).map(|entries| {
                            entries
                                .iter()
                                .filter_map(|entry| {
                                    let cid =
                                        entry.get("inputParams")?.get("id")?.as_str()?;
                                    let is_open =
                                        entry.get("open").and_then(|v| v.as_bool()).unwrap_or(false);
                                    (is_open && cid != id).then(|| cid.to_string())
                                })
                                .collect()
                        })
                    })
                    .unwrap_or_default();
            for other in others {
                brep_kernel::assembly_set_constraint_open_json(&other, false).map_err(js_err)?;
            }
        }
        brep_kernel::assembly_set_constraint_open_json(id, open).map_err(js_err)?;
        self.apply_assembly_fold(false);
        Ok(())
    }

    /// Reorder a constraint to `index` (drag-reorder).
    pub fn assembly_move_constraint(&mut self, id: &str, index: usize) -> Result<(), String> {
        self.ensure_assembly_synced();
        brep_kernel::assembly_move_constraint_json(id, index).map_err(js_err)?;
        self.after_constraint_mutation();
        Ok(())
    }

    /// Manual solve (the panel's Solve button): solve the session, fold, and
    /// ALWAYS re-run the display (that is the point of pressing Solve — it
    /// works with auto-solve disabled).
    pub fn assembly_run_solve(&mut self) -> Result<(), String> {
        self.ensure_assembly_synced();
        // Nothing to solve without components — bail BEFORE the kernel solve.
        // With no assembly session the kernel's solve/fold error paths build a
        // `JsValue`, and wasm-bindgen's `JsValue` is unimplemented on native
        // targets: the construction panics ("function not implemented on
        // non-wasm32 targets") in a nounwind context and ABORTS the desktop
        // app. An empty assembly solving to a no-op is also the correct result.
        if self.assembly_components().is_empty() {
            return Ok(());
        }
        brep_kernel::assembly_run_solve_json().map_err(js_err)?;
        self.apply_assembly_fold(true);
        self.rerun_history();
        Ok(())
    }

    // --- component actions (route to the owning ACOMP feature) --------------

    /// Insert a component instance (the palette/insert flow): resolve the
    /// parts-library entry (add or reuse), refresh the document's
    /// `partsLibrary` block, append an ACOMP feature referencing the RETURNED
    /// effective part name with an identity transform, and re-run. The FIRST
    /// component of the document writes `isFixed: true` EXPLICITLY (dialog-
    /// visible); later instances write `false`. Returns the new feature id
    /// (`ACOMP<digits>` — the history's global counter mints that exact form).
    pub fn insert_component(&mut self, insert: ComponentInsert<'_>) -> Result<String, String> {
        let part_name = match insert {
            ComponentInsert::Existing { part_name } => part_name.to_string(),
            ComponentInsert::New {
                name,
                source_key,
                source_signature,
                document_json,
            } => brep_kernel::add_part_to_library(name, source_key, source_signature, document_json)
                .map_err(js_err)?,
        };
        // The block must ride the request so the display runner ingests the
        // (new) entry on the very next run.
        if let Ok(library) = serde_json::from_str::<Value>(&brep_kernel::parts_library_json()) {
            self.history.set_parts_library(library);
        }
        let first = !(0..self.history.len()).any(|index| {
            matches!(
                self.history.feature_type(index).as_deref(),
                Some("ACOMP") | Some("ASSEMBLY COMPONENT")
            )
        });
        let id = self.history.next_feature_id("ACOMP");
        let feature = serde_json::json!({
            "type": "ACOMP",
            "inputParams": {
                "id": id,
                "partName": part_name,
                "transform": { "translate": [0, 0, 0], "rotateEulerDeg": [0, 0, 0] },
                "isFixed": first,
            },
            "persistentData": {}
        });
        self.add_feature(&feature.to_string())?;
        Ok(id)
    }

    /// Fix/Unfix a component: toggles the OWNING ACOMP feature's
    /// `inputParams.isFixed` (one truth, one undo lane) and re-runs.
    pub fn set_component_fixed(&mut self, component_id: &str, fixed: bool) -> Result<(), String> {
        let index = self
            .history
            .index_of(component_id)
            .ok_or_else(|| format!("no component feature '{component_id}'"))?;
        let mut params = self
            .history
            .feature_params(index)
            .unwrap_or_else(|| serde_json::json!({}));
        if let Some(map) = params.as_object_mut() {
            map.insert("isFixed".into(), Value::Bool(fixed));
        } else {
            return Err(format!("component '{component_id}': malformed inputParams"));
        }
        self.update_feature_params(component_id, &params.to_string())?;
        Ok(())
    }

    /// Select a component in the viewport: emphasis over exactly its member
    /// solids (the tree↔viewport sync lane; a viewport pick of any member
    /// lights the tree row through the same emphasis set).
    pub fn select_component(&mut self, component_id: &str) {
        self.select_components(&[component_id.to_string()]);
    }

    /// A component's member SOLID scene names (empty for an unknown id) — the
    /// selection/hover unit COMPONENT entries resolve to.
    pub fn component_member_solids(&self, component_id: &str) -> Vec<String> {
        self.assembly_components
            .iter()
            .filter(|record| record.id == component_id)
            .flat_map(|record| record.solids.iter().cloned())
            .collect()
    }

    /// TOGGLE a component in the current selection as ONE unit (the additive
    /// Ctrl/Cmd+click under COMPONENT promotion): when EVERY member solid is
    /// already selected the whole set deselects, otherwise the whole set joins
    /// the selection — the rest of the selection stays.
    pub fn toggle_component_selection(&mut self, component_id: &str) {
        let members = self.component_member_solids(component_id);
        if members.is_empty() {
            return;
        }
        let all_selected = members
            .iter()
            .all(|name| self.emphasis.selected_solids.contains(name));
        for name in members {
            if all_selected {
                self.emphasis.selected_solids.remove(&name);
            } else {
                self.emphasis.selected_solids.insert(name);
            }
        }
        self.emphasis.generation = self.emphasis.generation.wrapping_add(1);
        self.dirty = true;
    }

    /// Select SEVERAL components at once: emphasis over the union of their
    /// member solids (the interference window's row click highlights both
    /// participants of a pair through this).
    pub fn select_components(&mut self, component_ids: &[String]) {
        let members: Vec<String> = self
            .assembly_components
            .iter()
            .filter(|record| component_ids.iter().any(|id| id == &record.id))
            .flat_map(|record| record.solids.iter().cloned())
            .collect();
        let json = serde_json::json!({ "selected": { "solids": members } }).to_string();
        let _ = self.emphasis.apply_json(&json);
        self.dirty = true;
    }

    // --- constraint reference selection (the ref-select reuse) --------------

    /// Enter the modal reference picker for an ASSEMBLY CONSTRAINT's
    /// `elements`-style field (same widget, different commit target — Finish
    /// routes through [`Self::assembly_update_constraint_no_rerun`] instead of
    /// feature params). No roll-to-before: constraints pick against the FULL
    /// assembly.
    pub fn begin_ref_select_for_constraint(
        &mut self,
        constraint_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: constraint_id.to_string(),
            path,
            label,
            filter,
            multiple,
            names: seed_names,
            restore_index,
            target: RefSelectTarget::AssemblyConstraint,
        });
        self.sync_ref_select_emphasis();
    }

    /// Commit a finished constraint ref-select: read the constraint's params
    /// from the session state, write the picked names at the field path, and
    /// update (fold only — the caller's continuation reruns).
    pub(crate) fn assembly_commit_constraint_refs(
        &mut self,
        constraint_id: &str,
        path: &[String],
        names: &[String],
        multiple: bool,
    ) {
        let state = self.assembly_state_value();
        let Some(entry) = state
            .get("constraints")
            .and_then(Value::as_array)
            .and_then(|constraints| {
                constraints.iter().find(|entry| {
                    entry
                        .get("inputParams")
                        .and_then(|params| params.get("id"))
                        .and_then(Value::as_str)
                        == Some(constraint_id)
                })
            })
        else {
            self.push_notice(format!("unknown constraint '{constraint_id}'"));
            return;
        };
        let mut params = entry
            .get("inputParams")
            .cloned()
            .unwrap_or_else(|| serde_json::json!({}));
        let value = if multiple {
            Value::Array(names.iter().cloned().map(Value::String).collect())
        } else {
            Value::String(names.first().cloned().unwrap_or_default())
        };
        super::selection_ux::set_json_at(&mut params, path, value);
        if let Err(error) = self.assembly_update_constraint_no_rerun(constraint_id, &params.to_string())
        {
            self.push_notice(format!("constraint update failed: {error}"));
        }
    }

    /// Build the `{solidName}@x,y,z` COMPONENT-LOCAL vertex ref for a vertex
    /// pick on a component member (lane-E contract: world pick transformed by
    /// the owning component's inverse pose). `None` when the solid belongs to
    /// no component (vertex refs only exist for constraint selection).
    pub(crate) fn component_vertex_ref(
        &self,
        solid_name: &str,
        world_position: [f64; 3],
    ) -> Option<String> {
        let record = self.assembly_components.iter().find(|record| {
            record.solids.iter().any(|member| member == solid_name)
        })?;
        let local = rigid_inverse_point(&record.transform, world_position);
        Some(format!(
            "{solid_name}@{},{},{}",
            local[0], local[1], local[2]
        ))
    }
}

// ===========================================================================
// Tests — the insert-flow seam, the component projection, the constraint
// lifecycle through the fold, and the vertex-ref builder. All run under the
// synchronous InlineRunner (runner + main share this thread's kernel state,
// exactly like the wasm single-instance case behaves per call).
// ===========================================================================
#[cfg(test)]
mod tests {
    use super::*;

    /// A one-cube part document (the sub-part payload the insert flow embeds).
    fn part_document() -> String {
        serde_json::json!({
            "expressions": "",
            "configurator": {},
            "features": [{
                "type": "P.CU",
                "inputParams": {
                    "id": "Part",
                    "sizeX": 2.0, "sizeY": 3.0, "sizeZ": 4.0,
                    "transform": {
                        "position": [0.0, 0.0, 0.0],
                        "rotationEuler": [0.0, 0.0, 0.0],
                        "scale": [1.0, 1.0, 1.0]
                    },
                    "boolean": { "targets": [], "operation": "NONE" }
                },
                "persistentData": {}
            }]
        })
        .to_string()
    }

    fn fresh_state() -> EngineState {
        brep_kernel::clear_history_cache();
        EngineState::new()
    }

    /// Regression: hitting Solve with NO assembly components must not panic —
    /// an empty assembly must solve to a no-op, not crash the app.
    #[test]
    fn solve_with_no_components_does_not_panic() {
        let mut state = fresh_state();
        let _ = state.assembly_run_solve();
    }

    /// The ONE signature fn is stable across key order (the sorted-key walk)
    /// and sensitive to content — the two properties the `sourceSignature`
    /// up-to-date comparison rests on.
    #[test]
    fn document_signature_is_stable_and_content_sensitive() {
        let a = r#"{"features":[{"type":"P.CU","inputParams":{"id":"Part","sizeX":10}}]}"#;
        // Key order must not matter (stable sorted-key walk)…
        let a_reordered = r#"{"features":[{"inputParams":{"sizeX":10,"id":"Part"},"type":"P.CU"}]}"#;
        // …but content must.
        let b = r#"{"features":[{"type":"P.CU","inputParams":{"id":"Part","sizeX":14}}]}"#;
        assert_eq!(document_signature(a), document_signature(a));
        assert_eq!(document_signature(a), document_signature(a_reordered));
        assert_ne!(document_signature(a), document_signature(b));
    }

    /// THE INSERT SEAM: `add_part_to_library`'s RETURNED effective name lands
    /// in the ACOMP's `inputParams.partName`; the FIRST instance writes
    /// `isFixed: true` explicitly (dialog-visible), later ones `false`; one
    /// library entry backs N instances; the id counter mints `ACOMP<digits>`.
    #[test]
    fn insert_component_seeds_partname_and_first_instance_fixed() {
        let mut state = fresh_state();
        let document = part_document();

        let id1 = state
            .insert_component(ComponentInsert::New {
                name: "bracket",
                source_key: "bracket",
                source_signature: "sig-1",
                document_json: &document,
            })
            .expect("first insert");
        assert_eq!(id1, "ACOMP1", "the counter mints the ACOMP<digits> form");
        let params = state
            .history
            .feature_params(state.history.index_of(&id1).unwrap())
            .unwrap();
        assert_eq!(params["partName"], "bracket");
        assert_eq!(params["isFixed"], true, "first instance is EXPLICITLY fixed");
        assert_eq!(params["transform"]["translate"], serde_json::json!([0, 0, 0]));

        // Second instance from the EXISTING entry — no store read, not fixed.
        let id2 = state
            .insert_component(ComponentInsert::Existing { part_name: "bracket" })
            .expect("second insert");
        assert_eq!(id2, "ACOMP2");
        let params2 = state
            .history
            .feature_params(state.history.index_of(&id2).unwrap())
            .unwrap();
        assert_eq!(params2["partName"], "bracket");
        assert_eq!(params2["isFixed"], false);

        // ONE library entry backs both instances, and the document's
        // partsLibrary block mirrors the store (the SAVE contract).
        assert_eq!(state.parts_library_names(), vec!["bracket".to_string()]);
        let document_value: Value =
            serde_json::from_str(&state.history.request_json()).unwrap();
        assert!(
            document_value["partsLibrary"]["bracket"].is_object(),
            "the request document carries the library block for the runner/save"
        );

        // Re-inserting the SAME content under a different requested name
        // dedups by sourceKey+signature to the existing entry name.
        let id3 = state
            .insert_component(ComponentInsert::New {
                name: "bracket-again",
                source_key: "bracket",
                source_signature: "sig-1",
                document_json: &document,
            })
            .expect("dedup insert");
        let params3 = state
            .history
            .feature_params(state.history.index_of(&id3).unwrap())
            .unwrap();
        assert_eq!(params3["partName"], "bracket", "dedup returns the EXISTING entry name");
        assert_eq!(state.parts_library_names(), vec!["bracket".to_string()]);
    }

    /// The COMPONENT PROJECTION: two instances surface as two ComponentRecords
    /// (deterministic id order, part name + fixed flag + namespaced members),
    /// and deleting instances GCs the library entry when the LAST one goes.
    #[test]
    fn component_projection_and_library_gc_on_last_delete() {
        let mut state = fresh_state();
        let document = part_document();
        state
            .insert_component(ComponentInsert::New {
                name: "bracket",
                source_key: "bracket",
                source_signature: "sig-1",
                document_json: &document,
            })
            .unwrap();
        state
            .insert_component(ComponentInsert::Existing { part_name: "bracket" })
            .unwrap();

        let components = state.assembly_components();
        assert_eq!(components.len(), 2);
        assert_eq!(components[0].id, "ACOMP1");
        assert_eq!(components[1].id, "ACOMP2");
        assert_eq!(components[0].part_name, "bracket");
        assert!(components[0].fixed, "first instance grounded");
        assert!(!components[1].fixed);
        assert_eq!(components[0].solids, vec!["ACOMP1:Part".to_string()]);
        assert_eq!(components[1].solids, vec!["ACOMP2:Part".to_string()]);
        // The members are real display solids.
        assert!(state.scene.solid("ACOMP1:Part").is_some());
        assert!(state.scene.solid("ACOMP2:Part").is_some());

        // Delete one instance: the library entry SURVIVES (one instance left).
        state.delete_feature("ACOMP2");
        assert_eq!(state.assembly_components().len(), 1);
        assert_eq!(state.parts_library_names(), vec!["bracket".to_string()]);

        // Delete the last instance: the entry GCs and the document's
        // partsLibrary block is dropped (no orphaned payload in the file).
        state.delete_feature("ACOMP1");
        assert!(state.assembly_components().is_empty());
        assert!(state.parts_library_names().is_empty(), "orphan entry GC'd");
        let document_value: Value =
            serde_json::from_str(&state.history.request_json()).unwrap();
        assert!(
            document_value.get("partsLibrary").is_none(),
            "no dangling partsLibrary block after the last instance"
        );
    }

    /// Fix/Unfix routes to the OWNING feature's `inputParams.isFixed` and the
    /// re-run reflects it in the projection (one truth, one undo lane).
    #[test]
    fn set_component_fixed_routes_to_the_feature_and_reruns() {
        let mut state = fresh_state();
        state
            .insert_component(ComponentInsert::New {
                name: "bracket",
                source_key: "bracket",
                source_signature: "sig-1",
                document_json: &part_document(),
            })
            .unwrap();
        assert!(state.assembly_components()[0].fixed);

        state.set_component_fixed("ACOMP1", false).expect("unfix");
        let params = state
            .history
            .feature_params(state.history.index_of("ACOMP1").unwrap())
            .unwrap();
        assert_eq!(params["isFixed"], false, "the FEATURE param is the truth");
        assert!(
            !state.assembly_components()[0].fixed,
            "the projection follows after the re-run"
        );
        // Undoable like any model edit.
        state.undo();
        assert!(state.assembly_components()[0].fixed, "undo restores the flag");
    }

    /// Constraint lifecycle through the engine surface: add mints the id from
    /// the type's short name, the fold persists the block into the DOCUMENT,
    /// enable/disable + reorder round-trip, and a mutation is undoable.
    #[test]
    fn constraint_add_toggle_reorder_fold_and_undo() {
        let mut state = fresh_state();
        let document = part_document();
        state
            .insert_component(ComponentInsert::New {
                name: "bracket",
                source_key: "bracket",
                source_signature: "sig-1",
                document_json: &document,
            })
            .unwrap();
        state
            .insert_component(ComponentInsert::Existing { part_name: "bracket" })
            .unwrap();

        // Add: the kernel mints `{SHORT}{counter}`.
        let fixed_id = state
            .assembly_add_constraint(
                "fixed",
                &serde_json::json!({ "elements": ["ACOMP2"] }).to_string(),
            )
            .expect("add fixed");
        assert_eq!(fixed_id, "FIXD1");

        // The FOLD persisted the block into the document (pose-authority
        // contract: adopt BEFORE persisting or re-running).
        let document_value: Value =
            serde_json::from_str(&state.history.request_json()).unwrap();
        assert_eq!(document_value["assembly"]["constraints"][0]["type"], "fixed");
        assert_eq!(
            document_value["assembly"]["constraints"][0]["inputParams"]["id"],
            "FIXD1"
        );

        // Status rows come from the (re-run) session.
        let rows = state.assembly_statuses_value();
        assert_eq!(rows[0]["id"], "FIXD1");
        assert_eq!(rows[0]["enabled"], true);

        // Disable → status "disabled" after the auto-solve.
        state
            .assembly_set_constraint_enabled(&fixed_id, false)
            .expect("disable");
        let rows = state.assembly_statuses_value();
        assert_eq!(rows[0]["enabled"], false);
        assert_eq!(rows[0]["status"], "disabled");

        // A second constraint + reorder to the front.
        let second = state
            .assembly_add_constraint("parallel", "{}")
            .expect("add parallel");
        assert_eq!(second, "PARA2", "the id counter is shared and monotonic");
        state.assembly_move_constraint(&second, 0).expect("reorder");
        let rows = state.assembly_statuses_value();
        assert_eq!(rows[0]["id"], "PARA2");
        assert_eq!(rows[1]["id"], "FIXD1");

        // The reorder was checkpointed: ONE undo restores the old order.
        state.undo();
        let rows = state.assembly_statuses_value();
        assert_eq!(rows[0]["id"], "FIXD1");
        assert_eq!(rows[1]["id"], "PARA2");
    }

    /// The CONSTRAINT flavor of the reference picker commits the picked names
    /// into the constraint's `inputParams.elements` (through the update lane +
    /// fold), not into any feature — the RefSelectTarget routing.
    #[test]
    fn constraint_ref_select_commits_elements_to_the_constraint() {
        let mut state = fresh_state();
        let document = part_document();
        state
            .insert_component(ComponentInsert::New {
                name: "bracket",
                source_key: "bracket",
                source_signature: "sig-1",
                document_json: &document,
            })
            .unwrap();
        state
            .insert_component(ComponentInsert::Existing { part_name: "bracket" })
            .unwrap();
        let id = state.assembly_add_constraint("parallel", "{}").unwrap();

        state.begin_ref_select_for_constraint(
            &id,
            vec!["elements".into()],
            "Elements".into(),
            vec!["FACE".into(), "EDGE".into()],
            true,
            Vec::new(),
        );
        assert!(state.ref_select_active());
        // Simulate two viewport picks (the click path needs a camera; the
        // running name list is the picker's single source of truth).
        state.ref_select.as_mut().unwrap().names =
            vec!["ACOMP1:Part_PZ".to_string(), "ACOMP2:Part_NZ".to_string()];
        state.finish_ref_select();
        assert!(!state.ref_select_active(), "finish exits the modal");

        // The elements landed on the CONSTRAINT (session + document fold).
        let constraint_state = state.assembly_state_value();
        assert_eq!(
            constraint_state["constraints"][0]["inputParams"]["elements"],
            serde_json::json!(["ACOMP1:Part_PZ", "ACOMP2:Part_NZ"])
        );
        let document_value: Value =
            serde_json::from_str(&state.history.request_json()).unwrap();
        assert_eq!(
            document_value["assembly"]["constraints"][0]["inputParams"]["elements"],
            serde_json::json!(["ACOMP1:Part_PZ", "ACOMP2:Part_NZ"]),
            "the fold persisted the committed refs into the document"
        );
    }

    /// The vertex-ref builder: a world pick on a POSED component member maps
    /// through the component's inverse pose into the `{solid}@x,y,z`
    /// COMPONENT-LOCAL form; non-component solids yield none.
    #[test]
    fn component_vertex_ref_is_component_local() {
        let mut state = fresh_state();
        state
            .insert_component(ComponentInsert::New {
                name: "bracket",
                source_key: "bracket",
                source_signature: "sig-1",
                document_json: &part_document(),
            })
            .unwrap();
        // Move the instance to (10, 0, 0) through its feature transform.
        let mut params = state
            .history
            .feature_params(state.history.index_of("ACOMP1").unwrap())
            .unwrap();
        params["transform"]["translate"] = serde_json::json!([10.0, 0.0, 0.0]);
        state
            .update_feature_params("ACOMP1", &params.to_string())
            .unwrap();

        // The part-local corner (2,3,4) sits at world (12,3,4); the ref must
        // carry the LOCAL coordinates.
        let vertex_ref = state
            .component_vertex_ref("ACOMP1:Part", [12.0, 3.0, 4.0])
            .expect("component member yields a ref");
        assert_eq!(vertex_ref, "ACOMP1:Part@2,3,4");
        assert!(
            state.component_vertex_ref("Loose", [0.0; 3]).is_none(),
            "non-component solids build no vertex ref"
        );
    }
}