Wall Phase 3 milestone A: registry skeleton (metadata only)

Lays down the wall folder under @pascal-app/nodes with everything needed
to register the kind, but intentionally without runtime wiring:

- schema.ts re-exports WallNode from core (door/window/item still type
  their parentId against WallNode.shape.id, so the schema stays canonical
  there for now).
- parametrics.ts declares thickness / height / curveOffset for the Phase 4
  inspector. Endpoints and host children are edited via affordances, not
  number inputs, so they're not in parametrics.
- definition.ts encodes capabilities (surfaces, selectable, duplicable,
  deletable — no movable since wall's move is bespoke endpoint-drag),
  relations (hosts doors/windows/items, affectsSpatial slabs/ceilings/
  zones, linkedBy endpoint-match, cascadeDelete descendants), and the
  presentation metadata for the palette. Renderer / system / tool fields
  are deliberately absent — the existing wall-renderer.tsx and
  wall-system.tsx keep serving wall until milestone B.
- feature-flag.ts gates the eventual registration via
  NEXT_PUBLIC_USE_REGISTRY_FOR_WALL (same pattern Phase 2 used for spawn).
- wallDefinition is NOT yet appended to builtinPlugin.nodes — registration
  is what flips the Phase 0 dispatch shims, and we don't want that until
  the runtime port lands. Until then this file is metadata-only.

Two type-side changes pulled forward from Phase 4 to make a metadata-only
definition compile:

- NodeDefinition.renderer becomes optional (the three-checkbox model
  documented in wiki/architecture/node-definitions.md already promises
  this). RegistryRenderer in node-renderer.tsx gains a null-guard so an
  undefined renderer cleanly falls through to the legacy switch.

No runtime behavior change. Walls render and behave exactly as before.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

packages/nodes/src/wall/definition.ts

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+import type { NodeDefinition } from '@pascal-app/core'
+import { wallParametrics } from './parametrics'
+import { WallNode } from './schema'
+
+/**
+ * Wall — the Phase 3 stress test of the registry-driven node model.
+ *
+ * What this definition encodes today:
+ *  - **Capabilities**: cuttable (doors/windows punch holes), snappable
+ *    (other walls, doors, windows snap to wall geometry), surfaces (front
+ *    + back faces host items), selectable, duplicable, deletable.
+ *  - **Relations**: hosts doors/windows/items; affects spatial slabs +
+ *    ceilings + zones when moved; descendants cascade-delete; linked walls
+ *    follow corners via endpoint-match (consumed by the affordances in a
+ *    later milestone — the relations resolver already understands the
+ *    declaration).
+ *  - **Parametrics**: thickness / height / curveOffset for the inspector.
+ *
+ * What this definition does *not* yet encode:
+ *  - `geometry` / `renderer` / `system` runtime — the existing
+ *    `wall-renderer.tsx` + `wall-system.tsx` keep serving wall until
+ *    Milestone B ports them into this folder. Until then, this definition
+ *    is metadata-only and *intentionally not registered* in
+ *    `builtinPlugin.nodes` — the Phase 0 shims only flip behavior when a
+ *    kind is registered, so wall stays on its legacy path.
+ *  - `tool` — wall's placement + endpoint drag + curve drag tools port in
+ *    a follow-up milestone, expressed via the `DragAction` primitive so
+ *    the affordances declared in `relations` get real handles.
+ *
+ * Migration is gated by `feature-flag.ts` (env: `NEXT_PUBLIC_USE_REGISTRY_FOR_WALL`).
+ * See `plans/editor-node-registry.md#phase-3` for the milestone breakdown.
+ */
+export const wallDefinition: NodeDefinition<typeof WallNode> = {
+  kind: 'wall',
+  schemaVersion: 1,
+  schema: WallNode,
+  category: 'structure',
+
+  defaults: () => ({
+    object: 'node',
+    parentId: null,
+    visible: true,
+    metadata: {},
+    children: [],
+    start: [0, 0],
+    end: [3, 0],
+    frontSide: 'unknown',
+    backSide: 'unknown',
+  }),
+
+  capabilities: {
+    // Wall move is bespoke today (endpoint drag, linked-wall corner cascade,
+    // ALT-detach). `MoveRegistryNodeTool`'s "translate on X/Z plane" shape
+    // doesn't apply — wall stays on its own move tool until the affordance
+    // port. Leaving `movable` omitted keeps that dispatch.
+    selectable: { hitVolume: 'bbox' },
+    // Front + back faces host items (paintings, shelves, switches).
+    // `height` callback resolves per-instance so taller walls expose taller
+    // hosting surface — same shape used by shelf.top.
+    surfaces: {
+      // Sides config — wall has two faces; concrete face-selection logic
+      // stays in the renderer/system for now. Phase 4 will derive snap
+      // targets from this.
+      sides: { faces: 'all' },
+    },
+    duplicable: true,
+    deletable: true,
+  },
+
+  relations: {
+    // Doors / windows / items mount on walls. The host-resolver consumes
+    // this to validate `parentId` on creation and to re-anchor children
+    // when a wall moves (a milestone-B concern; the declaration lives here
+    // so the wiring exists ahead of time).
+    hosts: ['door', 'window', 'item'],
+    // Moving a wall dirties the slabs / ceilings / zones that border it.
+    // Today this is *not* wired (the existing `wall-system` doesn't cascade
+    // to slab / zone) — the registry resolver gains this behavior for free
+    // once wall is registered. This is the "slab reflow on wall move"
+    // behavior gain called out in Phase 3 acceptance.
+    affectsSpatial: ['slab', 'ceiling', 'zone'],
+    // Walls sharing an endpoint move together when a corner is dragged.
+    // The endpoint affordance (milestone C) uses this declaration via the
+    // shared cascade resolver — no hand-rolled `getLinkedWallSnapshots`.
+    linkedBy: 'endpoint-match',
+    // Deleting a wall deletes its hosted doors/windows/items (today's
+    // implicit behavior, now declarative).
+    cascadeDelete: 'descendants',
+  },
+
+  parametrics: wallParametrics,
+
+  // No `geometry` / `renderer` / `system` / `tool` fields yet — see file
+  // header. Adding them registers wall via `builtinPlugin.nodes` and flips
+  // the dispatch shims; do that in milestone B once the runtime port lands.
+
+  presentation: {
+    label: 'Wall',
+    description: 'A straight or curved wall segment. Hosts doors, windows, and wall-mounted items.',
+    icon: { kind: 'iconify', name: 'lucide:wall' },
+    paletteSection: 'structure',
+    paletteOrder: 10,
+  },
+
+  mcp: {
+    description: 'A wall segment defined by start + end points, with optional curve sagitta.',
+    // Wall has hand-written semantic MCP tooling (`create_wall` builds full
+    // rooms from polygons; this entry is for the auto-derived single-wall
+    // primitive). Stays auto-derived until Phase 4 says otherwise.
+  },
+}

packages/nodes/src/wall/feature-flag.ts

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+/**
+ * Feature flag for the registry-driven wall.
+ *
+ * Wall is the Phase 3 stress test — its scope is large enough (5 affordances,
+ * miter cascade, host re-anchor, slab/zone dirty propagation, undo
+ * correctness) that flipping it on uncontrolled would risk silently
+ * regressing every wall scene in production.
+ *
+ * Pattern mirrors `NEXT_PUBLIC_USE_REGISTRY_FOR_SPAWN` used during the
+ * Phase 2 spawn migration: when ON, `wallDefinition` is appended to
+ * `builtinPlugin.nodes` and the Phase 0 dispatch shims take over wall
+ * rendering / tooling. When OFF, the legacy wall paths run unchanged.
+ *
+ * Literal `process.env.NEXT_PUBLIC_USE_REGISTRY_FOR_WALL` access is required
+ * — Next.js only inline-substitutes literal env reads, so `process.env[name]`
+ * with a variable would always read undefined in client bundles.
+ *
+ * Drop this file the moment Phase 3 parity is signed off and wall is
+ * registered unconditionally.
+ */
+export const isWallRegistryEnabled = (): boolean => {
+  return process.env.NEXT_PUBLIC_USE_REGISTRY_FOR_WALL === 'true'
+}

packages/nodes/src/wall/index.ts

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+export { wallDefinition } from './definition'
+export { isWallRegistryEnabled } from './feature-flag'
+export { WallNode } from './schema'

packages/nodes/src/wall/parametrics.ts

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+import type { ParametricDescriptor } from '@pascal-app/core'
+import type { WallNode } from './schema'
+
+/**
+ * Inspector descriptor for wall.
+ *
+ * Wall has a few "structural" knobs (thickness, height, curve sagitta) and
+ * a few "presentation" knobs (front / back / interior / exterior material
+ * presets). Phase 4's `<ParametricInspector>` renders these directly.
+ *
+ * Endpoints (`start`, `end`) and host children are *not* exposed here —
+ * those are edited via affordances (endpoint drag handles) and child
+ * placement tools, not number inputs. `parametrics` is for "type a value
+ * and see it apply"; spatial manipulation belongs to tools/affordances.
+ */
+export const wallParametrics: ParametricDescriptor<WallNode> = {
+  groups: [
+    {
+      label: 'Dimensions',
+      fields: [
+        { key: 'thickness', kind: 'number', unit: 'm', min: 0.05, max: 0.6, step: 0.01 },
+        { key: 'height', kind: 'number', unit: 'm', min: 1.5, max: 6, step: 0.05 },
+        { key: 'curveOffset', kind: 'number', unit: 'm', min: -3, max: 3, step: 0.05 },
+      ],
+    },
+  ],
+}

packages/nodes/src/wall/schema.ts

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+/**
+ * Wall schema re-export.
+ *
+ * Wall's Zod schema lives in `@pascal-app/core` because doors, windows, and
+ * items still need to type-check their `parentId` against `WallNode.shape.id`
+ * before the migration to a `relations.hosts`-driven model is complete. The
+ * registry definition consumes it from here so the rest of the bundle
+ * imports a single canonical type.
+ */
+
+export type { WallNode as WallNodeType } from '@pascal-app/core'
+export { WallNode } from '@pascal-app/core'