feat(editor): preset-system primitives (#340) (#341)

* feat(editor): preset-system primitives — presettable, sceneApi subtree round-trip, isolate + setCaptureMode enum, headless exports Per pascalorg/editor#340 (redesigned: single live canvas, no Viewer scene prop). Core - `capabilities.presettable` on `NodeDefinition` + `isPresettable` / `isPresettableKind` helpers. Explicit `false` on level / building / site / zone / spawn / guide / scan / item; implicit `true` for any kind with `def.parametrics`. - `sceneApi.getSubtreeSnapshot(rootId)` + `materializeSubtree(subtree, position, parentId?)` for round-tripping a node subtree through catalog storage. Strips id / parentId / absolute root position / host refs (`wallId`, `wallT`); fresh IDs minted at materialize time; child ordering preserved (FIFO walk). Viewer - `<Viewer isolate>` prop + `ViewerHandle.setIsolated(ids | null)`. Walks `sceneRegistry`, hides every registered group not in the isolated set's ancestor + descendant closure. Building block for preset capture + future focus-mode UX. Editor - `useEditor.captureMode: CaptureMode` discriminated union (`idle` | `standard` | `preset`). `isCaptureMode` stays as a derived boolean for the existing read sites; `setCaptureMode` accepts both the boolean shape (back-compat) and the enum. - `preset` capture mode in `SnapshotCaptureOverlay`: drag locked to a square, mode-picker hidden, transparent flag forwarded through the `camera-controls:generate-thumbnail` emitter event. - Headless exports: `Inspector` (alias of `ParametricInspector`), `FloatingMenu` (alias of `FloatingActionMenu`), `ToolbarLeft` / `ToolbarRight` (aliases of `ViewerToolbarLeft` / `ViewerToolbarRight`), `useSelection` hook returning `{selectedIds, selectedNode, building/ level/zone}`, plus re-exports of `useScene` / `useViewer` from core / viewer so consumer shells (community, embedders) need only one import. Out of scope by design (see issue #340 "Out of scope"): a separate offscreen Viewer rendering an arbitrary subtree. The unified preset modal captures inside the live canvas via isolation + the existing snapshot pipeline — no `useScene` factory / React context refactor. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com> * refactor(editor): split snapshot/materialize into pure getSubtree + cloneNodesInto; add def.hostRefFields; auto-stage preset capture square Per pascalorg/editor#340 redesign discussion: the editor's scene API should expose *pure* primitives and let the host (community modal, embedders) own storage shape, position stripping, and host-ref re-derivation policy. Editor API delta - `sceneApi.getSubtreeSnapshot(rootId)` → `sceneApi.getSubtree(rootId)` Returns the live subtree verbatim (BFS via `children[]`, no clones, no stripping). Callers deep-clone if they need persistence. - `sceneApi.materializeSubtree(subtree, pos, parent?)` → `sceneApi.cloneNodesInto(nodes, { rootId, parentId?, position? })` Generic clone-and-insert. Deep-clones via JSON, mints fresh ids preserving the prefix, rewires parent/children, stamps position + parent if supplied. Host-ref-agnostic — `wallId`/`wallT` etc are preserved verbatim. - New `capabilities.hostRefFields?: string[]` on `NodeDefinition`. Declares per kind which schema fields are placement-derived so the host strips them at preset-save time. Declared on door (`['wallId']`), window (`['wallId']`), item (`['wallId', 'wallT']`). - New `getHostRefFields(def)` exported from `@pascal-app/core`. Removed the intermediate token-based payload format (`NodeSubtree`, `buildSubtreeSnapshot`, `materializeSubtree`, `SubtreeNode`). UX polish - `<SnapshotCaptureOverlay>` in `preset` mode now auto-stages a centered square crop sized to ~75% of the shorter viewport dimension. The user can pan / move / resize within square-aspect, but doesn't have to drag from scratch — clicking the capture button works immediately on entry. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com> * fix(editor): lock preset capture frame; allow item presets - SnapshotCaptureOverlay: in `preset` mode, the auto-staged centered square is now fully locked — corner handles hidden, the dim layer is click-through (no drag-to-move, no drag-to-resize). The user just adjusts the camera (orbit / pan / zoom) and clicks capture. The letterbox + dashed border stay visible as a cosmetic frame. - `item.capabilities.presettable` removed (implicit `true` via `def.parametrics`). Enables compositions like "table-with-plants", "shelf-with-books" where the preset root may be an item and other items ride along as descendants. The GLB-kind item catalog is unchanged; presets become siblings of GLB rows under the same `items` table. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com> * feat(editor): auto-frame camera on preset capture entry; restore on exit `<CustomCameraControls>` now watches `useEditor.captureMode` and, when preset capture mode begins, flies the camera to a pose that fits the union bounds of the isolated subtree inside the locked square crop — no more hunting for the subject after opening the modal. The pre-capture pose is stashed and restored on exit so the user lands exactly where they were. The user can still pan / orbit / zoom from the auto-staged pose if they want a different angle before snapping. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com> --------- Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
2026-05-28 09:49:50 -04:00
parent 350cad9c89
commit 1fd59dd9cd
31 changed files with 1087 additions and 113 deletions
@@ -130,6 +130,13 @@ export interface ThumbnailGenerateEvent {
   * that should fire immediately from the current camera pose.
   */
  snapLevels?: boolean
+  /**
+   * When true, keep the rendered alpha channel — emits a transparent PNG
+   * without baking the scene background into the output. Used by the
+   * preset capture flow so saved preset thumbnails composite cleanly on
+   * any palette background.
+   */
+  transparent?: boolean
 }

 export interface CameraControlFitSceneEvent {
@@ -110,6 +110,8 @@ function makeScene(nodes: Record<string, AnyNode>): SceneApi {
    markDirty: () => {},
    pauseHistory: () => {},
    resumeHistory: () => {},
+    getSubtree: () => null,
+    cloneNodesInto: () => null,
  }
 }

@@ -1,6 +1,24 @@
+export type {
+  ArcResizeHandle,
+  Cursor,
+  EditorApi,
+  EndpointMoveHandle,
+  HandleAnchor,
+  HandleAxis,
+  HandleDescriptor,
+  HandleList,
+  HandlePlacement,
+  HandlePortal,
+  LinearResizeHandle,
+  RadialResizeHandle,
+  TapActionHandle,
+} from './handles'
 export {
  discoverPlugins,
+  getHostRefFields,
  getSelectableKinds,
+  isPresettable,
+  isPresettableKind,
  isRegistryMovable,
  isRegistrySelectable,
  kindsWithFloorplanScope,
@@ -17,22 +35,14 @@ export {
  collectDescendants,
  type SpatialQuery,
 } from './relations-resolver'
-export type {
-  ArcResizeHandle,
-  Cursor,
-  EditorApi,
-  EndpointMoveHandle,
-  HandleAnchor,
-  HandleAxis,
-  HandleDescriptor,
-  HandleList,
-  HandlePlacement,
-  HandlePortal,
-  LinearResizeHandle,
-  RadialResizeHandle,
-  TapActionHandle,
-} from './handles'
 export { createSceneApi, type SceneStoreLike } from './scene-api'
+export {
+  type CloneNodesIntoOptions,
+  type CloneNodesIntoResult,
+  cloneNodesInto,
+  collectSubtree,
+  type Subtree,
+} from './subtree'
 export type {
  Affordance,
  AnyNodeDefinition,
@@ -1,6 +1,13 @@
 import { beforeEach, describe, expect, test } from 'bun:test'
 import { z } from 'zod'
-import { loadPlugin, nodeRegistry, registerNode } from './registry'
+import {
+  getHostRefFields,
+  isPresettable,
+  isPresettableKind,
+  loadPlugin,
+  nodeRegistry,
+  registerNode,
+} from './registry'
 import type { AnyNodeDefinition, Plugin } from './types'

 function makeDefinition(
@@ -70,6 +77,53 @@ describe('nodeRegistry', () => {
  })
 })

+describe('isPresettable', () => {
+  beforeEach(() => {
+    nodeRegistry._reset()
+  })
+
+  test('explicit true wins', () => {
+    const def = makeDefinition('explicit-true', { capabilities: { presettable: true } })
+    expect(isPresettable(def)).toBe(true)
+  })
+
+  test('explicit false wins even with parametrics', () => {
+    const def = makeDefinition('explicit-false', {
+      capabilities: { presettable: false },
+      parametrics: { groups: [] } as any,
+    })
+    expect(isPresettable(def)).toBe(false)
+  })
+
+  test('defaults to true when parametrics exists', () => {
+    const def = makeDefinition('param', { parametrics: { groups: [] } as any })
+    expect(isPresettable(def)).toBe(true)
+  })
+
+  test('defaults to false without parametrics', () => {
+    const def = makeDefinition('no-param')
+    expect(isPresettable(def)).toBe(false)
+  })
+
+  test('isPresettableKind looks up the registry', () => {
+    registerNode(makeDefinition('shelfy', { parametrics: { groups: [] } as any }))
+    expect(isPresettableKind('shelfy')).toBe(true)
+    expect(isPresettableKind('unknown')).toBe(false)
+  })
+})
+
+describe('getHostRefFields', () => {
+  test('returns the declared hostRefFields verbatim', () => {
+    const def = makeDefinition('door', { capabilities: { hostRefFields: ['wallId'] } })
+    expect(getHostRefFields(def)).toEqual(['wallId'])
+  })
+
+  test('defaults to an empty array when none declared', () => {
+    const def = makeDefinition('shelf')
+    expect(getHostRefFields(def)).toEqual([])
+  })
+})
+
 describe('loadPlugin', () => {
  beforeEach(() => {
    nodeRegistry._reset()
@@ -146,6 +146,34 @@ export function isRegistryMovable(kind: string): boolean {
  return false
 }

+/**
+ * Whether the kind can be saved as a reusable preset. Default: an
+ * explicit `capabilities.presettable` boolean wins; otherwise the kind
+ * is presettable iff it declares `def.parametrics`. Read by host apps
+ * (community shell) to gate "save as preset" UI on a selection.
+ */
+export function isPresettable(def: AnyNodeDefinition): boolean {
+  if (typeof def.capabilities.presettable === 'boolean') {
+    return def.capabilities.presettable
+  }
+  return def.parametrics !== undefined
+}
+
+export function isPresettableKind(kind: string): boolean {
+  const def = nodeRegistry.get(kind)
+  return def ? isPresettable(def) : false
+}
+
+/**
+ * Names of schema fields on `def` that are host references (`wallId`,
+ * `wallT`, etc.). Read by host apps at preset-save time to strip these
+ * from the stored payload — see `def.capabilities.hostRefFields` docs.
+ * Returns an empty array for kinds that don't declare any.
+ */
+export function getHostRefFields(def: AnyNodeDefinition): ReadonlyArray<string> {
+  return def.capabilities.hostRefFields ?? []
+}
+
 export async function loadPlugin(plugin: Plugin): Promise<void> {
  if (plugin.apiVersion !== HOST_API_VERSION) {
    throw new Error(
@@ -47,6 +47,8 @@ function makeFakeScene(nodes: Record<string, AnyNode>): SceneApi {
    markDirty: () => {},
    pauseHistory: () => {},
    resumeHistory: () => {},
+    getSubtree: () => null,
+    cloneNodesInto: () => null,
  }
 }

@@ -1,5 +1,10 @@
 import type { AnyNode, AnyNodeId } from '../schema/types'
 import { pauseSceneHistory, resumeSceneHistory } from '../store/history-control'
+import {
+  type CloneNodesIntoOptions,
+  collectSubtree,
+  cloneNodesInto as runCloneNodesInto,
+} from './subtree'
 import type { SceneApi } from './types'

 /**
@@ -14,6 +19,7 @@ export type SceneStoreLike = {
    rootNodeIds: AnyNodeId[]
    dirtyNodes: Set<AnyNodeId>
    createNode: (node: AnyNode, parentId?: AnyNodeId) => void
+    createNodes?: (ops: { node: AnyNode; parentId?: AnyNodeId }[]) => void
    updateNode: (id: AnyNodeId, data: Partial<AnyNode>) => void
    deleteNode: (id: AnyNodeId) => void
    markDirty: (id: AnyNodeId) => void
@@ -104,5 +110,32 @@ export function createSceneApi(store: SceneStoreLike): SceneApi {
      resumeSceneHistory(store)
      snapshot = null
    },
+
+    getSubtree(rootId) {
+      return collectSubtree(store.getState().nodes, rootId)
+    },
+
+    cloneNodesInto(nodes, opts: CloneNodesIntoOptions) {
+      const { rootId, nodes: cloned } = runCloneNodesInto(nodes, opts)
+      const root = cloned[0]
+      if (!root) return null
+      const state = store.getState()
+      const ops: { node: AnyNode; parentId?: AnyNodeId }[] = []
+      for (let i = 0; i < cloned.length; i += 1) {
+        const node = cloned[i]!
+        if (i === 0) {
+          ops.push(opts.parentId ? { node, parentId: opts.parentId } : { node })
+        } else {
+          ops.push({ node })
+        }
+      }
+      const batch = state.createNodes
+      if (batch) {
+        batch(ops)
+      } else {
+        for (const op of ops) state.createNode(op.node, op.parentId)
+      }
+      return rootId
+    },
  }
 }
@@ -0,0 +1,144 @@
+import { describe, expect, test } from 'bun:test'
+import type { AnyNode, AnyNodeId } from '../schema/types'
+import { cloneNodesInto, collectSubtree } from './subtree'
+
+function makeNode(id: string, type: string, extra: Record<string, unknown> = {}): AnyNode {
+  return {
+    object: 'node',
+    id,
+    type,
+    parentId: null,
+    visible: true,
+    metadata: {},
+    ...extra,
+  } as unknown as AnyNode
+}
+
+describe('collectSubtree', () => {
+  test('returns null for missing root', () => {
+    expect(collectSubtree({}, 'missing' as AnyNodeId)).toBeNull()
+  })
+
+  test('returns just the root for a leaf node', () => {
+    const root = makeNode('shelf_1', 'shelf', { width: 1 })
+    const sub = collectSubtree({ ['shelf_1' as AnyNodeId]: root }, 'shelf_1' as AnyNodeId)
+    expect(sub?.root).toBe(root)
+    expect(sub?.descendants).toEqual([])
+  })
+
+  test('walks descendants in BFS / declaration order', () => {
+    const nodes: Record<AnyNodeId, AnyNode> = {
+      ['shelf_1' as AnyNodeId]: makeNode('shelf_1', 'shelf', {
+        position: [0, 0, 0],
+        children: ['item_a', 'item_b'],
+        width: 1,
+      }),
+      ['item_a' as AnyNodeId]: makeNode('item_a', 'item', {
+        parentId: 'shelf_1',
+        position: [0, 0, 0],
+      }),
+      ['item_b' as AnyNodeId]: makeNode('item_b', 'item', {
+        parentId: 'shelf_1',
+        position: [0.3, 0, 0],
+      }),
+    }
+    const sub = collectSubtree(nodes, 'shelf_1' as AnyNodeId)
+    expect(sub?.descendants.map((n) => n.id)).toEqual(['item_a', 'item_b'])
+  })
+
+  test('returned nodes are live references — no cloning', () => {
+    const item = makeNode('item_a', 'item', { parentId: 'shelf_1', position: [0, 0, 0] })
+    const nodes: Record<AnyNodeId, AnyNode> = {
+      ['shelf_1' as AnyNodeId]: makeNode('shelf_1', 'shelf', { children: ['item_a'] }),
+      ['item_a' as AnyNodeId]: item,
+    }
+    const sub = collectSubtree(nodes, 'shelf_1' as AnyNodeId)
+    expect(sub?.descendants[0]).toBe(item)
+  })
+})
+
+describe('cloneNodesInto', () => {
+  test('clones a single root with fresh id and supplied position', () => {
+    const original = makeNode('door_orig', 'door', {
+      position: [1, 2, 3],
+      wallId: 'wall_x',
+      width: 0.9,
+    })
+    const { rootId, nodes } = cloneNodesInto([original], {
+      rootId: 'door_orig' as AnyNodeId,
+      position: [10, 0, -4],
+    })
+    expect(nodes).toHaveLength(1)
+    const cloned = nodes[0] as any
+    expect(cloned.id).toBe(rootId)
+    expect(cloned.id).not.toBe('door_orig')
+    expect(cloned.id.startsWith('door_')).toBe(true)
+    expect(cloned.position).toEqual([10, 0, -4])
+    expect(cloned.width).toBe(0.9)
+    // cloneNodesInto is host-ref-agnostic — wallId is preserved
+    // verbatim. Stripping is the caller's job (see getHostRefFields).
+    expect(cloned.wallId).toBe('wall_x')
+  })
+
+  test('preserves root position when none is supplied', () => {
+    const original = makeNode('shelf_orig', 'shelf', { position: [5, 0, 5] })
+    const { nodes } = cloneNodesInto([original], { rootId: 'shelf_orig' as AnyNodeId })
+    expect((nodes[0] as any).position).toEqual([5, 0, 5])
+  })
+
+  test('preserves parent/child subtree with remapped ids and relative positions', () => {
+    const shelf = makeNode('shelf_1', 'shelf', {
+      position: [5, 0, 5],
+      children: ['item_a', 'item_b'],
+    })
+    const itemA = makeNode('item_a', 'item', { parentId: 'shelf_1', position: [0, 0, 0] })
+    const itemB = makeNode('item_b', 'item', { parentId: 'shelf_1', position: [0.3, 0, 0] })
+
+    const { rootId, nodes: out } = cloneNodesInto([shelf, itemA, itemB], {
+      rootId: 'shelf_1' as AnyNodeId,
+      position: [99, 0, -99],
+    })
+    expect(out).toHaveLength(3)
+    const root = out[0] as any
+    expect(root.id).toBe(rootId)
+    expect(root.id).not.toBe('shelf_1')
+    expect(root.position).toEqual([99, 0, -99])
+    // Root's children rewritten to fresh ids; descendants' parentIds
+    // point at the new root id.
+    const ids = new Set(out.map((n) => (n as any).id))
+    expect(root.children).toHaveLength(2)
+    for (const cid of root.children) expect(ids.has(cid)).toBe(true)
+    for (let i = 1; i < out.length; i += 1) {
+      const desc = out[i] as any
+      expect(desc.parentId).toBe(rootId)
+      expect(Array.isArray(desc.position)).toBe(true)
+    }
+  })
+
+  test('parents the cloned root under opts.parentId when supplied', () => {
+    const orig = makeNode('shelf_1', 'shelf', { parentId: 'level_old' })
+    const { nodes } = cloneNodesInto([orig], {
+      rootId: 'shelf_1' as AnyNodeId,
+      parentId: 'level_new' as AnyNodeId,
+    })
+    expect((nodes[0] as any).parentId).toBe('level_new')
+  })
+
+  test('two clones produce disjoint id sets', () => {
+    const orig = makeNode('shelf_1', 'shelf', {
+      position: [0, 0, 0],
+      children: ['item_a'],
+    })
+    const child = makeNode('item_a', 'item', { parentId: 'shelf_1', position: [0, 0, 0] })
+    const first = cloneNodesInto([orig, child], { rootId: 'shelf_1' as AnyNodeId })
+    const second = cloneNodesInto([orig, child], { rootId: 'shelf_1' as AnyNodeId })
+    const idsA = new Set(first.nodes.map((n) => (n as any).id))
+    const idsB = new Set(second.nodes.map((n) => (n as any).id))
+    for (const id of idsA) expect(idsB.has(id)).toBe(false)
+  })
+
+  test('throws if rootId is missing from the input array', () => {
+    const orig = makeNode('shelf_1', 'shelf', {})
+    expect(() => cloneNodesInto([orig], { rootId: 'shelf_other' as AnyNodeId })).toThrow(/rootId/)
+  })
+})
@@ -0,0 +1,187 @@
+import { generateId } from '../schema/base'
+import type { AnyNode, AnyNodeId } from '../schema/types'
+
+// Generic, opinion-free primitives the host app composes to implement
+// catalog / paste / duplicate / preset flows.
+//
+// Design intent (see pascalorg/editor#340 redesign):
+//   - The editor exposes a *pure* live-scene walk + a generic clone-and-
+//     insert helper. It owns nothing about storage shape, position
+//     re-anchoring policy, or host-ref re-derivation.
+//   - The host (community-app, embedders, etc.) decides whether to
+//     persist the subtree as JSON, strip host fields before storage,
+//     stamp a placement position, re-attach to a wall on drop, etc.
+//
+// What the editor uniquely knows is which schema fields on each kind
+// are *host references* (e.g. `wallId` / `wallT` on a door hosted by a
+// wall). That knowledge lives on `def.hostRefFields` — read it via
+// `getHostRefFields(def)` and apply it at storage time. See
+// `wiki/architecture/node-definitions.md` (host refs section).
+
+/** A flat live-scene subtree rooted at `root`. */
+export type Subtree = {
+  /** The root node, exactly as stored in `useScene.nodes[rootId]`. */
+  root: AnyNode
+  /** Every descendant reachable from `root` via the data-model `children` array, in BFS order. */
+  descendants: AnyNode[]
+}
+
+function extractIdPrefix(id: string): string {
+  const i = id.indexOf('_')
+  return i === -1 ? 'node' : id.slice(0, i)
+}
+
+function getChildIds(node: AnyNode): AnyNodeId[] {
+  if ('children' in node && Array.isArray((node as { children?: unknown }).children)) {
+    return (node as { children: AnyNodeId[] }).children
+  }
+  return []
+}
+
+/**
+ * Collect the subtree of nodes rooted at `rootId` from the live scene.
+ *
+ * - BFS walk via `node.children` arrays — order is stable and matches
+ *   declaration order on container kinds.
+ * - Returns the live node references (not clones). Cheap; the caller
+ *   chooses whether to deep-clone for persistence.
+ * - Returns `null` if `rootId` is missing.
+ */
+export function collectSubtree(
+  nodes: Readonly<Record<AnyNodeId, AnyNode>>,
+  rootId: AnyNodeId,
+): Subtree | null {
+  const root = nodes[rootId]
+  if (!root) return null
+
+  const descendants: AnyNode[] = []
+  const seen = new Set<AnyNodeId>([rootId])
+  const queue: AnyNodeId[] = [...getChildIds(root)]
+  let head = 0
+  while (head < queue.length) {
+    const id = queue[head++]!
+    if (seen.has(id)) continue
+    const node = nodes[id]
+    if (!node) continue
+    seen.add(id)
+    descendants.push(node)
+    for (const childId of getChildIds(node)) queue.push(childId)
+  }
+
+  return { root, descendants }
+}
+
+export type CloneNodesIntoOptions = {
+  /**
+   * The id of the root node within `nodes` (i.e. the node whose
+   * `parentId` becomes `parentId` in the destination instead of being
+   * remapped to a sibling's fresh id). Required because `nodes` is a
+   * flat array — there's no other way to mark which one is the root.
+   */
+  rootId: AnyNodeId
+  /**
+   * Parent for the cloned root in the destination scene. When omitted,
+   * the root is inserted as a scene root (its `parentId` becomes the
+   * preserved value, often `null`).
+   */
+  parentId?: AnyNodeId
+  /**
+   * Optional override for the cloned root's `position` (most placement
+   * flows stamp the cursor / target point here). When omitted, the
+   * root's own `position` field is preserved verbatim. Descendants
+   * always keep their original positions — those are local to the root.
+   */
+  position?: readonly [number, number, number]
+}
+
+export type CloneNodesIntoResult = {
+  /** Fresh id assigned to the root in the destination scene. */
+  rootId: AnyNodeId
+  /** Every cloned node, root first, ready to feed into `createNodes`. */
+  nodes: AnyNode[]
+  /** Original id → fresh id map, mostly useful for tests and host-side bookkeeping. */
+  idMap: Map<AnyNodeId, AnyNodeId>
+}
+
+/**
+ * Clone a flat array of nodes with fresh IDs and rewired references,
+ * ready to insert via `useScene.createNodes`.
+ *
+ * Transformations applied:
+ *   1. Deep-clone each node via JSON round-trip (strips three.js refs,
+ *      functions, circular links — same trick `cloneLevelSubtree` uses).
+ *   2. Mint a fresh id for every node, preserving the prefix
+ *      (`wall_…`, `door_…`, etc.) so logs and lookups stay readable.
+ *   3. Rewrite `parentId`, `children[]` to use the fresh ids.
+ *   4. Stamp `position` onto the root if provided.
+ *   5. Set the root's `parentId` to `opts.parentId` when supplied.
+ *
+ * Intentionally generic — no awareness of host refs (`wallId`/`wallT`
+ * etc.). The caller is responsible for stripping or re-deriving those
+ * before / after calling this function. See `getHostRefFields(def)`.
+ */
+export function cloneNodesInto(
+  nodes: ReadonlyArray<AnyNode>,
+  opts: CloneNodesIntoOptions,
+): CloneNodesIntoResult {
+  // Phase 1 — mint fresh ids for every node, preserving the prefix.
+  const idMap = new Map<AnyNodeId, AnyNodeId>()
+  for (const node of nodes) {
+    const prefix = extractIdPrefix(node.id)
+    idMap.set(node.id, generateId(prefix) as AnyNodeId)
+  }
+
+  const rootFreshId = idMap.get(opts.rootId)
+  if (!rootFreshId) {
+    throw new Error(`cloneNodesInto: rootId "${opts.rootId}" not found in supplied nodes array`)
+  }
+
+  // Phase 2 — clone each node + rewire references.
+  const out: AnyNode[] = []
+  let root: AnyNode | null = null
+  for (const original of nodes) {
+    const cloned = JSON.parse(JSON.stringify(original)) as AnyNode
+    const freshId = idMap.get(original.id)!
+    ;(cloned as { id: AnyNodeId }).id = freshId
+    // parentId: root's parentId becomes opts.parentId (or preserved
+    // value if not supplied). Descendants point at the remapped parent.
+    if (original.id === opts.rootId) {
+      ;(cloned as { parentId: AnyNodeId | null }).parentId =
+        opts.parentId !== undefined
+          ? opts.parentId
+          : ((cloned as { parentId?: AnyNodeId | null }).parentId ?? null)
+    } else if (cloned.parentId) {
+      const parentFresh = idMap.get(cloned.parentId as AnyNodeId)
+      ;(cloned as { parentId: AnyNodeId | null }).parentId = parentFresh ?? null
+    }
+    // children[]: remap any internal references, drop external ones
+    // (a descendant pointing at a sibling that didn't make it into
+    // `nodes` would dangle — `filter` drops those gracefully).
+    if ('children' in cloned && Array.isArray((cloned as { children?: unknown }).children)) {
+      ;(cloned as { children: AnyNodeId[] }).children = (
+        cloned as { children: AnyNodeId[] }
+      ).children
+        .map((cid) => idMap.get(cid))
+        .filter((cid): cid is AnyNodeId => cid !== undefined)
+    }
+
+    if (original.id === opts.rootId) {
+      if (opts.position) {
+        ;(cloned as { position: [number, number, number] }).position = [
+          opts.position[0],
+          opts.position[1],
+          opts.position[2],
+        ]
+      }
+      root = cloned
+    } else {
+      out.push(cloned)
+    }
+  }
+
+  if (!root) {
+    throw new Error('cloneNodesInto: root node missing after clone')
+  }
+
+  return { rootId: rootFreshId, nodes: [root, ...out], idMap }
+}
@@ -4,6 +4,7 @@ import type { ZodObject, z } from 'zod'
 import type { MaterialSchema } from '../schema/material'
 import type { AnyNode, AnyNodeId } from '../schema/types'
 import type { HandleList } from './handles'
+import type { CloneNodesIntoOptions, Subtree } from './subtree'

 // ─── GeometryContext ─────────────────────────────────────────────────
 //
@@ -970,6 +971,43 @@ export type Capabilities = {
   * declaring the same flag.
   */
  floorplanLevelContainer?: boolean
+  /**
+   * Names of schema fields on this kind that are *host references* —
+   * values derived from where the node is placed (rather than declared
+   * by the user as part of the kind's parametric configuration). Read
+   * by host apps at preset-save time to strip these from the stored
+   * payload so a placed instance gets fresh host links at the new
+   * placement site (e.g. a door snapshot loses `wallId`/`wallT`; at
+   * placement the auto-attach UX re-derives them from the wall under
+   * the cursor).
+   *
+   * Kinds with no host refs omit this field (default `[]`).
+   *
+   * Examples:
+   *   - door: `['wallId', 'wallT']` (door hosted on a wall)
+   *   - window: `['wallId', 'wallT']`
+   *   - item with `attachTo`: depends on the asset; the kind's
+   *     `defaults()` or the dragging logic populates it dynamically.
+   */
+  hostRefFields?: string[]
+  /**
+   * Whether instances of this kind can be saved as a reusable preset
+   * (unified `items` catalog, `kind='preset'`). The editor itself does
+   * not act on this flag — host apps read it to gate "save as preset"
+   * UI on the selected node. Default resolution (callers should use the
+   * `isPresettable(def)` helper rather than reading this directly):
+   *
+   *   - explicit `true`  → presettable
+   *   - explicit `false` → not presettable
+   *   - undefined        → presettable when `def.parametrics` exists
+   *
+   * Structural / utility kinds (level, building, site, zone, spawn,
+   * guide, scan, item) opt out explicitly because saving them as a
+   * standalone preset has no meaning — items already have their own
+   * catalog, scans/guides carry user-uploaded imagery, and the rest
+   * are non-leaf scene containers.
+   */
+  presettable?: boolean
 }

 /**
@@ -1282,6 +1320,25 @@ export type SceneApi = {
  markDirty: (id: AnyNodeId) => void
  pauseHistory: () => void
  resumeHistory: () => void
+  /**
+   * Collect the subtree of live nodes rooted at `rootId` — `root` plus
+   * every descendant reachable via `children[]` in BFS order. Returns
+   * live node references (no clones); the caller decides whether to
+   * persist by value or pass them straight into {@link cloneNodesInto}.
+   * Returns `null` if `rootId` is missing.
+   */
+  getSubtree: (rootId: AnyNodeId) => Subtree | null
+  /**
+   * Clone a flat array of nodes into the live scene with fresh IDs and
+   * rewired parent / children references. Intentionally generic — see
+   * {@link cloneNodesInto} for the transformations applied. Does NOT
+   * strip or re-derive host references (e.g. `wallId` on a door); the
+   * caller is responsible for that policy (read {@link Capabilities.hostRefFields}
+   * on the relevant definition).
+   *
+   * Returns the new root id, or `null` if insertion failed.
+   */
+  cloneNodesInto: (nodes: ReadonlyArray<AnyNode>, opts: CloneNodesIntoOptions) => AnyNodeId | null
 }

 // ─── Registry surface ────────────────────────────────────────────────
@@ -52,6 +52,8 @@ function makeSpyScene(initial: Record<string, AnyNode> = {}): SceneApi & {
    resumeHistory: () => {
      calls.resumeHistory += 1
    },
+    getSubtree: () => null,
+    cloneNodesInto: () => null,
    _calls: calls,
  }
 }
@@ -52,6 +52,8 @@ function makeFakeScene(nodes: Record<string, AnyNode>): SceneApi {
    markDirty: () => {},
    pauseHistory: () => {},
    resumeHistory: () => {},
+    getSubtree: () => null,
+    cloneNodesInto: () => null,
  }
 }