editor: tool-defaults seeding + drawTool capability (fence presets) (#346)

* feat(editor): tool-defaults seeding + drawTool capability; fence consumes it

Adds a generic, transient `useEditor.toolDefaults` slice keyed by tool, set
via `setToolDefaults(tool, params)`. A draw tool's create path merges its
entry when minting a node and clears it on deactivation, so a host app can
prime the next-drawn node's parameters — placing a saved preset of a drawn
kind, or a future "small / medium / large" dimension picker for
wall / slab / ceiling.

Marks the kind with `capabilities.drawTool` (helper `isDrawnViaTool`) so host
apps know to route placement through `setToolDefaults(type) + setTool(type)`
instead of cloning a finished instance.

Wires fence end-to-end: it declares `drawTool: true`, its create path merges
`toolDefaults.fence`, and the draft preview (bar geometry, cursor, HUD label
heights) reflects the seeded height/thickness so the ghost matches what will
be built. The tool clears its own defaults on unmount.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

* fix(editor): restore dropped useEditor import in fence tool

The toolDefaults-seeding commit lost the `useEditor` import (formatter
stripped it), shipping a runtime ReferenceError when FenceTool mounts.
Re-add it.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.7 <noreply@anthropic.com>

packages/core/src/registry/index.ts

@@ -17,6 +17,8 @@ export {
   discoverPlugins,
   getHostRefFields,
   getSelectableKinds,
+  isDrawnViaTool,
+  isDrawnViaToolKind,
   isPresettable,
   isPresettableKind,
   isRegistryMovable,

packages/core/src/registry/registry.test.ts

@@ -2,6 +2,8 @@ import { beforeEach, describe, expect, test } from 'bun:test'
 import { z } from 'zod'
 import {
   getHostRefFields,
+  isDrawnViaTool,
+  isDrawnViaToolKind,
   isPresettable,
   isPresettableKind,
   loadPlugin,
@@ -124,6 +126,28 @@ describe('getHostRefFields', () => {
   })
 })
 
+describe('isDrawnViaTool', () => {
+  beforeEach(() => {
+    nodeRegistry._reset()
+  })
+
+  test('true when capability set', () => {
+    const def = makeDefinition('fence', { capabilities: { drawTool: true } })
+    expect(isDrawnViaTool(def)).toBe(true)
+  })
+
+  test('false when unset or not exactly true', () => {
+    expect(isDrawnViaTool(makeDefinition('column'))).toBe(false)
+    expect(isDrawnViaTool(makeDefinition('off', { capabilities: { drawTool: false } }))).toBe(false)
+  })
+
+  test('isDrawnViaToolKind looks up the registry', () => {
+    registerNode(makeDefinition('fence', { capabilities: { drawTool: true } }))
+    expect(isDrawnViaToolKind('fence')).toBe(true)
+    expect(isDrawnViaToolKind('unknown')).toBe(false)
+  })
+})
+
 describe('loadPlugin', () => {
   beforeEach(() => {
     nodeRegistry._reset()

packages/core/src/registry/registry.ts

@@ -174,6 +174,22 @@ export function getHostRefFields(def: AnyNodeDefinition): ReadonlyArray<string>
   return def.capabilities.hostRefFields ?? []
 }
 
+/**
+ * Whether instances of this kind are created by drawing with a build tool
+ * (tool id === node `type`) rather than dropping a finished instance. Read
+ * by host apps to route preset placement of such kinds through
+ * `setToolDefaults(type, params)` + `setTool(type)` — see
+ * `def.capabilities.drawTool` docs.
+ */
+export function isDrawnViaTool(def: AnyNodeDefinition): boolean {
+  return def.capabilities.drawTool === true
+}
+
+export function isDrawnViaToolKind(kind: string): boolean {
+  const def = nodeRegistry.get(kind)
+  return def ? isDrawnViaTool(def) : false
+}
+
 export async function loadPlugin(plugin: Plugin): Promise<void> {
   if (plugin.apiVersion !== HOST_API_VERSION) {
     throw new Error(

packages/core/src/registry/types.ts

@@ -1008,6 +1008,20 @@ export type Capabilities = {
    * are non-leaf scene containers.
    */
   presettable?: boolean
+  /**
+   * Instances of this kind are created by operating a build tool and
+   * drawing on the grid (clicking points), rather than dropping a
+   * finished instance. The tool id equals the node `type`. Host apps may
+   * seed the tool's starting parameters via
+   * `useEditor.setToolDefaults(type, params)` before activating it — the
+   * tool's create path merges those defaults when minting the node and
+   * clears its own entry on deactivation. Used so placing a saved preset
+   * of a drawn kind contributes its build parameters (a fence's
+   * height / style / post spacing) while the user draws the fresh span,
+   * and so a future "small / medium / large" picker can prime the same
+   * tool. Read via the `isDrawnViaTool(def)` helper. Default `false`.
+   */
+  drawTool?: boolean
 }
 
 /**