feat(mcp): add guided construction workflows

packages/mcp/src/prompts/from-brief.ts

@@ -1,17 +1,20 @@
 import type { McpServer } from '@modelcontextprotocol/sdk/server/mcp.js'
 import { z } from 'zod'
 import type { SceneBridge } from '../bridge/scene-bridge'
+import { SCENE_DESIGN_GUIDANCE } from './scene-guidance'
 
 const PREAMBLE = [
   'You are a Pascal 3D scene designer.',
-  'You have access to the `apply_patch` tool for all scene mutations. Prefer it over individual create_* tools so that your changes land as a single undoable step.',
-  'Build incrementally. Starting from an empty scene, first create a Site, then a Building, then one or more Levels; only after that do you create walls, zones, slabs, items, and openings.',
+  'You have access to semantic scene tools and the lower-level `apply_patch` tool. Prefer semantic construction/room/opening/furnishing tools for architectural work, and use `apply_patch` for bulk graph edits that need exact control.',
+  'Build incrementally with visible progress. Starting from an empty scene, first create/load a Site and Building, then create occupied Levels and `create_story_shell` once per story before detailed rooms, openings, furniture, a dedicated roof level via `create_roof`, and landscaping.',
   'Respect these invariants:',
   '  - Levels live under a Building.',
   '  - Walls, fences, zones, slabs, ceilings, roofs, stairs live under a Level.',
+  '  - Multi-story exterior walls are per-level story walls; never make lower-level walls taller to stand in for upper-level walls.',
   '  - Doors and windows live under a Wall (parentId = wallId).',
-  '  - Items live under a Wall, Ceiling, or Site.',
+  '  - Floor items live under a Level; wall/ceiling-attached items live under their target Wall or Ceiling; outdoor items can live under a Site.',
   'Use realistic dimensions in meters. Keep wall thickness small (0.1–0.3 m) and ceiling height 2.4–3.0 m unless the brief dictates otherwise.',
+  SCENE_DESIGN_GUIDANCE,
   'Respond ONLY with tool calls. Do not produce verbose narrative or prose; keep any explanations in short tool-call arguments.',
 ].join('\n')
 
@@ -29,7 +32,7 @@ export function buildFromBriefPrompt(args: {
   parts.push(
     '',
     '## Task',
-    'Produce a plan of `apply_patch` calls that realises the brief within the stated constraints. Start from an empty site. Call the vision / query tools only if you need extra context.',
+    'Produce tool calls that realise the brief within the stated constraints. Start from an empty site. Prefer create_story_shell/create_room/add_door/add_window/create_stair_between_levels/create_roof/furnish_room for architectural layout, use apply_patch for exact bulk graph work, and call validate_scene plus verify_scene after complex layouts.',
   )
   return parts.join('\n')
 }