docs(mcp): add 10-agent research on scene-save workflow

10 parallel research agents (R1-R10) investigated whether MCP can save
scenes as saveable entities that the user later opens in the editor —
rather than injecting via a dev-only window.__pascalScene hook.

Key findings:
- Editor is already backend-agnostic via onLoad/onSave callbacks (R2,R7)
- Current persistence is localStorage-only, single key (R1)
- Zero dynamic routes and no backend code yet — env declared (R4,R5)
- File import exists as "Load Build" but lacks Zod validation (R6)
- MCP-written scenes load cleanly into the editor today (R6, Casa del
  Sol test already proved this)
- Best path: filesystem-handoff this week, Supabase in weeks 2-4,
  Supabase Realtime for live mode in Q2. Skip Yjs for now. (R8)
- 4-5 weeks to private beta, 10-14 to GA (R9)
- 10 high-value ideas ranked; "photo -> scene" is the unblocker (R10)

SYNTHESIS.md pulls all 10 reports together with the recommended
implementation plan.

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

packages/mcp/test-reports/research/R7-editor-api.md

@@ -0,0 +1,46 @@
+# R7 — `@pascal-app/editor` public API
+
+## Exports (packages/editor/src/index.tsx)
+**Components:** `Editor` (default), `SettingsPanel`, `SitePanel`, `FloatingLevelSelector`, `SceneLoader`, `ViewerToolbarLeft`, `ViewerToolbarRight`, `Slider`, `SliderControl`
+**Hooks/Stores:** `useEditor`, `useCommandRegistry`, `useSidebarStore`, `useUploadStore`, `useAudio`, `usePaletteViewRegistry`, `useCommandPalette`
+**Utilities:** `applySceneGraphToEditor`, `SceneGraph` (type), `CATALOG_ITEMS`, `PresetsProvider`, `PresetsAdapter` (type)
+
+## `<Editor>` host integration points
+
+| Prop | Signature | Trigger | Host opportunity |
+|---|---|---|---|
+| `onLoad` | `() => Promise<SceneGraph \| null>` | Mount + `onLoad` identity change | Fetch scene by id from backend |
+| `onSave` | `(scene) => Promise<void>` | 1s debounce + `beforeunload` | Persist to backend |
+| `onDirty` | `() => void` | First edit after save | Show "unsaved" badge |
+| `onSaveStatusChange` | `(status) => void` | `idle/pending/saving/saved/paused/error` | Top-bar status indicator |
+| `onThumbnailCapture` | `(blob, cameraData) => void` | ~10s idle after camera/scene stable, 1920×1080 SSGI | Upload to cloud, use in scene list |
+| `appMenuButton`, `sidebarTop`, `navbarSlot`, `viewerToolbarLeft`, `viewerToolbarRight`, `sidebarOverlay`, `viewerBanner` | `ReactNode` | Render slots | **Drop in a "Scene picker"** |
+| `settingsPanelProps.onVisibilityChange` | `(visible) => void` | User toggles project visibility | Project-level permissions |
+| `sitePanelProps.onUploadAsset` | `(projectId, levelId, file, type)` | Scan/guide image upload | S3/Supabase Storage |
+| `sitePanelProps.onDeleteAsset` | `(projectId, url)` | User deletes scan/guide | Clean up backend |
+| `presetsAdapter` | `PresetsAdapter` | Preset CRUD | Replace localStorage with backend-backed presets |
+| `commandPaletteEmptyAction` | fn | No-match search | Route to AI / search |
+| `extraSidebarPanels` | `ExtraPanel[]` | Always visible | Add "Saved scenes" panel |
+
+## Sidebar slots suited for a scene switcher
+- **Layout v1:** `appMenuButton` (top-left) or `sidebarTop` (above tabs)
+- **Layout v2:** `navbarSlot` (full-width top nav)
+- **Both:** `extraSidebarPanels` to add a dedicated "Scenes" tab
+
+## Command palette extension
+```ts
+useCommandRegistry().register([
+  { id: 'editor.scene.open', label: 'Open scene…', group: 'Scene', execute: () => setShowSceneList(true) },
+  { id: 'editor.scene.new', label: 'New scene', group: 'Scene', shortcut: ['Meta', 'N'], execute: createNewScene },
+  { id: 'editor.scene.save-as', label: 'Save as…', group: 'Scene', execute: saveAs },
+])
+```
+
+## Effort to ship a minimal scene switcher inside this package
+- Add `extraSidebarPanels` consumer that takes a `scenes: SceneMeta[]` + `onOpen(id)` + `onDelete(id)` + `onCreate()` — ~150 lines.
+- Wire three palette commands — ~50 lines.
+- Consume `onThumbnailCapture` in the example host to populate list thumbnails — ~30 lines host-side.
+- **Total ≈ 1–2 days** for an in-editor scene browser, OR host-side if we keep the Editor scene-agnostic.
+
+## Verdict
+The Editor's architecture is **backend-agnostic by design**. Every persistence decision is a host callback. Implementing the user's vision is 100% about wiring up what already exists — no Editor refactor needed.