diff --git a/packages/mcp/src/prompts/from-brief.ts b/packages/mcp/src/prompts/from-brief.ts
new file mode 100644
index 00000000..f409757b
--- /dev/null
+++ b/packages/mcp/src/prompts/from-brief.ts
@@ -0,0 +1,61 @@
+import type { McpServer } from '@modelcontextprotocol/sdk/server/mcp.js'
+import { z } from 'zod'
+import type { SceneBridge } from '../bridge/scene-bridge'
+
+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.',
+  'Respect these invariants:',
+  '  - Levels live under a Building.',
+  '  - Walls, fences, zones, slabs, ceilings, roofs, stairs live under a Level.',
+  '  - Doors and windows live under a Wall (parentId = wallId).',
+  '  - Items live under a Wall, Ceiling, or 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.',
+  'Respond ONLY with tool calls. Do not produce verbose narrative or prose; keep any explanations in short tool-call arguments.',
+].join('\n')
+
+/**
+ * Build the user-facing prompt text for `from_brief`. Pure function for testability.
+ */
+export function buildFromBriefPrompt(args: {
+  brief: string
+  constraints?: string | undefined
+}): string {
+  const parts: string[] = [PREAMBLE, '', '## Brief', args.brief.trim()]
+  if (args.constraints && args.constraints.trim().length > 0) {
+    parts.push('', '## Constraints', args.constraints.trim())
+  }
+  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.',
+  )
+  return parts.join('\n')
+}
+
+export function registerFromBrief(server: McpServer, _bridge: SceneBridge): void {
+  server.registerPrompt(
+    'from_brief',
+    {
+      title: 'Generate a Pascal scene from a brief',
+      description:
+        'Produces a plan of apply_patch calls to create a scene from a natural-language brief.',
+      argsSchema: {
+        brief: z.string(),
+        constraints: z.string().optional(),
+      },
+    },
+    async ({ brief, constraints }) => ({
+      messages: [
+        {
+          role: 'user',
+          content: {
+            type: 'text',
+            text: buildFromBriefPrompt({ brief, constraints }),
+          },
+        },
+      ],
+    }),
+  )
+}
diff --git a/packages/mcp/src/prompts/index.ts b/packages/mcp/src/prompts/index.ts
new file mode 100644
index 00000000..e65d2d70
--- /dev/null
+++ b/packages/mcp/src/prompts/index.ts
@@ -0,0 +1,17 @@
+import type { McpServer } from '@modelcontextprotocol/sdk/server/mcp.js'
+import type { SceneBridge } from '../bridge/scene-bridge'
+import { registerFromBrief } from './from-brief'
+import { registerIterateOnFeedback } from './iterate-on-feedback'
+import { registerRenovationFromPhotos } from './renovation-from-photos'
+
+/**
+ * Registers all MCP prompts exposed by `@pascal-app/mcp`:
+ * - `from_brief`                — generate a scene from a natural-language brief
+ * - `iterate_on_feedback`       — minimal-diff patches from user feedback
+ * - `renovation_from_photos`    — photo-driven renovation plan via vision tools
+ */
+export function registerPrompts(server: McpServer, bridge: SceneBridge): void {
+  registerFromBrief(server, bridge)
+  registerIterateOnFeedback(server, bridge)
+  registerRenovationFromPhotos(server, bridge)
+}
diff --git a/packages/mcp/src/prompts/iterate-on-feedback.ts b/packages/mcp/src/prompts/iterate-on-feedback.ts
new file mode 100644
index 00000000..ecf52d04
--- /dev/null
+++ b/packages/mcp/src/prompts/iterate-on-feedback.ts
@@ -0,0 +1,47 @@
+import type { McpServer } from '@modelcontextprotocol/sdk/server/mcp.js'
+import { z } from 'zod'
+import type { SceneBridge } from '../bridge/scene-bridge'
+
+const PREAMBLE = [
+  'You are iterating on an existing Pascal scene based on user feedback.',
+  'Given the current state (read via the `pascal://scene/current` resource) and the user feedback below, propose the MINIMUM set of `apply_patch` operations that satisfies the feedback.',
+  'Rules:',
+  '  - Prefer updates over create+delete pairs when a field change will do.',
+  '  - Do not re-create nodes that already exist.',
+  '  - Do not touch nodes that are unrelated to the feedback.',
+  '  - Bundle related mutations into a single `apply_patch` call so they share one undo step.',
+  '  - Respond ONLY with tool calls. No prose.',
+].join('\n')
+
+/**
+ * Build the user-facing prompt text for `iterate_on_feedback`.
+ * Pure function for testability.
+ */
+export function buildIterateOnFeedbackPrompt(args: { feedback: string }): string {
+  return [PREAMBLE, '', '## User feedback', args.feedback.trim()].join('\n')
+}
+
+export function registerIterateOnFeedback(server: McpServer, _bridge: SceneBridge): void {
+  server.registerPrompt(
+    'iterate_on_feedback',
+    {
+      title: 'Iterate on a scene from user feedback',
+      description:
+        'Produces a minimal-diff plan of apply_patch calls in response to user feedback on the current scene.',
+      argsSchema: {
+        feedback: z.string(),
+      },
+    },
+    async ({ feedback }) => ({
+      messages: [
+        {
+          role: 'user',
+          content: {
+            type: 'text',
+            text: buildIterateOnFeedbackPrompt({ feedback }),
+          },
+        },
+      ],
+    }),
+  )
+}
diff --git a/packages/mcp/src/prompts/prompts.test.ts b/packages/mcp/src/prompts/prompts.test.ts
new file mode 100644
index 00000000..31d65a55
--- /dev/null
+++ b/packages/mcp/src/prompts/prompts.test.ts
@@ -0,0 +1,220 @@
+// Side-effect import MUST come first: installs RAF polyfill before core loads.
+import '../bridge/node-shims'
+
+import { beforeEach, describe, expect, test } from 'bun:test'
+import { Client } from '@modelcontextprotocol/sdk/client/index.js'
+import { InMemoryTransport } from '@modelcontextprotocol/sdk/inMemory.js'
+import { McpServer } from '@modelcontextprotocol/sdk/server/mcp.js'
+import useScene from '@pascal-app/core/store'
+import { SceneBridge } from '../bridge/scene-bridge'
+import { buildFromBriefPrompt, registerFromBrief } from './from-brief'
+import { buildIterateOnFeedbackPrompt, registerIterateOnFeedback } from './iterate-on-feedback'
+import { buildRenovationMessages, registerRenovationFromPhotos } from './renovation-from-photos'
+
+type ClientServerPair = {
+  client: Client
+  server: McpServer
+  bridge: SceneBridge
+  close: () => Promise<void>
+}
+
+async function spinUp(
+  register: (server: McpServer, bridge: SceneBridge) => void,
+): Promise<ClientServerPair> {
+  const bridge = new SceneBridge()
+  const server = new McpServer({ name: 'test', version: '0.0.0' })
+  register(server, bridge)
+  const client = new Client({ name: 'test-client', version: '0.0.0' })
+  const [clientTransport, serverTransport] = InMemoryTransport.createLinkedPair()
+  await Promise.all([server.connect(serverTransport), client.connect(clientTransport)])
+  return {
+    client,
+    server,
+    bridge,
+    close: async () => {
+      await client.close()
+      await server.close()
+    },
+  }
+}
+
+function resetScene(): void {
+  useScene.getState().unloadScene()
+  useScene.temporal.getState().clear()
+}
+
+describe('from_brief', () => {
+  beforeEach(() => resetScene())
+
+  test('includes brief in the returned user message', async () => {
+    const pair = await spinUp(registerFromBrief)
+    try {
+      const res = await pair.client.getPrompt({
+        name: 'from_brief',
+        arguments: { brief: 'A 60 sqm studio with a kitchenette' },
+      })
+      expect(res.messages).toHaveLength(1)
+      const m = res.messages[0]
+      expect(m).toBeDefined()
+      if (!m) return
+      expect(m.role).toBe('user')
+      expect(m.content.type).toBe('text')
+      if (m.content.type === 'text') {
+        expect(m.content.text).toContain('60 sqm studio')
+        expect(m.content.text).toContain('apply_patch')
+      }
+    } finally {
+      await pair.close()
+    }
+  })
+
+  test('appends constraints section when provided', async () => {
+    const pair = await spinUp(registerFromBrief)
+    try {
+      const res = await pair.client.getPrompt({
+        name: 'from_brief',
+        arguments: {
+          brief: 'Tiny house',
+          constraints: 'footprint under 40 sqm',
+        },
+      })
+      const m = res.messages[0]
+      expect(m).toBeDefined()
+      if (!m) return
+      if (m.content.type === 'text') {
+        expect(m.content.text).toContain('## Constraints')
+        expect(m.content.text).toContain('footprint under 40 sqm')
+      }
+    } finally {
+      await pair.close()
+    }
+  })
+
+  test('buildFromBriefPrompt omits constraints section when empty', () => {
+    const text = buildFromBriefPrompt({ brief: 'Studio', constraints: '' })
+    expect(text).not.toContain('## Constraints')
+    expect(text).toContain('Studio')
+  })
+})
+
+describe('iterate_on_feedback', () => {
+  beforeEach(() => resetScene())
+
+  test('returns single user message referencing the feedback and the scene resource', async () => {
+    const pair = await spinUp(registerIterateOnFeedback)
+    try {
+      const res = await pair.client.getPrompt({
+        name: 'iterate_on_feedback',
+        arguments: { feedback: 'Move the fridge to the opposite wall' },
+      })
+      expect(res.messages).toHaveLength(1)
+      const m = res.messages[0]
+      expect(m).toBeDefined()
+      if (!m) return
+      expect(m.role).toBe('user')
+      if (m.content.type === 'text') {
+        expect(m.content.text).toContain('Move the fridge')
+        expect(m.content.text).toContain('pascal://scene/current')
+        expect(m.content.text).toContain('apply_patch')
+      }
+    } finally {
+      await pair.close()
+    }
+  })
+
+  test('buildIterateOnFeedbackPrompt emphasises minimal diff', () => {
+    const text = buildIterateOnFeedbackPrompt({ feedback: 'x' })
+    expect(text.toLowerCase()).toContain('minimum')
+  })
+})
+
+describe('renovation_from_photos', () => {
+  beforeEach(() => resetScene())
+
+  test('parses JSON-array photo lists and emits image/text content', async () => {
+    const pair = await spinUp(registerRenovationFromPhotos)
+    try {
+      const longBase64 = 'A'.repeat(40) // length % 4 == 0, pure base64 chars.
+      const res = await pair.client.getPrompt({
+        name: 'renovation_from_photos',
+        arguments: {
+          currentPhotos: JSON.stringify(['https://example.com/current1.jpg', longBase64]),
+          referencePhotos: JSON.stringify(['data:image/png;base64,iVBORw0K']),
+          goals: 'make it look mid-century modern',
+        },
+      })
+      expect(res.messages.length).toBeGreaterThan(1)
+
+      // Intro text should mention goals + counts.
+      const intro = res.messages[0]
+      expect(intro).toBeDefined()
+      if (!intro) return
+      if (intro.content.type !== 'text') throw new Error('intro not text')
+      expect(intro.content.text).toContain('mid-century modern')
+      expect(intro.content.text).toContain('Current photos: 2')
+      expect(intro.content.text).toContain('Reference photos: 1')
+
+      // There should be at least one image content (from the base64) and one
+      // URL text fallback (from the https URL).
+      const kinds = res.messages.map((m) => m.content.type)
+      expect(kinds).toContain('image')
+      const textMessages = res.messages.filter((m) => m.content.type === 'text')
+      const hasUrlFallback = textMessages.some(
+        (m) => m.content.type === 'text' && m.content.text.startsWith('URL: https://'),
+      )
+      expect(hasUrlFallback).toBe(true)
+
+      // Final message should be a task directive.
+      const last = res.messages[res.messages.length - 1]
+      expect(last).toBeDefined()
+      if (!last) return
+      if (last.content.type === 'text') {
+        expect(last.content.text).toContain('## Task')
+        expect(last.content.text).toContain('apply_patch')
+      }
+    } finally {
+      await pair.close()
+    }
+  })
+
+  test('data-URL with explicit mimeType becomes image content', () => {
+    const messages = buildRenovationMessages({
+      currentPhotos: JSON.stringify(['data:image/png;base64,aGVsbG8='] as string[]),
+      referencePhotos: '[]',
+      goals: 'test',
+    })
+    const imageMsg = messages.find((m) => m.content.type === 'image')
+    expect(imageMsg).toBeDefined()
+    if (imageMsg && imageMsg.content.type === 'image') {
+      expect(imageMsg.content.mimeType).toBe('image/png')
+      expect(imageMsg.content.data).toBe('aGVsbG8=')
+    }
+  })
+
+  test('comma-separated fallback parses a list correctly', () => {
+    const messages = buildRenovationMessages({
+      currentPhotos: 'https://a.example/1.jpg, https://b.example/2.jpg',
+      referencePhotos: '',
+      goals: 'test',
+    })
+    const urlTextMsgs = messages.filter(
+      (m) => m.content.type === 'text' && m.content.text.startsWith('URL: https://'),
+    )
+    expect(urlTextMsgs.length).toBe(2)
+  })
+
+  test('empty lists produce no per-photo sections but still include task directive', () => {
+    const messages = buildRenovationMessages({
+      currentPhotos: '',
+      referencePhotos: '',
+      goals: 'nothing to do',
+    })
+    // 1 intro + 1 task = 2 messages.
+    expect(messages.length).toBe(2)
+    const last = messages[messages.length - 1]
+    expect(last).toBeDefined()
+    if (last && last.content.type === 'text') {
+      expect(last.content.text).toContain('## Task')
+    }
+  })
+})
diff --git a/packages/mcp/src/prompts/renovation-from-photos.ts b/packages/mcp/src/prompts/renovation-from-photos.ts
new file mode 100644
index 00000000..b177ccd5
--- /dev/null
+++ b/packages/mcp/src/prompts/renovation-from-photos.ts
@@ -0,0 +1,160 @@
+import type { McpServer } from '@modelcontextprotocol/sdk/server/mcp.js'
+import { z } from 'zod'
+import type { SceneBridge } from '../bridge/scene-bridge'
+
+const PREAMBLE = [
+  'You are renovating an existing room based on photos of the current space and reference photos of the target aesthetic.',
+  '',
+  'Follow this procedure:',
+  '  1. Call `analyze_floorplan_image` and/or `analyze_room_photo` on EACH current photo to extract walls, rooms, fixtures, and approximate dimensions. Do the same for reference photos.',
+  '  2. Compare the current-state analyses to the reference-state analyses. Identify concrete deltas (materials, fixtures, layout changes) that align with the renovation goals.',
+  '  3. Emit a single `apply_patch` call containing the minimum set of patches needed to converge the current scene toward the goals.',
+  '',
+  'Rules:',
+  '  - Do not invent dimensions. Pull them from the analysis tool results.',
+  '  - Do not modify nodes that are unrelated to the goals.',
+  '  - Respond ONLY with tool calls. No prose.',
+].join('\n')
+
+function isDataUrl(s: string): boolean {
+  return s.startsWith('data:')
+}
+function isHttpUrl(s: string): boolean {
+  return s.startsWith('http://') || s.startsWith('https://')
+}
+/**
+ * Rough base64 detector: length multiple of 4, only base64 chars, at least 32 chars long.
+ * Deliberately conservative — when in doubt we fall back to text `URL: ...`.
+ */
+function looksLikeBase64(s: string): boolean {
+  if (s.length < 32) return false
+  if (s.length % 4 !== 0) return false
+  return /^[A-Za-z0-9+/=]+$/.test(s)
+}
+
+type PromptContent =
+  | { type: 'text'; text: string }
+  | { type: 'image'; data: string; mimeType: string }
+
+/** Extract a base64 payload from a data-URL, or return the raw string. */
+function toImageContent(source: string): PromptContent {
+  if (isDataUrl(source)) {
+    const match = /^data:([^;,]+)?(?:;base64)?,(.*)$/.exec(source)
+    if (match) {
+      const mimeType = match[1] && match[1].length > 0 ? match[1] : 'image/jpeg'
+      const data = match[2] ?? ''
+      return { type: 'image', data, mimeType }
+    }
+    return { type: 'text', text: `URL: ${source}` }
+  }
+  if (isHttpUrl(source)) {
+    return { type: 'text', text: `URL: ${source}` }
+  }
+  if (looksLikeBase64(source)) {
+    return { type: 'image', data: source, mimeType: 'image/jpeg' }
+  }
+  return { type: 'text', text: `URL: ${source}` }
+}
+
+/** Parse the stringified list argument (JSON array or comma-separated fallback). */
+function parsePhotoList(raw: string | string[] | undefined): string[] {
+  if (Array.isArray(raw)) {
+    return raw.map((s) => String(s)).filter((s) => s.length > 0)
+  }
+  const str = (raw ?? '').trim()
+  if (str.length === 0) return []
+  if (str.startsWith('[')) {
+    try {
+      const parsed = JSON.parse(str)
+      if (Array.isArray(parsed)) {
+        return parsed.map((s) => String(s)).filter((s) => s.length > 0)
+      }
+    } catch {
+      /* fall through to comma-split */
+    }
+  }
+  return str
+    .split(',')
+    .map((s) => s.trim())
+    .filter((s) => s.length > 0)
+}
+
+/**
+ * Build the full messages array. Pure function for testability.
+ */
+export function buildRenovationMessages(args: {
+  currentPhotos: string[] | string | undefined
+  referencePhotos: string[] | string | undefined
+  goals: string
+}): Array<{
+  role: 'user'
+  content: PromptContent
+}> {
+  const current = parsePhotoList(args.currentPhotos)
+  const reference = parsePhotoList(args.referencePhotos)
+
+  const intro = [
+    PREAMBLE,
+    '',
+    '## Goals',
+    args.goals.trim(),
+    '',
+    '## Inputs',
+    `Current photos: ${current.length} item(s)`,
+    `Reference photos: ${reference.length} item(s)`,
+  ].join('\n')
+
+  const messages: Array<{ role: 'user'; content: PromptContent }> = [
+    { role: 'user', content: { type: 'text', text: intro } },
+  ]
+
+  if (current.length > 0) {
+    messages.push({
+      role: 'user',
+      content: { type: 'text', text: '## Current photos' },
+    })
+    for (const src of current) {
+      messages.push({ role: 'user', content: toImageContent(src) })
+    }
+  }
+  if (reference.length > 0) {
+    messages.push({
+      role: 'user',
+      content: { type: 'text', text: '## Reference photos' },
+    })
+    for (const src of reference) {
+      messages.push({ role: 'user', content: toImageContent(src) })
+    }
+  }
+
+  messages.push({
+    role: 'user',
+    content: {
+      type: 'text',
+      text: '## Task\nProduce `apply_patch` operations that drive the current scene toward the goals, using only dimensions and fixtures you derived from the analysis tools.',
+    },
+  })
+
+  return messages
+}
+
+export function registerRenovationFromPhotos(server: McpServer, _bridge: SceneBridge): void {
+  server.registerPrompt(
+    'renovation_from_photos',
+    {
+      title: 'Plan a renovation from photos',
+      description:
+        'Plan a minimal-patch renovation given current-state photos, reference-state photos, and free-form goals.',
+      argsSchema: {
+        // MCP prompt arguments are stringly-typed; accept a JSON array or a
+        // comma-separated list of base64 payloads / data URLs / http(s) URLs.
+        currentPhotos: z.string(),
+        referencePhotos: z.string(),
+        goals: z.string(),
+      },
+    },
+    async ({ currentPhotos, referencePhotos, goals }) => ({
+      messages: buildRenovationMessages({ currentPhotos, referencePhotos, goals }),
+    }),
+  )
+}
diff --git a/packages/mcp/src/resources/catalog-items.ts b/packages/mcp/src/resources/catalog-items.ts
new file mode 100644
index 00000000..6b7da031
--- /dev/null
+++ b/packages/mcp/src/resources/catalog-items.ts
@@ -0,0 +1,39 @@
+import type { McpServer } from '@modelcontextprotocol/sdk/server/mcp.js'
+import type { SceneBridge } from '../bridge/scene-bridge'
+
+/**
+ * `pascal://catalog/items` — item catalog (if the host supplies one).
+ *
+ * `@pascal-app/core` does NOT expose a runtime item catalog — that is the host
+ * app's responsibility. In headless / standalone MCP mode we therefore return
+ * a stable, machine-readable "unavailable" payload so agents can detect this
+ * and fall back to free-form item creation.
+ */
+export function registerCatalogItems(server: McpServer, _bridge: SceneBridge): void {
+  server.registerResource(
+    'catalog-items',
+    'pascal://catalog/items',
+    {
+      title: 'Item catalog',
+      description:
+        'Catalog of placeable items. Not available in core; the host app is expected to override this resource when it has a catalog.',
+      mimeType: 'application/json',
+    },
+    async (uri) => {
+      const payload = {
+        status: 'catalog_unavailable' as const,
+        items: [] as never[],
+        note: '@pascal-app/core does not ship a runtime item catalog; the host app is expected to provide one by overriding this resource.',
+      }
+      return {
+        contents: [
+          {
+            uri: uri.href,
+            mimeType: 'application/json',
+            text: JSON.stringify(payload),
+          },
+        ],
+      }
+    },
+  )
+}
diff --git a/packages/mcp/src/resources/constraints.ts b/packages/mcp/src/resources/constraints.ts
new file mode 100644
index 00000000..fa586b35
--- /dev/null
+++ b/packages/mcp/src/resources/constraints.ts
@@ -0,0 +1,100 @@
+import type { McpServer } from '@modelcontextprotocol/sdk/server/mcp.js'
+import { ResourceTemplate } from '@modelcontextprotocol/sdk/server/mcp.js'
+import type { AnyNode, SlabNode, WallNode } from '@pascal-app/core/schema'
+import { getWallPlanFootprint } from '@pascal-app/core/wall'
+import type { SceneBridge } from '../bridge/scene-bridge'
+
+type WallFootprint = {
+  wallId: string
+  footprint: Array<[number, number]>
+}
+
+type ConstraintsPayload = {
+  levelId: string
+  slabs: SlabNode[]
+  wallPolygons: WallFootprint[]
+}
+
+type ConstraintsError = {
+  error: 'level_not_found'
+  levelId: string
+  slabs: never[]
+  wallPolygons: never[]
+}
+
+/**
+ * Empty `WallMiterData` — we don't compute junctions here. The footprint
+ * falls back to a simple rectangle based on start/end + thickness, which is
+ * correct for non-intersecting walls and an acceptable approximation for
+ * constraint hints.
+ *
+ * Typed via `Parameters<typeof getWallPlanFootprint>[1]` to avoid `any` and
+ * to stay in sync with the core signature.
+ */
+const EMPTY_MITER_DATA: Parameters<typeof getWallPlanFootprint>[1] = {
+  junctionData: new Map(),
+  junctions: new Map(),
+}
+
+function buildPayload(bridge: SceneBridge, levelId: string): ConstraintsPayload | ConstraintsError {
+  const level = bridge.getNode(levelId as never)
+  if (!level || level.type !== 'level') {
+    return {
+      error: 'level_not_found',
+      levelId,
+      slabs: [] as never[],
+      wallPolygons: [] as never[],
+    }
+  }
+
+  const all = bridge.findNodes({ levelId: levelId as never })
+  const slabs: SlabNode[] = []
+  const walls: WallNode[] = []
+  for (const n of all as AnyNode[]) {
+    if (n.type === 'slab') slabs.push(n as SlabNode)
+    else if (n.type === 'wall') walls.push(n as WallNode)
+  }
+
+  const wallPolygons: WallFootprint[] = []
+  for (const wall of walls) {
+    const points = getWallPlanFootprint(wall, EMPTY_MITER_DATA)
+    wallPolygons.push({
+      wallId: wall.id,
+      footprint: points.map((p) => [p.x, p.y] as [number, number]),
+    })
+  }
+
+  return { levelId, slabs, wallPolygons }
+}
+
+/**
+ * `pascal://constraints/{levelId}` — per-level geometric constraints used as
+ * input hints for agents: slab nodes (with polygons/holes/elevation) + each
+ * wall's plan-view footprint polygon.
+ */
+export function registerConstraints(server: McpServer, bridge: SceneBridge): void {
+  server.registerResource(
+    'constraints',
+    new ResourceTemplate('pascal://constraints/{levelId}', { list: undefined }),
+    {
+      title: 'Level constraints',
+      description:
+        'Per-level constraints: slab nodes and wall plan footprints. Returns {error:"level_not_found"} if the level id is unknown.',
+      mimeType: 'application/json',
+    },
+    async (uri, variables) => {
+      const rawLevelId = variables.levelId
+      const levelId = Array.isArray(rawLevelId) ? rawLevelId[0] : rawLevelId
+      const payload = buildPayload(bridge, levelId ?? '')
+      return {
+        contents: [
+          {
+            uri: uri.href,
+            mimeType: 'application/json',
+            text: JSON.stringify(payload),
+          },
+        ],
+      }
+    },
+  )
+}
diff --git a/packages/mcp/src/resources/index.ts b/packages/mcp/src/resources/index.ts
new file mode 100644
index 00000000..583c5082
--- /dev/null
+++ b/packages/mcp/src/resources/index.ts
@@ -0,0 +1,22 @@
+import type { McpServer } from '@modelcontextprotocol/sdk/server/mcp.js'
+import type { SceneBridge } from '../bridge/scene-bridge'
+import { registerCatalogItems } from './catalog-items'
+import { registerConstraints } from './constraints'
+import { registerSceneCurrent } from './scene-current'
+import { registerSceneSummary } from './scene-summary'
+
+/**
+ * Registers all MCP resources exposed by `@pascal-app/mcp`.
+ *
+ * Resources:
+ * - `pascal://scene/current`          — application/json, full snapshot
+ * - `pascal://scene/current/summary`  — text/markdown, human summary
+ * - `pascal://catalog/items`          — application/json, host-supplied catalog
+ * - `pascal://constraints/{levelId}`  — application/json, per-level constraints
+ */
+export function registerResources(server: McpServer, bridge: SceneBridge): void {
+  registerSceneCurrent(server, bridge)
+  registerSceneSummary(server, bridge)
+  registerCatalogItems(server, bridge)
+  registerConstraints(server, bridge)
+}
diff --git a/packages/mcp/src/resources/resources.test.ts b/packages/mcp/src/resources/resources.test.ts
new file mode 100644
index 00000000..c2277572
--- /dev/null
+++ b/packages/mcp/src/resources/resources.test.ts
@@ -0,0 +1,260 @@
+// Side-effect import MUST come first: installs RAF polyfill before core loads.
+import '../bridge/node-shims'
+
+import { beforeEach, describe, expect, test } from 'bun:test'
+import { Client } from '@modelcontextprotocol/sdk/client/index.js'
+import { InMemoryTransport } from '@modelcontextprotocol/sdk/inMemory.js'
+import { McpServer } from '@modelcontextprotocol/sdk/server/mcp.js'
+import { WallNode, ZoneNode } from '@pascal-app/core/schema'
+import useScene from '@pascal-app/core/store'
+import { SceneBridge } from '../bridge/scene-bridge'
+import { registerCatalogItems } from './catalog-items'
+import { registerConstraints } from './constraints'
+import { registerSceneCurrent } from './scene-current'
+import { registerSceneSummary } from './scene-summary'
+
+type ClientServerPair = {
+  client: Client
+  server: McpServer
+  bridge: SceneBridge
+  close: () => Promise<void>
+}
+
+async function spinUp(
+  register: (server: McpServer, bridge: SceneBridge) => void,
+): Promise<ClientServerPair> {
+  const bridge = new SceneBridge()
+  const server = new McpServer({ name: 'test', version: '0.0.0' })
+  register(server, bridge)
+  const client = new Client({ name: 'test-client', version: '0.0.0' })
+  const [clientTransport, serverTransport] = InMemoryTransport.createLinkedPair()
+  await Promise.all([server.connect(serverTransport), client.connect(clientTransport)])
+  return {
+    client,
+    server,
+    bridge,
+    close: async () => {
+      await client.close()
+      await server.close()
+    },
+  }
+}
+
+/** Reset the store between tests so temporal history and nodes don't leak. */
+function resetScene(): void {
+  useScene.getState().unloadScene()
+  useScene.temporal.getState().clear()
+}
+
+describe('pascal://scene/current', () => {
+  beforeEach(() => resetScene())
+
+  test('returns the full scene JSON', async () => {
+    const pair = await spinUp(registerSceneCurrent)
+    try {
+      pair.bridge.loadDefault()
+      const res = await pair.client.readResource({ uri: 'pascal://scene/current' })
+      expect(res.contents).toHaveLength(1)
+      const content = res.contents[0]
+      expect(content).toBeDefined()
+      const c = content as { uri: string; mimeType?: string; text?: string }
+      expect(c.mimeType).toBe('application/json')
+      expect(c.uri).toBe('pascal://scene/current')
+      const parsed = JSON.parse(c.text ?? '{}')
+      expect(parsed).toHaveProperty('nodes')
+      expect(parsed).toHaveProperty('rootNodeIds')
+      expect(parsed).toHaveProperty('collections')
+      expect(Array.isArray(parsed.rootNodeIds)).toBe(true)
+      expect(parsed.rootNodeIds.length).toBeGreaterThan(0)
+    } finally {
+      await pair.close()
+    }
+  })
+
+  test('reflects mutations to the store', async () => {
+    const pair = await spinUp(registerSceneCurrent)
+    try {
+      pair.bridge.loadDefault()
+      const beforeRes = await pair.client.readResource({
+        uri: 'pascal://scene/current',
+      })
+      const beforeText = (beforeRes.contents[0] as { text: string }).text
+      const before = JSON.parse(beforeText)
+      const beforeCount = Object.keys(before.nodes).length
+
+      // Add a zone.
+      const level = pair.bridge
+        .findNodes({ type: 'level' as never })
+        .find((n) => n.type === 'level')
+      if (!level) throw new Error('no level')
+      const zone = ZoneNode.parse({
+        name: 'Living',
+        parentId: level.id,
+        polygon: [
+          [0, 0],
+          [3, 0],
+          [3, 3],
+          [0, 3],
+        ],
+      })
+      pair.bridge.createNode(zone, level.id as never)
+
+      const afterRes = await pair.client.readResource({
+        uri: 'pascal://scene/current',
+      })
+      const afterText = (afterRes.contents[0] as { text: string }).text
+      const after = JSON.parse(afterText)
+      expect(Object.keys(after.nodes).length).toBe(beforeCount + 1)
+    } finally {
+      await pair.close()
+    }
+  })
+})
+
+describe('pascal://scene/current/summary', () => {
+  beforeEach(() => resetScene())
+
+  test('returns markdown with counts and bbox', async () => {
+    const pair = await spinUp(registerSceneSummary)
+    try {
+      pair.bridge.loadDefault()
+      const res = await pair.client.readResource({
+        uri: 'pascal://scene/current/summary',
+      })
+      const content = res.contents[0] as { uri: string; mimeType?: string; text?: string }
+      expect(content.mimeType).toBe('text/markdown')
+      const text = content.text ?? ''
+      expect(text.startsWith('# Scene summary')).toBe(true)
+      expect(text).toContain('Sites:')
+      expect(text).toContain('Buildings:')
+      expect(text).toContain('Levels:')
+      expect(text).toContain('Scene bbox')
+    } finally {
+      await pair.close()
+    }
+  })
+
+  test('estimated floor area sums zone polygon areas', async () => {
+    const pair = await spinUp(registerSceneSummary)
+    try {
+      pair.bridge.loadDefault()
+      const level = pair.bridge
+        .findNodes({ type: 'level' as never })
+        .find((n) => n.type === 'level')
+      if (!level) throw new Error('no level')
+      const zone = ZoneNode.parse({
+        name: 'Big',
+        parentId: level.id,
+        polygon: [
+          [0, 0],
+          [4, 0],
+          [4, 3],
+          [0, 3],
+        ],
+      })
+      pair.bridge.createNode(zone, level.id as never)
+
+      const res = await pair.client.readResource({
+        uri: 'pascal://scene/current/summary',
+      })
+      const text = (res.contents[0] as { text: string }).text
+      expect(text).toContain('12.00 m^2')
+    } finally {
+      await pair.close()
+    }
+  })
+
+  test('empty scene returns a markdown skeleton without crashing', async () => {
+    const pair = await spinUp(registerSceneSummary)
+    try {
+      // deliberately do NOT call loadDefault()
+      const res = await pair.client.readResource({
+        uri: 'pascal://scene/current/summary',
+      })
+      const text = (res.contents[0] as { text: string }).text
+      expect(text.startsWith('# Scene summary')).toBe(true)
+      expect(text).toContain('Total nodes: 0')
+    } finally {
+      await pair.close()
+    }
+  })
+})
+
+describe('pascal://catalog/items', () => {
+  beforeEach(() => resetScene())
+
+  test('returns catalog_unavailable payload', async () => {
+    const pair = await spinUp(registerCatalogItems)
+    try {
+      const res = await pair.client.readResource({ uri: 'pascal://catalog/items' })
+      const content = res.contents[0] as { uri: string; mimeType?: string; text?: string }
+      expect(content.mimeType).toBe('application/json')
+      const parsed = JSON.parse(content.text ?? '{}')
+      expect(parsed.status).toBe('catalog_unavailable')
+      expect(parsed.items).toEqual([])
+      expect(typeof parsed.note).toBe('string')
+    } finally {
+      await pair.close()
+    }
+  })
+})
+
+describe('pascal://constraints/{levelId}', () => {
+  beforeEach(() => resetScene())
+
+  test('returns slabs + wall footprints for a known level', async () => {
+    const pair = await spinUp(registerConstraints)
+    try {
+      pair.bridge.loadDefault()
+      const level = pair.bridge
+        .findNodes({ type: 'level' as never })
+        .find((n) => n.type === 'level')
+      if (!level) throw new Error('no level')
+      // Add a wall so wallPolygons is non-empty.
+      const wall = WallNode.parse({
+        parentId: level.id,
+        start: [0, 0],
+        end: [4, 0],
+        thickness: 0.2,
+      })
+      pair.bridge.createNode(wall, level.id as never)
+
+      const res = await pair.client.readResource({
+        uri: `pascal://constraints/${level.id}`,
+      })
+      const content = res.contents[0] as { uri: string; mimeType?: string; text?: string }
+      expect(content.mimeType).toBe('application/json')
+      const parsed = JSON.parse(content.text ?? '{}')
+      expect(parsed.levelId).toBe(level.id)
+      expect(Array.isArray(parsed.slabs)).toBe(true)
+      expect(Array.isArray(parsed.wallPolygons)).toBe(true)
+      expect(parsed.wallPolygons.length).toBe(1)
+      expect(parsed.wallPolygons[0].wallId).toBe(wall.id)
+      expect(Array.isArray(parsed.wallPolygons[0].footprint)).toBe(true)
+      expect(parsed.wallPolygons[0].footprint.length).toBeGreaterThan(0)
+      // Each footprint point should be [x, y].
+      for (const pt of parsed.wallPolygons[0].footprint) {
+        expect(pt).toHaveLength(2)
+      }
+    } finally {
+      await pair.close()
+    }
+  })
+
+  test('returns {error:"level_not_found"} for unknown levelId', async () => {
+    const pair = await spinUp(registerConstraints)
+    try {
+      pair.bridge.loadDefault()
+      const res = await pair.client.readResource({
+        uri: 'pascal://constraints/level_nope',
+      })
+      const content = res.contents[0] as { text?: string }
+      const parsed = JSON.parse(content.text ?? '{}')
+      expect(parsed.error).toBe('level_not_found')
+      expect(parsed.slabs).toEqual([])
+      expect(parsed.wallPolygons).toEqual([])
+    } finally {
+      await pair.close()
+    }
+  })
+})
diff --git a/packages/mcp/src/resources/scene-current.ts b/packages/mcp/src/resources/scene-current.ts
new file mode 100644
index 00000000..85be0208
--- /dev/null
+++ b/packages/mcp/src/resources/scene-current.ts
@@ -0,0 +1,29 @@
+import type { McpServer } from '@modelcontextprotocol/sdk/server/mcp.js'
+import type { SceneBridge } from '../bridge/scene-bridge'
+
+/**
+ * `pascal://scene/current` — full `{ nodes, rootNodeIds, collections }` snapshot.
+ *
+ * Static URI (not a template). MIME `application/json`.
+ */
+export function registerSceneCurrent(server: McpServer, bridge: SceneBridge): void {
+  server.registerResource(
+    'scene-current',
+    'pascal://scene/current',
+    {
+      title: 'Current scene',
+      description:
+        'Complete snapshot of the live Pascal scene: nodes dict, rootNodeIds, collections.',
+      mimeType: 'application/json',
+    },
+    async (uri) => ({
+      contents: [
+        {
+          uri: uri.href,
+          mimeType: 'application/json',
+          text: JSON.stringify(bridge.exportJSON()),
+        },
+      ],
+    }),
+  )
+}
diff --git a/packages/mcp/src/resources/scene-summary.ts b/packages/mcp/src/resources/scene-summary.ts
new file mode 100644
index 00000000..b3adc646
--- /dev/null
+++ b/packages/mcp/src/resources/scene-summary.ts
@@ -0,0 +1,216 @@
+import type { McpServer } from '@modelcontextprotocol/sdk/server/mcp.js'
+import type { AnyNode, AnyNodeType } from '@pascal-app/core/schema'
+import type { SceneBridge } from '../bridge/scene-bridge'
+
+type Poly2D = ReadonlyArray<readonly [number, number]>
+
+/** Shoelace polygon area (absolute, square meters). */
+function polygonArea(poly: Poly2D): number {
+  if (!Array.isArray(poly) || poly.length < 3) return 0
+  let sum = 0
+  for (let i = 0; i < poly.length; i++) {
+    const a = poly[i]
+    const b = poly[(i + 1) % poly.length]
+    if (!a || !b) continue
+    sum += a[0] * b[1] - b[0] * a[1]
+  }
+  return Math.abs(sum) / 2
+}
+
+type BBox = {
+  min: [number, number, number]
+  max: [number, number, number]
+  empty: boolean
+}
+
+function emptyBBox(): BBox {
+  return {
+    min: [Number.POSITIVE_INFINITY, Number.POSITIVE_INFINITY, Number.POSITIVE_INFINITY],
+    max: [Number.NEGATIVE_INFINITY, Number.NEGATIVE_INFINITY, Number.NEGATIVE_INFINITY],
+    empty: true,
+  }
+}
+
+function expandBBox(bbox: BBox, x: number, y: number, z: number): void {
+  if (!Number.isFinite(x) || !Number.isFinite(y) || !Number.isFinite(z)) return
+  bbox.empty = false
+  if (x < bbox.min[0]) bbox.min[0] = x
+  if (y < bbox.min[1]) bbox.min[1] = y
+  if (z < bbox.min[2]) bbox.min[2] = z
+  if (x > bbox.max[0]) bbox.max[0] = x
+  if (y > bbox.max[1]) bbox.max[1] = y
+  if (z > bbox.max[2]) bbox.max[2] = z
+}
+
+/** Fold a node's world-relevant points into the running bbox. */
+function foldNodeIntoBBox(node: AnyNode, bbox: BBox): void {
+  // Walls / fences: 2D start/end. Treat missing y as 0.
+  if (node.type === 'wall' || node.type === 'fence') {
+    const anyNode = node as { start?: [number, number]; end?: [number, number] }
+    if (anyNode.start) expandBBox(bbox, anyNode.start[0], 0, anyNode.start[1])
+    if (anyNode.end) expandBBox(bbox, anyNode.end[0], 0, anyNode.end[1])
+    return
+  }
+  // Zone / slab / ceiling: polygon + optional holes. Treat ground plane y=0.
+  if (node.type === 'zone' || node.type === 'slab' || node.type === 'ceiling') {
+    const poly = (node as { polygon?: Array<[number, number]> }).polygon
+    if (Array.isArray(poly)) {
+      for (const p of poly) {
+        if (Array.isArray(p) && p.length >= 2) expandBBox(bbox, p[0], 0, p[1])
+      }
+    }
+    return
+  }
+  // Positioned nodes (building/item/roof/stair/scan/guide/...):
+  const pos = (node as { position?: [number, number, number] }).position
+  if (Array.isArray(pos) && pos.length >= 3) {
+    expandBBox(bbox, pos[0], pos[1], pos[2])
+  }
+}
+
+function countByType(nodes: AnyNode[]): Record<string, number> {
+  const out: Record<string, number> = {}
+  for (const n of nodes) {
+    out[n.type] = (out[n.type] ?? 0) + 1
+  }
+  return out
+}
+
+/** Build the markdown summary. Pure over the SceneGraph snapshot. */
+export function buildSceneSummaryMarkdown(snapshot: ReturnType<SceneBridge['exportJSON']>): string {
+  const { nodes, rootNodeIds } = snapshot
+  const allNodes = Object.values(nodes) as AnyNode[]
+
+  const sites = allNodes.filter((n) => n.type === 'site')
+  const buildings = allNodes.filter((n) => n.type === 'building')
+  const levels = allNodes.filter((n) => n.type === 'level')
+
+  const bbox = emptyBBox()
+  for (const n of allNodes) foldNodeIntoBBox(n, bbox)
+
+  const lines: string[] = []
+  lines.push('# Scene summary')
+  lines.push('')
+  lines.push(`- Sites: ${sites.length}  Buildings: ${buildings.length}  Levels: ${levels.length}`)
+  lines.push(`- Root nodes: ${rootNodeIds.length}`)
+  lines.push(`- Total nodes: ${allNodes.length}`)
+  lines.push('')
+
+  // Hierarchy table
+  lines.push('## Hierarchy')
+  lines.push('')
+  lines.push('| Site | Building | Level |')
+  lines.push('| --- | --- | --- |')
+  if (sites.length === 0 && buildings.length === 0 && levels.length === 0) {
+    lines.push('| _(empty scene)_ | | |')
+  } else {
+    for (const site of sites) {
+      const sName = (site as { name?: string }).name ?? site.id
+      const siteBuildings = allNodes.filter((n) => n.type === 'building' && n.parentId === site.id)
+      if (siteBuildings.length === 0) {
+        lines.push(`| ${sName} | _(none)_ | |`)
+        continue
+      }
+      for (const b of siteBuildings) {
+        const bName = (b as { name?: string }).name ?? b.id
+        const bLevels = allNodes.filter((n) => n.type === 'level' && n.parentId === b.id)
+        if (bLevels.length === 0) {
+          lines.push(`| ${sName} | ${bName} | _(none)_ |`)
+          continue
+        }
+        for (const l of bLevels) {
+          const lName = (l as { name?: string }).name ?? l.id
+          lines.push(`| ${sName} | ${bName} | ${lName} |`)
+        }
+      }
+    }
+  }
+  lines.push('')
+
+  // Per-level detail
+  if (levels.length > 0) {
+    lines.push('## Per level')
+    lines.push('')
+    for (const level of levels) {
+      const lName = (level as { name?: string }).name ?? level.id
+      // Nodes whose ancestry includes this level.
+      const levelNodes = allNodes.filter(
+        (n) => n.id !== level.id && walkToLevel(n, nodes as Record<string, AnyNode>) === level.id,
+      )
+      const counts = countByType(levelNodes)
+      const countKeys = Object.keys(counts).sort() as AnyNodeType[]
+
+      // Estimated floor area = sum of zone polygon areas on this level.
+      const zones = levelNodes.filter((n) => n.type === 'zone') as Array<
+        AnyNode & { polygon: Array<[number, number]> }
+      >
+      let floorAreaSq = 0
+      for (const z of zones) {
+        floorAreaSq += polygonArea(z.polygon)
+      }
+
+      lines.push(`### ${lName}`)
+      lines.push('')
+      if (countKeys.length === 0) {
+        lines.push('- _(no descendants)_')
+      } else {
+        const parts = countKeys.map((k) => `${k}=${counts[k]}`)
+        lines.push(`- Node counts: ${parts.join(', ')}`)
+      }
+      lines.push(`- Estimated floor area (zones): ${floorAreaSq.toFixed(2)} m^2`)
+      lines.push('')
+    }
+  }
+
+  // BBox
+  lines.push('## Scene bbox (meters)')
+  lines.push('')
+  if (bbox.empty) {
+    lines.push('- _(no positioned nodes)_')
+  } else {
+    lines.push(`- min: [${bbox.min.map((v) => v.toFixed(3)).join(', ')}]`)
+    lines.push(`- max: [${bbox.max.map((v) => v.toFixed(3)).join(', ')}]`)
+  }
+
+  return lines.join('\n')
+}
+
+/** Walk up parentId until we find a level; return its id or null. */
+function walkToLevel(node: AnyNode, nodes: Record<string, AnyNode>): string | null {
+  const seen = new Set<string>()
+  let current: AnyNode | undefined = node
+  while (current && !seen.has(current.id)) {
+    seen.add(current.id)
+    if (current.type === 'level') return current.id
+    const pid: string | null = current.parentId
+    if (!pid) return null
+    current = nodes[pid]
+  }
+  return null
+}
+
+/**
+ * `pascal://scene/current/summary` — human-readable scene overview.
+ * MIME `text/markdown`.
+ */
+export function registerSceneSummary(server: McpServer, bridge: SceneBridge): void {
+  server.registerResource(
+    'scene-summary',
+    'pascal://scene/current/summary',
+    {
+      title: 'Scene summary (markdown)',
+      description:
+        'Markdown overview: sites/buildings/levels, per-level node counts, zone floor areas, scene bbox.',
+      mimeType: 'text/markdown',
+    },
+    async (uri) => ({
+      contents: [
+        {
+          uri: uri.href,
+          mimeType: 'text/markdown',
+          text: buildSceneSummaryMarkdown(bridge.exportJSON()),
+        },
+      ],
+    }),
+  )
+}