diff --git a/docs/audits/block-api-coverage.md b/docs/audits/block-api-coverage.md
index 615fa00b..7a19438c 100644
--- a/docs/audits/block-api-coverage.md
+++ b/docs/audits/block-api-coverage.md
@@ -46,6 +46,7 @@
 | tooltipcard | ✅ | ✅ | ➖ | ✅ | ➖ | ➖ |
 | dbview | ✅ | ✅ | ➖ | ✅ | ➖ | ➖ |
 | dbform | ✅ | ✅ | ➖ | ✅ | ➖ | ➖ |
+| meeting | ✅ | ✅ | ➖ | ✅ | ➖ | ➖ |
 | form | ✅ | ✅ | ➖ | ✅ | ➖ | ➖ |
 | openbook.ledger/journal-entry | ✅ | ✅ | ➖ | ✅ | ➖ | ✅ |
 | openbook.ledger/trial-balance | ✅ | ✅ | ➖ | ✅ | ➖ | ✅ |
diff --git a/docs/meeting-block.md b/docs/meeting-block.md
new file mode 100644
index 00000000..4e52a824
--- /dev/null
+++ b/docs/meeting-block.md
@@ -0,0 +1,44 @@
+# Meeting block — THE REPRESENTATION CONTRACT (MEET-4)
+
+`meeting` is a `kit` block with `nature: 'container'`, no required parent, and
+`kitValue: false`. It publishes no reactive value. Its `children` are ordinary
+manual-note blocks (paragraphs, todos, headings, groups, etc.), not transcript
+segments. No dedicated notes slot or child-only type is required.
+
+All top-level props are optional. Missing status means `idle`; missing arrays
+mean empty lists; missing summary/title mean empty text; missing startedAt means
+not started. These are consumer defaults, not schema-inserted persisted values.
+As with other block props, patches shallow-merge; `null` removes a top-level key.
+Unknown top-level props remain allowed for forward compatibility.
+
+| Prop | Stored shape and meaning |
+| --- | --- |
+| `status` | `'idle' \| 'recording' \| 'processing' \| 'done'`. Validation checks the enum, not state transitions. |
+| `audioChunks` | Ordered array of `{assetId: string, durationMs: number, startedAtMs?: number}`. `assetId` is a nonempty asset reference (max 512 characters), never inline audio. `durationMs` is the chunk duration; optional `startedAtMs` is an offset from meeting start, **not** Unix time. Array order is capture/playback order. |
+| `transcript` | Ordered array of `{startMs: number, endMs: number, text: string}`. Offsets are relative to meeting start; `endMs >= startMs`. Text is plain text. Array order is display order; overlapping segments are allowed. |
+| `summary` | Plain string; no rich-text runs or Markdown interpretation is required. |
+| `startedAt` | Unix epoch milliseconds, a finite nonnegative number. |
+| `title` | Optional plain string. |
+
+All durations and offsets are finite nonnegative numbers in milliseconds;
+fractional milliseconds are accepted. Every listed nested field is required
+except `startedAtMs`; nested objects reject extra keys and null fields. Empty
+arrays and empty transcript text are valid. Cross-field `endMs >= startMs` is
+checked at runtime and described in the JSON schema (standard JSON Schema cannot
+express a comparison to a sibling field). Asset existence, timeline sorting,
+status transitions, and transcription size limits are producer responsibilities.
+
+Audio chunks and transcript segments use structured props, following existing
+kit option/rich-run arrays and the form's structured schema prop. They are
+machine-produced snapshots, while manual notes need independently editable CRDT
+children. Each array is one prop value: updates replace the whole array, with
+no per-segment merge guarantee. Recording/transcription producers should batch
+updates and serialize writes to avoid concurrent array replacement losing data.
+This keeps the first representation small and consistent; large-transcript
+storage migration, if needed later, must explicitly version this contract.
+
+MEET-4 registers a minimal meeting shell through `registerArtifactKit` in both
+editor and viewer hosts. It displays title, status, and saved note-block count;
+notes remain stored but are not yet rendered/editable inside the shell. It has
+no slash-menu entry or recording controls. MEET-5 replaces this renderer and
+must render the existing child blocks rather than migrate them into props.
diff --git a/packages/mcp/README.md b/packages/mcp/README.md
index ce54205f..9d0002ff 100644
--- a/packages/mcp/README.md
+++ b/packages/mcp/README.md
@@ -93,6 +93,7 @@ Call `list_block_types` for the machine-readable source of truth: every entry ha
 | `tooltipcard` | `term:string`, `tip:string` |
 | `dbview` | `pageId:string` |
 | `dbform` | `databaseId:string`, `viewId:string` |
+| `meeting` | `status:"idle"/"recording"/"processing"/"done"`, `audioChunks:[{assetId:string,durationMs:number,startedAtMs?:number}]`, `transcript:[{startMs:number,endMs:number,text:string}]`, `summary:string`, `startedAt:number`, `title:string`; container children are manual notes; [representation contract](../../docs/meeting-block.md) |
 | `form` | `formId:string`, `submissionKey:string`, `enabled:boolean`, `databaseId:string`, `schema:object`, `label:string`, `description:string` |
 
 Shared input/frame props are `name`, `label`, and `description` strings plus `compact` and `interactive` booleans. A structured option's `value` defaults to a slug of its `label`; `selected` contains those string values.
diff --git a/packages/mcp/scripts/blockTypes.test.mts b/packages/mcp/scripts/blockTypes.test.mts
index 85f78bba..230b5b1f 100644
--- a/packages/mcp/scripts/blockTypes.test.mts
+++ b/packages/mcp/scripts/blockTypes.test.mts
@@ -157,6 +157,22 @@ async function main(): Promise<void> {
   check('an invalid structured option is refused with a typed error naming opts',
     isError(badOpts) && /"opts"/.test(resultText(badOpts)) && /object/i.test(resultText(badOpts)));
 
+  const meetingProps = {status: 'done', audioChunks: [{assetId: 'audio-1', durationMs: 500, startedAtMs: 0}], transcript: [{startMs: 0, endMs: 500, text: 'Hello'}], summary: 'Agreed', startedAt: 1234, title: 'Review'};
+  const meetingPage = await seed.savePage({name: 'Meeting target', data: {editor: 'blocks', blockdoc: {blocks: [{id: 'meeting1', type: 'meeting', children: [{id: 'note1', type: 'paragraph', text: [{t: 'Notes'}]}]}]}, editorjs: {blocks: []}, values: [], names: []}});
+  const meetingUpdate = await mcp.client.callTool({name: 'update_block_props', arguments: {pageId: meetingPage.id, blockId: 'meeting1', props: meetingProps}});
+  check('meeting structured props update is accepted', !isError(meetingUpdate));
+  const meetingCreate = await mcp.client.callTool({name: 'append_blocks', arguments: {pageId: meetingPage.id, blocks: [{type: 'meeting', props: meetingProps, children: [{type: 'paragraph', text: 'Manual notes'}]}]}});
+  check('meeting creation with manual note children is accepted', !isError(meetingCreate));
+  for (const props of [{status: 'paused'}, {audioChunks: [{assetId: 'a', durationMs: -1}]}, {transcript: [{startMs: 2, endMs: 1, text: 'Reversed'}]}]) {
+    const badCreate = await mcp.client.callTool({name: 'append_blocks', arguments: {pageId: meetingPage.id, blocks: [{type: 'meeting', props}]}});
+    const badUpdate = await mcp.client.callTool({name: 'update_block_props', arguments: {pageId: meetingPage.id, blockId: 'meeting1', props}});
+    check(`meeting rejects invalid creation and update: ${JSON.stringify(props)}`, isError(badCreate) && isError(badUpdate));
+  }
+  const meetingListing = JSON.parse(resultText(await mcp.client.callTool({name: 'list_block_types', arguments: {types: ['meeting']}})));
+  assert.equal(meetingListing.blocks.length, 1);
+  assert.deepEqual(meetingListing.blocks[0].propsSchema.properties.transcript.items.required, ['startMs', 'endMs', 'text']);
+  check('meeting listing publishes container nature and structured propsSchema', meetingListing.blocks[0].nature === 'container');
+
   console.log('\nAPI-2: plugin block types — rejected while uninstalled, accepted once installed');
   const uninstalled = await mcp.client.callTool({
     name: 'create_artifact_page',
diff --git a/packages/mcp/src/server.ts b/packages/mcp/src/server.ts
index f5fdb6a1..1942e7cd 100644
--- a/packages/mcp/src/server.ts
+++ b/packages/mcp/src/server.ts
@@ -25,6 +25,7 @@ import {
   findUnknownBlockType,
   FORM_FIELD_KINDS,
   invalidBlockProps,
+  invalidBlockTreeProps,
   insertBlocks,
   isHttpUrl,
   KIT_VALUE_BLOCK_TYPES,
@@ -609,7 +610,7 @@ function nestedBlockSchema(typeDesc: string, propsDesc: string): z.ZodType<Neste
 }
 
 /**
- * Validate a nested payload's STRUCTURE — the container parent/child contract
+ * Validate a nested payload's declared props and STRUCTURE — the container parent/child contract
  * (a `children` array only on a container-nature type; a child-only type only
  * under its matching container; every table square), plus the
  * {@link MAX_BLOCK_DEPTH} / {@link MAX_BLOCK_NODES} caps. Returns an error
@@ -618,14 +619,14 @@ function nestedBlockSchema(typeDesc: string, propsDesc: string): z.ZodType<Neste
  * payload is refused with a clear message instead of silently dropping to a
  * wall of "Unsupported block" placeholders.
  *
- * The rules are the SDK block-type catalogue's (`blockTreeError`) — one source
+ * The rules are the SDK block-type catalogue's (`blockTreeError` and
+ * `invalidBlockTreeProps`) — one source
  * shared with the in-app agent. Block TYPES are otherwise unvalidated here for
  * `append_blocks` (the apply layer is type-agnostic so custom/plugin leaves
- * keep working) — only the STRUCTURE the model would silently discard is
- * rejected. `create_artifact_page` additionally gates types (see below).
+ * keep working). Declared prop values are validated at every depth. `create_artifact_page` additionally gates types (see below).
  */
 const blockPayloadError = (blocks: NestedBlockInput[]): string | null =>
-  blockTreeError(blocks, {maxDepth: MAX_BLOCK_DEPTH, maxNodes: MAX_BLOCK_NODES});
+  blockTreeError(blocks, {maxDepth: MAX_BLOCK_DEPTH, maxNodes: MAX_BLOCK_NODES}) ?? invalidBlockTreeProps(blocks);
 
 /**
  * The write-tool kind an MCP mutation maps to (the same identifiers the in-app
diff --git a/packages/sdk/src/blockCatalogue.test.ts b/packages/sdk/src/blockCatalogue.test.ts
index 0ef41ead..4310c0e1 100644
--- a/packages/sdk/src/blockCatalogue.test.ts
+++ b/packages/sdk/src/blockCatalogue.test.ts
@@ -17,6 +17,7 @@ import {
   CONTAINER_BLOCK_TYPES,
   findUnknownBlockType,
   invalidBlockProps,
+  invalidBlockTreeProps,
   isPluginBlockType,
   KNOWN_BLOCK_TYPE_IDS,
   MAX_BLOCK_DEPTH,
@@ -242,3 +243,48 @@ describe('generated tool text', () => {
     for (const type of KNOWN_BLOCK_TYPE_IDS) expect(guidance).toContain(type);
   });
 });
+
+
+describe('meeting representation contract (MEET-4)', () => {
+  it('is a kit container with typed structured props and no reactive value', () => {
+    expect(blockTypeInfo('meeting')).toMatchObject({category: 'kit', nature: 'container', kitValue: false});
+    expect(blockTreeError([{type: 'meeting', children: [{type: 'paragraph', text: 'Manual notes'}]}])).toBeNull();
+    for (const status of ['idle', 'recording', 'processing', 'done']) {
+      expect(invalidBlockProps('meeting', {status, startedAt: 1234, title: 'Review', summary: 'Agreed.',
+        audioChunks: [{assetId: 'audio-1', durationMs: 500, startedAtMs: 0}, {assetId: 'audio-2', durationMs: 250}],
+        transcript: [{startMs: 0, endMs: 500, text: 'Hello'}],
+      })).toBeNull();
+    }
+    expect(invalidBlockProps('meeting', {})).toBeNull();
+    expect(invalidBlockProps('meeting', {status: null, audioChunks: null, transcript: null, summary: null, startedAt: null, title: null})).toBeNull();
+  });
+
+  it.each([
+    {status: 'paused'}, {startedAt: -1}, {startedAt: '2026-01-01'}, {summary: []}, {title: 1},
+    {audioChunks: ['asset']}, {audioChunks: [{assetId: 'a'}]}, {audioChunks: [{assetId: '', durationMs: 1}]},
+    {audioChunks: [{assetId: 'a', durationMs: -1}]}, {audioChunks: [{assetId: 'a', durationMs: 1, startedAtMs: -1}]},
+    {audioChunks: [{assetId: 'a', durationMs: Infinity}]}, {audioChunks: [{assetId: 'a', durationMs: 1, extra: true}]},
+    {transcript: [{startMs: 0, text: 'Missing end'}]}, {transcript: [{startMs: 2, endMs: 1, text: 'Reversed'}]},
+    {transcript: [{startMs: -1, endMs: 1, text: 'Negative'}]}, {transcript: [{startMs: 0, endMs: 1, text: 1}]},
+  ])('rejects malformed props: %j', (props) => {
+    expect(invalidBlockProps('meeting', props)).toContain('Invalid prop');
+  });
+
+  it('publishes nested item schemas and required fields to agents', () => {
+    const {blocks} = JSON.parse(blockCatalogueText([], ['meeting']));
+    expect(blocks).toHaveLength(1);
+    expect(blocks[0].propsSchema.properties.status.enum).toEqual(['idle', 'recording', 'processing', 'done']);
+    expect(blocks[0].propsSchema.properties.audioChunks.items.required).toEqual(['assetId', 'durationMs']);
+    expect(blocks[0].propsSchema.properties.transcript.items.required).toEqual(['startMs', 'endMs', 'text']);
+  });
+});
+
+
+describe('creation prop validation', () => {
+  it('validates nested blocks with the same schemas as prop updates', () => {
+    expect(invalidBlockTreeProps([{type: 'group', children: [{type: 'meeting', props: {status: 'paused'}}]}])).toContain('Invalid prop "status"');
+    expect(invalidBlockTreeProps([{type: 'heading', props: {level: 'two'}}])).toContain('Invalid prop "level"');
+    expect(invalidBlockTreeProps([{type: 'meeting', props: []}])).toContain('expected an object');
+    expect(invalidBlockTreeProps([{type: 'meeting'}, {type: 'plugin/widget', props: {anything: true}}, {type: 'meeting', props: {title: null, future: {x: 1}}}])).toBeNull();
+  });
+});
diff --git a/packages/sdk/src/blockCatalogue.ts b/packages/sdk/src/blockCatalogue.ts
index ae2dc957..2c86bf60 100644
--- a/packages/sdk/src/blockCatalogue.ts
+++ b/packages/sdk/src/blockCatalogue.ts
@@ -31,7 +31,7 @@ export {BLOCK_PROP_JSON_SCHEMAS, BLOCK_PROP_SCHEMAS} from './blockPropSchemas';
 
 /** How a block stores content: `container` blocks carry child blocks in
  *  `children`, `text` blocks carry rich text in `text`, `void` blocks carry
- *  only `props` (all kit widgets are void). */
+ *  only `props`. Kit blocks may also be containers. */
 export type BlockNature = 'container' | 'text' | 'void';
 
 /** The value shapes per-type prop validation understands. Deliberately coarse
@@ -109,6 +109,7 @@ const CATALOGUE_LITERAL = [
   {type: 'tooltipcard', category: 'kit', nature: 'void', props: {term: 'string', tip: 'string'}, hint: '{term,tip}'},
   {type: 'dbview', category: 'kit', nature: 'void', props: {pageId: 'string'}, hint: 'embedded live database view {pageId} — the page hosting the database'},
   {type: 'dbform', category: 'kit', nature: 'void', props: {databaseId: 'string', viewId: 'string'}, hint: 'embedded database form {databaseId,viewId} — a live reference, never a copied schema or capability'},
+  {type: 'meeting', category: 'kit', nature: 'container', kitValue: false, props: {status: 'string', audioChunks: 'array', transcript: 'array', summary: 'string', startedAt: 'number', title: 'string'}, hint: 'meeting recording {status?,audioChunks?:[{assetId,durationMs,startedAtMs?}],transcript?:[{startMs,endMs,text}],summary?,startedAt?,title?}; times in ms, startedAt is Unix epoch; children hold manual notes; see docs/meeting-block.md'},
   {type: 'form', category: 'kit', nature: 'void', kitValue: false, props: {formId: 'string', submissionKey: 'string', enabled: 'boolean', databaseId: 'string', schema: 'object', label: 'string', description: 'string'}, hint: 'public form definition {formId,submissionKey,enabled,databaseId?,schema}'},
 ] as const satisfies readonly BlockTypeInfo[];
 
@@ -134,9 +135,9 @@ export const KIT_VALUE_BLOCK_TYPES: ReadonlySet<string> = new Set(
   BLOCK_TYPE_CATALOGUE.filter((entry) => entry.kitValue === true).map((entry) => entry.type),
 );
 
-/** Core types whose `children` hold ordinary blocks. */
-export const CONTAINER_BLOCK_TYPES: ReadonlySet<CoreBlockType> = new Set(
-  BLOCK_TYPE_CATALOGUE.filter((e) => e.nature === 'container').map((e) => e.type as CoreBlockType),
+/** Catalogued types whose `children` hold ordinary blocks (including kit containers). */
+export const CONTAINER_BLOCK_TYPES: ReadonlySet<string> = new Set(
+  BLOCK_TYPE_CATALOGUE.filter((e) => e.nature === 'container').map((e) => e.type),
 );
 
 /** Core types that carry editable rich text. */
@@ -284,7 +285,7 @@ export function blockTreeError(
           structural = parentType
             ? `A "${type}" block must be a direct child of a "${needs}" block, not a "${parentType}" block (at "${here}").`
             : `A "${type}" block can't be top-level — it belongs directly inside a "${needs}" block (at "${here}").`;
-        } else if (hasChildren && !CONTAINER_BLOCK_TYPES.has(type as CoreBlockType)) {
+        } else if (hasChildren && !CONTAINER_BLOCK_TYPES.has(type)) {
           structural = `A "${type}" block can't hold children — only container blocks (${[...CONTAINER_BLOCK_TYPES].join(', ')}) do (at "${here}"). The nested blocks would be dropped.`;
         } else if (type === 'table' && hasChildren) {
           structural = raggedTableError(children, here);
@@ -339,6 +340,30 @@ export function invalidBlockProps(type: string, props: Record<string, unknown>):
   return `Invalid prop "${prop}" of a "${type}" block: ${issue.message} (got ${clipJson(props[prop])}).`;
 }
 
+/** Validate declared props throughout a creation payload. Call blockTreeError
+ * first to enforce structure/size limits. Plugin and unknown props retain the
+ * same permissive behavior as update_block_props. */
+export function invalidBlockTreeProps(blocks: readonly unknown[], depth = 1): string | null {
+  if (depth > TYPE_WALK_MAX_DEPTH) return null; // structure validation owns depth errors
+  for (const raw of blocks) {
+    if (!raw || typeof raw !== 'object') continue;
+    const block = raw as {type?: unknown; props?: unknown; children?: unknown};
+    const type = String(block.type ?? '');
+    if (block.props !== undefined) {
+      if (!block.props || typeof block.props !== 'object' || Array.isArray(block.props)) {
+        return `Invalid props of a "${type}" block: expected an object.`;
+      }
+      const error = invalidBlockProps(type, block.props as Record<string, unknown>);
+      if (error) return error;
+    }
+    if (Array.isArray(block.children)) {
+      const error = invalidBlockTreeProps(block.children, depth + 1);
+      if (error) return error;
+    }
+  }
+  return null;
+}
+
 const clipJson = (v: unknown): string => {
   const s = JSON.stringify(v) ?? String(v);
   return s.length > 40 ? `${s.slice(0, 40)}…` : s;
@@ -388,10 +413,10 @@ export function addBlocksGuidance(): string {
     'Append rich blocks to a page — text, layouts, tables, media, interactive inputs, and charts. User approves before they are added.',
     'Each block is {type, text?, props?, children?}. `text` is a plain string (or rich runs [{"t","a":{b,i,u,s,c,a}}]); `children` nests blocks inside containers. Call list_block_types for the full catalogue including installed plugin blocks.',
     `TEXT: ${core.filter((e) => e.nature === 'text' && !e.parent).map(hinted).join('; ')}.`,
-    `CONTAINERS (use children): ${core.filter((e) => e.nature === 'container' || e.parent).map(hinted).join('; ')}. Give every table row the same number of cells.`,
+    `CONTAINERS (use children): ${BLOCK_TYPE_CATALOGUE.filter((e) => e.nature === 'container' || e.parent).map(hinted).join('; ')}. Give every table row the same number of cells.`,
     `MEDIA/OTHER: ${core.filter((e) => e.nature === 'void').map(hinted).join('; ')}.`,
     `INPUTS (each publishes props.name into the reactive scope): ${kit.filter((e) => e.kitValue).map(hinted).join('; ')}.`,
-    `REACTIVE DISPLAY/ACTIONS (props.source is a JS expression over input names): ${kit.filter((e) => !e.kitValue).map(hinted).join('; ')}.`,
+    `REACTIVE DISPLAY/ACTIONS (props.source is a JS expression over input names): ${kit.filter((e) => !e.kitValue && e.nature !== 'container').map(hinted).join('; ')}.`,
     'Example: a budget widget → [{"type":"heading","text":"Budget","props":{"level":2}},{"type":"columns","children":[{"type":"column","props":{"span":5},"children":[{"type":"slider","props":{"name":"spent","label":"Spent","value":80,"min":0,"max":200}},{"type":"number","props":{"name":"budget","label":"Budget","value":120}}]},{"type":"column","props":{"span":7},"children":[{"type":"kitchart","props":{"kind":"bar","title":"Spent vs budget","labels":"Spent, Budget","source":"[spent, budget]"}},{"type":"statuslight","props":{"label":"On track","source":"budget - spent","okAt":0,"warnAt":-20}}]}]}].',
   ].join('\n');
 }
diff --git a/packages/sdk/src/blockPropSchemas.ts b/packages/sdk/src/blockPropSchemas.ts
index 0daf2dcf..56e07684 100644
--- a/packages/sdk/src/blockPropSchemas.ts
+++ b/packages/sdk/src/blockPropSchemas.ts
@@ -43,6 +43,22 @@ const opts = array(option, 'Structured selectable options.');
 const attrs = object({b: boolean(), i: boolean(), u: boolean(), s: boolean(), c: boolean(), a: string('Safe http, https, or mailto link.')});
 const run = object({t: string('Run text.'), a: attrs}, 'One rich-text run.', ['t']);
 const runs = array(run, 'Rich-text runs.');
+// MEET-4 representation contract: docs/meeting-block.md. Nested objects are
+// strict; top-level props retain the catalogue's nullable patch semantics.
+const audioChunk = object({
+  assetId: {schema: z.string().min(1).max(512), json: {type: 'string', minLength: 1, maxLength: 512}},
+  durationMs: number('Chunk duration in milliseconds.', 0),
+  startedAtMs: number('Offset from the meeting start in milliseconds.', 0),
+}, 'One audio asset in capture order.', ['assetId', 'durationMs']);
+const transcriptSegment = object({
+  startMs: number('Inclusive offset from the meeting start in milliseconds.', 0),
+  endMs: number('Exclusive offset from the meeting start in milliseconds; must be >= startMs.', 0),
+  text: string('Plain transcript text.'),
+}, 'One transcript segment in display order.', ['startMs', 'endMs', 'text']);
+transcriptSegment.schema = transcriptSegment.schema.refine(
+  (segment) => segment.endMs >= segment.startMs,
+  {message: 'endMs must be greater than or equal to startMs', path: ['endMs']},
+);
 const common = {bg: text};
 const frame = {name: text, label: text, description: text, compact: boolean(), interactive: boolean()};
 const inputText = {...frame, value: text, placeholder: text};
@@ -71,6 +87,14 @@ const fields = {
   formula: {...frame, source: expression('Expression evaluated over the reactive scope.')},
   linkcard: {title: text, url: text, description: text}, tooltipcard: {term: text, tip: text},
   dbview: {pageId: id}, dbform: {databaseId: id, viewId: id},
+  meeting: {
+    status: enumeration(['idle', 'recording', 'processing', 'done'], 'Absent means idle.'),
+    audioChunks: array(audioChunk, 'Audio chunks in capture order; replace the entire array when updating.'),
+    transcript: array(transcriptSegment, 'Plain-text segments in display order; replace the entire array when updating.'),
+    summary: string('Plain-text summary.'),
+    startedAt: number('Meeting start as Unix epoch milliseconds.', 0),
+    title: text,
+  },
   form: {formId: id, submissionKey: text, enabled: boolean(), databaseId: id, schema: freeObject, label: text, description: text},
 } satisfies Record<string, Record<string, Field>>;
 
diff --git a/packages/sdk/src/index.ts b/packages/sdk/src/index.ts
index c6d9c29b..1a7a8227 100644
--- a/packages/sdk/src/index.ts
+++ b/packages/sdk/src/index.ts
@@ -554,6 +554,7 @@ export {
   unknownBlockTypeMessage,
   blockTreeError,
   invalidBlockProps,
+  invalidBlockTreeProps,
   blockCatalogueText,
   addBlocksGuidance,
   type BlockNature,
diff --git a/packages/server/src/ai/agent.ts b/packages/server/src/ai/agent.ts
index d63033e7..a3f57675 100644
--- a/packages/server/src/ai/agent.ts
+++ b/packages/server/src/ai/agent.ts
@@ -19,6 +19,7 @@ import {
   CONTAINER_BLOCK_TYPES,
   findUnknownBlockType,
   invalidBlockProps,
+  invalidBlockTreeProps,
   KIT_VALUE_BLOCK_TYPES,
   providerSettings,
   movePageTool,
@@ -1060,6 +1061,8 @@ export class AgentRunner {
           if (structural) return structural;
           const bad = unknownBlockTypeMessage(findUnknownBlockType(blocks, {installedPluginIds: await this.installedPluginIds()}));
           if (bad) return bad;
+          const propError = invalidBlockTreeProps(blocks);
+          if (propError) return propError;
           const normalizeBlockText = (value: unknown): unknown => {
             if (!value || typeof value !== 'object' || Array.isArray(value)) return value;
             const block = value as Record<string, unknown>;
diff --git a/packages/server/src/ai/agentBlockTypes.test.ts b/packages/server/src/ai/agentBlockTypes.test.ts
index eef33a35..c337fa50 100644
--- a/packages/server/src/ai/agentBlockTypes.test.ts
+++ b/packages/server/src/ai/agentBlockTypes.test.ts
@@ -261,3 +261,28 @@ describe('list_block_types', () => {
     expect(afterCatalogue.pluginBlocks.every((entry: {category: string}) => entry.category === 'plugin')).toBe(true);
   });
 });
+
+
+describe('meeting agent surface (MEET-4)', () => {
+  it('accepts notes and structured props, rejects malformed creation and updates', async () => {
+    const page = await store.upsertPage({name: `meeting-${seq}`, data: {
+      editor: 'blocks', blockdoc: {blocks: [{id: 'meeting1', type: 'meeting'}]}, editorjs: {blocks: []}, values: [], names: [],
+    }});
+    const props = {status: 'done', audioChunks: [{assetId: 'audio-1', durationMs: 500}], transcript: [{startMs: 0, endMs: 500, text: 'Hello'}]};
+    const added = await runTool('add_blocks', {pageId: page.id, blocks: [{type: 'meeting', props, children: [{type: 'paragraph', text: 'Notes'}]}]});
+    expect(added.result).toContain('SUGGESTED for review');
+    expect((await runTool('update_block_props', {pageId: page.id, blockId: 'meeting1', props})).result).toContain('SUGGESTED for review');
+    for (const invalid of [{status: 'paused'}, {audioChunks: [{assetId: 'a', durationMs: -1}]}, {transcript: [{startMs: 2, endMs: 1, text: 'Reversed'}]}]) {
+      for (const [tool, args] of [
+        ['add_blocks', {pageId: page.id, blocks: [{type: 'meeting', props: invalid}]}],
+        ['update_block_props', {pageId: page.id, blockId: 'meeting1', props: invalid}],
+      ] as const) {
+        const response = await runTool(tool, args);
+        expect(response.result).toContain('Invalid prop');
+        expect(response.events.some((event) => event.type === 'suggestions')).toBe(false);
+      }
+    }
+    const listed = JSON.parse((await runTool('list_block_types', {types: ['meeting']})).result);
+    expect(listed.blocks.find((block: {type: string}) => block.type === 'meeting').propsSchema.properties.transcript.items.required).toEqual(['startMs', 'endMs', 'text']);
+  });
+});
diff --git a/packages/ui/src/blockeditor/MeetingBlockPlaceholder.tsx b/packages/ui/src/blockeditor/MeetingBlockPlaceholder.tsx
new file mode 100644
index 00000000..c2ee56a1
--- /dev/null
+++ b/packages/ui/src/blockeditor/MeetingBlockPlaceholder.tsx
@@ -0,0 +1,14 @@
+import {blockChildren, blockProp} from './model';
+import type {CustomBlockDef, CustomBlockProps} from './registry';
+
+/** MEET-5 replaces this shell. The container model already preserves notes;
+ * this placeholder deliberately offers no recording controls or slash entry. */
+const MeetingBlockPlaceholder = ({block}: CustomBlockProps) => (
+  <section aria-label="Meeting">
+    <strong>{blockProp<string>(block, 'title') || 'Meeting'}</strong>
+    <p>{blockProp<string>(block, 'status') || 'idle'} — Meeting view coming soon.</p>
+    <p>{blockChildren(block)?.length ?? 0} note blocks saved.</p>
+  </section>
+);
+
+export const MEETING_BLOCK: CustomBlockDef = {type: 'meeting', render: MeetingBlockPlaceholder};
diff --git a/packages/ui/src/blockeditor/kit/index.ts b/packages/ui/src/blockeditor/kit/index.ts
index f18f6aa5..1c9dbda5 100644
--- a/packages/ui/src/blockeditor/kit/index.ts
+++ b/packages/ui/src/blockeditor/kit/index.ts
@@ -4,6 +4,7 @@ import {INPUT2_BLOCKS} from './inputs2';
 import {PROGRESS_BLOCKS} from './progress';
 import {CHART_BLOCKS} from './charts';
 import {CARD_BLOCKS} from './cards';
+import {MEETING_BLOCK} from '../MeetingBlockPlaceholder';
 
 export {evalExpr, formatValue, inputScope, INPUT_TYPES} from './scope';
 export {CHART_KINDS} from './charts';
@@ -17,7 +18,7 @@ export {CHART_KINDS} from './charts';
  * out of reusable, collaborative blocks.
  */
 export function registerArtifactKit(): void {
-  for (const def of [...INPUT_BLOCKS, ...INPUT2_BLOCKS, ...PROGRESS_BLOCKS, ...CHART_BLOCKS, ...CARD_BLOCKS]) {
+  for (const def of [...INPUT_BLOCKS, ...INPUT2_BLOCKS, ...PROGRESS_BLOCKS, ...CHART_BLOCKS, ...CARD_BLOCKS, MEETING_BLOCK]) {
     const d = def as unknown as CustomBlockDef;
     // Tag the built-ins so the slash menu files them under "Interactive blocks"
     // (third-party plugin blocks fall through to "Extensions").
diff --git a/packages/ui/src/blockeditor/model.ts b/packages/ui/src/blockeditor/model.ts
index 77191ff9..51e44df8 100644
--- a/packages/ui/src/blockeditor/model.ts
+++ b/packages/ui/src/blockeditor/model.ts
@@ -94,7 +94,7 @@ export const TEXT_BLOCKS: ReadonlySet<BlockType> = TEXT_BLOCK_TYPES;
 
 /** Block types whose `children` hold ordinary blocks — the catalogue's
  *  `container` nature. */
-export const CONTAINER_BLOCKS: ReadonlySet<BlockType> = CONTAINER_BLOCK_TYPES;
+export const CONTAINER_BLOCKS: ReadonlySet<AnyBlockType> = CONTAINER_BLOCK_TYPES;
 
 export type BlockMap = Y.Map<unknown>;
 
diff --git a/packages/ui/src/blockeditor/registryCatalogue.test.tsx b/packages/ui/src/blockeditor/registryCatalogue.test.tsx
index 24adc0b3..e0d85802 100644
--- a/packages/ui/src/blockeditor/registryCatalogue.test.tsx
+++ b/packages/ui/src/blockeditor/registryCatalogue.test.tsx
@@ -27,7 +27,7 @@ import {registeredBlockTypes} from './registry';
 import {registerArtifactKit} from './kit';
 import {registerReactiveBlocks} from './reactiveBlocks';
 import {INPUT_TYPES, inputValue} from './kit/scope';
-import {CONTAINER_BLOCKS, createDoc, rootBlocks, TEXT_BLOCKS} from './model';
+import {blockToJSON, CONTAINER_BLOCKS, createDoc, rootBlocks, TEXT_BLOCKS} from './model';
 import {registerDatabaseBlock} from '@/components/database/InlineDatabaseBlock';
 import {registerDatabaseFormBlock} from '@/components/database/DatabaseFormBlock';
 import {registerFormBlock} from './FormBlockView';
@@ -62,6 +62,15 @@ describe('registry ↔ catalogue drift guard', () => {
     expect(KNOWN_BLOCK_TYPE_IDS.size).toBe(BLOCK_TYPE_CATALOGUE.length);
   });
 
+  it('meeting container notes and structured props survive the UI model round trip', () => {
+    const props = {status: 'done', audioChunks: [{assetId: 'audio-1', durationMs: 500}], transcript: [{startMs: 0, endMs: 500, text: 'Hello'}]};
+    const doc = createDoc([{type: 'meeting', props, children: [{type: 'paragraph', text: 'Manual notes'}]}]);
+    const json = blockToJSON(rootBlocks(doc).get(0));
+    expect(json.props).toEqual(props);
+    expect(json.children).toHaveLength(1);
+    expect(json.children?.[0]).toMatchObject({type: 'paragraph', text: [{t: 'Manual notes'}]});
+  });
+
   it('the model\'s nature sets ARE the catalogue\'s', () => {
     expect(TEXT_BLOCKS).toBe(TEXT_BLOCK_TYPES);
     expect(CONTAINER_BLOCKS).toBe(CONTAINER_BLOCK_TYPES);