Merge branch 'master' into worktree/web-session-titles

# Conflicts:
#	apps/web/tests/smoke-real.e2e.ts
#	packages/client/connection/tests/fixture.spec.ts
#	packages/host/runtime/README.md
#	packages/host/runtime/src/api-proxy.ts

packages/host/apiproxy/src/api/events.schema.ts

@@ -17,6 +17,7 @@ export const askUserQuestionItemSchema = z.object({
   id: z.string(),
   question: z.string(),
   header: z.string().optional(),
+  detail: z.string().optional(),
   options: z.array(z.object({ label: z.string(), description: z.string().optional() })).optional(),
   multiSelect: z.boolean().optional(),
 }) satisfies z.ZodType<Wire<AskUserQuestionItem>>
@@ -28,7 +29,10 @@ export const muxFrameSchema = z.discriminatedUnion('type', [
   z.object({ type: z.literal('session/title'), sessionId: sessionIdSchema, title: z.string().min(1), eventSeq: z.number().int().nonnegative(), updatedAt: z.number() }),
   z.object({ type: z.literal('approval/requested'), sessionId: sessionIdSchema, approvalId: approvalRequestIdSchema, toolName: z.string(), callId: z.string().optional(), reason: z.string().optional() }),
   z.object({ type: z.literal('approval/resolved'), sessionId: sessionIdSchema, approvalId: approvalRequestIdSchema, outcome: z.union([z.literal('allowed-once'), z.literal('rejected'), z.literal('cancelled'), z.literal('unavailable')]) }),
-  z.object({ type: z.literal('question/requested'), sessionId: sessionIdSchema, questions: z.array(askUserQuestionItemSchema) }),
+  // Non-empty by wire contract: the user-interaction service rejects empty
+  // batches at ask() (EMPTY_QUESTIONS), so an empty frame is host breakage
+  // and must fail loud here, not reach the composer.
+  z.object({ type: z.literal('question/requested'), sessionId: sessionIdSchema, questions: z.array(askUserQuestionItemSchema).min(1) }),
   z.object({ type: z.literal('question/resolved'), sessionId: sessionIdSchema, questionRpcId: rpcIdSchema, outcome: z.union([z.literal('answered'), z.literal('cancelled')]) }),
   z.object({ type: z.literal('stream/error'), error: rpcErrorSchema }),
 ]) as unknown as z.ZodType<MuxFrame>

packages/host/apiproxy/src/api/rpc.schema.ts

@@ -33,6 +33,7 @@ export const rpcIdSchema = z.string() as unknown as z.ZodType<RpcId>
 /** Error body: discriminated by code, per-branch details aligned to RpcErrorDetailsMap; details is required. */
 export const rpcErrorSchema: z.ZodType<RpcError> = z.discriminatedUnion('code', [
   z.object({ code: z.literal('bad-request'), message: z.string(), details: z.object({ issues: z.array(z.custom<ZodIssue>()) }) }),
+  z.object({ code: z.literal('cancelled'), message: z.string(), details: z.object({}) }),
   z.object({ code: z.literal('session-not-found'), message: z.string(), details: z.object({ sessionId: z.string() }) }),
   z.object({ code: z.literal('agent-busy'), message: z.string(), details: z.object({ reason: z.string() }) }),
   z.object({ code: z.literal('internal'), message: z.string(), details: z.object({}) }),

packages/host/apiproxy/src/api/rpc.ts

@@ -30,6 +30,7 @@ export function RpcId(id: string): RpcId {
 /** Error code → details type map (a second table isomorphic to RpcMethodMap). New code = one row here + one branch in the error schema. */
 export interface RpcErrorDetailsMap {
   'bad-request': { issues: ZodIssue[] }
+  'cancelled': {}
   'session-not-found': { sessionId: SessionId }
   'agent-busy': { reason: string }
   'internal': {}

packages/host/apiproxy/tests/rpc-schemas.spec.ts

@@ -29,6 +29,7 @@ describe('RpcId', () => {
 describe('rpcErrorSchema', () => {
   it('accepts every code branch with its required details', () => {
     expect(rpcErrorSchema.parse({ code: 'bad-request', message: 'm', details: { issues: [] } }).code).toBe('bad-request')
+    expect(rpcErrorSchema.parse({ code: 'cancelled', message: 'm', details: {} }).code).toBe('cancelled')
     expect(rpcErrorSchema.parse({ code: 'session-not-found', message: 'm', details: { sessionId: 's' } }).code).toBe('session-not-found')
     expect(rpcErrorSchema.parse({ code: 'agent-busy', message: 'm', details: { reason: 'r' } }).code).toBe('agent-busy')
     expect(rpcErrorSchema.parse({ code: 'internal', message: 'm', details: {} }).code).toBe('internal')
@@ -142,6 +143,10 @@ describe('events frame schemas', () => {
     expect(askUserQuestionItemSchema.parse({ id: 'q', question: 'Q?' }).id).toBe('q')
   })
 
+  it('rejects an empty question batch (ask() guarantees at least one, so an empty frame is host breakage)', () => {
+    expect(() => muxFrameSchema.parse({ type: 'question/requested', sessionId: 's', questions: [] })).toThrow()
+  })
+
   it('accepts every host frame branch', () => {
     const frames = [
       { type: 'host/session-added', sessionId: 's', parentSessionId: 'p' },