refactor(web): drop the permission RPC pair and turn-anchoring machinery

The session.permissions/setPermission unary pair, the PermissionOption wire
DTO, the client Session wrappers, and the fixture/fake mirrors all leave the
wire: the read side moves to the 'permissions' session projection and the
write side moves to the /permission command in follow-up commits, so the
web protocol gains no permission methods at all.

The pendingSwitches + prompt-submit flush + hasOpenTurn move also goes.
Knob events no longer need turn enclosure: the persistence scanner keeps
standalone events after the last turn/end as part of the preserved prefix
(remove-synthetic-log-only-turns), none of the three knob invariants demand
an open turn, and the setters append bare events. An idle switch commits
immediately; hasOpenTurn stays a user-approval private fold (its audit pair
is the one contract that still requires enclosure).

The old PermissionSelect chip and its mount-time fetch die with the RPCs
(the resident composer broke the mount-once assumption); the projection-fed
replacement lands with the Access seat swap.

packages/client/runtime/tests/fake-api.ts

@@ -81,12 +81,6 @@ export class FakeApiClient implements IApiClient {
     payload => Promise.resolve(ok({ selected: { provider: payload.provider, model: payload.model } }))
   onPrompt: (payload: unknown) => Promise<RpcResponse<{ accepted: true }>> = () => Promise.resolve(ok({ accepted: true as const }))
   onCancel: (payload: unknown) => Promise<RpcResponse<{ accepted: true }>> = () => Promise.resolve(ok({ accepted: true as const }))
-  onPermissions: (payload: unknown) =>
-  Promise<RpcResponse<{ options: { value: string; name: string; description?: string }[]; currentValue: string }>> =
-    () => Promise.resolve(ok({ options: [], currentValue: 'custom' }))
-
-  onSetPermission: (payload: { sessionId: SessionId; value: string }) => Promise<RpcResponse<{ currentValue: string }>> =
-    payload => Promise.resolve(ok({ currentValue: payload.value }))
 
   onDescribe: (payload: unknown) => Promise<RpcResponse<{ version: string; cwd: string; attachedSessions: number }>> =
     () => Promise.resolve(ok({ version: '0-fake', cwd: '/f', attachedSessions: 0 }))
@@ -111,8 +105,6 @@ export class FakeApiClient implements IApiClient {
       this.record('session.selectModel', payload, this.onSelectModel(payload)),
     prompt: (payload: unknown) => this.record('session.prompt', payload, this.onPrompt(payload)),
     cancel: (payload: unknown) => this.record('session.cancel', payload, this.onCancel(payload)),
-    permissions: (payload: unknown) => this.record('session.permissions', payload, this.onPermissions(payload)),
-    setPermission: (payload: { sessionId: SessionId; value: string }) => this.record('session.setPermission', payload, this.onSetPermission(payload)),
   }
 
   readonly host: IApiClient['host'] = {

packages/client/runtime/tests/manager.spec.ts

@@ -358,7 +358,7 @@ describe('connected generation', () => {
 describe('waiting-approval list bit', () => {
   it('lights on requested, survives replay duplicates, and clears on resolved — without instantiation', () => {
     const manager = new SessionManager(new FakeApiClient())
-    manager.handleHostEnvelope({ rpcId: 'h1' as never, payload: { type: 'host/session-added', sessionId: S1 } })
+    manager.handleHostEnvelope({ rpcId: 'h1' as never, payload: { type: 'host/session-added', sessionId: S1, blank: false } })
     expect(manager.getListSnapshot().items[0]?.waitingApproval).toBe(false)
     manager.handleMuxEnvelope({ rpcId: 'ra' as never, payload: { type: 'approval/requested', sessionId: S1, approvalId: 'ap1' as never, toolName: 'rm' } })
     expect(manager.getListSnapshot().items[0]?.waitingApproval).toBe(true)
@@ -371,7 +371,7 @@ describe('waiting-approval list bit', () => {
 
   it('clears only when the last outstanding question resolves; session-removed drops the bit', () => {
     const manager = new SessionManager(new FakeApiClient())
-    manager.handleHostEnvelope({ rpcId: 'h1' as never, payload: { type: 'host/session-added', sessionId: S1 } })
+    manager.handleHostEnvelope({ rpcId: 'h1' as never, payload: { type: 'host/session-added', sessionId: S1, blank: false } })
     manager.handleMuxEnvelope({ rpcId: 'r1' as never, payload: { type: 'approval/requested', sessionId: S1, approvalId: 'a1' as never, toolName: 'rm' } })
     manager.handleMuxEnvelope({ rpcId: 'r2' as never, payload: { type: 'approval/requested', sessionId: S1, approvalId: 'a2' as never, toolName: 'rm' } })
     manager.handleMuxEnvelope({ rpcId: 'rx' as never, payload: { type: 'approval/resolved', sessionId: S1, approvalId: 'a1' as never, outcome: 'rejected' as never } })
@@ -386,7 +386,7 @@ describe('waiting-approval list bit', () => {
 
   it('drops stale bits on reconnect — the reopen replay re-adds still-pending questions', () => {
     const manager = new SessionManager(new FakeApiClient())
-    manager.handleHostEnvelope({ rpcId: 'h1' as never, payload: { type: 'host/session-added', sessionId: S1 } })
+    manager.handleHostEnvelope({ rpcId: 'h1' as never, payload: { type: 'host/session-added', sessionId: S1, blank: false } })
     manager.handleMuxEnvelope({ rpcId: 'ra' as never, payload: { type: 'approval/requested', sessionId: S1, approvalId: 'ap1' as never, toolName: 'rm' } })
     expect(manager.getListSnapshot().items[0]?.waitingApproval).toBe(true)
     manager.handleConnected() // resolved-while-disconnected questions send no frame

packages/client/runtime/tests/session.spec.ts

@@ -816,27 +816,3 @@ describe('reference stability (the memo contract)', () => {
     expect(resolved.pending).toBe(after.pending)
   })
 })
-
-describe('permissions / setPermission', () => {
-  it('passes the select read and switch through with the session id', async () => {
-    const { api, session } = makeSession()
-    api.onPermissions = () => Promise.resolve(ok({ options: [{ value: 'workspace-write', name: 'workspace-write' }], currentValue: 'workspace-write' }))
-    const read = await session.permissions()
-    expect(read.ok).toBe(true)
-    if (read.ok) expect(read.value.currentValue).toBe('workspace-write')
-    expect(api.callsOf('session.permissions')).toMatchObject([{ sessionId: SID }])
-
-    const switched = await session.setPermission('danger-full-access')
-    expect(switched.ok).toBe(true)
-    if (switched.ok) expect(switched.value.currentValue).toBe('danger-full-access')
-    expect(api.callsOf('session.setPermission')).toMatchObject([{ sessionId: SID, value: 'danger-full-access' }])
-  })
-
-  it('folds transport failures into the error branch', async () => {
-    const { api, session } = makeSession()
-    api.onPermissions = () => Promise.reject(new Error('down'))
-    api.onSetPermission = () => Promise.reject(new Error('down'))
-    expect((await session.permissions()).ok).toBe(false)
-    expect((await session.setPermission('x')).ok).toBe(false)
-  })
-})