feat(tools): live dispatch lifecycle + native-contract parallel sub-calls in Code Mode

The bridge replaces its serialization queue with a pool that reuses the
native concurrency contract: submissions classify through
registry.executionMode (fail-closed isConcurrencySafe), start strictly in
submission order, overlap up to the validated maxParallelSubCalls config
(default 10; 1 restores serial), and exclusive calls drain the pool, run
alone, and bar later calls. Each started sub-call logs a
tool/code-dispatch-start event at pool entry; the existing
tool/code-dispatch settles the pair (started ⇔ settles exactly once;
abandoned queued calls log neither). SDK prompt guidance now states the
true Promise.all contract — re-recorded across every code/both-mode
snapshot (plus the stale cordis-dynamic-toolchain fixture gaining the
required description arg).

Client: CodeSubCall widens to RunningToolCall | ToolResultNode — starts
land the running shape (rows wear the native running ring), settles
replace in place preserving start order, callTime pairs to the start
time. Fixture emits start/settle pairs; jsdom pins the running sub-row;
runtime specs pin in-place settlement and out-of-order completion.

packages/client/runtime/tests/event-script.ts

@@ -26,6 +26,11 @@ export const ev = {
     at(seq, { type: 'tool/call', data: { turn, step, callId, name, arguments: args } }),
   toolResult: (seq: number, turn: number, callId: string, body: string, step = 0): SessionEvent =>
     at(seq, { type: 'tool/result', surfaceOp: 'append', data: { turn, step, callId, content: text(body), isError: false } }),
+  codeDispatchStart: (seq: number, parentCallId: string, n: number, name: string, args: unknown): SessionEvent =>
+    at(seq, {
+      type: 'tool/code-dispatch-start',
+      data: { parentCallId, subCallId: `${parentCallId}:code:${n}`, name, arguments: args },
+    }),
   codeDispatch: (seq: number, parentCallId: string, n: number, name: string, args: unknown, body: string, isError = false): SessionEvent =>
     at(seq, {
       type: 'tool/code-dispatch',

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

@@ -645,6 +645,32 @@ describe('resync', () => {
 })
 
 describe('run_code sub-dispatch indexing', () => {
+  it('a start event lands as a running-shaped sub-call and its settle replaces it in place', async () => {
+    const { api, session } = makeSession()
+    api.onHistory = () => histResponse(plainTurn(0, 0, '问', '答'))
+    await session.open()
+    const feed = (event: SessionEvent) => { session.handleMuxEnvelope('r' as never, { type: 'session/event', sessionId: SID, event }) }
+    feed(ev.turnStart(6, 1))
+    feed(ev.toolCall(7, 1, 'p1', 'run_code', '{"code":"1","description":"d"}'))
+    feed(ev.codeDispatchStart(8, 'p1', 1, 'bash', { command: 'sleep' }))
+    feed(ev.codeDispatchStart(9, 'p1', 2, 'read', { path: 'a.txt' }))
+    const live = session.getSnapshot().codeDispatches.get('p1')
+    expect(live).toHaveLength(2)
+    // Running shape (no 'kind'): the exact RunningToolCall form native rows use.
+    expect(live?.[0]).toMatchObject({ callId: 'p1:code:1', name: 'bash', argsRaw: '{"command":"sleep"}' })
+    expect(live?.[0] !== undefined && 'kind' in live[0]).toBe(false)
+    // Settle out of order (parallel run): #2 first — replaces in place, keeping start order.
+    feed(ev.codeDispatch(10, 'p1', 2, 'read', { path: 'a.txt' }, 'alpha'))
+    const mixed = session.getSnapshot().codeDispatches.get('p1')
+    expect(mixed?.map(sub => 'kind' in sub)).toEqual([false, true])
+    expect(mixed?.[1]).toMatchObject({ callId: 'p1:code:2', content: [{ type: 'text', text: 'alpha' }] })
+    // The settle carries the paired start's time as callTime (duration source).
+    feed(ev.codeDispatch(11, 'p1', 1, 'bash', { command: 'sleep' }, 'done'))
+    const settled = session.getSnapshot().codeDispatches.get('p1')
+    expect(settled?.map(sub => 'kind' in sub)).toEqual([true, true])
+    expect(settled?.[0]).toMatchObject({ callId: 'p1:code:1', callTime: 1_700_000_000_008 })
+  })
+
   it('indexes live tool/code-dispatch events under their parent as native-shaped result nodes', async () => {
     const { api, session } = makeSession()
     api.onHistory = () => histResponse(plainTurn(0, 0, '问', '答'))