fix(web): narrow request lifecycle fences

packages/client/runtime/tests/client-apply.spec.ts

@@ -136,8 +136,7 @@ describe('runtime client apply', () => {
     bench.sinks?.onDisconnected?.()
     expect(session.getSnapshot().modelRequest).toBeNull()
 
-    // A second failed generation does not produce another deduplicated
-    // `reconnecting` state transition, but its own disconnect callback still
+    // Every failed generation invokes its own disconnect callback, which
     // clears telemetry received before that generation's handshake failed.
     bench.sinks?.onMuxEnvelope?.({
       rpcId: 'request-2' as never,

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

@@ -169,6 +169,26 @@ describe('instances', () => {
       },
     })
     expect(session.getSnapshot().modelRequest).toBeNull()
+    manager.handleMuxEnvelope({
+      rpcId: 'resumed-subscription' as never,
+      payload: { type: 'session/subscribed', sessionId: S1, lastSeq: 0 },
+    })
+    manager.handleMuxEnvelope({
+      rpcId: 'resumed-request' as never,
+      payload: {
+        type: 'session/model-request',
+        sessionId: S1,
+        turn: 1,
+        step: 1,
+        provider: 'test',
+        model: 'resumed',
+        contextWindow: 256_000,
+      },
+    })
+    expect(session.getSnapshot().modelRequest).toMatchObject({
+      model: 'resumed',
+      contextWindow: 256_000,
+    })
 
     manager.handleMuxEnvelope({
       rpcId: 'request-before-lazy-removal' as never,

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

@@ -833,8 +833,9 @@ describe('resync', () => {
     expect(session.getSnapshot()).toMatchObject({
       openState: 'error',
       openError: {
-        code: 'internal',
-        message: 'connection lost while loading session history',
+        code: 'cancelled',
+        message: 'session history request cancelled after connection loss',
+        details: {},
       },
     })
 
@@ -843,12 +844,34 @@ describe('resync', () => {
     expect(session.getSnapshot()).toMatchObject({
       openState: 'error',
       openError: {
-        code: 'internal',
-        message: 'connection lost while loading session history',
+        code: 'cancelled',
+        message: 'session history request cancelled after connection loss',
+        details: {},
       },
     })
   })
 
+  it('settles an in-flight older-page load when its connection generation dies', async () => {
+    const { api, session } = makeSession()
+    api.onHistory = () => histResponse(plainTurn(6, 1, '新问', '新答'), true)
+    await session.open()
+    const stale = deferred<Awaited<ReturnType<FakeApiClient['onHistory']>>>()
+    api.onHistory = () => stale.promise
+    const paging = session.loadOlder()
+    expect(session.getSnapshot().loadingOlder).toBe(true)
+
+    session.handleReconnecting()
+    expect(session.getSnapshot().loadingOlder).toBe(false)
+
+    stale.resolve(ok({
+      events: entries(plainTurn(0, 0, '旧问', '旧答')) as never[],
+      hasMore: false,
+    }))
+    await paging
+    expect(session.getSnapshot().loadingOlder).toBe(false)
+    expect(session.getSnapshot().nodes.map(node => node.seq)).toEqual([7, 9])
+  })
+
   it('clears request telemetry on reconnect and drops a stale in-flight history response', async () => {
     const { api, session } = makeSession()
     const stale = deferred<Awaited<ReturnType<FakeApiClient['onHistory']>>>()