fix(coding): preserve renderer recovery state

tests/unit/coding-conversations-store.test.tsx

@@ -194,6 +194,46 @@ describe('coding Conversation store', () => {
     expect(store.getState().entriesByConversationId['conversation-b'].reducer.invalidation).toBeNull();
   });
 
+  it('replays target patches that arrive while a gap snapshot is loading', async () => {
+    const recovery = deferred<ConversationSnapshot>();
+    const getSnapshot = vi.fn(() => recovery.promise);
+    const store = createCodingConversationStore({
+      getSnapshot,
+      openEvents: vi.fn(),
+      submitPrompt: vi.fn(),
+      createId: ids(),
+    });
+    store.getState().applySnapshotEvent(snapshotEvent(snapshot('conversation-a')));
+
+    store.getState().applyPatchEvent(patchEvent('conversation-a', 2, {
+      op: 'run.state',
+      run: { status: 'running', runId: 'run-gap' },
+    }));
+    store.getState().applyPatchEvent(patchEvent('conversation-a', 3, {
+      op: 'run.state',
+      run: {
+        status: 'error',
+        runId: 'run-gap',
+        terminalReason: 'failed',
+      },
+    }));
+    recovery.resolve({
+      ...snapshot('conversation-a', 1, 2),
+      run: { status: 'running', runId: 'run-gap' },
+    });
+
+    await waitFor(() => {
+      expect(selectCodingConversationSnapshot('conversation-a')(store.getState()))
+        .toMatchObject({
+          cursor: { workerGeneration: 1, seq: 3 },
+          run: { status: 'error', runId: 'run-gap', terminalReason: 'failed' },
+        });
+    });
+    expect(getSnapshot).toHaveBeenCalledTimes(1);
+    expect(store.getState().entriesByConversationId['conversation-a'].reducer.invalidation)
+      .toBeNull();
+  });
+
   it('uses native EventSource reconnect without reopening or replaying a mutation', async () => {
     const source = new FakeEventSource();
     const openEvents = vi.fn(async () => source as unknown as EventSource);
@@ -276,6 +316,9 @@ describe('coding Conversation store', () => {
     await submission;
     expect(store.getState().requestsByConversationId['conversation-a']['request-1'].status)
       .toBe('accepted');
+    store.getState().applySnapshotEvent(snapshotEvent(snapshot('conversation-a')));
+    expect(selectCodingConversationSnapshot('conversation-a')(store.getState())?.nodes[0])
+      .toMatchObject({ id: 'node-1', clientRequestId: 'request-1', status: 'optimistic' });
     store.getState().applyPatchEvent(patchEvent('conversation-a', 1, {
       op: 'message.upsert',
       node: {
@@ -350,6 +393,7 @@ describe('coding Conversation store', () => {
     })).rejects.toThrow('Delivery is uncertain');
     source.fail();
     source.open();
+    source.emit('snapshot', snapshotEvent(snapshot('conversation-a')));
 
     expect(store.getState().draftsByConversationId['conversation-a'].text).toBe('Do not replay');
     expect(store.getState().requestsByConversationId['conversation-a']['request-1'])