fix(coding): restore sending after queued messages settle

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

@@ -621,6 +621,28 @@ describe('coding Conversation store', () => {
     expect(store.getState().requestsByConversationId['conversation-a']).toEqual({});
   });
 
+  it.each(['steer', 'follow-up'] as const)('clears %s acceptance even when settlement precedes the response', async (mode) => {
+    const pending = deferred<PromptAcceptance>();
+    const store = createCodingConversationStore({
+      getSnapshot: vi.fn(),
+      openEvents: vi.fn(),
+      submitPrompt: vi.fn(() => pending.promise),
+      createId: ids(),
+    });
+    const running = snapshot('conversation-a');
+    running.run = { status: 'running', mode: 'prompt', runId: 'run-1' };
+    store.getState().applySnapshotEvent(snapshotEvent(running));
+    store.getState().setDraft('conversation-a', '排队的消息');
+    const submission = store.getState().submitPrompt({ conversationId: 'conversation-a', mode });
+    const settled = snapshot('conversation-a', 1, 1);
+    settled.run = { status: 'idle', mode: 'prompt', runId: 'run-1', terminalReason: 'completed', settledAt: 1_000 };
+    store.getState().applySnapshotEvent(snapshotEvent(settled));
+    pending.resolve({ ...acceptance('conversation-a', 'request-1'), mode });
+    await submission;
+    expect(store.getState().requestsByConversationId['conversation-a']).toEqual({});
+    expect(store.getState().draftsByConversationId['conversation-a'].text).toBe('');
+  });
+
   it('preserves the optimistic UI id when a reconnect snapshot is already durable', async () => {
     const store = createCodingConversationStore({
       getSnapshot: vi.fn(),