fix(ai-chat): guard "Send now" against a stale-status race (#198 review)

Addresses the open findings from the #198 ("Interrupt agent / send now")
code review (posted on PR #200's thread).

- sendNow: branch on the live status read from a new `statusRef` (updated
  every render) instead of the closure-captured `isStreaming`. If the turn
  finished between render and click, stale-true `isStreaming` made sendNow
  arm flushOnAbortRef/interruptNextSendRef and call a no-op stop(), leaving
  the one-shot flags armed to leak into a later turn. Reading the live
  status takes the not-streaming branch (send immediately) instead.
  Dependency array trimmed from [isStreaming, setQueue, stop] to
  [setQueue, stop].
- queued-state comment: drop the incorrect "(onFinish does not fire then)"
  claim — onFinish fires on every terminal outcome, only a clean finish
  flushes the queue, and a deliberate "Send now" flushes the promoted head
  via the abort branch of onFinish.

The third review finding (missing i18n keys "Send now" / "Interrupt and
send now") was already resolved in f789be9c.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

apps/client/src/features/ai-chat/components/chat-thread.tsx

@@ -182,9 +182,12 @@ export default function ChatThread({
   // LOCAL state so it is scoped to this conversation: it is cleared when the user
   // deliberately switches chat / starts a new chat (the parent remounts this via
   // `key`), but it SURVIVES in-place new-chat id adoption (no remount), so a
-  // message queued during a brand-new chat's first turn is not lost. On Stop or
-  // error the queue is intentionally preserved (onFinish does not fire then) so
-  // the user decides what to do with the pending messages.
+  // message queued during a brand-new chat's first turn is not lost. On a normal
+  // Stop / disconnect / error the queue is intentionally preserved (onFinish still
+  // fires on every terminal outcome, but only a CLEAN finish flushes it) so the
+  // user decides what to do with the pending messages. The one exception is a
+  // deliberate "Send now", which also calls stop() and then flushes the promoted
+  // head via the abort branch of onFinish (see sendNow / onFinish below).
   const [queued, setQueued] = useState<QueuedMessage[]>([]);
   // Mirror the queue in a ref so the `onFinish` flush always reads the latest
   // queue without a stale closure; `setQueue` updates BOTH the ref and the state.
@@ -347,12 +350,28 @@ export default function ChatThread({
 
   const isStreaming = status === "submitted" || status === "streaming";
 
+  // Mirror the live `status` in a ref (updated every render) so event handlers
+  // fired from a stale render — notably `sendNow` clicked in the sub-frame window
+  // after a turn finished but before the re-render — branch on the CURRENT status,
+  // not the value captured in their closure. Prevents arming the interrupt/flush
+  // refs when nothing is actually streaming (see sendNow).
+  const statusRef = useRef(status);
+  statusRef.current = status;
+
   // "Send now" on a queued message: interrupt the current turn and immediately
   // send THIS message. Any other queued messages stay queued and flush normally
   // after the new turn finishes.
   const sendNow = useCallback(
     (id: string) => {
-      if (isStreaming) {
+      // Branch on the LIVE status (statusRef), not the closure-captured
+      // `isStreaming`: if the turn finished between this render and the click,
+      // treat it as not-streaming and send immediately, instead of arming a
+      // flush/interrupt that no abort will ever consume (the stop() below would be
+      // a no-op and the flags would leak into a later turn).
+      const liveStatus = statusRef.current;
+      const liveStreaming =
+        liveStatus === "submitted" || liveStatus === "streaming";
+      if (liveStreaming) {
         // Promote the chosen message to the head so the existing onFinish→flushNext
         // sends exactly it, then interrupt: the abort triggers onFinish below.
         setQueue(promoteToHead(queuedRef.current, id));
@@ -367,7 +386,7 @@ export default function ChatThread({
         sendMessageRef.current?.({ text: msg.text });
       }
     },
-    [isStreaming, setQueue, stop],
+    [setQueue, stop],
   );
 
   // Clear the stopped marker as soon as a new turn begins streaming, and drop any