fix: harden long conversation continuity

session-reply-wait.test.mjs

@@ -35,6 +35,53 @@ test('consumeSessionEventsUntilFinish resolves on Finish', async () => {
   assert.equal(result.tokenState.totalTokens, 12);
 });
 
+test('consumeSessionEventsUntilFinish ignores a stale unscoped Finish before request activity', async () => {
+  const frames = [
+    'data: {"type":"Finish","token_state":{"totalTokens":0}}\n\n',
+    'data: {"type":"ActiveRequests","request_id":"req-fresh","request_ids":["req-fresh"]}\n\n',
+    'data: {"type":"Finish","request_id":"req-fresh","token_state":{"totalTokens":0}}\n\n',
+    'data: {"type":"Message","request_id":"req-fresh","message":{"role":"assistant"}}\n\n',
+    'data: {"type":"Finish","token_state":{"totalTokens":12}}\n\n',
+  ];
+  const stream = new ReadableStream({
+    start(controller) {
+      for (const frame of frames) controller.enqueue(new TextEncoder().encode(frame));
+      controller.close();
+    },
+  });
+
+  const result = await consumeSessionEventsUntilFinish(stream, {
+    requestId: 'req-fresh',
+    timeoutMs: 5000,
+    requireRequestActivityBeforeUnscopedFinish: true,
+  });
+
+  assert.equal(result.tokenState.totalTokens, 12);
+});
+
+test('consumeSessionEventsUntilFinish fails fast when an empty Finish has no later activity', async () => {
+  const stream = new ReadableStream({
+    start(controller) {
+      controller.enqueue(new TextEncoder().encode(
+        'data: {"type":"Finish","request_id":"req-empty","token_state":{"totalTokens":0}}\n\n',
+      ));
+    },
+  });
+
+  await assert.rejects(
+    consumeSessionEventsUntilFinish(stream, {
+      requestId: 'req-empty',
+      timeoutMs: 5000,
+      emptyFinishGraceMs: 5,
+      requireRequestActivityBeforeUnscopedFinish: true,
+    }),
+    (error) => {
+      assert.equal(error.code, 'SESSION_EMPTY_FINISH');
+      return true;
+    },
+  );
+});
+
 test('consumeSessionEventsUntilFinish records a successful raster generate_image result', async () => {
   const toolResult = JSON.stringify({
     ok: true,