Preserve preview harness, editor, email and task improvements

Snapshot current maintainer-preview application changes and regression fixtures for integration into lab. Excludes local runtime data, evaluation outputs and source backups. Focused Python regression selection: 140 passed; full suite not certified.

tests/test_agent_runs_terminal_order.py

@@ -28,3 +28,27 @@ def test_done_is_published_only_after_generator_cleanup():
         agent_runs._RUNS.pop(session_id, None)
 
     asyncio.run(scenario())
+
+
+def test_finish_request_is_bound_to_the_exact_active_run():
+    async def scenario():
+        session_id = 'finish-editor-run-test'
+        gate = asyncio.Event()
+
+        async def stream():
+            await gate.wait()
+            yield 'data: [DONE]\n\n'
+
+        run = agent_runs.start(session_id, stream())
+        await asyncio.sleep(0)
+        assert not agent_runs.request_finish(session_id, 'stale-run-id')
+        assert not agent_runs.should_finish(session_id)
+        assert agent_runs.request_finish(session_id, run.run_id)
+        assert agent_runs.should_finish(session_id)
+        gate.set()
+        async for _ in agent_runs.subscribe(session_id, run):
+            pass
+        assert not agent_runs.should_finish(session_id)
+        agent_runs._RUNS.pop(session_id, None)
+
+    asyncio.run(scenario())