fs-test checks an unattended detached session expires its messages on its own

Round 7 saw messages linger for minutes in a detached session. With nothing
attached they do expire, on the session's own clock (nextWake schedules the
look, expireUnattended drops them); the merge did not regress it, and a
session driven only over 9P now has a test that it does, with no request in
between. With a frontend attached a message stays until its next key or
click, as config.md and detached.md say; the lingering the agent saw is that.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

1 files changed, 16 insertions, 0 deletions

diff --git a/test/fs.py b/test/fs.py
index 67edf01e..890e75f6 100644
--- a/test/fs.py
+++ b/test/fs.py
@@ -451,6 +451,21 @@ def exit_answers(binary):
                 raise AssertionError("Exit did not quit the editor")
 
 
+def unattended_messages_expire(binary):
+    """With nothing attached, a message leaves after MessageLinger on its own
+    clock: no key, no click, no other request comes to move it along."""
+    with tempfile.TemporaryDirectory(prefix='pardes-msg-') as directory:
+        with session(binary, Path(directory), 'msg') as (client, _):
+            client.write('/pane/1/ctl', b'Msg lingering-words\n')
+            def shown():
+                screen = json.loads(client.read('/screen'))
+                return 'lingering-words' in ''.join(cell[0] for cell in screen['cells'])
+            assert shown()
+            # Reading /screen is itself a request, so wait without asking.
+            time.sleep(2.5)
+            assert not shown(), 'an unattended message outlived MessageLinger'
+
+
 def signal_cleans_up(binary):
     """A detached session told to stop by a signal unlinks its sockets."""
     for sig in [signal.SIGTERM, signal.SIGINT, signal.SIGHUP]:
@@ -471,6 +486,7 @@ def test(binary, quic=False):
     started = time.monotonic()
     run_file(binary)
     exit_answers(binary)
+    unattended_messages_expire(binary)
     signal_cleans_up(binary)
     for options, message in [
         (['--fs'], b'no such option'),