test(issue-18): measure the wall-clock close on the record and widen the loop worker's wall clock

Both tests ran against the public broker with second-scale budgets: the
error publish after the close can take 10-20 s, and a worker's `started`
must land before a 12 s wall clock. Assert the close time from the record's
updated_at and give the loop scenario a 30 s wall clock.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01VCgu9Fa9iT7TbJUSzdq4Ff

tests/test_issue14_delivery_ack.py

@@ -503,9 +503,14 @@ def test_wrapper_idle_grace_never_outlives_the_wall_clock(tmp_path):
     # The heartbeats were honoured: the job was not closed after the first idle
     # window, it stayed open up to the wall clock ...
     assert elapsed >= timeout_s - 1, f"closed before the wall clock: {elapsed:.1f}s\n{stderr}"
-    # ... and not a moment past it beyond closing and publishing the error
-    # (the error publish alone can take ~10 s against the public broker).
-    assert elapsed <= timeout_s + 15, f"idle grace outlived --timeout {timeout_s}s: {elapsed:.1f}s\n{stderr}"
+    # ... and the close itself landed within the wall clock plus a small margin.
+    # Measured on the record's own close time: the error publish that follows
+    # the close can take 10-20 s against the public broker and is not what
+    # this test is about.
+    import calendar
+    closed_at = calendar.timegm(time.strptime(job_data["updated_at"], "%Y-%m-%dT%H:%M:%SZ"))
+    close_delay = closed_at - started
+    assert close_delay <= timeout_s + 8, f"idle grace outlived --timeout {timeout_s}s: closed after {close_delay:.0f}s\n{stderr}"
 
 
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