Production bug + missing test coverage. c5b4c48 ("fix: lazy session
creation — defer DB row until first message (#18370)") moved
pending_title application from the eager _start_agent_build path to a
post-message-complete handler. The original block had:
except ValueError as e:
current["pending_title"] = None
logger.info("Dropping pending title for session %s: %s", sid, e)
except Exception:
logger.warning("Failed to apply pending title ...", exc_info=True)
…differentiating "title is invalid / duplicate, retrying won't help"
(ValueError, drop) from "transient DB failure, retry on next message"
(other Exception, keep + log).
The replacement block collapsed both into:
except Exception:
pass # Best effort — auto-title will handle it below
…so a duplicate-title session keeps the same dud pending_title forever,
hitting set_session_title with the same losing argument on every
message-complete. Auto-title can't kick in because pending_title still
shadows it.
Fix: extract a documented _apply_pending_session_title helper that
restores the three-branch semantics (success → clear, ValueError →
drop, other Exception → retain). Call it from the
message-complete handler instead of the inline try/except.
Test rewrite: the previous test_session_create_drops_pending_title_on_valueerror
exercised an obsolete code path (eager apply during session.create) that
no longer existed after c5b4c48. Replace with four focused tests against
the helper:
- drops_on_valueerror — invariant from the original test name
- clears_on_success — happy path
- retains_on_transient_exception — guards the new "don't lose title
on a flaky DB" behaviour
- no_op_without_pending — most calls hit this path
Mutation-tested mentally: deleting the `session["pending_title"] = None`
in the ValueError branch fails drops_on_valueerror; deleting the same in
the success branch fails clears_on_success; widening except ValueError
to except Exception fails retains_on_transient_exception.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
claude-ceo-assistant
3697e6cea2