The shutdown banner promised "send any message after restart to resume
where you left off" but the code did the opposite: a drain-timeout
restart skipped the .clean_shutdown marker, which made the next startup
call suspend_recently_active(), which marked the session suspended,
which made get_or_create_session() spawn a fresh session_id with a
'Session automatically reset. Use /resume...' notice — contradicting
the banner.
Introduce a resume_pending state on SessionEntry that is distinct from
suspended. Drain-timeout shutdown flags active sessions resume_pending
instead of letting startup-wide suspension destroy them. The next
message on the same session_key preserves the session_id, reloads the
transcript, and the agent receives a reason-aware restart-resume
system note that subsumes the existing tool-tail auto-continue note
(PR #9934).
Terminal escalation still flows through the existing
.restart_failure_counts stuck-loop counter (PR #7536, threshold 3) —
no parallel counter on SessionEntry. suspended still wins over
resume_pending in get_or_create_session() so genuinely stuck sessions
converge to a clean slate.
Spec: PR #11852 (BrennerSpear). Implementation follows the spec with
the approved correction (reuse .restart_failure_counts rather than
adding a resume_attempts field).
Changes:
- gateway/session.py: SessionEntry.resume_pending/resume_reason/
last_resume_marked_at + to_dict/from_dict; SessionStore
.mark_resume_pending()/clear_resume_pending(); get_or_create_session()
returns existing entry when resume_pending (suspended still wins);
suspend_recently_active() skips resume_pending entries.
- gateway/run.py: _stop_impl() drain-timeout branch marks active
sessions resume_pending before _interrupt_running_agents();
_run_agent() injects reason-aware restart-resume system note that
subsumes the tool-tail case; successful-turn cleanup also clears
resume_pending next to _clear_restart_failure_count();
_notify_active_sessions_of_shutdown() softens the restart banner to
'I'll try to resume where you left off' (honest about stuck-loop
escalation).
- tests/gateway/test_restart_resume_pending.py: 29 new tests covering
SessionEntry roundtrip, mark/clear helpers, get_or_create_session
precedence (suspended > resume_pending), suspend_recently_active
skip, drain-timeout mark reason (restart vs shutdown), system-note
injection decision tree (including tool-tail subsumption), banner
wording, and stuck-loop escalation override.
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