Addresses review on #51077 (kxee). The continuable-cron mirror reused
gateway.mirror.mirror_to_session, which writes role=assistant — re-
introducing the exact alternation violation #2313 (37a997945)
deliberately removed: a cron brief landing as assistant after the
agent's last turn yields assistant->assistant, which breaks strict-
alternation providers (OpenAI/OpenRouter) per issue #2221. The mirror/
mirror_source metadata is also dropped at the SQLite boundary, so the
[Delivered from cron] label is lost on replay.
This is an intentional, opt-in (default OFF) reversal of #2313's
'cron output does not belong in interactive history' for the reply-to-
cron use case — gated behind cron.mirror_delivery / attach_to_session.
Fixes:
- mirror_to_session gains a role param (default 'assistant' — interactive
send_message mirror unchanged, it IS the agent speaking). Cron paths
pass role='user' with a '[Cron delivery: <task>]' prefix so the brief
collapses via repair_message_sequence's consecutive-user merge on every
provider, and stays distinguishable on replay despite the metadata drop.
- thread_seeded: defer seeding + the flag until delivery into the new
thread actually succeeds. Previously set pre-delivery, so an open-
succeeds / deliver-fails case both stranded a seeded-but-unseen brief
AND suppressed the DM-fallback mirror.
- seed mirror now passes user_id='system:cron' to resolve the exact
thread-keyed session row it just created.
- dedupe the duplicate BasePlatformAdapter import in _deliver_result.
- trim oversized docstrings to non-obvious WHY (AGENTS.md).
- docs: document cron.mirror_delivery / attach_to_session in
website/docs/user-guide/features/cron.md.
- test: assert the cron mirror writes role='user' with the label prefix.
204 cron+mirror tests pass.
b177d4ee48