Adds an opt-in path so a cron job's delivered output is also appended to
the TARGET chat's gateway session transcript (as an assistant turn), so a
user reply to a recurring delivery (daily brief, reminder) is answered with
the delivery in context instead of 'what is that?' amnesia.
- Reuses the shipped gateway.mirror.mirror_to_session — the same primitive
interactive send_message mirroring already uses. No messaging-toolset
change (cron still can't call send_message; this rides delivery).
- Gated: per-job attach_to_session overrides global cron.mirror_delivery
(config.yaml). Default OFF — historical isolation preserved byte-for-byte.
- Mirrors the CLEAN agent output, not the cron header/footer wrapper.
- Alternation/cache-safe: append lands at a turn boundary, never mid-loop,
never mutates the cached system prompt. Cold-start (no target session)
is a silent no-op; mirror errors never fail a successful delivery.
- Surfaced on the cronjob tool (attach_to_session) + config schema.
Driven by enterprise cron-as-control-plane use case. 10 new tests; full
cron + cronjob-tool suites pass (600).
1b181724fa