Birds: opt-in session continuity across flights

[pgagnidze]

Birds are stateless today. Every flight is a fresh Claude session. This is the right default, but some birds would benefit from cross-flight context (monitoring, tracking changes over time).

Slack threads already do this: store provider_session_id, pass --resume on the next message. The cron_run handler just skips this path. A resumeSession bird config flag would wire it up, with a staleness cap to avoid context window degradation.

[Koroqe]

Session continuity is key for anything beyond one-shot tasks. We solved this by having each agent phase write artifacts (specs, test plans, review notes) to disk, so the next session picks up right where it left off without needing to resume the actual LLM context. Works well for long-running pipelines: https://github.com/Koroqe/claude-code-sdlc

[pgagnidze]

@Koroqe Thanks for the input. This is definitely a priority and coming soon.