Outbound Thread Conversation

The thread's conversation history via a live channel read — the structured digest (cleaned, deduped, oldest-first) that also feeds the Slack ping recap, each message carrying an LLM summary clause (the drawer shows summaries first, full text on expand). Summaries cache on the thread row keyed by the digest signature, so re-opens don't re-pay the LLM call. Served on its own endpoint so the drawer opens fast and a channel-API failure degrades one section, not the whole detail view.