feat(briefs): store briefs after each completed turn

[HazAT]

Stacked on #1805. Milestone 3 of conversation briefs: production wiring of storage and generation. No user-visible surface yet; search, API, and dashboard follow in #1808 and #1810.

What

• Brief generation is an app-level opt-in: createApp({ briefs: { enabled: true } }), mirroring experimental features. It is off by default because it costs one default-model call per completed Turn; the example app, the junior init scaffold, and junior chat enable it. Integration tests stay off unless they opt in, so no test turn ever reaches the model gateway.
• junior_conversation_briefs: append-only versions, one per completed Turn (conversation_id, version PK; unique conversation_id, turn_id; through_seq; GIN index on search_text for feat(briefs): search briefs from the agent, API, and feed #1808).
• A core briefs.updateBrief task delivered through the existing plugin task queue after Slack, web, and local Turns with a user instruction. It builds its input from durable SQL events through the same event-to-entry mapping the CLI snapshot adapter uses, runs the tuned generator with the configured default model, and stores the next version under a per-conversation lock.
• Robustness rules, each covered by a test:
  • a retried Turn never calls the model again; it re-emits its event idempotently so a stored Brief cannot lose its cost record;
  • a Turn already covered by a newer Brief (out-of-order delivery) is skipped before any model call;
  • child conversations and purged private conversations are skipped;
  • the storage transaction refuses to write a Brief for a purged non-public conversation, so a purge racing an in-flight task cannot resurrect private content, and leftover private Brief rows keep a tree eligible for purge.
• briefs/brief_updated structured conversation event with version, model id, item counts, and model cost. Cost rolls into the conversation auxiliary-cost breakdown under the briefs namespace and renders in conversation history.
• Purge rule: public briefs survive transcript expiry; a non-public root loses its briefs in the same step that scrubs its title. Private stays private.
• TERMINOLOGY.md gains Brief; the module README documents storage, versioning, purge, and the privacy gate later readers must apply.

Verification

• tests/component/briefs/conversation-brief-task.test.ts (new), the extended purge scenario in tests/component/conversations/retention.test.ts, the plugin task scheduling and event rendering tests: 84 tests pass against Postgres.
• tests/unit/cli/init-cli.test.ts keeps the scaffold aligned with the example app.
• pnpm typecheck, pnpm --filter @sentry/junior lint, pnpm migration-metadata:check, pnpm file-length:check, pnpm test-architecture:check.

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Project	Deployment	Actions	Updated
junior-docs	Ready	Preview	Sep 9, 2026 9:23pm UTC

[cursor]

Cursor Bugbot has reviewed your changes and found 1 potential issue.

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[cursor]

Public purge races fail the task

Medium Severity

The task lets a purged public Conversation continue so a stored Brief can re-emit its event, but when no Brief exists yet it still requires the turn_completed row. Purge has already deleted that event, so readTurnCompletedSeq throws and retries keep failing.

Additional Locations (1)

• packages/junior/src/chat/briefs/task.ts#L44-L68

 

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