[Bug]: Deleting a thread says it permanently clears its history, but V2 keeps every event and projection row #17845

Area

apps/server

Steps to reproduce

1. On Orchestrator V2, run a thread for one turn with at least one tool call.
2. Delete it from the sidebar. The dialog says: "This permanently clears conversation history for this thread."
3. With the server running or stopped, open statev2.sqlite read-only and count the thread's rows:

   SELECT count(*) FROM orchestration_events WHERE aggregate_kind = 'thread' AND stream_id = :thread_id;
   SELECT count(*) FROM orchestration_v2_projection_turn_items WHERE thread_id = :thread_id;
   SELECT count(*) FROM orchestration_v2_projection_messages WHERE thread_id = :thread_id;

Expected behavior

The thread's conversation history (messages, turn items with tool output, reasoning, and the events that carry them) is removed from the database, as the dialog says. A minimal tombstone may stay so clients drop the thread.

Actual behavior

Every row stays. planThreadDeletion (apps/server/src/orchestration-v2/ThreadDeletion.ts:58) emits thread.deleted with deletedAt and cancels open work; nothing deletes rows. The projection gets deleted_at set, and reads filter on it. Each delete also appends more events (the delete plus the cancellations).

On one install, a thread deleted on 2026-10-08 still has all 48 of its events (48.6 KB of payload), 6 turn items and 2 messages. Across that install, 45 deleted threads still hold 365 MB; 44 of them were deleted before the V2 migration, so that total also reflects V1 behavior.

The dialog text is in apps/web/src/components/Sidebar.tsx:4807 and :4460 (bulk), apps/web/src/hooks/useThreadActions.ts:992, and apps/web/src/hooks/useThreadActionMenu.ts:318.

ProjectionMaintenance.compactEventStore does not help. It keeps the newest event of each kind and never removes a deleted thread's history; besides, nothing in production calls it (#15759, #16558).

Impact

Minor bug or occasional failure

Version or commit

Observed on nightly 0.0.46-nightly.20261007.2787. Same code on main @ 8c777fbfad (checked statically).

Environment

Linux x86_64, headless T3 server, Orchestrator V2.

Logs or stack traces

deleted threads in orchestration_v2_projection_threads: 45 (1 deleted after the V2 migration)
that V2-era thread: events 48 (48,642 payload bytes), turn items 6, messages 2
all deleted threads together: ~365 MB logical across events, turn items and nodes

Workaround

None in the app. Rows can be removed only by hand with the server stopped, followed by VACUUM. auto_vacuum is off, so deleted pages do not shrink the file.

Either the delete should purge the thread's history (events, receipts, projections, keeping a tombstone), or the dialog should say the thread is hidden, not cleared. Which one is the maintainers' call. A purge path is the bigger change and overlaps the retention discussion in #6897.

Drafted with Claude Opus 5.5 in Claude Code (T3 Code harness); counts measured read-only on the install above.

🤖 Generated with Claude Code