* feat: structured memory system — typed/scoped memories with BM25 relevance and metacognitive prompting
Replace flat key-value memories table with structured_memories (migration 014).
Four memory types (user/project/feedback/reference), three scopes
(global/workstream/user). Consolidate remember/recall/forget into two tools:
memory (action-based: save/search/delete/list) and recall (conversation
history only).
BM25 relevance scoring (extracted to turnstone/core/bm25.py) selects top-5
memories for system message injection based on conversation context.
Metacognitive prompting injects ephemeral nudges after corrections, tool
denials, workstream resume, and completion signals.
Scope isolation enforced: system message injection and nudge counts filtered
to visible memories only (global + current workstream + authenticated user).
User scope requires authentication. Content capped at 32KB. ILIKE/LIKE
metacharacters escaped in both backends.
113 new tests (2053 total).
* fix: CI failure + copilot review feedback
- Fix time.monotonic() cooldown: use None sentinel instead of 0.0
default (monotonic clock starts at boot, not epoch — fresh CI
runners have uptime < 300s so cooldown check always triggered)
- Catch sa.exc.IntegrityError specifically in upsert instead of
broad Exception (copilot review)
- Preserve existing description/type on upsert when caller doesn't
explicitly set them (copilot review)
- Add last_accessed + access_count columns to schema/migration for
future LRU/LFU eviction support
Patrick Buckley