docs-frontmatter-cleanup: the 11 invalid last_updated frontmatter scalars quoted — double-quote convention applied uniformly (one escaped quote in phase-0.md), annotation prose verbatim; PyYAML sweep over docs/**/*.md + tasks/*.md reports 0 failures, taskgraph validate green (79 tasks); task status -> completed with Notes (recorded sweep command, date-scalar caveat) + Summary

docs/research/phase-0.md

@@ -1,11 +1,11 @@
 ---
 status: draft
-last_updated: 2026-10-04 (Phase 0 complete and the register promoted:
+last_updated: "2026-10-04 (Phase 0 complete and the register promoted:
 docs/architecture/ opened with ADR-001..007 carrying the resolved
 decisions and the OQ tracker mirroring OQ-ST-01..08 1:1. Phase 0
 research itself is closed; remaining work is in docs/architecture/
 open-questions.md. One erratum fixed in OQ-ST-04's tx-friction line —
-thread-affinity is SQLite-side, previously garbled as "pg-side".)
+thread-affinity is SQLite-side, previously garbled as \"pg-side\".)"
 ---
 
 # alkstore — Phase 0 (Exploration)