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/architecture/README.md

@@ -1,8 +1,8 @@
 ---
 status: draft
-last_updated: 2026-10-10 (ADR-024: the mem engine adopted as a third
+last_updated: "2026-10-10 (ADR-024: the mem engine adopted as a third
 engine — engine-mem.md added, ADR table row, index updated for the
-implementation phase)
+implementation phase)"
 ---
 
 # alkstore — Architecture