Redistribute point-in-time architecture/ artifacts to plans/engineering-notes/

[stijn-dejongh]

Why

The Common-Docs section audit (docs/plans/engineering-notes/common-docs-section-audit.md)
found docs/architecture/ — the docs-wide canonical living-design zone — polluted with
point-in-time (concern bucket (c)) research/audit prose that belongs in
docs/plans/engineering-notes/ per Common-Docs ADR 2026-06-27-1 (D3/D4/D7).

What — per-file disposition (from the audit)

Move 9 firmly-misfiled files, adjudicate 1 borderline file:

• architecture/883-research-synthesis.md → plans/engineering-notes/ — self-declares
  "Point-in-time pre-spec research synthesis for mission Add mission-type governance profiles for non-software missions #883 … superseded by the ADR and
  brief where they differ."
• architecture/883-mission-type-authority-brief.md → plans/engineering-notes/ — companion
  pre-spec authority brief; superseded by ADR 2026-07-14-2.
• architecture/audits/*.md (7 files, whole subdir) → plans/engineering-notes/:
  2026-05-11-findings-vs-issues-update.md, 2026-05-11-issue-992-984-audit-comments.md,
  2026-05-822-crosscheck.md, 2026-05-caacs-meta-assessment.md,
  2026-05-phase3-f1-knowledge-capture-plan.md, 2026-05-phase3-issue-drafts-and-triage.md,
  2026-05-spec-kitty-caacs.md — dated 2026-05 Code-as-a-Crime-Scene forensic
  audits/triage/issue-draft dumps (one carries a fork-local absolute path + branch
  feat/caacs-doctrine). Point-in-time reports, not architecture.
• Adjudicate architecture/assessments/code-as-a-crime-scene-overview.md — verify it is
  a durable explainer of the CaaCS method (stays in architecture/) rather than only a
  pointer into the dated 2026-05 audits (fold into this move if so).

IA-mechanics obligations (inherited from #2851's pattern — every move needs all of these)

• Redirect-map entry per moved path (scripts/docs/redirect_map.yaml)
• Relative-link fix (relative_link_fixer --check)
• Page-inventory regen (docs/development/3-2-page-inventory.yaml lockfile +
  check_docs_freshness --ci)
• related: frontmatter edges on both the moved files and their referrers
• Terminology guard (tests/architectural/test_no_legacy_terminology.py)

Boundary vs #2227 (related, not duplicate)

#2227 ("Common Docs Mission B residuals") is a different scope: ~25 historical prose
mentions of architecture/<era> paths in docs bodies (not broken links, not misfiled files)
plus 2 HELP-DRIFT warnings — a content-modernization pass. This ticket is about physically
relocating 9–10 misfiled point-in-time files out of architecture/. Coordinate so the two
don't double-touch the same files (e.g. if #2227's prose sweep happens to also touch
audits/).

Do not double-pick — in-flight mission already implements this

An in-flight mission docs-structural-sanity-01KY53KJ (branch
docs/common-docs-section-audit on the stijn-dejongh fork) already implements this exact
finding — specced + planned + tasked, WP01/03/04 content done, currently parked on the
#2841 coord-tooling blocker. Check that mission before starting fresh work on this ticket.

Sizing

Size M (per audit).

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Source: docs/plans/engineering-notes/common-docs-section-audit.md (candidate 1).