fix(nap): archive undated decisions and add count-based fallback

[diberry]

fix(nap): Archive undated decisions and add count-based fallback

Fixes #20 — decisions.md grows unbounded because archiveDecisions() silently fails on real-world content.

Bugs Fixed

Bug 1: Undated entries immune to archival

• daysAgoFromLine() returns null for entries without YYYY-MM-DD dates
• The split logic put null daysAgo into recent → never archived
• Fix: Three-bucket split (old/undated/recent). Undated entries are archived alongside aged-out ones when file exceeds threshold.

Bug 2: Age-only pruning fails for active projects

• If all entries are <30 days old, old.length === 0 → returns null regardless of file size
• Active projects blow past 20KB in days with all entries recent
• Fix: Count-based fallback. When nothing is age-archived, sorts entries oldest-first and greedily keeps the most-recent entries that fit under the 20KB threshold.

Evidence

Both bugs confirmed on bradygaster/squad@dev — verified the code is identical upstream. This repo's decisions.md is at 345KB (17× the 20KB threshold). Archival has been silently returning null since Feb 28.

TDD Approach

5 new test cases written first (red), then implementation (green):

1. ✅ archives undated entries when file exceeds threshold
2. ✅ archives mixed dated+undated — keeps recent dated, archives undated
3. ✅ archives entries when all are recent but file exceeds threshold (count-based fallback)
4. ✅ preserves all entries — no data loss during archival
5. ✅ secondary pass keeps most recent entries by date, archives oldest

Result: 43/43 nap tests pass. No existing tests broken.

Changes

File	Lines	What
packages/squad-cli/src/cli/core/nap.ts	+43	3-bucket split + count-based fallback in archiveDecisions()
test/nap.test.ts	+156	5 new test cases + generateDecisions() helper

Postmortem

Full postmortem posted on #20.

Root cause: Commit aaefeb1 (Feb 28) — Copilot wrote implementation + 38 tests in one pass. Tests used synthetic 2024-01-XX dated fixtures, never challenging the "entries always have dates" assumption. The happy path worked; adversarial cases were never considered.

Key lesson: "AI writes the tests it believes in, not the tests that break it." Adversarial test generation must be a deliberate separate step by a different agent.

10-Agent Team Review

Issues #20 and #21 received full team reviews from Flight, EECOM, FIDO, Procedures, and Telemetry. Key findings:

• squad doctor already exists (extend, don't recreate)
• Zero squad.decisions.* OTel metrics exist (subsystem is completely dark)
• Union merge driver (merge=union) conflicts with line-deletion archival
• Highest-ROI future fix: coordinator pre-spawn decision filtering (API already supports it)

Follow-up Issues Created

#	Title	Owner
#22	## heading awareness in archiveDecisions	EECOM
#23	Data-loss invariant test	FIDO
#24	Scribe charter format mandate	Procedures
#25	Silent-failure detection in nap report	EECOM
#26	Archival test checklist for CONTRIBUTING	Procedures
#27	Coordinator pre-spawn decision filtering	EECOM
#28	decisions-index.md as separate file	EECOM
#29	squad.decisions.* OTel metrics	Telemetry
#30	Extend squad doctor with size checks	EECOM
#31	Troubleshooting guide docs	Procedures
#32	Coordinator diagnostic breadcrumbs as OTel	Telemetry
#33	Scribe task reorder with HARD GATE	Procedures
#34	Configurable thresholds in config.json	EECOM
#35	Decision lifecycle states	EECOM
#36	Ralph idle-watch archival trigger	EECOM
#37	Contract comment for archiveDecisions	EECOM

[diberry]

Superseded by bradygaster/squad PR bradygaster#627 which merged the count-based fallback with Procedures' correction (undated entries preserved). Our fix in this PR was partially rejected by Procedures for the same reason Brady adopted. No longer needed.