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# null-tier & tier-split record (reviewed, not vanished)

## Phase 4 — tier split by subtraction

The 895 universal lessons were partitioned into three orthogonal tiers by the subtraction test (most-general tier where each lesson keeps its teeth). 31 lessons genuinely SPLIT into a generic/loop principle + a specific application, cross-referenced. Verified: 0 lessons in two tiers, 0 missing, 0 broken cross-refs (895 = 212+526+188 − 31 split halves rejoined).

- **crewrift-specific**: 212 lessons · AGENTS.md 3 / skills 104 / guides 100 / tools 5 · 59 neg · 57 unverified
- **optimization-loop**: 526 lessons · AGENTS.md 17 / skills 286 / guides 198 / tools 25 · 181 neg · 223 unverified
- **generic**: 188 lessons · AGENTS.md 9 / skills 95 / guides 78 / tools 6 · 69 neg · 111 unverified

### Audit corrections applied

A tier-purity audit (120-lesson sample, 3 agents) found the tiers ~97% correctly placed and all three packages standalone-coherent (cross-tier mentions are pointers/examples, not dependencies). The one systematic error: **13 cogs-vs-clips (machina_1) lessons had been mis-assigned to the crewrift tier** — CvC is a distinct Coworld game, not crewrift social-deduction. All 13 were reassigned crewrift→loop (where the rest of the CvC content lives). No items lost; this was a re-tiering, not a cut.

### Items kept at the specific tier (would go vacuous if generalized)

Per the subtraction test's rule 3, lessons whose value lives in their specifics were deliberately NOT promoted to a more general tier (generalizing them to e.g. 'test your changes' would strip their teeth). These remain at crewrift/loop by design, not by oversight.

## Phase 3 cuts (carried forward)

- 6,094 normalized records → 3,130 deduped → 895 synthesized (the dominant transform was merge/synthesis, not deletion).
- ~24 atoms cut outright as vacuous/off-topic/pure-restatement during 3B/3C.
- Full atomic set preserved for audit at `haul/records/all_records.json`; synthesized set at `haul/records/universal_lessons.json`.
