Prereg: docs/phase8_prereg.md (d0f3f82 + amendments 191d804, aff6c42, 77486af, all committed before any contest call). Raw artifacts in substrate_experiment/phase8/ (contest_rows.jsonl, grades_contest.jsonl, aggregate8.json, label_map.jsonl, llm_cache/).
Setup: 200-unit corpus from real autonet session traces; 25 questions selected where bare Haiku fails (calibration mean 1.12/5, gate #3 passed); 5 arms; two blind graders (Opus 4.8, Sonnet 5; r=0.57, clears the 0.4 gate); 4% null grades (under the 10% abort gate); no guard aborts; context parity held.
| Arm | Mean |
|---|---|
| A bare | 1.220 [1.113, 1.340] |
| B rag (payloads only) | 1.587 [1.373, 1.827] |
| C ledger (payloads + verdict claims, vote re-rank) | 1.307 [1.153, 1.507] |
| D256 substrate (equilibrated re-rank) | 1.433 [1.253, 1.653] |
| D64 | 1.387 [1.233, 1.567] |
- B−A = +0.367, p=0.012: retrieval genuinely helps on an unknown domain. First positive evidence for the substrate value prop's retrieval leg (phase 7's negative was a saturated-domain artifact).
- C−B = −0.280, p=0.012: injecting verdict claims INTO the context hurts. Verdicts belong in ranking, not in the prompt.
- Primary: D256−C = +0.127, Holm p=0.054, CI [+0.03, +0.24]: equilibrated standing beats vote-count standing by a small, probably real, margin that fails the pre-registered bar (p<0.05 AND diff≥0.25).
- D64−D256 = −0.05, n.s.: embedding dim 64 vs 256 doesn't matter here.
DEMOTE equilibration. Expansion rule not triggered (CI excludes 0). Per the gate: mint pricing moves toward explicit debate standing (economics change requires user ratification); equilibration becomes an experimental kernel; quantum-inference path parked.
Honest nuance recorded: the primary effect is positive with a CI excluding zero: equilibration is not worthless, it is small. It failed the magnitude bar that was set, before data, as "earns its complexity."
- Retrieval arm (payloads only) was the best overall: the two-plane data path is validated as the product surface.
- Standing should re-rank and price, never fill context (C−B).
- All context arms remain far from a knowledgeable ceiling (~1.6/5): retrieval quality / corpus depth, not standing math, is the binding constraint on answer quality.