INST-5 · Auditable classifications & adoption (umbrella: 5a + 5b)

> **Umbrella** · split into two child issues (see task list). Kept open as a tracking umbrella. Item derived from the fact-checking cycle analysis (**2026-07-03, v2**).

### Finding (evidence)
Cross → final adoption (old 98.7%) is **unauditable** — `report.classification` equals the initial value (in the 29 initial≠cross cases, the "final" adopts the cross **0×**; 20× stays on the initial, 9 have no final). Robust inter-rater initial↔cross: **84.5% (N=187)**.

### Split
- [ ] #2507 — INST-5a · Persist the reviewer's **initial** classification as a durable field — 🔴 P (quick win)
- [ ] #2508 — INST-5b · Store all three classifications + `agreement.*` booleans — 🟡 M

### Reconciliation (D2) — inter-rater adoption metric
Two numbers measure adjacent things: **84.5% (N=187)** is overall initial↔cross concordance; the **44.4%** (cross adoption in divergent cases) is **not reproducible** with today's fields — with `report.classification`, the final adopts the cross **0×** in the 29 divergent cases. The 44.4% needs an independent `final` that **does not exist today** — which is exactly what INST-5a creates. **Acceptance:** do not use 44.4% as fact until 5a/5b ship; only 84.5% is citable today.

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- **Epic:** #2489