RQ2-P3: re-word §7 calibration gate (naive→mechanical mix), re-run GREEN

Operator ruling (Andre, 2026-07-21): the STOP was correct and the diagnosis
right — §7 items 1-2 did not fail because the instrument is broken, but because
they were worded under the naive-funnel prior. Under the ratified posterior the
pool is a MIX (shared bridge → shared exit_signature → larger anonymity set →
higher H). Corrected pre-freeze, logged transparently (no HARKing).

- rq2p3-mechanism-prereg.md §7: item 1 re-anchored on the FROZEN bridge-federated
  branch (injective fresh-bridge → m_i=1 → H≈0, constant c=1/C — a pool draws with
  replacement so it cannot reproduce the zero-variance degeneracy); item 2 B=1 →
  c=1.0 AND high H (maximal mix, "low H" refuted by construction); added a §7 scope
  note (the gate validates the INSTRUMENT and must NOT pre-assert the H-vs-c sign —
  that stays the two-sided confirmatory question H1/H2). Confirmatory hypotheses
  unchanged.
- docs/stage-05-rq2p3-gate-clarification.md: dated deviation-rationale log (cites
  the dry-pass output, no number invented; records the two-sided direction-agnostic
  pre-commitment is untouched; the mix ρ 0→+0.838 is an exploratory finding that
  strengthens note-unique-bridge-artifact.md).
- rq2p3_calibration.py: item-1 teeth moved to frozen_branch_regression() on the
  untouched bridge-federated branch; item-2 now asserts c=1.0 AND high H; added
  all_pass aggregate. confirm.py/stats.py/confirm_load_rq2.py untouched.

Re-run: all four gate items PASS with real teeth (all_pass=True). Synthetic/DRY
only, no confirmatory record read. FREEZE STAYS A HUMAN GATE: §10 empty, no
confirmatory RQ2-P3 cell until operator records the SHA-256 + signs off. Lead
prereg SHA f22331a72e... untouched; worktree-only.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

docs/rq2p3-mechanism-prereg.md

@@ -112,15 +112,41 @@ Run order randomized within cell; deterministic from an ordering seed distinct f
 
 ## 7. Instrument-validation gate (boolean; blocks the confirmatory run)
 
+> **Re-worded 2026-07-21, pre-freeze (deviation logged in `stage-05-rq2p3-gate-clarification.md`).**
+> Items 1–2 were originally written under the naive-funnel prior ("pool reproduces the
+> zero-variance degeneracy"; "B=1 → low H"). Both are mechanically wrong under the *ratified*
+> posterior and were corrected **before freeze** — see the §7 scope note below. No hypothesis
+> changed (H1/H2/H3 in §2 stay two-sided/direction-agnostic); only a mis-specified validation
+> gate was fixed. The original dry-pass output that exposed this is cited in the deviation log.
+
 All must pass **before** any confirmatory cell:
 
-1. **Reproduce the lead degeneracy.** `B = 50, alpha = 0` → `c_i ≈ 1/50` constant, ρ undefined
-   — a regression check that this instrument reproduces the published RQ2-P3 result.
-2. **Extremes.** `B = 1` → all circuits share one bridge → `c = 1.0`, minimal set, low H.
+1. **Reproduce the lead degeneracy — on the FROZEN branch, not the pool.** The lead
+   zero-variance degeneracy is a property of the **injective fresh-bridge map** (a unique
+   bridge per circuit seed = effectively no reuse). A finite pool of **any** size `B` draws
+   **with replacement**, so birthday collisions make concentration non-constant and ρ defined —
+   a pool **cannot and must not** be expected to reproduce the fresh-bridge degeneracy. The
+   regression check therefore anchors on the actual frozen `bridge-federated` branch
+   (UNTOUCHED): it must still yield **unique exit-signatures → `m_i = 1` → `H_i ≈ 0`, constant
+   `c_i = 1/C`**. That is the real "lead reproduces" teeth.
+2. **B = 1 boundary.** `B = 1` → all circuits share the one bridge → **`c = 1.0`** (keep this
+   concentration tooth). Under the ratified posterior the anonymity set is then **all** circuits
+   sharing the exit house, so `H_i` sits at the **HIGH end (maximal mix)** — the "low H" gloss
+   was the naive-funnel error and is refuted **by construction** here. Expect high H.
 3. **Monotonicity.** Realized mean top-3 concentration is **monotone decreasing in B** and
    **increasing in alpha**, across the sweep, on a dry (non-confirmatory) calibration pass.
 4. **Entropy calibration unchanged.** H = log₂N on equiprobable synthetic senders (inherited).
 
+**§7 scope note (why items 1–2 do NOT assert an H-vs-c sign).** This gate validates the
+**instrument** — concentration varies monotonically (item 3), entropy is exact (item 4), the
+frozen branch is untouched (item 1), and the B=1 boundary hits `c = 1.0` (item 2). It **must not
+pre-assert the sign of H-vs-concentration**, because that sign *is* the two-sided confirmatory
+question (H1/H2). Baking "expect low H at high concentration" into a validation gate would be
+**funnel-circular**; removing it makes the study **more** rigorous, not less. The confirmatory
+hypotheses in §2 stay two-sided/direction-agnostic — **UNCHANGED**. (Note: the dry calibration
+pass already *previews* a mix, ρ 0→+0.838 across the sweep; this is surfaced openly as an
+exploratory preview and does **not** relax the two-sided pre-commitment.)
+
 If any gate item fails → STOP, do not report; surface as NEEDS-OPERATOR.
 
 ## 8. Analysis plan