Merge pull request #928 from AdaWorldAPI/claude/jirak-math-theorems-harvest-rfii13

board: record merged PR #927 (arc entry + LATEST_STATE) — chain terminates here

Author: AdaWorldAPI

.claude/board/LATEST_STATE.md

@@ -1,3 +1,12 @@
+## 2026-08-12 — lance-graph #927 (MERGED) — board hygiene for #926 + the living-vs-ledger correction rule
+
+### Current Contract Inventory — no new types (board entries + one report correction)
+
+- **Fisher-z ring-mean ratio is 4.7×, not 5×** (18.07 / 3.84). Caught by verifying the new board entry's own figures against the committed JSONs before landing it: **9 of 10 exact, this was the tenth** — a 6 % overstatement in the favourable direction.
+- **⚠ LIVING DOCUMENTS vs APPEND-ONLY LEDGERS take OPPOSITE correction discipline.** A **living document** (report, code, JSON, PR description) is landed on directly → **fix every copy**. An **append-only ledger** is read newest-first and its value is the audit trail → **freeze the merged entry, correct in a NEW one**. I edited a merged `EPIPHANIES` entry in place and unmarked while citing the *grep-for-its-twins* rule; reverted same-PR. **A correct rule generalized past its domain** — third instance of that shape in this repo (#921's doctrine-vs-domain, this arc's Fisher-z rank/tail-vs-level).
+- **One-command append-only audit:** `git diff origin/main..HEAD -- .claude/board/` — **zero removed lines proves a pure prepend**, since a prepend cannot delete. Measured +13/−0, +10/−0, +0/−0 across the three board files.
+- **Note on assurance:** #927 was a draft through four review cycles, so **no automated reviewer read these entries** — CodeRabbit skips drafts and the explicit trigger hit the rate limit. The figures rest on self-verification against the committed JSONs.
+
 ## 2026-08-12 — lance-graph #926 (MERGED) — the storm spine, the 12-byte L4 carrier, and the propagation failure mode
 
 ### Current Contract Inventory — no new types (probes + report + board; zero Rust, zero product code)

.claude/board/PR_ARC_INVENTORY.md

@@ -1,3 +1,18 @@
+## 2026-08-12 — lance-graph #927 (MERGED) — #926's board hygiene, one rounding caught by self-verification, and the rule I broke while citing it
+
+- **Added.** `PR_ARC_INVENTORY` + `LATEST_STATE` entries for the merged #926. One correction to `COMET_TAIL_REPORT.md` §6.1. **This entry exists because #927 was MIXED, not hygiene-only** — it landed hygiene *and* a correction, and the rule's termination clause exempts only the pure case. #927's own PR description called itself "hygiene-only"; that was written before the correction landed and was wrong by the time it merged.
+- **The rounding `[G]`.** Before landing a permanent append-only record, every figure in the new entries was verified against the committed JSONs. **Nine of ten matched exactly** — 0.9434/0.9090 spine, 0.07 Pa carve-D RMSE delta, +1.59 Pa carve-D bias, +92.76 Pa carve-A bias, 0.9129 carve-A R², 0.684 CT-F14, 8.3× storm-tail, 138.4× L4x penalty. **The tenth did not: "5× worse" where 18.07 / 3.84 = 4.71×** — a 6 % overstatement in the FAVOURABLE direction, one commit from being frozen. Fixed in the report and in both new board entries.
+- **⊘ Locked — LIVING DOCUMENTS and APPEND-ONLY LEDGERS take OPPOSITE correction discipline, and I applied the wrong one.** #926's headline lesson was *"when correcting a claim, grep for its twins"*. Carrying that into `EPIPHANIES.md` I edited a **merged** entry's number in place, **unmarked** — history rewriting, precisely what an append-only ledger exists to prevent. Reverted in the same PR.
+  - **A living document** (report, code, JSON artifact, PR description) is landed on directly by a reader, so a stale claim there is a trap → **correct every copy**.
+  - **An append-only ledger** is read newest-first and its value IS the audit trail → **freeze the merged entry; the correction goes in a NEW entry**. Erasing the old number destroys the evidence that it was ever believed.
+  - Getting this wrong in the safe direction leaves one stale number. Getting it wrong the way I did **erases the record that the number was ever wrong.**
+  - **The failure mode is a correct rule generalized past its domain** — the same shape as `E-…-A-DOCTRINE-WRITTEN-FOR-ONE-DOMAIN-IS-NOT-AUTOMATICALLY-RIGHT-FOR-THE-NEXT` (#921), and the same shape as this arc's Fisher-z finding (right for a rank/tail read, wrong for an interpolate/level read). Three instances now; the pattern is not about any one rule.
+- **The falsifier that closed it `[G]`.** "Where else did I do this?" was answered by measurement, not memory: `git diff origin/main..HEAD` on all three board files gave **+13/−0, +10/−0, +0/−0**. **Zero removed lines is the structural proof of a pure prepend** — a prepend cannot delete, so no historical entry was rewritten anywhere in the PR. Worth reusing: it is a one-command append-only audit.
+- **Process note.** #927 sat as a draft through four review cycles — CodeRabbit skips drafts, and an explicit `@coderabbitai review` was consumed by the rate limit — so **no automated reviewer ever read these entries**; the figures rest on the self-verification above. The operator marked it ready and merged it. Cursor Bugbot was usage-limited throughout (billing, not a finding).
+- **Deferred.** No EPIPHANIES entry minted for the living-vs-ledger distinction: recording it here keeps the follow-up PR **pure hygiene**, which the termination clause discharges. Promote it to EPIPHANIES on request — the content is above, not lost.
+
+**Confidence (2026-08-12):** merged. The rounding fix is `[G]` (arithmetic). The living-vs-ledger distinction is `[G]` as a rule of this repo's own governance and `[H]` as a general claim about documentation. **The chain terminates with the pure-hygiene PR that records THIS entry** — no type, plan, deliverable, epiphany or code there, so per the termination clause it owes nothing further.
+
 ## 2026-08-12 — lance-graph #926 (MERGED) — the storm spine (90.9–94.3 %), the 12-byte L4 carrier, and five corrections that were each a claim fixed in ONE of its homes
 
 - **Added.** `probes/weather-p1/COMET_TAIL_REPORT.md` (the canonical document: falsification ledger §4–§5.11, **§6.1** the L4 carrier, **§6.2** the three registers, §9 the spine/moderators reframe) + **10 probe scripts with committed JSON results**. EPIPHANIES: `E-THE-HEADLINE-NUMBER-MEASURED-A-MODEL-NOBODY-CLAIMED-1`, `E-SPINE-FOUND-MODERATORS-MISSING-1`, `E-THE-BYTE-WAS-ONLY-THE-SELECTOR-THE-PAIR-IS-THE-CARRIER-1`, `E-ZERO-FOR-ELEVEN-…` cross-refs. **9 919 insertions / 28 files: 47 % results-JSON, 36 % probe scripts, 17 % prose — zero Rust, zero library/product code, no test harness.** This PR changes no product surface; it is measurement apparatus and its output.