[HARDENING] PENDING-139 AMENDMENT 1 — a third blind spot in the drift check, and it is a unit mismatch

The register-integrity check cannot detect an in-place rewrite of a placed
ruling's disposition fields, because such a rewrite produces no amendment-shaped
block and the check's unit is the block. Distinct in kind from the parent item's
two defects: (A) and (B) are marker defects, repairable by fixing a regex; this
one is not, because the thing to be detected never enters the population the
regex runs over.

Observed, not predicted. The steward rewrote REVIEWED-140's three disposition
fields in place today (fb02605), completing a ruling interrupted on 2026-09-17.
The check ran afterwards and reported all-resolve. The silence is correct on the
merits — no amendment was involved and nothing was lost — but the instrument
could not have reported otherwise on any input of this shape, including one that
was not legitimate.

Also measured and recorded in the amendment, because the jurist named it at
REVIEWED-140 row 4 as beyond its reach: register commits are NOT atomic per
entry. Over the last twelve commits touching REVIEWED.md, five added two entries
at once, one added none, and several bundled the register with up to nine
unrelated files. Git history is a real but coarse witness. That bounds option 2,
the recommended remedy, and it means the toy's hash-chained ledger in PENDING-187
is stronger than the document register it is modelled on.

Recommendation is option 2 (derive the check from git) and NOT before PENDING-146
settles: option 3 would prescribe more amendments to a register whose
amendment-attribution convention is the open question, and 37 of the existing 59
unattributable blocks would be actively mis-filed by an id-keyed repair.

Filed as `## PENDING-139 — AMENDMENT 1:` per the 2026-09-14 form, with the
instrument run before and after and the counts predicted in advance:
43/102/59 -> 44/103/59, NOT ESTABLISHED unchanged. A bare `### AMENDMENT`
heading would have joined the 59 this amendment discusses.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

PENDING.md

@@ -5062,3 +5062,32 @@ Jurist review (2026-09-17) found the design sound on all five points Fable flagg
 **Files affected:** None yet. A new, isolated working directory for the build; no existing repo is touched.
 
 **Awaiting:** Steward ruling — AUTHORIZED / DEFERRED / REJECTED — on proceeding to build. Full jurist review: this conversation, 2026-09-17.
+
+## PENDING-139 — AMENDMENT 1: a third blind spot, and it is a unit mismatch rather than a marker defect
+
+**Date:** 2026-09-20
+**Tag:** [HARDENING]
+
+**Summary:** `governance-drift-check.py`'s register-integrity check cannot detect an in-place rewrite of a **placed ruling's disposition fields**, because such a rewrite produces no amendment-shaped block and the check's unit is the block. This is distinct in kind from the two defects the parent item records: (A) and (B) are *marker* defects — a `###` heading the pattern fails to match, a negated token read as an assertion — repairable by fixing a regex. This one is not repairable by fixing a regex, because the thing to be detected never enters the population the regex runs over.
+
+**Observed 2026-09-20, not predicted.** The steward rewrote REVIEWED-140's `Decision:`, `Ruled by:` and `Authorized by:` fields in place, completing a ruling that had been begun 2026-09-17 and interrupted mid-write. The check ran immediately afterwards and reported `register integrity: 43 attributable amendment block(s) checked, all resolve`. **The silence is correct on the merits** — completing an interrupted entry is legitimate, no amendment was involved, and nothing was lost — **but the instrument could not have reported otherwise on any input of this shape**, including a rewrite that was not legitimate. A net that cannot fire on a class has not been shown to protect against it; per the ladder, its silence is uninformative rather than reassuring.
+
+**Why the parent item does not cover it.** PENDING-139's prospective exposure is *an amendment replacing the record it amends* — the REVIEWED-87 shape the check was earned from on 2026-08-07. Both parties to that shape are amendment-shaped blocks, so both are inside the check's unit and the failure is that the regex misses one of them. The exposure named here has **no amendment at either end**: a placed entry is edited, the edit leaves no block, and the register retains no trace that any field ever read differently. Same instrument, same file, different failure mode; filed here rather than as a new item so the instrument's exposures stay in one place and the remedy can be ruled once.
+
+**Class.** Unit mismatch — the instrument's unit is the amendment block, the question's unit is the entry. Fifth-plus instance of this class in the record since 2026-09-08 (`register_scan`'s header-vs-block, the `12/63` preamble-recorded-vs-delivered near-miss, the `31/28` predicate incommensurability, the `[:72]`/`[:100]` truncations). **It is the class that reading does not catch** — each instance was found by running something, never by looking harder.
+
+**What today's events also establish, bearing on the remedy.** Register commits are **not atomic per entry**, measured over the last twelve commits touching `REVIEWED.md`: five added two entries in one commit, one added none (an in-place edit), and several bundled the register with two to nine unrelated files. So git history is a *real* but *coarse* witness — it preserves that something changed and can show the prior bytes, but a single commit may carry several entries and unrelated files, so `git log -- REVIEWED.md` does not isolate a given ruling's edit history without further work. This is the same fact the jurist flagged at REVIEWED-140 row 4 as beyond its reach, measured here by the party that has the substrate.
+
+**Options.**
+1. **Content-hash each placed entry** and check the hashes against a stored manifest — detects any field rewrite, at the cost of a manifest that must itself be maintained and that becomes a second place the truth lives.
+2. **Derive the check from git** — compare each entry's current text against its text at the commit that placed it, and report entries whose disposition fields differ. No new stored state; bounded by the coarseness measured above.
+3. **Require that a placed ruling's disposition fields are never edited in place** — corrections arrive as amendments — and let the existing block machinery cover it. Cheapest to state, but it is a convention with no detector, which is the disarmed-tripwire class the parent item already names.
+4. **Accept and record.** The exposure is prospective, as it was for (A); no loss has occurred.
+
+**Recommendation:** Option 2, and not before PENDING-146 settles. Option 3 would add amendments to a register whose amendment-attribution convention is exactly what PENDING-146 has open — 59 blocks already cannot be attributed, and 37 of those would be actively mis-filed by an id-keyed repair. **Prescribing more amendments before the convention is ruled writes more of the population the convention question exists to bound.** Option 1 duplicates state the substrate already holds. Option 2 reads the substrate directly and adds nothing to maintain.
+
+⚠ **This amendment's own filing is a check on the finding it reports.** It is filed as `## PENDING-139 — AMENDMENT 1:` — the id+marker form established 2026-09-14 — and the instrument was run before and after with the counts predicted in advance. A bare `### AMENDMENT` heading here would have joined the 59 it discusses.
+
+**Files affected:** `scripts/governance-drift-check.py` (register-integrity check); no change made under this amendment.
+
+**Awaiting:** Steward annotation, with PENDING-139's two original defects — one ruling for the instrument, not three.