check-doc-checkpoint is per-COMMIT, so a branch that records evidence and projects it in different commits cannot go green without a rewrite

[localai-bot]

scripts/check-doc-checkpoint.py classifies a change to .agents/benchmark-record.md as a measurement and then requires the same commit to also edit docs/STATUS.md and docs/BENCHMARKS.md. It walks per commit, and it does so in every flag form, including --base/--head, which is the form CI uses:

python3 scripts/check-doc-checkpoint.py --base "$PR_BASE" --head "$PR_HEAD"   # ci.yml:540

So on a branch whose forensic record and whose public projection landed in different commits, the gate is red and cannot be made green without rewriting history. Adding the missing surface in a later commit does not help: the earlier commit is still in the range and is still reported.

Reproduced on row/LTX25-DIT-ATTN-FLASH (#1549, PR #1557):

ERROR: commit 2aa78c69b: changed .agents/benchmark-record.md: measurement recorded
  but did not update docs/STATUS.md.
ERROR: commit 2f39a9426: changed .agents/benchmark-record.md: measurement recorded
  but did not update docs/BENCHMARKS.md, docs/STATUS.md.

--staged on the repairing commit reports OK, and the whole-branch diff carries all three surfaces, so the branch satisfies the RULE while failing the GATE.

Why this is the shape AGENTS.md names rather than a user error. ## Records says: "A gate often creates the lock. If a checker requires every change to edit one shared file, the checker is defective. Move the obligation to a per-row surface. Do not delete the obligation." Here the obligation is real -- a measurement is a claim and the projections are how it reaches a reader -- but it is levied per COMMIT against two files that every concurrent branch also writes. The three ways to satisfy it are all bad:

1. put every forensic append in the same commit as both projection edits, which forbids the ordinary shape of recording evidence as it arrives and then projecting it once;
2. rewrite the branch, which needs force-push authority for a records edit;
3. never append to benchmark-record.md except in a projection commit, which is the surface AGENTS.md explicitly designates as the append-only detail file and which check-public-doc-tables.py actively routes prose into ("move the detail to .agents/benchmark-record.md").

Rule (3) and the table checker are in direct tension: one checker pushes detail INTO benchmark-record.md, the other penalises the commit that puts it there.

Not fixed in flow. A semantic checker change needs its own spec, a red-before test and green-after evidence, and this one is about what "a commit" means to a range gate -- not a small, clear fix. Candidate directions, none chosen here: classify over the whole base..head diff rather than per commit for the PR form; or exempt .agents/benchmark-record.md from being a measurement TRIGGER while keeping docs/BENCHMARKS.md as one, since the forensic file is by construction the place detail is moved TO.

Consequence today: PR #1557 carries a documentation-checkpoint red that its own branch content does not deserve, and the squash-merged commit on main would pass the same gate because it carries all three surfaces at once.

[localai-bot]

Superseded by #1674. That change removes the per-commit documentation checkpoint instead of changing its range semantics, so this checker repair is no longer needed.