test(hooks): the installed-hook parity check saw one repository, not every governed root (BACKLOG #1376)

docs/BACKLOG.md

@@ -17530,6 +17530,12 @@ site_prefixes   1      2       50.0%   <- would FAIL a flat 80% rule
 > 🔢 **Filed 2026-08-28 (lander) - found by builder 1 while screening before claiming.**
 >
 > **Scored 2026-09-03 -> P2.** Value **6/10** · Difficulty **3/10** · _quick win_. Not started, and the vault-side state is worse than the filing shows. Measured today against the vault checked out beside this repo: it ships scripts/worktree/install-gate.ps1, scripts/worktree/install-selfheal.ps1 and scripts/coord/install-git-hooks.ps1 and none of tests/test_gate_installed_parity.py, tests/test_selfheal_installed_parity.py or tests/test_installed_coord_hooks.py, against a control of 526 entries in its tests/ tree. Value is above parity-with-a-clean-workaround because the vault's own copies are far adrift and nothing there reports it -- its scripts/hooks/worktree_gate.ps1 is 23,430 bytes dated 2026-07-29 against the engine's 208,171, so running the installer it ships would replace the one machine-wide gate with a July build, and its .git/hooks carries no push_guard.py and no pre-push hook at all. The engine-side workaround is real but one-sided and post-hoc: tests/test_gate_installed_parity.py:46 compares the SHARED installed gate under ~/.claude/hooks against the engine source and would go red after such an install, but tests/test_installed_coord_hooks.py:62 roots its git-hook half at the ENGINE repo, so the vault's per-repo hooks are covered by nothing. Landing it means porting about 1,960 lines into a repo that has pytest infra (pyproject.toml:221 testpaths, tests/conftest.py) but no such seam, and it is less mechanical than it looks, because the ported parity assertions would red on day one against the vault's older sources and so force a ruling on which copy is authoritative.
+>
+> 🚧 **Partly built 2026-09-03 (builder).** The engine-side half of this row is closed; the port is not, and it is blocked on a ruling nobody but the owner may make. **What landed:** `tests/test_installed_coord_hooks.py` no longer roots its git-hook half at this repository alone. It reads the worktree gate's machine allowlist (`~/.claude/hooks/worktree-gate.repos.txt`) and, for every governed root, audits that root's installed payloads against **that root's own** committed `scripts/hooks/` source, using **that root's own** installer to say which payloads it manages. Nothing is compared across roots, so the widening presumes no answer to the authority question. Three controls guard it: the audit is driven against constructed roots in `tmp_path` in both conditions -- one whose installed payload matches its committed source, one whose does not -- so the untouched baseline sits beside the finding instead of being assumed, and a third pins that an installer whose payload list cannot be read reports UNAUDITABLE rather than clean. **THE NAMED BLOCKER on the rest of this row is an owner ruling: which checkout's copy of a shared governance script is authoritative.** Until it is ruled the three instruments cannot be ported, because every one of their assertions compares an installed copy against a source, and in the vault they would fire on day one against older sources -- which decides the question by landing rather than by ruling.
+>
+> 🚧 **Re-measured 2026-09-03 at engine `fd44b0f17` and vault `b2ca63d16`, with controls.** The three instruments are still ABSENT from the vault and the three installers still PRESENT there. Positive control: the same `git ls-tree -r --name-only origin/main -- tests` filter that returned none of the three returned four other `*_parity.py` files, so the search can see a present case; the vault `tests/` tree holds 527 entries. **Two figures in the scoring line above, and in its copy in the summary table, have moved and are deliberately left uncorrected there rather than edited into another seat's dated measurement:** the vault's `scripts/hooks/worktree_gate.ps1` is **23,042** bytes at its `origin/main`, last touched 2026-07-24, against the engine's **205,331**, last touched 2026-09-01 -- not 23,430 against 208,171. Only the byte counts moved, because both files moved; the finding is unchanged, and the vault still ships a July build of the gate. **New, and it is why the port is more than a copy:** the vault's `install-git-hooks.ps1` declares no `$payloads` list the engine's parser can read, so even the widened audit reports that root UNAUDITABLE instead of comparing anything. The repair is either an edit to that installer or a wider parser, and choosing between them is the same ruling.
+>
+> 🚧 **A separate, live host condition, recorded here so nobody mistakes it for this item's red.** On the reference box `test_the_installed_coord_hook_matches_the_committed_source` fails for both payloads and is correct to. The copies installed under the ENGINE's own shared `.git/hooks` are exact but older revisions of this repository's sources: `claim_check.py` matches commit `a729131dc` (2026-08-24) and so lacks the fail-closed fix from `68f7cd699`; `push_guard.py` matches `29eae2a2e` (2026-08-27). That is host state, not a repository defect, and it was not silenced to get a green. The repair is an operator running `scripts\coord\install-git-hooks.ps1` from a plain terminal in the primary checkout.
 > Verdict: build
 > Closing-act: code