fix(ci): let an administrator merge their own green PR

`required_approvals: 1` on `main` was a lock-out, not a protection. Gitea
refuses to let a PR's author approve their own PR, and `jakman85` is the only
collaborator — so no account in existence could approve a PR the operator
opened, including the PR that would fix that. Measured 2026-10-01 on PR #35:
gate green in 1m41s, reviews `[]`, `required_approvals: 1`, unmergeable.

It was never the documented design either: `ci/approval-policy.sh`'s header and
`ci/gate.sh:194` both already describe the model as "required_approvals drops
to 0 and the GATE decides", and `require-gate.sh`'s own closing note named this
failure and prescribed this remedy. 2026-09-30's entry flagged the 1-vs-0
disagreement as unresolved; this settles it at 0.

Layer 1 — branch protection. required_approvals 1 -> 0 in the declaration, plus
infra/gitea/allow-admin-self-merge.sh to apply it live (target read FROM the
declaration, so the script cannot drift from what the gate checks).
require-gate.sh moves to 0 too; left at 1 it would re-impose the lock-out on its
next run. The narrow choice is deliberate: the other way to unblock an owner is
block_admin_merge_override: false, which would re-open what
block-admin-override.sh was written to close (PRs #5-#9, zero approvals). This
drops the approval COUNT only — block_admin_merge_override and
enable_status_check stay true and are asserted after the PATCH, so a red gate
stays unmergeable by everyone, administrators included.

Layer 2 — ci/approval-policy.sh. Sensitive paths still need a non-author
approval the sole admin cannot get, so an administrator may waive it with an
`/approve-override <reason>` comment: directive must start a line, reason
mandatory, permission re-checked LIVE, invalidated by a new commit, and the
overrider + reason printed in the gate log and job summary. Candidate selection
is the pure, offline ci/approval-override.py (23 unit assertions, all passing);
authorisation stays in the fail-closed stage. Every new failure mode blocks.

The cost, stated not buried: for an administrator, "a change to the gate cannot
be gated by the gate" is now advisory rather than structural. Unavoidable with
one human; what is bought back is an attributed, commit-scoped record instead of
a silent bypass. And the uncomfortable part, accepted as an operator decision:
authorisation is by live permission alone, and the AGENT account `gitea-admin`
also holds `owner` — so an agent can clear its own PR this way. Documented in
approval-policy.json, the stage header, and CLAUDE.md (which tells agents not
to). Narrowing needs no code change: add `override_admins` and the stage already
requires membership.

Adjacent fix, in scope because `make -C ci test` is the only runner for the
suite added here: ci/tests/gate-decision.test.sh hand-maintained a stub list
that "must name EVERY stage gate.sh runs" and omitted `approval-policy` (added
to gate.sh by PR #17), so run_stage hit exit 127 and 15 of 50 assertions failed.
Verified pre-existing on pristine origin/main @ 0c7e8dd. The list is now derived
from gate.sh's own run_stage lines, so the omission cannot recur; the suite goes
15-failed -> 50 passing and `make -C ci test` goes FAILED -> all suites passed.

Toolbox gate: rc 3 UNDETERMINED — every stage green except `gitea-settings`
(no SETTINGS_API_TOKEN locally) and `conformance` (no cluster). NOT a green run.

The live rule is UNCHANGED and still reads 1 — mutating it is an operator
action. Until allow-admin-self-merge.sh is run, ci/gitea-settings.sh will
correctly report DRIFT and this PR will be red.

Co-Authored-By: Claude Opus 5 (1M context) <[email protected]>

CLAUDE.md

@@ -36,6 +36,28 @@ sensitive path, so the policy cannot be widened or narrowed without a human.
 
 That stage is **fail-closed** — if it cannot evaluate, it blocks. Unlike `gitea-settings`, where a
 missing credential is a lock-out, here a skip would be a bypass.
+
+**The administrator override (2026-10-01).** The rule above was unsatisfiable for the one human
+who runs this repo: Gitea refuses to let an author approve their own PR, and `jakman85` is the
+only collaborator — so a sensitive-path PR the operator opened could never be merged, *including
+the PR that would fix that.* An administrator may therefore waive the review by commenting on
+the PR:
+
+    /approve-override <reason>
+
+The directive must **start a line**, the **reason is mandatory**, the commenter's `admin`/`owner`
+permission is re-checked **live** when the gate runs, and the comment must be **newer than the
+head commit** — push again and you must override again. The overrider, the timestamp and the
+reason are printed in the gate log and the job summary. For an administrator, "a change to the
+gate cannot be gated by the gate" is therefore **advisory, not structural**; what is kept is an
+attributed record of each waiver. Note that the agent account `gitea-admin` also holds `owner`
+here, so an agent *can* clear this on its own PR — **do not**: posting that directive to unblock
+your own agent work is exactly the self-approval the stage exists to prevent. Get the operator
+to post it, or move the change out of the sensitive paths.
+
+**`required_approvals` on `main` is `0`**, not 1 — the gate is the approver. That drops the
+approval *count* only: `block_admin_merge_override` and `enable_status_check` both remain `true`,
+so **a red gate is unmergeable by everyone, administrators included.**
 - **Do not `kubectl apply` / `edit` / `patch` a durable change.** Flux reconciles `main`;
   anything applied by hand is drift that the next reconcile reverts or, worse, adopts.
 
@@ -53,12 +75,19 @@ Verified against the live Gitea on 2026-09-29:
 | `main` protected, direct push rejected | ✅ `protected: true`, `user_can_push: false` — **verified by a real rejected push**, not by the API's word |
 | PR blocked until the gate passes | ✅ `enable_status_check: true`, context `gate / gate (pull_request)` |
 | Gate runs on every PR | ✅ runner `incluster-dind` online; ~1m35s |
-| Approval required before merge | ✅ `required_approvals: 1` |
+| Gate cannot be overridden, by anyone | ✅ `block_admin_merge_override: true` |
+| Human approval required before merge | ⬜ **No — `required_approvals: 0` since 2026-10-01.** The gate is the approver; sensitive paths are gated by `ci/approval-policy.sh` instead. See §1 |
 
-All four were FALSE as recently as 2026-09-29, while this repo's own log asserted they were
+The first three were FALSE as recently as 2026-09-29, while this repo's own log asserted they were
 true. They are true now because each was measured, and the push rejection was provoked rather
 than assumed. **Re-measure before relying on any of them** — see §2b.
 
+The fourth row deliberately changed on 2026-10-01. `required_approvals: 1` was a **lock-out**, not
+a protection: with a single collaborator and Gitea refusing author self-approval, nothing could
+satisfy it (measured on PR #35 — green gate, zero reviews, unmergeable). It also contradicted the
+model already written into `ci/approval-policy.sh` and `ci/gate.sh`. Rationale and the live-change
+script: `infra/gitea/allow-admin-self-merge.sh`.
+
 Still not covered: `vars.CLUSTER_AVAILABLE` is unset, so **L2/L3 conformance does not run in
 CI**. A green PR therefore proves the L0/L1 offline subset, not runtime behaviour.