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]>

infra/gitea/README.md

@@ -52,7 +52,7 @@ All four steps are complete and each was verified, not assumed:
 | 1. Runner registered | ✅ `incluster-dind` online. Root cause of its absence was a stale `/data/.runner` identity; clearing the PVC forced re-registration |
 | 2. Gate observed green on a real PR | ✅ `gate / gate (pull_request)` ~1m35s |
 | 3. `enable_status_check: true` | ✅ context `gate / gate (pull_request)` — that one ONLY |
-| 4. Collaborator + approvals | ✅ `jakman85` is owner; `required_approvals: 1` |
+| 4. Collaborator + approvals | ✅ `jakman85` is owner. `required_approvals` was raised to 1 here and **lowered back to 0 on 2026-10-01** — see §6, it was a lock-out |
 
 Direct push to `main` was **provoked and rejected** (`pre-receive hook declined`) as
 `gitea-admin`, a site admin — so push protection is not merely declared, it holds for the
@@ -124,6 +124,55 @@ the stage goes **green on a real PR**, and only then set `REQUIRE_GITEA_SETTINGS
 **Changing the declaration is how you change policy.** If the live state is what you now want,
 edit this JSON in the same commit — deliberately, in review — rather than letting the two drift.
 
+### 6. `allow-admin-self-merge.sh` — undoing the lock-out step 4 created (2026-10-01)
+
+Step 4 above raised `required_approvals` to 1. That was a **lock-out, not a protection**, and the
+note at the bottom of `require-gate.sh` had already said why: *Gitea will not let an author approve
+their own PR.* With `jakman85` the only collaborator, there was no account in existence that could
+approve a PR `jakman85` opened.
+
+Measured 2026-10-01 — **PR #35**: `gate / gate (pull_request)` **success in 1m41s**, reviews `[]`,
+`required_approvals: 1`, `block_admin_merge_override: true`. Unmergeable, permanently, with no
+action available to its author. The same was true of any PR fixing it.
+
+It was also never the documented design. `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
+`decisions/2026-09-30-flux-deploy-notification-inhibited.md` flagged the 1-vs-0 disagreement as
+unresolved and not that session's to settle. So this is a correction toward the stated intent, not
+a weakening away from it.
+
+    ./infra/gitea/allow-admin-self-merge.sh      # required_approvals -> 0 (read from the declaration)
+
+**What stays switched on, and why that is the point.** The other way to unblock an owner is
+`block_admin_merge_override: false`, and it would have been the wrong one — that re-opens exactly
+what §5 above closed, letting the one account that merges bypass the gate itself. This script
+touches the approval **count** only and *verifies* afterwards that `block_admin_merge_override` and
+`enable_status_check` are both still `true`, failing loudly if the PATCH disturbed either:
+
+| | before | after |
+|---|---|---|
+| `required_approvals` | 1 | **0** |
+| `block_admin_merge_override` | true | true (asserted) |
+| `enable_status_check` | true | true (asserted) |
+
+So a **red gate is still unmergeable by everyone, administrators included**. What changed is that
+a *green* one no longer needs a signature that cannot exist.
+
+**Security-relevant changes are still reviewed** — by `ci/approval-policy.sh` against
+`approval-policy.json` `sensitive_paths`, not by this field. An administrator waives that review
+only by posting `/approve-override <reason>` on the PR: reason mandatory, permission re-checked
+live, invalidated by a new commit, and recorded by account in the gate summary. Note that the
+**agent account `gitea-admin` also reports permission `owner`**, so it can clear its own PRs that
+way; that is an accepted consequence of authorising by permission alone, and the route to
+narrowing it (an `override_admins` allowlist, already honoured by the code) is written down in
+`approval-policy.json`.
+
+**Sequencing.** `ci/gitea-settings.sh` compares live against the declaration *from the branch under
+test*, and `REQUIRE_GITEA_SETTINGS=true`. So merge any other open PRs **before** running this, then
+run it, then re-run the gate on the branch carrying the new declaration. Any PR left open across
+the change declares 1 against a live 0 and goes **red until rebased** — the detector working, not
+a fault. The script's header spells the order out.
+
 ## `conformance-trigger-kubeconfig.sh` — the narrow L2/L3 trigger credential
 
 Implements `docs/plans/l2-l3-conformance-ci-wiring.md` §3 item 6 (= §5 step 7): mint a
@@ -204,6 +253,8 @@ it. The name matters — see the note under the behaviour table above.)
 2. **Watch the gate actually report on a real PR**, and note the context name it produced.
 3. **Only then set `enable_status_check: true`** with that exact context.
 4. Add the human reviewer as a repo collaborator, then raise `required_approvals` to 1.
+   — **Step 4 was REVERSED on 2026-10-01 (§6).** It assumed a reviewer distinct from the author
+   would exist. One never did, so this step produced a lock-out. Do not re-apply it.
 
 > **Do not do step 3 before step 1.** A required status check with no runner leaves every
 > PR permanently pending — including the PR that would fix it. That half is measured: PR #1