docs(decisions): move PR #19's handoff out of the frozen DECISIONS-LOG.md

This branch originally appended ~99 lines to the tail of DECISIONS-LOG.md. That
tail is the hunk every concurrent branch collides on: measured against the live
Gitea on 2026-09-29, four of the five open PRs were mergeable:false and
DECISIONS-LOG.md was the ONLY conflicting path in all four. PR #19 was one of them.
Nothing was wrong with the change; the log's storage format serialised work that
was otherwise parallel.

So the handoff now lives in its own file, decisions/2026-09-29-conformance-trigger-kubeconfig.md,
in the one-entry-per-file layout PR #24 introduces (frontmatter date/branch/title,
plus "What changed" / "What I verified" / "What I did NOT verify"). Concurrent
branches then touch disjoint paths and there is nothing to merge.

The branch was rebuilt on today's main with the DECISIONS-LOG.md change dropped
entirely; infra/gitea/README.md and infra/gitea/conformance-trigger-kubeconfig.sh
are byte-identical to the original commits. The original commit that touched ONLY
DECISIONS-LOG.md -- the measurement that PR #19's CI has no approval-policy check
-- was dropped as a commit and its substance folded into the new entry verbatim in
meaning, including every UNVERIFIED it recorded.

No content was upgraded. The script is still UNEXECUTED: nothing minted, no Gitea
object written, no kubectl mutation, and the Gitea variables API shape remains
documentation rather than measurement.

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

decisions/2026-09-29-conformance-trigger-kubeconfig.md

@@ -0,0 +1,125 @@
+---
+date: 2026-09-29
+branch: feat/conformance-trigger-kubeconfig
+title: The trigger credential script — it REFUSES, on purpose, and it is UNEXECUTED
+---
+
+## What changed
+
+Delivered `infra/gitea/conformance-trigger-kubeconfig.sh` —
+`docs/plans/l2-l3-conformance-ci-wiring.md` §3 item 6 — plus its section in
+`infra/gitea/README.md`. **The script is UNEXECUTED.** Minting a cluster credential and
+changing Gitea variables are operator actions; nothing was minted, no Gitea object was
+written, no `kubectl` mutation was made. Everything below is a claim about the *script*,
+not about the platform.
+
+*What it does.* Mints a token for `conformance/conformance-trigger` (TokenRequest), wraps
+**only that token** with the cluster CA and server into a kubeconfig, stores it as the
+Actions secret `CONFORMANCE_TRIGGER_KUBECONFIG` (legal name — **not** the reserved `GITEA_`
+prefix), and sets `vars.CLUSTER_AVAILABLE` only as a separately-requested,
+precondition-gated, TTY-confirmed final step. The token is never printed and never reaches
+argv: it goes into a 0600 file and into the PUT **body file**. The script refuses to run
+under `set -x`.
+
+*The design decision worth reviewing: TWO precondition classes.*
+
+- **mint-blocking (cluster-side):** SA/Role/RoleBinding present, and ClusterPolicy
+  `conformance-trigger-job-shape` present + `Enforce` + `failurePolicy: Fail` + Ready. If any
+  fails, **nothing is minted**. Rationale: Kubernetes puts no `use` check on a Job's
+  `serviceAccountName`, so a `create jobs` token in that namespace IS the privileged
+  `conformance-runner` identity unless the admission policy bounds it. RBAC cannot fix that
+  (plan §4); minting before the boundary is live would hand CI the escalation the boundary
+  exists to close.
+- **arm-blocking (repo-side):** digest-pinned `CONFORMANCE_RUNNER_IMAGE`, an init-container
+  plus the admitted image in `chainsaw-job.yaml`, and `CONFORMANCE_TRIGGER_KUBECONFIG`
+  referenced in `ci/conformance.sh` **code rather than a comment**. These block only the
+  variable, because storing the secret early is harmless and is the plan's own order.
+
+**Measured in the tree at the time of writing: all three arm-blocking checks FAIL** (no
+`CONFORMANCE_RUNNER_IMAGE` in `conformance/versions.env`; `chainsaw-job.yaml` is still the
+skeleton with an empty `workspace` emptyDir and the stock chainsaw image; `ci/conformance.sh`
+names the trigger kubeconfig only in its TODO comment). So on a live run today the script
+would provision the secret and then **refuse to arm `CLUSTER_AVAILABLE`**, naming each
+missing item — which is the intended behaviour, not a defect. §3 items 1, 2 and 4 are the
+work that unblocks it.
+
+*Both writes are verified the way `set-ci-token.sh` learned to.* `curl -sS` exits 0 on an
+HTTP error, so status alone proves nothing: each write checks `%{http_code}` **and** reads
+the object back. For the secret that is presence-by-name only (Gitea never returns secret
+values) and the script says so rather than implying the content was checked; for the variable
+it asserts the value reads back as exactly `true`.
+
+*Noted, not fixed at the time (since fixed on this branch).* `infra/gitea/README.md`'s
+detector table still named `GITEA_SETTINGS_TOKEN` — the illegal name PR #15 replaced with
+`SETTINGS_API_TOKEN`. The second commit on this branch corrects the README's table and its
+closing "remaining step" line, and records what `ci/gitea-settings.sh` actually does
+(`TOKEN="${SETTINGS_API_TOKEN:-${GITEA_SETTINGS_TOKEN:-}}"` — the old name survives only as a
+local-run environment variable, never as CI wiring, because the secret that would feed it
+cannot be created at all). Documentation only, no behaviour change. Still NOT fixed, because
+it is outside this PR's diff: `ci/gitea-settings.sh:45` instructs the reader to create a repo
+secret `GITEA_SETTINGS_TOKEN`, which is impossible.
+
+*Rework, 2026-09-29.* This branch originally appended ~99 lines to the tail of
+`DECISIONS-LOG.md`. That is the hunk every concurrent branch collided on and the sole reason
+PR #19 was `mergeable: false`. The branch was rebuilt on today's `main` with the
+`DECISIONS-LOG.md` change dropped entirely, and this file is that handoff moved into
+`decisions/`. The changes to `infra/gitea/**` are byte-identical to the original three
+commits; the commit that contained only the log append was dropped and its substance folded
+in below.
+
+## What I verified
+
+*Of the script, before it stores anything:* it PROVES the credential narrow — `auth whoami`
+must return `system:serviceaccount:conformance:conformance-trigger`; a real `get jobs`
+round-trip must succeed; then an `auth can-i` matrix asserts BOTH halves — granted
+(`create/get jobs`, `get pods`, `get pods/log`) and **denied** (`delete jobs`, `create
+pods/exec`, `get secrets`, `create jobs` in `default`, `get nodes`,
+`'*' '*' --all-namespaces`). A mismatch aborts before anything is stored, and the message
+says explicitly **not** to widen `conformance/incluster/rbac.yaml` to make it pass. That is a
+property of the code as read, not of an execution.
+
+*Of PR #19's CI, measured rather than assumed — and it contradicts the brief.* The brief for
+this work stated this PR's CI would FAIL `approval-policy` because `infra/gitea/**` is
+security-relevant. Measured on the PR head commit's `/statuses`:
+
+    gate / gate (pull_request)          success   Successful in 1m34s
+    gate / conformance (pull_request)   pending   Blocked by required conditions
+
+`.gitea/workflows/` on `main` contains only `gate.yml` and the dormant `merge-gate.yaml`.
+**No path-scoped approval policy exists**, so nothing machine-enforces "security-relevant
+paths need a human"; that rule rests entirely on `required_approvals: 1` plus a reviewer
+actually reading the diff. Another instance of the CLAUDE.md §2b failure mode — a control
+believed to exist because a brief said so. If the policy is intended, it is missing and needs
+its own change. And per this repo's own rule, that green `gate` tick is **not** evidence this
+script works: the gate never executes `infra/gitea/**`, and the L2/L3 stage skipped.
+
+*Gate on the reworked branch (pinned toolbox, from the agent worktree, `DEV_KUBECONFIG=/dev/null`
+plus the `ENGINE` bind-mount shim per CLAUDE.md §3):* `MERGE GATE: UNDETERMINED`, **rc 3**.
+Diff base `origin/main @ c59fe9f923c4` ... this branch's head; touched requirement resolved as
+`R-ENV-01`. `spec-immutability`, `decisions-log`, `lint`, `l0`, `render-golden` and `l1` all
+green; the gate decision names exactly one stage that did not run — `gitea-settings`
+(`SETTINGS_API_TOKEN` is a credential this agent does not hold, unwired repo-wide). The
+`conformance` stage also reported SKIPPED (`CLUSTER_AVAILABLE!=true`, Phase 0). The new
+`decisions-log` stage — merged to `main` as PR #24 after this rework began — validated this very
+file: "archive frozen, 2 entries well-formed", with `DECISIONS-LOG.md` unchanged and matching
+`decisions/ARCHIVE.sha256`. rc 3 is UNDETERMINED, not green, and is not reported as green here.
+
+## What I did NOT verify
+
+**The script has never executed.** Not one line of it has run against Gitea or against the
+cluster. Only `bash -n` was run (clean); `shellcheck` is not on the host and there is no
+shellcheck stage in the gate.
+
+- The Gitea variables API shape (POST-creates / PUT-updates, body field `value` not `data`)
+  is from **documentation, not measurement**. The script tries POST then falls back to PUT,
+  prints the response body on failure, and treats the read-back as the authority.
+- The Kyverno readiness field (`.status.ready` vs. a Ready condition) is handled both ways
+  and treats "neither present" as a block rather than assuming ready — but which form this
+  cluster actually reports is **unmeasured**.
+- Whether the kubeconfig's embedded server URL is reachable from the runner pod **cannot be
+  known from here** — hence `--server`, and a hard refusal on a loopback address.
+- No credential was minted, no Actions secret was created, `vars.CLUSTER_AVAILABLE` was not
+  set, and no `can-i` matrix was ever run against a real token. The narrowness argument above
+  is read from the RBAC and the script, not observed.
+- The gate proves only its L0/L1 offline subset. L2/L3 conformance did not run, so nothing
+  here is evidence about runtime behaviour.