feat(pm-agent): the kubelet's pull credential, and the seventh field admission had not read

The registry had two blockers. #59 fixed the first (nodes resolved the hostname to the
non-hairpinned WAN and failed TLS against the router's CN=%D cert). This is the second:
the pull is unauthenticated, and this registry refuses unauthenticated clients outright —
measured 2026-10-05, its anonymous token carries access: null and every path 401s.

pm-agent-registry is a dockerconfigjson Secret (SOPS, placeholders) referenced by
imagePullSecrets on the dispatcher Deployment and on the committed worker Job template. It
holds the SAME Gitea token as pm-agent-credentials, because the two consumers need two
formats: the application reads a raw token from env, the kubelet reads a dockerconfigjson
before any container starts. Same one-value-in-two-files pattern as the Keycloak client
secret, documented in both .example files. The operator's part is the value plus one new
scope: read:package.

ADMISSION GAINED A SEVENTH RULE. imagePullSecrets is a pod-spec field no container
references, which is exactly why it is easy to leave unread — the same shape of omission
as initContainers, ephemeralContainers, env and envFrom before it. The kubelet reads the
named Secret, in this namespace, before anything runs. Rule 1's pattern now REQUIRES the
committed entry; rule 7 forbids any other and any second one. Both halves are needed: a
foreach over an absent list yields no result.

The leverage is small and the policy says so: the image is digest-pinned, so a different
pull credential cannot change WHAT runs. Pinned anyway — 'only the committed shape' is the
premise, and the rule costs four lines.

kyverno test: 33 passed, 0 failed (was 28). Three new fixtures, each a real path: the
committed entry plus a second one, a different Secret, and none at all.

The gate also caught me shipping the Secret in plaintext — I never ran sops -e -i on the
placeholder. Recorded in the handoff entry, because the file looked finished.

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

platform/pm-agent/README.md

@@ -71,21 +71,33 @@ Both are deliberate, and both fail **visibly** rather than silently:
      inventory, never typed on a node. Apply it scoped to that one task:
      `cd infra/ansible && ansible-playbook playbooks/node-baseline.yml -e k3s_hosts=k3s_prod
      --tags hosts`.
-   - **The pull is still unauthenticated** once the node reaches the right endpoint. An
-     unauthenticated client gets nothing from this Gitea's registry, and there is no
-     `imagePullSecret` anywhere in the tree. Consistent with the agent credential decision
-     (local Gitea accounts with PATs), the fix is a `dockerconfigjson` for a local Gitea
-     account whose token carries `read:package`, referenced from the Deployment and the
-     committed worker Job template — not built yet, because minting that token is yours.
+   - **The pull must be authenticated** once the node reaches the right endpoint: an
+     unauthenticated client gets nothing from this registry. **Now wired** —
+     `pm-agent-registry` is a `dockerconfigjson` Secret referenced by both the Deployment and
+     the committed worker Job template, and the admission policy pins it to exactly that
+     name. What is left to you is the value: the Gitea token must carry **`read:package`** in
+     addition to `write:repository` and `write:issue`, and the dockerconfigjson is built from
+     it. Steps:
+     [`pm-agent-registry.sops.yaml.example`](./pm-agent-registry.sops.yaml.example).
 
    The same two apply to `conformance-runner`: same registry path, same push-then-pin model,
    never pulled either.
-2. **The credentials are placeholders.** `pm-agent-credentials.sops.yaml` is encrypted to the
-   repository's age recipient but holds `REPLACE-ME-…` strings. The hand-off —
-   which Gitea account to create, which scopes, and why it must *not* be an administrator —
-   is in [`pm-agent-credentials.sops.yaml.example`](./pm-agent-credentials.sops.yaml.example).
-   Until then the dispatcher CrashLoops with `GET /user returned no login — is GITEA_TOKEN
-   valid?`.
+2. **The credentials are placeholders — two Secrets, one token.** Both are encrypted to the
+   repository's age recipient and both hold `REPLACE-ME-…` strings:
+
+   | Secret | type | read by | hand-off |
+   |---|---|---|---|
+   | `pm-agent-credentials` | Opaque | the application, as env | [`.example`](./pm-agent-credentials.sops.yaml.example) |
+   | `pm-agent-registry` | dockerconfigjson | the **kubelet**, before any container starts | [`.example`](./pm-agent-registry.sops.yaml.example) |
+
+   They hold the **same** Gitea token in two formats, because a Secret cannot be both — the
+   same one-value-in-two-files pattern the Keycloak client secret already uses here. So mint
+   it once, with all three scopes: `read:package` (the pull), `write:repository` (clone,
+   branch push, pull request) and `write:issue` (issue comments). The first `.example`
+   explains which account to create and why it must *not* be an administrator.
+
+   Until they are filled in: the pull fails `401`, and if you fix only the pull, the
+   dispatcher CrashLoops with `GET /user returned no login — is GITEA_TOKEN valid?`.
 
 Its Flux Kustomization is `wait: false` precisely because of those two states: a workload
 that is *expected* to be unhealthy for a while must never be able to gate anything.
@@ -148,6 +160,7 @@ Job from a committed template. **The model's output is data, never a command.**
 | **cannot** | clone from or push to anywhere but `gitea.gitea.svc.cluster.local:3000`: `pm-worker` validates `PM_GITEA_URL` against a one-entry allowlist baked into the image. In-cluster consumers reach a service by its cluster-local name — a different path by design from how a client outside the cluster reaches it — so the external hostname is not an accepted value |
 | **cannot** | authenticate a `git push` **during the model session**: `GIT_ASKPASS` is unset for its duration, so the restriction is structural rather than a request in a prompt |
 | **cannot** | be created in any shape but the committed one — see the admission policy |
+| **cannot** | have the kubelet read any Secret but `pm-agent-registry` on its behalf: `imagePullSecrets` is pinned to exactly that one name |
 
 ### What is *not* defended, stated plainly
 
@@ -193,14 +206,15 @@ Two things answer it, and neither is sufficient alone:
    `command` with no args, that powerless SA, no mounted token, `restartPolicy: Never`,
    non-root with no privilege escalation and a read-only root filesystem, only the
    `workspace`/`tmp` **emptyDir** volumes, no init or ephemeral containers, only the
-   committed env **names**, and no `envFrom`.
+   committed env **names**, no `envFrom`, and exactly one `imagePullSecret` — the committed
+   one.
 
-Six rules, because pinning `command` only moves the injection to whatever adjacent field
+Seven rules, because pinning `command` only moves the injection to whatever adjacent field
 nobody enumerated — on the sibling policy that was `initContainers` (measured: a Job with a
 compliant `containers[0]` and a privileged init container was **admitted**, pass 3 fail 0),
 then `ephemeralContainers`, then `env`, then `envFrom`. All of them are closed here from the
-start, and `platform/kyverno/tests/pm-agent/` proves each refusal offline: **28 assertions,
-28 passing** under the pinned `kyverno` CLI. The worker's own input guards have their own
+start, and `platform/kyverno/tests/pm-agent/` proves each refusal offline: **33 assertions,
+33 passing** under the pinned `kyverno` CLI. The worker's own input guards have their own
 offline probe — `infra/agent/probe-validation.sh`, **17 refusals** — because a guard nothing
 exercises is a claim rather than a control.