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]>

decisions/2026-10-06-pm-agent-registry-pull-secret.md

@@ -0,0 +1,88 @@
+---
+date: 2026-10-06
+branch: feat/pm-agent-registry-pull-secret
+title: The kubelet's pull credential — the second half of making agent-runner pullable, and the seventh field the admission policy had not read
+---
+
+## What changed
+
+The registry had two blockers. The first — the nodes resolving the registry hostname to the
+non-hairpinned WAN and failing TLS against the router's `CN=%D` certificate — was diagnosed
+and fixed by an `/etc/hosts` pin, merged in #59 and applied by the operator. This is the
+second: **the pull is unauthenticated, and this registry refuses unauthenticated clients
+outright.**
+
+`pm-agent-registry` is a new `kubernetes.io/dockerconfigjson` Secret, SOPS-encrypted with
+placeholder values, referenced by `imagePullSecrets` on both the dispatcher Deployment and
+the committed worker Job template. It is a **second Secret holding 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. That
+duplication is the established pattern here (the Keycloak client secret is mirrored the same
+way, for the same reason) and it is documented in both `.example` files.
+
+The operator's part is the value, and one scope: the Gitea token must now carry
+**`read:package`** alongside `write:repository` and `write:issue`. Steps are in
+`platform/pm-agent/pm-agent-registry.sops.yaml.example`, including the trap that
+`.dockerconfigjson`'s registry key must be the bare host as the image reference spells it —
+with a scheme or a port it matches nothing, the kubelet pulls anonymously, and the failure is
+indistinguishable from the Secret being absent.
+
+**The admission policy gained a seventh rule.** `imagePullSecrets` is a pod-spec field that
+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 and rule 7 forbids any other or any second one; both halves are
+needed because a `foreach` over an absent list yields no result.
+
+The leverage is small and worth saying so: the image is digest-pinned, so a different pull
+credential cannot change *what* runs, and the only Secrets in this namespace are the agent's
+own. It is pinned anyway, because "only the committed shape" is this policy's whole premise
+and the rule costs four lines.
+
+## What I verified
+
+- **`kyverno test platform/kyverno/tests/pm-agent` → 33 passed, 0 failed** under the pinned
+  CLI (was 28 before this change). Three new fixtures, each a real path rather than a style
+  violation: `extra-pull-secret` (the committed entry PLUS a second one — rule 1's array
+  pattern is satisfied by the first element, which is why the count is asserted separately),
+  `wrong-pull-secret` (a different Secret in this namespace), and `no-pull-secret` (absent
+  entirely, refused by rule 1's pattern because rule 7's foreach cannot see it).
+- **`PM_SELFTEST=1 pm-dispatch` → exit 0**, now also asserting that the committed Job
+  template names exactly `pm-agent-registry` — so the template and the policy cannot drift
+  apart without the image build failing.
+- **`./ci/gate.sh` in the pinned toolbox, from a §0 worktree → exit 3 (UNDETERMINED)**, with
+  `gitea-settings` the only stage that did not run (no `SETTINGS_API_TOKEN` on this
+  workstation). Every other stage green, `spec-immutability` included. rc 3 is not a pass.
+- **The gate caught me shipping the Secret in plaintext.** I wrote the placeholder
+  `pm-agent-registry.sops.yaml` and never ran `sops -e -i` on it. `no-plaintext-secrets`
+  refused it with both halves named — "has no top-level `sops:` block with a mac" and
+  "Secret value '.dockerconfigjson' is not SOPS ciphertext" — which is exactly the check
+  earning its place: the file looked finished, and the value was a placeholder, so nothing
+  about reading the diff would have made it obvious. Encrypted, and the stage is green.
+- **The registry really does refuse anonymous clients**, measured before building this
+  (2026-10-05): the anonymous registry token's `access` claim is `null`, every `/v2/…`
+  path answers 401 whether it exists or not, and `/api/v1/packages/Home-Network` replies
+  `{"message":"token is required"}`. That is why this is a credential and not a posture
+  tweak.
+
+## What I did NOT verify
+
+- **That the pull now works.** Nothing has been pushed to that registry and the committed
+  digest is still the all-zero placeholder, so neither half of the registry fix has been
+  exercised end to end. The first real pull is what proves both at once — and if it fails, the
+  error names which half: `x509 … not valid for any names` is the resolution pin, `401` /
+  `unauthorized` is this credential.
+- **That the `/etc/hosts` pin from #59 took effect.** The operator applied it; I could not
+  confirm the effect, because the dispatcher pod's retained events are all repeating
+  `BackOff` with no fresh `Pulling`, so the `x509` message still visible is the one from
+  before the play ran. Not evidence either way.
+- **Whether `read:package` is sufficient** for a pull from a Gitea package of this type. It is
+  the documented read scope for packages; nothing here has exercised it, because no package
+  exists yet.
+- **The dockerconfigjson placeholder is not a valid credential and is not meant to be.** Its
+  `auth` field is a `REPLACE-ME` string rather than base64, so a pull with it will fail at
+  authentication rather than be mistaken for working.
+- **Anything about runtime.** Unchanged from the previous entries: the image has never been
+  built or pushed, no dispatcher has authenticated to Gitea, no issue has been triaged, no
+  worker Job has ever been created, and the admission policy — live, `Enforce`, now seven
+  rules — has still never admitted or refused a real Job.