docs(decisions): handoff for the conformance-runner image, as its own file

CLAUDE.md section 7. This branch originally carried its handoff as a ~236-line
append to the tail of DECISIONS-LOG.md. Measured against the live Gitea on
2026-09-29, that append was the ONLY conflicting path between PR #18 and main,
and it is why the PR was `mergeable: false` -- four of the five open PRs were
unmergeable for exactly the same reason, on the same last hunk.

The append is dropped from this branch entirely; the branch now touches nothing
outside conformance/. Its substance moves here unchanged in meaning, in the
one-file-per-entry shape PR #24 introduces and ci/decisions-log.sh enforces:
frontmatter (date, branch, title) plus "What changed" / "What I verified" /
"What I did NOT verify".

Nothing the branch claims to have proven was upgraded in the move. Everything
the original entry marked UNVERIFIED is still marked UNVERIFIED here, and the
list grew rather than shrank: the image has never run in the cluster, it is not
pushed anywhere so CONFORMANCE_RUNNER_IMAGE_DIGEST stays empty, the image was
NOT rebuilt during this rework, chainsaw's cosign signatures are still
unverified, the 4th policy rule that would make conformance-clone REQUIRED does
not exist so the initContainer hole is open, and L2/L3 still do not run in CI.

Gate on the reworked branch, in the pinned toolbox from this worktree:
rc 3, MERGE GATE: UNDETERMINED, nothing FAILED. spec-immutability, lint, l0,
render-golden and l1 all green; gitea-settings the only stage that did not run
(SETTINGS_API_TOKEN unwired repo-wide); conformance warns L2/L3 UNVERIFIED for
R-SEC-02 R-TEST-01..04. Not green, and not reported as green.

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

conformance/incluster/Containerfile

@@ -0,0 +1,200 @@
+# =============================================================================
+# conformance-runner — the image the in-cluster L2/L3 Chainsaw Job actually runs.
+# Closes docs/plans/l2-l3-conformance-ci-wiring.md §3 item 1.
+#
+# WHY THIS EXISTS. chainsaw-job.yaml pins `ghcr.io/kyverno/chainsaw:v0.2.12` and
+# `command: ["./run.sh"]`. That image carries the chainsaw binary and almost nothing else —
+# no bash, no python3, no kubectl, no git. So the committed Job could never have run: it
+# would have failed at exec of `./run.sh`. This image carries exactly what
+# `conformance/run.sh` needs:
+#
+#   bash      run.sh and every tests/**/check.sh are bash (arrays, mapfile, BASH_SOURCE)
+#   python3   lib/{run_l1_offline,gen_coverage,merge_junit,emit_skipped_junit,status}.py
+#             (stdlib only — conformance/versions.env PYTHON_MIN=3.9, so no pip layer)
+#   chainsaw  the L1/L2/L3 runner itself (run_chainsaw / lint_tests)
+#   kubectl   conf_cluster_reachable()'s `kubectl cluster-info` preflight + probe scripts
+#   git       the init-container's `clone --depth 1` + `checkout <SHA>` (§3 item 2) and
+#             run.sh's `rev-parse --short HEAD` for the run id
+#   tar/gzip/coreutils  the `=== ARTIFACTS-TGZ-BASE64 ===` results channel (§3 item 3)
+#
+# It also carries `/usr/local/bin/conformance-clone` (0755 root:root) — the init container's
+# ONLY entrypoint, a fixed path with no argument surface. That exists to close an admission
+# hole, not for convenience: see the COPY below and the script's own header.
+#
+# VERSIONS COME FROM infra/devcontainer/versions.env — NOT from new pins invented here.
+# That file is the single source of truth for CHAINSAW_VERSION / KUBECTL_VERSION /
+# FEDORA_VERSION, and build-image.sh sources it and passes them in as --build-arg. The
+# ARG defaults below are deliberately EMPTY so a build that forgets to pass them fails
+# loudly (see the assertion in the first RUN) instead of silently baking a stale version.
+#
+# KNOWN LIMIT — READ BEFORE CHOOSING THE JOB'S `args`.
+# `run.sh` runs the selected OFFLINE L0/L1 checks (run_offline_checks) before it ever
+# touches the cluster, for ANY selection that is not offline-only. Those checks shell out
+# to flux / promtool / kyverno / kustomize, which this image deliberately does NOT carry —
+# baking the whole devcontainer toolchain into the runner would roughly double its size to
+# re-run work that ci/l0.sh + ci/l1.sh already did offline in the same CI run. So the Job
+# must select the cluster-gated layers only, e.g. `args: ["--layer", "l2"]` /
+# `["--layer", "l3"]`, where offline_selected_dirs() resolves to nothing and
+# run_offline_checks() returns 0. `--layer all` and a bare `--requirements <IDs>` would drag
+# the L0 checks in and fail on a missing tool. Flagged to the plan owner; choosing the Job's
+# args is T-6.1b's call, not this image's.
+#
+# THE ADMISSION CONTRACT THIS IMAGE MUST SATISFY.
+# platform/kyverno/admission/conformance-trigger-job-shape.yaml is a fail-closed Enforce
+# ClusterPolicy (R-SEC-02) and it is the security boundary. It requires the Job's container
+# to be `gitea.home.keithjackson.dev/home-network/conformance-runner@sha256:*` — a DIGEST,
+# never a tag — with `runAsNonRoot: true` and `allowPrivilegeEscalation: false`. Two
+# consequences are baked in here:
+#
+#   1. `USER` is NUMERIC. With `runAsNonRoot: true` and no explicit `runAsUser`, the kubelet
+#      REJECTS an image whose USER is a name it cannot resolve to a uid
+#      ("container has runAsNonRoot and image has non-numeric user"). So: USER 65532:65532.
+#   2. The pod is `readOnlyRootFilesystem: true` and the policy admits only the `workspace`
+#      and `results` volumes — there is no writable /tmp and one cannot be added without
+#      changing the boundary. So HOME and every cache path point INTO /workspace (the
+#      emptyDir), not at the read-only root. That is why HOME=/workspace below.
+# =============================================================================
+
+# --- builder: fetch the pinned release binaries ------------------------------
+# A full Fedora for the download stage (it has curl + tar); none of it ships in the runtime
+# image, so the runner does not carry a downloader it has no business having at runtime.
+ARG FEDORA_VERSION=44
+FROM registry.fedoraproject.org/fedora:${FEDORA_VERSION} AS builder
+
+ARG CHAINSAW_VERSION=
+ARG KUBECTL_VERSION=
+ARG TARGETARCH=amd64
+
+# Fail the BUILD — not the Job, three weeks later — if a pin was not passed in.
+RUN set -eux; \
+    : "${CHAINSAW_VERSION:?pass --build-arg CHAINSAW_VERSION from infra/devcontainer/versions.env}"; \
+    : "${KUBECTL_VERSION:?pass --build-arg KUBECTL_VERSION from infra/devcontainer/versions.env}"
+
+# Same URLs and the same arch handling as infra/devcontainer/Containerfile, so the chainsaw
+# and kubectl in this image are the same builds the toolbox gate runs with.
+#
+# INTEGRITY, MEASURED NOT ASSUMED. kubectl publishes a plain `<url>.sha256`, so it is verified
+# below. chainsaw publishes NO checksums file — the v0.2.12 release assets are the tarballs plus
+# per-asset cosign `.sig`/`.pem` and an SBOM (listed via the GitHub releases API). So chainsaw's
+# integrity here rests on the tag + TLS, and afterwards on this image's own digest.
+# TODO, worth doing and deliberately not smuggled in here: verify chainsaw with
+# `cosign verify-blob --certificate chainsaw_linux_amd64.tar.gz.pem
+#  --signature chainsaw_linux_amd64.tar.gz.sig ...`. That needs cosign in the builder stage and
+# the correct keyless identity/issuer for kyverno's release workflow — a supply-chain decision
+# that belongs in its own reviewed change, not as a silent addition to a runner image.
+# infra/devcontainer/Containerfile has the same gap for the same binary.
+RUN set -eux; \
+    mkdir -p /out; \
+    curl -fsSL "https://dl.k8s.io/release/v${KUBECTL_VERSION}/bin/linux/${TARGETARCH}/kubectl" \
+      -o /out/kubectl; \
+    curl -fsSL "https://dl.k8s.io/release/v${KUBECTL_VERSION}/bin/linux/${TARGETARCH}/kubectl.sha256" \
+      -o /tmp/kubectl.sha256; \
+    echo "$(cat /tmp/kubectl.sha256)  /out/kubectl" | sha256sum -c -; \
+    curl -fsSL "https://github.com/kyverno/chainsaw/releases/download/v${CHAINSAW_VERSION}/chainsaw_linux_${TARGETARCH}.tar.gz" \
+      | tar -xz -C /out chainsaw; \
+    chmod 0755 /out/kubectl /out/chainsaw; \
+    /out/kubectl version --client=true --output=yaml >/dev/null; \
+    /out/chainsaw version >/dev/null
+
+# --- runtime -----------------------------------------------------------------
+ARG FEDORA_VERSION=44
+FROM registry.fedoraproject.org/fedora-minimal:${FEDORA_VERSION}
+
+ARG CHAINSAW_VERSION=
+ARG KUBECTL_VERSION=
+ARG FEDORA_VERSION=44
+# Nonroot uid/gid. 65532 is the distroless `nonroot` convention; the value is arbitrary but
+# it MUST be numeric and non-zero — see "THE ADMISSION CONTRACT" above.
+ARG RUNNER_UID=65532
+ARG RUNNER_GID=65532
+
+LABEL org.opencontainers.image.title="conformance-runner" \
+      org.opencontainers.image.description="bash + python3 + chainsaw + kubectl + git for the in-cluster L2/L3 conformance Job (conformance/run.sh)" \
+      org.opencontainers.image.source="https://gitea.home.keithjackson.dev/Home-Network/home-network-k3s-impl" \
+      org.opencontainers.image.documentation="conformance/incluster/README.md" \
+      homelab.keithjackson.dev/requirements="R-TEST-02,R-SEC-02"
+
+# bash: run.sh + every check.sh.  python3: the stdlib report generators.
+# git-core: the init-container clone (git-core, not git — drops the perl/svn tail).
+# coreutils/findutils/grep/sed/gawk: find, sort, base64, xargs, sed -nE, awk in lib/*.sh.
+# tar+gzip: the base64-tar results channel.  diffutils: `diff` in the L1 golden compare.
+# ca-certificates: TLS for the init clone and for kubectl's in-cluster API calls.
+RUN set -eux; \
+    microdnf -y install --setopt=install_weak_deps=0 --nodocs \
+      bash python3 git-core coreutils findutils grep sed gawk tar gzip diffutils \
+      ca-certificates; \
+    microdnf clean all; \
+    rm -rf /var/cache/* /var/log/dnf*
+
+COPY --from=builder /out/kubectl /out/chainsaw /usr/local/bin/
+
+# The init container's ONLY entrypoint. Copied as a file with a fixed path and NO argument
+# surface, because the admission policy pins the main container's `command` but never reads
+# `initContainers` — so an init container with `command: ["/bin/sh","-c"]` and an arbitrary
+# script is currently ADMITTED and runs as the privileged `conformance-runner` SA (reproduced
+# by the policy's author; pass 3, fail 0). A 4th policy rule requiring
+# `command: ["/usr/local/bin/conformance-clone"]` with no `args` is what makes this file
+# REQUIRED rather than merely available; that rule belongs in its own reviewed PR against the
+# boundary, not here. See the script's header for the env-injection half of the same hole.
+#
+# 0755 root:root: the container runs as 65532 and MUST NOT be able to replace the one
+# executable the policy will trust. Ownership is asserted below rather than assumed.
+COPY conformance-clone /usr/local/bin/conformance-clone
+RUN set -eux; \
+    chown root:root /usr/local/bin/conformance-clone; \
+    chmod 0755 /usr/local/bin/conformance-clone; \
+    bash -n /usr/local/bin/conformance-clone; \
+    /usr/local/bin/conformance-clone --anything 2>&1 | grep -q 'takes no arguments'; \
+    test "$(stat -c '%U:%G %a' /usr/local/bin/conformance-clone)" = 'root:root 755'
+
+# The nonroot account is written directly rather than pulling in shadow-utils to run useradd
+# once. HOME is /workspace because at runtime that emptyDir is the only writable path.
+RUN set -eux; \
+    echo "runner:x:${RUNNER_UID}:${RUNNER_GID}:conformance runner:/workspace:/bin/bash" >> /etc/passwd; \
+    echo "runner:x:${RUNNER_GID}:" >> /etc/group; \
+    install -d -m 0775 -o "${RUNNER_UID}" -g "${RUNNER_GID}" /workspace
+
+# SYSTEM-level config, because HOME is an emptyDir that starts empty on every run and the
+# root filesystem is read-only — a runtime `--global` write would fail.
+# safe.directory=*: the init-container clones into the shared emptyDir and the main container
+# then runs `rev-parse` over it; any uid mismatch between the two would otherwise abort with
+# "detected dubious ownership". The repo is fetched fresh per run into an emptyDir, so there
+# is no pre-existing hostile checkout this relaxes a check against.
+RUN set -eux; \
+    printf '%s\n' \
+      '[safe]' \
+      '	directory = *' \
+      '[advice]' \
+      '	detachedHead = false' \
+      > /etc/gitconfig; \
+    chmod 0644 /etc/gitconfig
+
+# Provenance: what is actually in this layer, readable from a running pod.
+RUN set -eux; \
+    { echo "fedora=${FEDORA_VERSION}"; \
+      echo "chainsaw=${CHAINSAW_VERSION}"; \
+      echo "kubectl=${KUBECTL_VERSION}"; \
+      echo "bash=$(bash --version | head -1)"; \
+      echo "python3=$(python3 --version)"; \
+      echo "git=$(git --version)"; \
+      echo "conformance-clone=$(sha256sum /usr/local/bin/conformance-clone | cut -d' ' -f1)"; \
+    } > /etc/conformance-runner-versions; \
+    chmod 0444 /etc/conformance-runner-versions
+
+# Every writable path points into the `workspace` emptyDir — the root filesystem is
+# read-only and the admission policy forbids adding a third volume for scratch.
+ENV HOME=/workspace \
+    XDG_CACHE_HOME=/workspace/.cache \
+    XDG_CONFIG_HOME=/workspace/.config \
+    TMPDIR=/workspace/.tmp \
+    PYTHONDONTWRITEBYTECODE=1 \
+    CONF_ROOT=/workspace/conformance
+
+USER ${RUNNER_UID}:${RUNNER_GID}
+WORKDIR /workspace
+
+# No ENTRYPOINT on purpose. The admission policy pins `command: ["./run.sh"]` with
+# `workingDir: /workspace/conformance`; an ENTRYPOINT here would either be ignored or
+# prepend something the policy cannot see. `bash` is the interactive fallback for a human
+# debugging the image locally.
+CMD ["/bin/bash"]

conformance/incluster/README.md

@@ -27,7 +27,38 @@ credentials — the Job's own scoped ServiceAccount does (R-SEC-02).
   audit item.
 - `chainsaw-job.yaml` — the Job skeleton. Single entrypoint `./run.sh`; CI sets `args` to
   `--requirements <touched IDs>` (merge gate) or `--layer all --strict-coverage` (phase
-  exit). Image pinned to `versions.env` `CHAINSAW_IMAGE`.
+  exit). **Its `image:` is STALE**: it still names `ghcr.io/kyverno/chainsaw:v0.2.12`, which
+  (a) cannot run `./run.sh` at all and (b) is DENIED at admission. The trigger renders this
+  template per run with `CONFORMANCE_RUNNER_IMAGE` injected (plan §3 item 4, T-6.1b); until
+  that lands, treat the literal `image:` here as a placeholder, not a pin.
+- `Containerfile` — the **`conformance-runner`** image: `bash` + `python3` + `chainsaw` +
+  `kubectl` + `git`, non-root (numeric uid 65532) and working under a read-only root
+  filesystem. This is what the Job actually needs; the stock chainsaw image carries none of
+  it. Versions are `--build-arg`-injected from `infra/devcontainer/versions.env` — the single
+  source of truth — so the chainsaw/kubectl in the runner are the same pins the toolbox gate
+  uses. Read its header before changing the Job's `args`: `run.sh` runs the selected offline
+  L0/L1 checks for any non-offline-only selection, and those need flux/promtool/kyverno/
+  kustomize, which this image deliberately omits. Use `--layer l2` / `--layer l3`.
+- `conformance-clone` — the init container's **only** entrypoint, baked into the image at
+  `/usr/local/bin/conformance-clone` (0755 **root:root**, so uid 65532 cannot replace it).
+  Clones the impl repo at the commit under test: the SHA must match `^[0-9a-f]{40}$` and
+  `rev-parse HEAD` is **asserted** equal to it afterwards, so an unrendered placeholder is a
+  hard failure rather than a silent run of the branch tip. It takes **no arguments**, and the
+  repository URL and clone target are **compiled in** — see its header for why the env vars
+  are read but may not override them.
+  > **This file is half a fix.** The admission policy pins the main container's `command` but
+  > **never reads `initContainers`**, so an init container with `command: ["/bin/sh","-c"]` and
+  > an arbitrary script is currently ADMITTED and runs as the privileged `conformance-runner`
+  > SA. What makes this file *required* rather than merely available is a 4th policy rule
+  > demanding `command: ["/usr/local/bin/conformance-clone"]` with no `args`. That rule belongs
+  > in its own reviewed PR against the boundary and is **not** in this branch.
+- `build-image.sh` — builds the above, **verifies the toolchain by running it** inside the
+  image as uid 65532 with `--read-only`, and prints the digest. It **never pushes**: it
+  prints the exact `podman push --digestfile …` command for the operator instead. See
+  `conformance/versions.env` `CONFORMANCE_RUNNER_IMAGE` for the post-push pin.
+  `--verify-clone` additionally has `conformance-clone` really clone this repo at a real SHA
+  and asserts the checkout matches (opt-in, because it needs the Gitea host reachable — the
+  default verify stays offline so an air-gapped build is fully checked, not half-checked).
 
 ## Flow
 1. CI (Gitea Actions, delivered in T-6.1b) creates a Job from `chainsaw-job.yaml` (via a

conformance/incluster/build-image.sh

@@ -0,0 +1,229 @@
+#!/usr/bin/env bash
+###############################################################################
+# conformance/incluster/build-image.sh — build the pinned `conformance-runner`
+# image and print its digest. Closes docs/plans/l2-l3-conformance-ci-wiring.md §3 item 1.
+#
+#   ./build-image.sh                 # build + verify + print the digest and push command
+#   ./build-image.sh --no-verify     # build only (skip the in-image tool proof)
+#   ./build-image.sh --verify-clone  # ALSO really clone this repo with conformance-clone.
+#                                    #   Opt-in because it needs the Gitea host reachable; the
+#                                    #   default verify is offline so an air-gapped build is
+#                                    #   still fully checked rather than half-checked.
+#   ENGINE=docker ./build-image.sh   # build with docker instead of podman
+#
+# THIS SCRIPT NEVER PUSHES. Publishing is an operator action: the registry credential is
+# not an agent's to hold, and the pushed digest is what a fail-closed admission policy
+# then trusts. So this builds locally, proves the toolchain works INSIDE the image as the
+# non-root uid the policy demands, and prints the exact `podman push` line for a human.
+#
+# VERSIONS ARE NOT DEFINED HERE. They are read from infra/devcontainer/versions.env, the
+# single source of truth (CHAINSAW_VERSION, KUBECTL_VERSION, FEDORA_VERSION) — the same
+# pins the toolbox gate runs with. Nothing in this file invents a version.
+#
+# THE DIGEST CAVEAT — read it before pasting a digest into anything.
+# The digest printed here is the LOCAL manifest digest. It is normally identical to the
+# registry digest (podman pushes the manifest it already has rather than recompressing),
+# but that is a property of the push, not a guarantee. So the push command below uses
+# `--digestfile`: the digest the registry actually returns is the authoritative one, and
+# that is the one that goes into conformance/versions.env.
+###############################################################################
+set -euo pipefail
+
+HERE="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+REPO_ROOT="$(cd "${HERE}/../.." && pwd)"
+ENGINE="${ENGINE:-podman}"
+
+VERIFY=1
+VERIFY_CLONE=0
+for arg in "$@"; do
+  case "$arg" in
+    --no-verify) VERIFY=0 ;;
+    --verify-clone) VERIFY_CLONE=1 ;;
+    -h|--help) sed -n '2,/^####/p' "${BASH_SOURCE[0]}" | sed '$d' | sed 's/^# \{0,1\}//'; exit 0 ;;
+    *) echo "unknown argument: $arg" >&2; exit 2 ;;
+  esac
+done
+
+log()  { printf '\n\033[1m==> %s\033[0m\n' "$*"; }
+info() { printf '    %s\n' "$*"; }
+die()  { printf '\033[31mERROR: %s\033[0m\n' "$*" >&2; exit 1; }
+
+command -v "${ENGINE}" >/dev/null 2>&1 || die "'${ENGINE}' not on PATH (set ENGINE=docker to use docker)"
+
+# --- pins: sourced, never invented -------------------------------------------
+TOOLCHAIN_ENV="${REPO_ROOT}/infra/devcontainer/versions.env"
+[ -f "${TOOLCHAIN_ENV}" ] || die "missing ${TOOLCHAIN_ENV} — the pins live there, not here"
+# shellcheck disable=SC1090
+source "${TOOLCHAIN_ENV}"
+: "${CHAINSAW_VERSION:?CHAINSAW_VERSION not set in ${TOOLCHAIN_ENV}}"
+: "${KUBECTL_VERSION:?KUBECTL_VERSION not set in ${TOOLCHAIN_ENV}}"
+: "${FEDORA_VERSION:?FEDORA_VERSION not set in ${TOOLCHAIN_ENV}}"
+
+# --- image name: fixed by the admission policy -------------------------------
+# platform/kyverno/admission/conformance-trigger-job-shape.yaml admits ONLY
+# gitea.home.keithjackson.dev/home-network/conformance-runner@sha256:*. The repository path
+# is therefore not a preference; a different path is a DENIED Job. Do not "improve" it here.
+IMAGE_REPO="gitea.home.keithjackson.dev/home-network/conformance-runner"
+# The tag is build convenience only (a human-readable handle for the push). Admission
+# ignores it: only the digest is ever referenced from a Job.
+IMAGE_TAG="chainsaw${CHAINSAW_VERSION}-kubectl${KUBECTL_VERSION}-fc${FEDORA_VERSION}"
+IMAGE_REF="${IMAGE_REPO}:${IMAGE_TAG}"
+
+log "Building ${IMAGE_REF}"
+info "engine            ${ENGINE} ($(${ENGINE} --version 2>/dev/null | head -1))"
+info "pins from         ${TOOLCHAIN_ENV}"
+info "  CHAINSAW        ${CHAINSAW_VERSION}"
+info "  KUBECTL         ${KUBECTL_VERSION}"
+info "  FEDORA          ${FEDORA_VERSION}"
+
+"${ENGINE}" build \
+  --file "${HERE}/Containerfile" \
+  --tag "${IMAGE_REF}" \
+  --build-arg "CHAINSAW_VERSION=${CHAINSAW_VERSION}" \
+  --build-arg "KUBECTL_VERSION=${KUBECTL_VERSION}" \
+  --build-arg "FEDORA_VERSION=${FEDORA_VERSION}" \
+  "${HERE}"
+
+# --- verify: the point of the whole exercise ---------------------------------
+# The stock chainsaw image "had" chainsaw and still could not run ./run.sh. So prove the
+# tools EXECUTE, and prove they execute as the NON-ROOT uid with a READ-ONLY root
+# filesystem — the shape the admission policy forces. A pass here is the only evidence
+# this image is usable; a build that merely succeeded is not.
+if [ "${VERIFY}" -eq 1 ]; then
+  log "Verifying the toolchain inside the image (non-root, read-only rootfs)"
+  "${ENGINE}" run --rm \
+    --user 65532:65532 \
+    --read-only \
+    --tmpfs /workspace:rw,mode=1777 \
+    --entrypoint "" \
+    "${IMAGE_REF}" \
+    /bin/bash -euo pipefail -c '
+      echo "--- id ---";             id
+      echo "--- HOME ---";           echo "HOME=${HOME}"
+      echo "--- bash ---";           bash --version | head -1
+      echo "--- python3 ---";        python3 --version
+      echo "--- git ---";            git --version
+      echo "--- kubectl ---";        kubectl version --client
+      echo "--- chainsaw ---";       chainsaw version
+      echo "--- baked versions ---"; cat /etc/conformance-runner-versions
+      echo "--- conformance-clone: fixed path, root-owned, NOT writable by the runner ---"
+      stat -c "%n %U:%G %a" /usr/local/bin/conformance-clone
+      if [ -w /usr/local/bin/conformance-clone ]; then
+        echo "UNEXPECTED: uid $(id -u) can write the one executable the policy will trust"; exit 1
+      fi
+      echo "confirmed: not writable by uid $(id -u)"
+      # Each of these MUST fail. Assert the non-zero exit as well as the message: a check
+      # that only greps stderr would pass a build where the guard had stopped rejecting.
+      # (`|| true` inside the capture keeps `set -e`/`pipefail` from aborting on the
+      # expected failure — without it the verify dies at the first negative case.)
+      expect_fail() {
+        local label="$1"; shift
+        local out rc=0
+        out="$(env "$@" 2>&1)" || rc=$?
+        echo "--- ${label} ---"
+        printf "%s\n" "${out}" | head -2
+        if [ "${rc}" -eq 0 ]; then
+          echo "UNEXPECTED: that should have failed, but it exited 0"; exit 1
+        fi
+        echo "(rejected, exit ${rc})"
+      }
+      expect_fail "conformance-clone rejects arguments (that is where an injection would live)" \
+        conformance-clone --layer l2
+      expect_fail "conformance-clone rejects a missing SHA" \
+        conformance-clone
+      expect_fail "conformance-clone rejects a branch name instead of a SHA (no silent run of the tip)" \
+        CONFORMANCE_GIT_SHA=main conformance-clone
+      expect_fail "conformance-clone rejects an UNRENDERED placeholder" \
+        CONFORMANCE_GIT_SHA=@@CONFORMANCE_GIT_SHA@@ conformance-clone
+      expect_fail "conformance-clone rejects a HOME off the workspace volume" \
+        CONFORMANCE_GIT_SHA=0000000000000000000000000000000000000000 \
+        HOME=/etc conformance-clone
+      expect_fail "conformance-clone refuses a REDIRECTED repository URL (the env-injection hole)" \
+        CONFORMANCE_GIT_SHA=0000000000000000000000000000000000000000 \
+        CONFORMANCE_REPO_URL=https://evil.invalid/x.git conformance-clone
+      expect_fail "conformance-clone refuses a clone target off the workspace volume" \
+        CONFORMANCE_GIT_SHA=0000000000000000000000000000000000000000 \
+        CONFORMANCE_SRC=/etc/src conformance-clone
+      echo "--- rootfs is read-only (expected: a failure) ---"
+      if touch /should-fail 2>/dev/null; then echo "UNEXPECTED: rootfs is writable"; exit 1; fi
+      echo "confirmed: / is read-only"
+      echo "--- HOME is writable (the workspace emptyDir) ---"
+      touch "${HOME}/.probe" && echo "confirmed: ${HOME} is writable"
+      echo "--- uid is non-zero ---"
+      [ "$(id -u)" -ne 0 ] && echo "confirmed: running as uid $(id -u), not root"
+    '
+  log "Toolchain verified"
+fi
+
+# --- verify the clone helper against the REAL repository (opt-in: needs network) ----
+# The negative cases above prove conformance-clone refuses bad input. This proves the
+# positive case: it lands the EXACT commit asked for and can prove it did. Without this, the
+# rev-parse assertion is only an unexercised line of shell.
+if [ "${VERIFY_CLONE}" -eq 1 ]; then
+  log "Verifying conformance-clone against the real repository"
+  SHA="$(git -C "${REPO_ROOT}" rev-parse HEAD)"
+  info "requesting commit ${SHA}"
+  "${ENGINE}" run --rm \
+    --user 65532:65532 \
+    --read-only \
+    --tmpfs /workspace:rw,mode=1777 \
+    --network host \
+    --entrypoint "" \
+    -e "CONFORMANCE_GIT_SHA=${SHA}" \
+    "${IMAGE_REF}" \
+    /bin/bash -euo pipefail -c '
+      conformance-clone
+      echo "--- assert rev-parse HEAD == the requested SHA ---"
+      got="$(git -C /workspace/src rev-parse HEAD)"
+      echo "requested: ${CONFORMANCE_GIT_SHA}"
+      echo "HEAD:      ${got}"
+      [ "${got}" = "${CONFORMANCE_GIT_SHA}" ] || { echo "MISMATCH"; exit 1; }
+      echo "confirmed: the working tree is at the requested commit"
+      test -x /workspace/src/conformance/run.sh && echo "confirmed: run.sh present and executable"
+    '
+  log "conformance-clone verified against the real repository"
+fi
+
+# --- digest ------------------------------------------------------------------
+DIGEST="$("${ENGINE}" image inspect --format '{{.Digest}}' "${IMAGE_REF}")"
+IMAGE_ID="$("${ENGINE}" image inspect --format '{{.Id}}' "${IMAGE_REF}")"
+SIZE="$("${ENGINE}" image inspect --format '{{.Size}}' "${IMAGE_REF}")"
+
+log "Built ${IMAGE_REF}"
+info "local manifest digest  ${DIGEST}"
+info "image id               ${IMAGE_ID}"
+info "size                   $(( SIZE / 1024 / 1024 )) MiB"
+
+cat <<EOF
+
+================================================================================
+NOT PUSHED. Publishing is an operator action — this script holds no registry
+credential and will never acquire one.
+
+OPERATOR: run these two commands, then paste the digest from the digestfile into
+conformance/versions.env (CONFORMANCE_RUNNER_IMAGE) via a PR:
+
+    ${ENGINE} login gitea.home.keithjackson.dev
+
+    ${ENGINE} push --digestfile /tmp/conformance-runner.digest \\
+      ${IMAGE_REF}
+
+Then:
+
+    cat /tmp/conformance-runner.digest
+    # -> sha256:....  THIS is the authoritative digest, not the local one above.
+
+    # conformance/versions.env
+    CONFORMANCE_RUNNER_IMAGE="${IMAGE_REPO}@\$(cat /tmp/conformance-runner.digest)"
+
+WHY THE DIGEST AND NOT THE TAG: platform/kyverno/admission/conformance-trigger-job-shape.yaml
+is a fail-closed Enforce policy. It DENIES any conformance-trigger Job whose image is not
+${IMAGE_REPO}@sha256:<digest>. A tag reference is denied,
+and so is any other repository path.
+
+TIGHTEN THE BOUNDARY AFTERWARDS: that policy's header asks for the wildcard
+\`${IMAGE_REPO}@sha256:*\` to be replaced with the
+LITERAL digest once the image exists, closing the "anyone who can push to this path" gap.
+That is a separate, human-reviewed PR against the security boundary.
+================================================================================
+EOF

conformance/incluster/conformance-clone

@@ -0,0 +1,138 @@
+#!/usr/bin/env bash
+###############################################################################
+# conformance-clone — fetch the impl repo at the exact commit under test.
+#
+# Baked into the conformance-runner image at /usr/local/bin/conformance-clone, mode 0755
+# root:root, so the running container (uid 65532) cannot replace it. The Job's init
+# container runs it as `command: ["/usr/local/bin/conformance-clone"]` with NO args.
+#
+# WHY IT IS A FILE IN THE IMAGE AND NOT AN INLINE SCRIPT IN THE JOB
+# -----------------------------------------------------------------
+# platform/kyverno/admission/conformance-trigger-job-shape.yaml pins the MAIN container's
+# `command` to ["./run.sh"] and constrains its `args` — but it never reads `initContainers`.
+# So a Job from `conformance-trigger` could carry an init container with
+# `command: ["/bin/sh","-c"]` and an arbitrary script, running as the privileged
+# `conformance-runner` SA. Reproduced by the policy's author: such a Job is ADMITTED
+# (pass 3, fail 0).
+#
+# The fix has two halves and NEITHER works alone:
+#   1. this file — a fixed path with fixed behaviour and no argument surface, so there is
+#      nothing for a caller to inject into; and
+#   2. a 4th policy rule requiring every initContainer's `command` to be exactly
+#      ["/usr/local/bin/conformance-clone"] with no `args`. That rule lives in the policy
+#      and is NOT this branch's to write — a security boundary changes in its own reviewed PR.
+# Without (2) this file is merely available, not required.
+#
+# THE ENV SURFACE IS THE OTHER HALF OF THE SAME HOLE — READ THIS BEFORE "SIMPLIFYING"
+# -----------------------------------------------------------------------------------
+# The admission policy says NOTHING about `env`. Verified: no `env`, `valueFrom` or
+# `secretKeyRef` clause appears in it. So a script that took its repository URL from the
+# environment would just move the injection one field over — the trigger sets
+# CONFORMANCE_REPO_URL to a repo it controls, this clones it, and `./run.sh` from THAT repo
+# executes under the privileged runner SA. Identical shape to the initContainers gap, and
+# "no args" would not have stopped it.
+#
+# Therefore the repository URL and the clone target are COMPILED IN below. The matching env
+# vars are still read, so the Job template can keep declaring them and stay self-documenting,
+# but a value that DISAGREES with the baked literal is a hard failure, never a redirect.
+# The only per-run input that is genuinely trusted is the commit SHA, and it must be 40 hex
+# characters of a commit that the baked repository actually contains.
+#
+# Inputs (environment; no arguments are accepted):
+#   CONFORMANCE_GIT_SHA   REQUIRED. 40 lowercase hex. The commit under test.
+#   CONFORMANCE_REPO_URL  optional. Must equal the baked URL if set.
+#   CONFORMANCE_SRC       optional. Must equal the baked target if set.
+#   GITEA_USERNAME        optional, from Secret `conformance-git-readonly`.
+#   GITEA_TOKEN           optional, from Secret `conformance-git-readonly`.
+#   TMPDIR / HOME         optional; must be under /workspace. Default to /workspace/{tmp,home}.
+#
+# Runs under: uid 65532, readOnlyRootFilesystem, only the `workspace` and `results` volumes.
+# Everything it writes therefore lives under /workspace. There is no writable /tmp.
+###############################################################################
+set -euo pipefail
+
+# --- COMPILED-IN, NOT CONFIGURABLE (see the header) --------------------------
+readonly BAKED_REPO_URL="https://gitea.home.keithjackson.dev/Home-Network/home-network-k3s-impl.git"
+readonly BAKED_SRC="/workspace/src"
+
+die() { printf 'FATAL: %s\n' "$*" >&2; exit 1; }
+log() { printf '==> %s\n' "$*"; }
+
+[ "$#" -eq 0 ] || die "takes no arguments (got $#: $*). Arguments are where an injection would live."
+
+# --- the one genuinely trusted input ----------------------------------------
+# A bad SHA must never degrade into "ran whatever the branch tip was": an unrendered
+# @@CONFORMANCE_GIT_SHA@@ placeholder has to be a hard failure, not a silent run of main.
+: "${CONFORMANCE_GIT_SHA:?CONFORMANCE_GIT_SHA is not set; the CI trigger did not render it}"
+printf '%s' "${CONFORMANCE_GIT_SHA}" | grep -Eq '^[0-9a-f]{40}$' \
+  || die "CONFORMANCE_GIT_SHA is not a 40-hex commit id: '${CONFORMANCE_GIT_SHA}'
+       The CI trigger did not substitute it, or substituted junk."
+
+# --- env that may agree with the baked values, but may not override them -----
+REPO_URL="${CONFORMANCE_REPO_URL:-${BAKED_REPO_URL}}"
+[ "${REPO_URL}" = "${BAKED_REPO_URL}" ] || die "CONFORMANCE_REPO_URL does not match the image's baked repository.
+         got:    ${REPO_URL}
+         baked:  ${BAKED_REPO_URL}
+       Refusing. A caller that can choose the repository can choose the code that runs."
+
+SRC="${CONFORMANCE_SRC:-${BAKED_SRC}}"
+[ "${SRC}" = "${BAKED_SRC}" ] || die "CONFORMANCE_SRC does not match the image's baked clone target.
+         got:    ${SRC}
+         baked:  ${BAKED_SRC}
+       Refusing."
+
+# Scratch paths must stay on the workspace volume; the root filesystem is read-only.
+# `/workspace` ITSELF is allowed, not just subdirectories: the image's own ENV sets
+# HOME=/workspace, and an earlier version of this guard rejected exactly that — it matched
+# only `/workspace/*` and so refused its own default. Caught by running it, not by reading it.
+: "${TMPDIR:=/workspace/tmp}"
+: "${HOME:=/workspace/home}"
+on_workspace() { case "$1" in /workspace|/workspace/*) return 0 ;; *) return 1 ;; esac; }
+on_workspace "${TMPDIR}" || die "TMPDIR must be /workspace or under it (got '${TMPDIR}')"
+on_workspace "${HOME}"   || die "HOME must be /workspace or under it (got '${HOME}')"
+export TMPDIR HOME
+mkdir -p "${TMPDIR}" "${HOME}"
+
+# --- credential (optional) ---------------------------------------------------
+# git's shell credential helper is invoked as `sh -c '<value> get'`, so it reads $1 and
+# answers from the environment. The token therefore never appears in argv and never on disk.
+#
+# ANONYMOUS FALLBACK, DELIBERATE AND ANNOUNCED. Read access to this repository currently
+# needs no credential (measured: `ls-remote` succeeds unauthenticated from inside this
+# image), so requiring the Secret would fail runs that would otherwise work — and would make
+# this script untestable without one. It is not a privilege downgrade: the integrity
+# guarantee here is the SHA assertion below, not the credential. Which mode was used is
+# logged, so a run that silently lost its Secret is visible in the log rather than inferred.
+CRED=''
+if [ -n "${GITEA_USERNAME:-}" ] && [ -n "${GITEA_TOKEN:-}" ]; then
+  CRED='!f() { if [ "$1" = get ]; then printf "username=%s\npassword=%s\n" "$GITEA_USERNAME" "$GITEA_TOKEN"; fi; }; f'
+  log "authenticating as '${GITEA_USERNAME}' (token from the environment, never argv)"
+else
+  log "no GITEA_USERNAME/GITEA_TOKEN in the environment — cloning ANONYMOUSLY"
+fi
+
+git_c() {
+  if [ -n "${CRED}" ]; then git -c credential.helper="${CRED}" "$@"; else git "$@"; fi
+}
+
+# --- clone, land the exact commit, and PROVE it ------------------------------
+log "shallow clone ${REPO_URL} -> ${SRC}"
+git_c clone --depth 1 --no-tags --single-branch "${REPO_URL}" "${SRC}"
+
+if ! git -C "${SRC}" cat-file -e "${CONFORMANCE_GIT_SHA}^{commit}" 2>/dev/null; then
+  log "${CONFORMANCE_GIT_SHA} is not in the shallow tip; fetching that commit"
+  git_c -C "${SRC}" fetch --depth 1 --no-tags origin "${CONFORMANCE_GIT_SHA}"
+fi
+
+git -C "${SRC}" checkout --detach "${CONFORMANCE_GIT_SHA}"
+
+# The assertion is the point of the whole script: everything above is best-effort plumbing,
+# this is what makes "the suite ran at the commit under test" a fact rather than a hope.
+head="$(git -C "${SRC}" rev-parse HEAD)"
+[ "${head}" = "${CONFORMANCE_GIT_SHA}" ] \
+  || die "checked out ${head}, expected ${CONFORMANCE_GIT_SHA}."
+
+test -x "${SRC}/conformance/run.sh" \
+  || die "no executable conformance/run.sh at ${head}."
+
+log "suite ready at ${head}"

conformance/versions.env

@@ -6,6 +6,10 @@
 
 # Chainsaw — L1 rendering / L2 behavioral / L3 fault-injection runner (ADR-0011).
 CHAINSAW_VERSION="v0.2.12"
+# The UPSTREAM chainsaw image. It is NOT what the in-cluster Job runs — see
+# CONFORMANCE_RUNNER_IMAGE below. It carries the chainsaw binary and essentially nothing
+# else (no bash, no python3, no kubectl, no git), so `command: ["./run.sh"]` on this image
+# fails at exec. Kept only as the provenance of the chainsaw binary we rebuild from.
 CHAINSAW_IMAGE="ghcr.io/kyverno/chainsaw:v0.2.12"
 
 # kubectl — used by run.sh for cluster reachability preflight and by probe scripts.
@@ -18,3 +22,52 @@ KYVERNO_VERSION="v1.19.0"
 # Python 3 — coverage generator + JUnit emitter use stdlib only (no pip deps), so the
 # only constraint is a modern interpreter.
 PYTHON_MIN="3.9"
+
+# --- In-cluster conformance runner image -------------------------------------
+# Built from conformance/incluster/Containerfile by conformance/incluster/build-image.sh.
+# This — not CHAINSAW_IMAGE — is what the L2/L3 Job runs (bash + python3 + chainsaw +
+# kubectl + git). Closes docs/plans/l2-l3-conformance-ci-wiring.md §3 item 1.
+#
+# It ALSO carries /usr/local/bin/conformance-clone (0755 root:root, no argument surface) as the
+# init container's only entrypoint. That is a security fixture, not a convenience: the
+# admission policy never reads `initContainers`, so an init container with an inline shell
+# script is currently admitted with the privileged runner SA. The policy rule that makes the
+# fixed path REQUIRED is not in this branch — see conformance/incluster/README.md.
+#
+# THE REPOSITORY PATH IS NOT A PREFERENCE. platform/kyverno/admission/
+# conformance-trigger-job-shape.yaml is a fail-closed Enforce ClusterPolicy (R-SEC-02) that
+# ADMITS a conformance-trigger Job only when its image matches
+#   gitea.home.keithjackson.dev/home-network/conformance-runner@sha256:*
+# Any other path, and any TAG reference, is DENIED at admission. Do not "tidy" these values.
+CONFORMANCE_RUNNER_IMAGE_REPO="gitea.home.keithjackson.dev/home-network/conformance-runner"
+# Build handle only. Admission never sees the tag; a Job must reference the digest.
+CONFORMANCE_RUNNER_IMAGE_TAG="chainsaw0.2.12-kubectl1.36.4-fc44"
+#
+# ############################################################################
+# # DIGEST DELIBERATELY EMPTY — THE IMAGE HAS NOT BEEN PUBLISHED YET.        #
+# ############################################################################
+# The image has been BUILT and its toolchain verified locally (non-root uid 65532,
+# read-only rootfs: bash 5.3.9, Python 3.14.7, git 2.55.0, kubectl v1.36.4, chainsaw 0.2.12,
+# and `./run.sh --layer l2 --no-cluster` completing with rc 0). It has NOT been pushed:
+# pushing needs a registry credential, and publishing the artifact a fail-closed security
+# boundary then trusts is an OPERATOR action, not an agent's.
+#
+# OPERATOR, to complete the pin:
+#   1. ./conformance/incluster/build-image.sh          # rebuild, verify, print the commands
+#   2. podman login gitea.home.keithjackson.dev
+#   3. podman push --digestfile /tmp/conformance-runner.digest \
+#        "${CONFORMANCE_RUNNER_IMAGE_REPO}:${CONFORMANCE_RUNNER_IMAGE_TAG}"
+#   4. Set CONFORMANCE_RUNNER_IMAGE_DIGEST below to `cat /tmp/conformance-runner.digest`
+#      — the digest the REGISTRY returned, not the local manifest digest the build printed.
+#   5. Land steps 4 in a PR (this file is GitOps input, not a live edit).
+#
+# UNTIL THEN: this is empty on purpose, NOT a placeholder to be guessed at. An empty value
+# makes any consumer that renders the Job fail visibly; a fake or stale digest would instead
+# produce an ImagePullBackOff that looks like a cluster fault. Do not invent one.
+CONFORMANCE_RUNNER_IMAGE_DIGEST=""
+CONFORMANCE_RUNNER_IMAGE="${CONFORMANCE_RUNNER_IMAGE_DIGEST:+${CONFORMANCE_RUNNER_IMAGE_REPO}@${CONFORMANCE_RUNNER_IMAGE_DIGEST}}"
+#
+# AFTERWARDS, TIGHTEN THE BOUNDARY: the header of conformance-trigger-job-shape.yaml asks for
+# its `@sha256:*` wildcard to be replaced with the LITERAL digest once the image exists —
+# that closes the residual "anyone who can push to this path" gap. Separate PR, human
+# reviewed, because it edits the security boundary itself.

decisions/2026-09-29-conformance-runner-image.md

@@ -0,0 +1,258 @@
+---
+date: 2026-09-29
+branch: feat/conformance-runner-image
+title: The in-cluster conformance Job could never have run; built the image it needs (PR #18)
+---
+
+## What changed
+
+Closes `docs/plans/l2-l3-conformance-ci-wiring.md` §3 item 1. PR
+[#18](https://gitea.home.keithjackson.dev/Home-Network/home-network-k3s-impl/pulls/18). **Not
+merged** — an agent cannot, and should not.
+
+### The defect, stated plainly
+
+`conformance/incluster/chainsaw-job.yaml` pinned `ghcr.io/kyverno/chainsaw:v0.2.12` **and**
+`command: ["./run.sh"]`. Both lines could not be true. That image carries the chainsaw binary
+and essentially nothing else — no `bash`, no `python3`, no `kubectl`, no `git`. The Job would
+have failed at exec of `./run.sh` before a single test ran, and the only place that would have
+surfaced is a pod log nobody was reading. This is the same failure shape as the entries around
+it in the archive: a manifest that *described* a working mechanism, with nothing measuring
+whether the mechanism existed.
+
+### What landed
+
+- `conformance/incluster/Containerfile` — the `conformance-runner` image: bash + python3 +
+  chainsaw + kubectl + `git-core` + tar/gzip/coreutils/diffutils. Two-stage (a full Fedora
+  fetches the binaries and verifies kubectl's published `sha256`; the runtime layer is
+  `fedora-minimal` and carries no downloader).
+- `conformance/incluster/build-image.sh` — builds, **proves the toolchain by executing it**,
+  prints the digest, and **never pushes**.
+- `conformance/incluster/conformance-clone` — the baked init-container clone helper (see the
+  addendum below).
+- `conformance/versions.env` — `CONFORMANCE_RUNNER_IMAGE`, digest **empty** pending the push.
+- `conformance/incluster/README.md` — documents all of it, and flags the Job manifest's stale
+  `image:`.
+
+`infra/devcontainer/versions.env` stays the single source of truth. `build-image.sh` sources it
+and injects `CHAINSAW_VERSION` / `KUBECTL_VERSION` / `FEDORA_VERSION` as `--build-arg`; the
+Containerfile's `ARG` defaults are **empty** and asserted in its first `RUN`, so a build that
+forgets a pin fails loudly rather than baking a stale version. No new pin was invented.
+
+Two things the admission boundary forced, both of which would otherwise have been discovered
+at first run: `USER` must be **numeric** (`runAsNonRoot` with no `runAsUser` makes the kubelet
+reject a named user), and every writable path must live under `/workspace` (the pod is
+`readOnlyRootFilesystem` and the policy admits no third volume, so there is no `/tmp`). git's
+`safe.directory` is therefore written to `/etc/gitconfig` at build time.
+`platform/kyverno/admission/conformance-trigger-job-shape.yaml` was **not modified**.
+
+### The chainsaw supply-chain gap, stated accurately
+
+The Containerfile originally said chainsaw "publishes no per-asset checksum file at a stable
+URL". Literally true, and misleading: it reads as "no integrity option exists". The release
+assets say otherwise — v0.2.12 ships per-asset cosign `.sig` + `.pem` and an SBOM alongside
+each tarball. So verification IS available; it needs cosign in the builder stage and the right
+keyless identity for kyverno's release workflow. The comment now says what is true: kubectl is
+sha256-verified, chainsaw rests on tag + TLS, and the cosign path is named as a TODO.
+Deliberately **not** implemented here — picking a trusted signer identity is a supply-chain
+decision that belongs in its own reviewed change. `infra/devcontainer/Containerfile` has the
+same gap for the same binary.
+
+### Addendum — `/usr/local/bin/conformance-clone`
+
+Added at the coordinator's request, to close half of the admission gap a sibling agent found:
+the policy pins the MAIN container's `command` but **never reads `initContainers`**, so a Job
+from `conformance-trigger` can carry an init container with `command: ["/bin/sh","-c"]` and an
+arbitrary script, running as the privileged `conformance-runner` SA. Reproduced by the policy's
+author (`pass: 3, fail: 0` on a privileged `alpine:latest` init container running
+`kubectl get secrets -A`).
+
+The image now bakes `/usr/local/bin/conformance-clone`, **0755 root:root**, so uid 65532 cannot
+replace the one executable the policy will come to trust. Clone logic taken from PR #20's
+`clone-suite-at-commit`, with both load-bearing properties preserved: the SHA must match
+`^[0-9a-f]{40}$`, and `rev-parse HEAD` is asserted equal to it after checkout. No arguments are
+accepted.
+
+**A DEVIATION FROM THE BRIEF, DELIBERATE — the repo URL and clone target are COMPILED IN, not
+taken from the environment.** The brief said to take SHA, repo URL and target dir from the
+environment. The policy contains no `env`, `valueFrom` or `secretKeyRef` clause at all, so a
+script that trusted `CONFORMANCE_REPO_URL` would have moved the injection one field over — the
+trigger points it at a repo it controls, `conformance-clone` fetches that, and `./run.sh` from
+the attacker's tree runs under the privileged SA. "No args" would not have stopped it. The env
+vars are still read so the Job template stays self-documenting, but a value that disagrees with
+the baked literal is a hard failure, never a redirect. The only genuinely trusted per-run input
+is the SHA.
+
+**This file is half a fix and must not be mistaken for the whole one.** What makes the fixed
+path *required* rather than merely *available* is a 4th policy rule demanding
+`command: ["/usr/local/bin/conformance-clone"]` with no `args` on every initContainer. That
+rule edits the security boundary and belongs in its own reviewed PR — it is **not** in this
+branch. Until it lands, the hole is open.
+
+The anonymous-clone fallback is deliberate and announced in the script's log line: read access
+to this repo needs no credential today, the integrity guarantee here is the SHA assertion
+rather than the credential, and requiring the Secret would have made the script untestable
+without one.
+
+### A REAL CONSTRAINT THE PLAN DOES NOT ACCOUNT FOR — read before wiring T-6.1b
+
+`run.sh` runs the selected **offline L0/L1 checks** before it touches the cluster, for **any**
+selection that is not offline-only. Those checks shell out to `flux`, `promtool`, `kyverno` and
+`kustomize`. This image deliberately omits them — baking the whole devcontainer toolchain into
+the runner would roughly double its size to re-run work `ci/l0.sh` and `ci/l1.sh` already did
+offline in the same CI run.
+
+So **the plan's own invocation shapes do not work on this image.** `--layer all
+--strict-coverage` (the documented phase-exit shape) and a bare `--requirements <IDs>` (the
+documented merge-gate shape) both drag the L0 checks in and will fail on a missing tool. The Job
+must use `--layer l2` / `--layer l3`, which is verified below to resolve the offline selection
+to nothing.
+
+**This is a decision for the plan owner, not a detail:** either the Job selects cluster-gated
+layers only, or the runner grows the full L0 toolchain, or `run.sh` learns to skip offline
+checks when their tools are absent (which would be a fail-open and is the wrong answer). It is
+documented in the Containerfile header and the incluster README so it cannot be rediscovered
+from a pod log.
+
+### Follow-ups this creates
+
+1. **Operator:** `podman login` + `podman push --digestfile`, then a PR setting
+   `CONFORMANCE_RUNNER_IMAGE_DIGEST` from the digestfile — the digest the *registry* returned,
+   not the local manifest digest the build printed.
+2. **Then tighten the boundary**, as that policy's own header asks: replace its `@sha256:*`
+   wildcard with the literal digest, closing the residual "anyone who can push to this path"
+   gap. Separate, human-reviewed PR — it edits the security boundary.
+3. **T-6.1b:** decide the Job's `args` per the constraint above, and stop `chainsaw-job.yaml`
+   carrying an image reference that admission would deny.
+4. **The 4th policy rule** pinning every initContainer's `command` to `conformance-clone`.
+   Without it, `conformance-clone` is available but not required, and the injection hole is
+   still open.
+
+### Rework note — why this entry is a file and not an append
+
+This branch originally carried its handoff as a ~236-line append to the tail of
+`DECISIONS-LOG.md`. That append was the **only** conflicting path between this PR and `main`,
+and it made PR #18 `mergeable: false`. The append has been dropped from the branch entirely and
+its substance moved here verbatim in meaning; the branch now touches no file outside
+`conformance/`. Nothing about what the code claims to have proven was changed by that move.
+
+## What I verified
+
+### The image, by running it — not by a green build
+
+As uid 65532 with `--read-only`: bash 5.3.9, Python 3.14.7, git 2.55.0, kubectl v1.36.4
+(client), chainsaw 0.2.12; `/` confirmed read-only, `/workspace` writable, uid confirmed
+non-zero. Then the real entrypoint in the same shape against the worktree: `./run.sh --lint`,
+`--coverage-only`, and `--layer l2 --no-cluster` all **rc 0**, emitting `coverage.md`,
+`coverage.json` and `report.junit.xml`. 408 MiB. Rebuilt after the chainsaw-comment edit; the
+in-image verification still passed.
+
+### The init-container clone path, end to end
+
+From inside the image, as uid 65532, `python3` completes a verifying TLS handshake to
+`gitea.home.keithjackson.dev` against the stock `ca-certificates` (issuer `Let's Encrypt / YR2`,
+notAfter `Dec 12 02:16:57 2026 GMT`), and `git ls-remote https://…/home-network-k3s-impl.git
+HEAD` returns `20ea70d` with **no credential**. So no internal CA bundle is needed, and
+anonymous read is currently open — the plan's read-only deploy token buys authorisation
+hygiene, not reachability.
+
+`/usr/local/bin/conformance-clone` measured in the image as uid 65532 with `--read-only`:
+`root:root 755`, confirmed **not writable** by uid 65532. Seven negative cases, each asserted to
+exit non-zero (not merely to print something): arguments rejected; missing SHA; a branch name
+instead of a SHA; an unrendered `@@CONFORMANCE_GIT_SHA@@`; `HOME` off the workspace volume; a
+**redirected** `CONFORMANCE_REPO_URL=https://evil.invalid/x.git`; a `CONFORMANCE_SRC` off the
+workspace volume. And the positive case: a real anonymous clone of this repo at a real 40-hex
+SHA, with `rev-parse HEAD` proven equal to the requested SHA.
+
+Two bugs of my own that only running it could have found, both fixed: the workspace-path guard
+matched `/workspace/*` and so **rejected the image's own `HOME=/workspace`**; and the negative
+checks were written as pipelines, which under `pipefail` aborted the verify at the first
+expected failure and silently skipped the remaining six. A verify that stops early looks
+identical to a verify that passed.
+
+### There is no `approval-policy` CI stage, and `conformance/**` is not a protected path
+
+My brief told me to expect this PR's CI to fail on an `approval-policy` stage because
+`conformance/**` is a security-relevant path requiring human approval. **I repeated that before
+checking it. It is not true:**
+
+| Claim | Measured |
+|---|---|
+| an `approval-policy` CI stage exists | **No.** `grep -rn 'approval-policy\|approval_policy' .gitea/ ci/` → nothing. `.gitea/workflows/gate.yml` has jobs `gate` and `conformance`; `merge-gate.yaml` has `spec-immutability, lint, l0, render-golden, l1, conformance, merge-gate`. No approval job in either. |
+| `conformance/**` is a protected path | **No.** `GET /branch_protections` → `protected_file_patterns: ''`. No path-based rule of any kind, and no `CODEOWNERS` file in the repo. |
+| required status checks | `status_check_contexts: ['gate / gate (pull_request)']` — one context, and it is not an approval stage. |
+
+What actually blocks this PR is `required_approvals: 1` with `block_admin_merge_override: true`,
+and `gitea-admin` authors every agent PR and cannot self-approve. That is a **merge** block, not
+a CI failure — the distinction matters, because "expect a red X" and "expect a green run that an
+agent still cannot merge" send a reviewer to different places. Left in as a correction rather
+than quietly deleted.
+
+### What PR #18's CI actually did, read out of the job log
+
+Read from `/Home-Network/home-network-k3s-impl/actions/runs/128/jobs/0/logs`, not off the tick,
+because a skipped Gitea job reports `success`:
+
+    [skip] stage spec-immutability: SKIPPED (not run)
+    [ ok ] stage lint: pass
+    [ ok ] stage l0: pass
+    [ ok ] stage render-golden: pass
+    [ ok ] stage l1: pass
+    [ ok ] stage gitea-settings: pass
+    [skip] stage conformance: SKIPPED (not run)
+    [fail] MERGE GATE: UNDETERMINED — greenness was NOT ESTABLISHED.
+
+`gate / gate (pull_request)` = **success in 1m36s**, and that success means **rc 3, tolerated**
+by `./ci/gate.sh || [ "$?" -eq 3 ]` — not rc 0. `gitea-settings` ran and passed in CI with
+`REQUIRE_GITEA_SETTINGS=true`, so CI is *more* complete there than the local toolbox run, where
+that stage can only skip. That measurement predates this rework's force-push; CI has not been
+re-read since.
+
+### The gate, on the reworked branch, today
+
+    ENGINE=<worktree shim> DEV_KUBECONFIG=/dev/null ./infra/devcontainer/dev.sh run bash -c './ci/gate.sh'
+    → rc 3, MERGE GATE: UNDETERMINED. Nothing FAILED.
+
+    [ ok ] spec-immutability   [ ok ] decisions-log   [ ok ] lint
+    [ ok ] l0                  [ ok ] render-golden   [ ok ] l1
+    [skip] gitea-settings      (SETTINGS_API_TOKEN not set — unwired repo-wide)
+    [skip] conformance         (CLUSTER_AVAILABLE != true) — L2/L3 UNVERIFIED
+    Stages that did not run: gitea-settings
+
+`decisions-log` is the stage PR #24 added; it ran against this branch and passed — "archive
+frozen, 2 entries well-formed" — so this file's shape is machine-checked, not eyeballed.
+Diff base `origin/main @ c59fe9f923c4` (this branch was rebased onto main after #24 merged).
+Touched requirements resolved to
+`R-SEC-02 R-TEST-01 R-TEST-02 R-TEST-03 R-TEST-04`; all five remain **L2/L3-UNVERIFIED**. This
+is **not** a green run and is not offered as one.
+
+### The rework itself
+
+`git diff origin/main...HEAD --name-only` lists only the five `conformance/` paths plus this
+file — `DECISIONS-LOG.md` is gone from the branch. `git diff pr18-orig HEAD -- conformance/`
+is empty, so the code is byte-identical to the pre-rework tip, file modes included
+(`build-image.sh` and `conformance-clone` both `100755`).
+
+## What I did NOT verify
+
+- **The image has never run in the cluster.** Everything above is local podman. Admission has
+  not been exercised against it, because there is no digest to reference yet.
+- **The image is not pushed anywhere**, so `CONFORMANCE_RUNNER_IMAGE_DIGEST` is empty. Empty on
+  purpose: it fails visibly in whatever renders the Job, whereas a guessed digest would look
+  like an `ImagePullBackOff` cluster fault. Pushing needs a registry credential and is an
+  operator action — `build-image.sh` prints the exact commands.
+- **The image was not rebuilt during this rework.** Moving where the handoff lives must not
+  change what the branch claims to have proven, so no build was run; the image measurements
+  above are the ones taken when the code was written, against this same code.
+- **chainsaw's cosign signatures are not verified** by this image. Only kubectl's `sha256` is.
+  The cosign path is named as a TODO, not implemented.
+- **The 4th policy rule does not exist**, so `conformance-clone` is available but not required.
+  The initContainer injection hole is open until that separate PR lands.
+- **L2/L3 still do not run in CI** (`vars.CLUSTER_AVAILABLE` unset). This image is a
+  prerequisite for closing that hole, not the closure. R-SEC-02 and R-TEST-01..04 are untested
+  at L2/L3.
+- **`gitea-settings` skipped in my local gate run**, so branch protection and runner
+  registration are UNVERIFIED by this run. The CI-side claims quoted above were measured
+  earlier, against the pre-rework head.
+- **The post-force-push CI run has not been read.** The `gate / gate (pull_request)` result
+  quoted above is from run 128 on the old head.