Qualify canonical relay images for staged delivery (#6781)

## Why Phase 1 of progressive delivery needs an explicit eligibility boundary before deployment automation can safely consume relay artifacts. Today the canonical Docker workflow can publish independently of the same-SHA CI result, the relay does not expose its source/build identity, and the Helm chart only renders mutable tags. The existing `ghcr.io/block/buzz-staging-dev` workflow in #6709 remains a manual pre-merge preview lane. It is deliberately not a canonical promotion input. ## What changed - Compile the full source SHA and GitHub Actions build identity into canonical relay binaries and expose it at `/_status`. - Gate creation of tagged multi-architecture manifests on the latest exact-SHA `CI` push run succeeding on `main` or `release`. - Preserve the signed SLSA provenance and add a signed, release-only deployment-eligibility predicate with source, build run, qualifying CI run, and exact compatible Buzz chart version. - Keep failed or pending builds untagged and without an eligibility predicate; preview-package artifacts are excluded by package and signer contract. - Add optional `image.digest` support to Buzz chart `0.1.8`, retaining the existing tag fallback. - Document verification and the intentional boundary between image/chart compatibility and backwards-compatible database migrations. ## Risk and rollout Canonical tag publication now waits for same-SHA CI and fails closed when the newest matching run fails. Per-architecture blobs may remain untagged after a failed qualification; they are not promotion inputs. Debug manifests are also CI-gated but do not receive the release eligibility predicate. There are no migration or schema-orchestration changes. The companion BuilderBot infrastructure PR will pin a separately verified canonical main digest and expose a read-only running-deployment inspection command. Signed eligibility is available only for artifacts published after this workflow lands. ## Verification - Blox: workflow contract fixtures, including stale-green rejection and predicate structure - Blox: `actionlint` for `ci.yml` and `docker.yml` - Blox: 46 Helm unit tests, chart lint, and production/quickstart render fixtures - Blox: relay status unit test, workspace Rust formatting, and workspace all-target clippy - Live evidence: exact-SHA CI selector chose successful run `32857345153` for source `9d1e4b257657f382d3111ce748f3da8d063b7671` - Existing canonical digest provenance verified with `gh attestation verify` ## References - #6709 — developer-preview precursor; intentionally separate from canonical eligibility - `docs/deployment-identity.md` *Generated with Codex* --------- Signed-off-by: Luke Tornquist <tornquist@squareup.com>
2026-10-27 04:30:52 +00:00 · 2026-08-25 14:44:49 -04:00
parent 7ba1197aa6
commit f249710331
17 changed files with 467 additions and 10 deletions
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -75,6 +75,8 @@ jobs:
              - '.github/workflows/ci.yml'
      - name: Release workflow source contract
        run: scripts/test-release-ref-contract.sh
+      - name: Relay image eligibility contract
+        run: scripts/test-relay-image-eligibility-workflow.sh
      - name: Desktop release candidate contract
        run: scripts/test-desktop-release-candidate.sh
      - name: OSS desktop promotion contract
--- a/.github/workflows/docker.yml
+++ b/.github/workflows/docker.yml
@@ -49,6 +49,10 @@ on:
      - "Dockerfile.push-gateway"
      - ".dockerignore"
      - ".github/workflows/docker.yml"
+      - "deploy/charts/buzz/Chart.yaml"
+      - "scripts/create-deployment-eligibility-predicate.jq"
+      - "scripts/select-qualified-ci-run.jq"
+      - "scripts/test-relay-image-eligibility-workflow.sh"
      - "Cargo.toml"
      - "Cargo.lock"
      - "rust-toolchain.toml"
@@ -172,6 +176,10 @@ jobs:
          target: runtime
          platforms: ${{ matrix.platform }}
          labels: ${{ steps.meta.outputs.labels }}
+          build-args: |
+            BUZZ_SOURCE_SHA=${{ github.sha }}
+            BUZZ_BUILD_ID=github-actions:${{ github.run_id }}:${{ github.run_attempt }}
+            BUZZ_BUILD_URL=https://github.com/${{ github.repository }}/actions/runs/${{ github.run_id }}/attempts/${{ github.run_attempt }}
          # Push by digest, not by tag — the merge job assembles the tags
          # into one multi-arch manifest. This is what makes the native-arm
          # matrix possible.
@@ -190,6 +198,10 @@ jobs:
          target: runtime-debug
          platforms: ${{ matrix.platform }}
          labels: ${{ steps.meta.outputs.labels }}
+          build-args: |
+            BUZZ_SOURCE_SHA=${{ github.sha }}
+            BUZZ_BUILD_ID=github-actions:${{ github.run_id }}:${{ github.run_attempt }}
+            BUZZ_BUILD_URL=https://github.com/${{ github.repository }}/actions/runs/${{ github.run_id }}/attempts/${{ github.run_attempt }}
          outputs: type=image,name=${{ env.IMAGE_NAME }},push-by-digest=true,name-canonical=true,push=${{ github.event_name != 'pull_request' }}
          cache-from: |
            type=registry,ref=${{ env.IMAGE_NAME }}-buildcache:${{ matrix.arch }}
@@ -222,11 +234,86 @@ jobs:
          if-no-files-found: error
          retention-days: 1

+  qualify:
+    name: Qualify relay image source
+    if: github.event_name != 'pull_request'
+    runs-on: ubuntu-24.04
+    timeout-minutes: 70
+    permissions:
+      actions: read
+      contents: read
+    outputs:
+      source_sha: ${{ steps.qualify.outputs.source_sha }}
+      ci_run_id: ${{ steps.qualify.outputs.ci_run_id }}
+      ci_run_attempt: ${{ steps.qualify.outputs.ci_run_attempt }}
+      ci_run_url: ${{ steps.qualify.outputs.ci_run_url }}
+      chart_version: ${{ steps.qualify.outputs.chart_version }}
+    steps:
+      - name: Checkout source
+        uses: actions/checkout@df4cb1c069e1874edd31b4311f1884172cec0e10  # v6.0.3
+        with:
+          persist-credentials: false
+
+      - name: Require successful same-SHA CI run
+        id: qualify
+        env:
+          GH_TOKEN: ${{ github.token }}
+          SOURCE_SHA: ${{ github.sha }}
+        run: |
+          set -euo pipefail
+
+          if [[ ! "$SOURCE_SHA" =~ ^[0-9a-f]{40}$ ]]; then
+            echo "::error::Invalid source SHA: $SOURCE_SHA"
+            exit 1
+          fi
+
+          deadline=$((SECONDS + 3900))
+          while (( SECONDS < deadline )); do
+            payload=$(gh api \
+              "/repos/${GITHUB_REPOSITORY}/actions/workflows/ci.yml/runs?head_sha=${SOURCE_SHA}&event=push&per_page=100")
+            successful_run=$(jq -c --arg source_sha "$SOURCE_SHA" \
+              -f "$GITHUB_WORKSPACE/scripts/select-qualified-ci-run.jq" <<<"$payload")
+
+            if [[ -n "$successful_run" ]]; then
+              ci_run_id=$(jq -r '.id' <<<"$successful_run")
+              ci_run_attempt=$(jq -r '.run_attempt' <<<"$successful_run")
+              ci_run_url=$(jq -r '.html_url' <<<"$successful_run")
+              chart_version=$(awk '/^version:/ { print $2; exit }' deploy/charts/buzz/Chart.yaml)
+              if [[ ! "$chart_version" =~ ^[0-9]+\.[0-9]+\.[0-9]+([+-][0-9A-Za-z.-]+)?$ ]]; then
+                echo "::error::Invalid Buzz chart version: $chart_version"
+                exit 1
+              fi
+              {
+                echo "source_sha=$SOURCE_SHA"
+                echo "ci_run_id=$ci_run_id"
+                echo "ci_run_attempt=$ci_run_attempt"
+                echo "ci_run_url=$ci_run_url"
+                echo "chart_version=$chart_version"
+              } >>"$GITHUB_OUTPUT"
+              echo "Qualified source $SOURCE_SHA with CI run $ci_run_id (attempt $ci_run_attempt)."
+              exit 0
+            fi
+
+            matching=$(jq --arg source_sha "$SOURCE_SHA" '[.workflow_runs[] | select(.head_sha == $source_sha) | select(.event == "push") | select(.head_branch == "main" or .head_branch == "release")] | length' <<<"$payload")
+            pending=$(jq --arg source_sha "$SOURCE_SHA" '[.workflow_runs[] | select(.head_sha == $source_sha) | select(.event == "push") | select(.head_branch == "main" or .head_branch == "release") | select(.status != "completed")] | length' <<<"$payload")
+            if (( matching > 0 && pending == 0 )); then
+              echo "::error::No successful CI run exists for source $SOURCE_SHA"
+              jq -r --arg source_sha "$SOURCE_SHA" '.workflow_runs[] | select(.head_sha == $source_sha) | "run=\(.id) attempt=\(.run_attempt) status=\(.status) conclusion=\(.conclusion)"' <<<"$payload"
+              exit 1
+            fi
+
+            echo "Waiting for same-SHA CI qualification ($matching matching, $pending pending)..."
+            sleep 30
+          done
+
+          echo "::error::Timed out waiting for successful CI qualification of $SOURCE_SHA"
+          exit 1
+
  merge:
    name: Merge ${{ matrix.variant }} multi-arch manifest
    if: github.event_name != 'pull_request'
    runs-on: ubuntu-24.04
-    needs: build
+    needs: [build, qualify]
    timeout-minutes: 15
    permissions:
      contents: read
@@ -286,6 +373,10 @@ jobs:
        env:
          IMAGE_NAME: ${{ env.IMAGE_NAME }}
          META_TAGS: ${{ steps.meta.outputs.tags }}
+          SOURCE_SHA: ${{ needs.qualify.outputs.source_sha }}
+          CI_RUN_ID: ${{ needs.qualify.outputs.ci_run_id }}
+          CI_RUN_ATTEMPT: ${{ needs.qualify.outputs.ci_run_attempt }}
+          CHART_VERSION: ${{ needs.qualify.outputs.chart_version }}
        run: |
          set -euo pipefail
          # Build -t flags from the metadata-action output.
@@ -300,7 +391,15 @@ jobs:
            digests+=("${IMAGE_NAME}@sha256:${digest}")
          done

-          docker buildx imagetools create "${tags[@]}" "${digests[@]}"
+          annotations=(
+            --annotation "index:org.opencontainers.image.revision=${SOURCE_SHA}"
+            --annotation "index:xyz.block.buzz.build.id=github-actions:${GITHUB_RUN_ID}:${GITHUB_RUN_ATTEMPT}"
+            --annotation "index:xyz.block.buzz.qualification.ci-run-id=${CI_RUN_ID}"
+            --annotation "index:xyz.block.buzz.qualification.ci-run-attempt=${CI_RUN_ATTEMPT}"
+            --annotation "index:xyz.block.buzz.qualification.ci-conclusion=success"
+            --annotation "index:xyz.block.buzz.helm-chart.version=${CHART_VERSION}"
+          )
+          docker buildx imagetools create "${tags[@]}" "${annotations[@]}" "${digests[@]}"

          # Capture the merged manifest digest for the attestation step.
          first_tag=$(echo "$META_TAGS" | head -n1)
@@ -317,17 +416,58 @@ jobs:
          subject-digest: ${{ steps.manifest.outputs.digest }}
          push-to-registry: true

+      - name: Create deployment eligibility predicate
+        if: matrix.variant == 'release'
+        env:
+          SOURCE_SHA: ${{ needs.qualify.outputs.source_sha }}
+          CI_RUN_ID: ${{ needs.qualify.outputs.ci_run_id }}
+          CI_RUN_ATTEMPT: ${{ needs.qualify.outputs.ci_run_attempt }}
+          CI_RUN_URL: ${{ needs.qualify.outputs.ci_run_url }}
+          CHART_VERSION: ${{ needs.qualify.outputs.chart_version }}
+        run: |
+          jq -n \
+            --arg source_repository "$GITHUB_REPOSITORY" \
+            --arg source_ref "$GITHUB_REF" \
+            --arg source_sha "$SOURCE_SHA" \
+            --arg build_workflow ".github/workflows/docker.yml" \
+            --argjson build_run_id "$GITHUB_RUN_ID" \
+            --argjson build_run_attempt "$GITHUB_RUN_ATTEMPT" \
+            --arg build_run_url "https://github.com/${GITHUB_REPOSITORY}/actions/runs/${GITHUB_RUN_ID}/attempts/${GITHUB_RUN_ATTEMPT}" \
+            --arg qualification_workflow ".github/workflows/ci.yml" \
+            --argjson qualification_run_id "$CI_RUN_ID" \
+            --argjson qualification_run_attempt "$CI_RUN_ATTEMPT" \
+            --arg qualification_run_url "$CI_RUN_URL" \
+            --arg chart_version "$CHART_VERSION" \
+            -f "$GITHUB_WORKSPACE/scripts/create-deployment-eligibility-predicate.jq" \
+            >/tmp/deployment-eligibility.json
+
+      - name: Attest deployment eligibility
+        if: matrix.variant == 'release'
+        uses: actions/attest@1e69f48acb82d1966a394da916b4c1698aa569d6  # v4.2.2
+        with:
+          subject-name: ${{ env.IMAGE_NAME }}
+          subject-digest: ${{ steps.manifest.outputs.digest }}
+          predicate-type: https://buzz.block.xyz/attestations/deployment-eligibility/v1
+          predicate-path: /tmp/deployment-eligibility.json
+          push-to-registry: true
+
      - name: Summary
        env:
          IMAGE_NAME: ${{ env.IMAGE_NAME }}
          VARIANT: ${{ matrix.variant }}
          MERGED_DIGEST: ${{ steps.manifest.outputs.digest }}
          META_TAGS: ${{ steps.meta.outputs.tags }}
+          SOURCE_SHA: ${{ needs.qualify.outputs.source_sha }}
+          CI_RUN_URL: ${{ needs.qualify.outputs.ci_run_url }}
+          CHART_VERSION: ${{ needs.qualify.outputs.chart_version }}
        run: |
          {
            echo "### Published \`${IMAGE_NAME}\` (${VARIANT})"
            echo
            echo "**Digest:** \`${MERGED_DIGEST}\`"
+            echo "**Source:** \`${SOURCE_SHA}\`"
+            echo "**Compatible Buzz chart:** \`${CHART_VERSION}\`"
+            echo "**Qualifying CI:** ${CI_RUN_URL} (success)"
            echo
            echo "**Tags:**"
            echo '```'
@@ -338,6 +478,13 @@ jobs:
            echo '```'
            echo "gh attestation verify oci://${IMAGE_NAME}@${MERGED_DIGEST} --owner block"
            echo '```'
+            if [[ "$VARIANT" == "release" ]]; then
+              echo
+              echo "Verify deployment eligibility:"
+              echo '```'
+              echo "gh attestation verify oci://${IMAGE_NAME}@${MERGED_DIGEST} --repo block/buzz --signer-workflow block/buzz/.github/workflows/docker.yml --predicate-type https://buzz.block.xyz/attestations/deployment-eligibility/v1 --source-digest ${SOURCE_SHA}"
+              echo '```'
+            fi
          } >> "$GITHUB_STEP_SUMMARY"

  push-gateway-build:
--- a/8
+++ b/8
@@ -67,6 +67,14 @@ COPY --from=planner /build/recipe.json recipe.json
 # scoping to -p buzz-relay misses transitive deps and re-builds them later.
 RUN cargo chef cook --release --recipe-path recipe.json
 COPY . .
+# Compile immutable artifact identity into the relay. Defaults preserve local
+# and third-party builds that do not run in provenance-aware CI.
+ARG BUZZ_SOURCE_SHA=unknown
+ARG BUZZ_BUILD_ID=local
+ARG BUZZ_BUILD_URL=unknown
+ENV BUZZ_SOURCE_SHA=${BUZZ_SOURCE_SHA} \
+    BUZZ_BUILD_ID=${BUZZ_BUILD_ID} \
+    BUZZ_BUILD_URL=${BUZZ_BUILD_URL}
 RUN cargo build --release --locked -p buzz-relay --bin buzz-relay \
                                   -p buzz-admin --bin buzz-admin \
                                   -p buzz-pair-relay --bin buzz-pair-relay
--- a/crates/buzz-relay/src/build_info.rs
+++ b/crates/buzz-relay/src/build_info.rs
@@ -0,0 +1,16 @@
+//! Build-time identity compiled into the relay binary.
+
+/// Full source commit SHA, or `unknown` outside a provenance-aware build.
+pub(crate) fn source_sha() -> &'static str {
+    option_env!("BUZZ_SOURCE_SHA").unwrap_or("unknown")
+}
+
+/// Stable build identifier, or `local` outside CI.
+pub(crate) fn build_id() -> &'static str {
+    option_env!("BUZZ_BUILD_ID").unwrap_or("local")
+}
+
+/// Build details URL, or `unknown` outside CI.
+pub(crate) fn build_url() -> &'static str {
+    option_env!("BUZZ_BUILD_URL").unwrap_or("unknown")
+}
--- a/crates/buzz-relay/src/lib.rs
+++ b/crates/buzz-relay/src/lib.rs
@@ -3,6 +3,7 @@
 //! NIP-01 WebSocket relay for Buzz private team communication.

 mod admission;
+mod build_info;

 /// REST API route handlers.
 pub mod api;
--- a/crates/buzz-relay/src/router.rs
+++ b/crates/buzz-relay/src/router.rs
@@ -413,14 +413,22 @@ async fn readiness_handler(State(state): State<Arc<AppState>>) -> impl IntoRespo
    }
 }

-/// Status endpoint — service name, version, uptime.
-async fn status_handler(State(state): State<Arc<AppState>>) -> impl IntoResponse {
-    let uptime_secs = state.started_at.elapsed().as_secs();
-    Json(json!({
+fn status_payload(uptime_secs: u64) -> serde_json::Value {
+    json!({
        "service": "buzz-relay",
        "version": env!("CARGO_PKG_VERSION"),
        "uptime_seconds": uptime_secs,
-    }))
+        "build": {
+            "source_sha": crate::build_info::source_sha(),
+            "id": crate::build_info::build_id(),
+            "url": crate::build_info::build_url(),
+        },
+    })
+}
+
+/// Status endpoint — service name, version, uptime, and intrinsic build identity.
+async fn status_handler(State(state): State<Arc<AppState>>) -> impl IntoResponse {
+    Json(status_payload(state.started_at.elapsed().as_secs()))
 }

 /// `/_mesh` — live mesh status: peer table, connection/phi state, per-peer
@@ -506,6 +514,23 @@ mod tests {
        assert!(!should_serve_spa("/arbitrary", true));
    }

+    #[test]
+    fn status_payload_exposes_source_and_build_identity() {
+        let payload = status_payload(42);
+
+        assert_eq!(payload["service"], "buzz-relay");
+        assert_eq!(payload["version"], env!("CARGO_PKG_VERSION"));
+        assert_eq!(payload["uptime_seconds"], 42);
+        for field in ["source_sha", "id", "url"] {
+            assert!(
+                payload["build"][field]
+                    .as_str()
+                    .is_some_and(|value| !value.is_empty()),
+                "build.{field} must be a non-empty string"
+            );
+        }
+    }
+
    #[tokio::test(flavor = "current_thread")]
    async fn http_and_datastore_spans_are_exported_in_the_same_trace() {
        let exporter = InMemorySpanExporter::default();
--- a/deploy/charts/buzz/Chart.yaml
+++ b/deploy/charts/buzz/Chart.yaml
@@ -7,7 +7,7 @@ description: |
  PostgreSQL and Redis. Configurable for single-node evaluation
  (subcharts on) and HA production (external services, existingSecret).
 type: application
-version: 0.1.7
+version: 0.1.8
 appVersion: "0.1.0"
 home: https://github.com/block/buzz
 sources:
@@ -24,7 +24,7 @@ maintainers:
 annotations:
  artifacthub.io/changes: |
    - kind: added
-      description: Generic init-container, volume, volume-mount, command, and args extension points for the relay Pod.
+      description: Optional immutable relay image digest pinning with backwards-compatible tag fallback.
  artifacthub.io/license: Apache-2.0

 # Optional eval-only subcharts. Production deploys disable both and point
--- a/deploy/charts/buzz/README.md
+++ b/deploy/charts/buzz/README.md
@@ -12,7 +12,7 @@ This chart has two operating profiles selected by values:
 ## Quickstart (eval only)

 ```sh
-helm install buzz oci://ghcr.io/block/buzz/charts/buzz --version 0.1.7 \
+helm install buzz oci://ghcr.io/block/buzz/charts/buzz --version 0.1.8 \
  --create-namespace --namespace buzz \
  --set quickstart=true \
  --set postgresql.enabled=true \
@@ -29,6 +29,15 @@ intent marker surfaced in NOTES.txt; the bundled services are opted in via the
 four `*.enabled` flags above (see `ci/quickstart-values.yaml` for the exact set
 CI installs). Eval-only: every bundled service is a single replica with no HA.

+For immutable delivery, pin the OCI digest instead of a tag. `image.digest`
+overrides `image.tag` when both are present:
+
+```yaml
+image:
+  repository: ghcr.io/block/buzz
+  digest: sha256:<64-lowercase-hex-characters>
+```
+
 ## Production (GitOps)

 The chart is designed for ArgoCD and Flux. Both render charts with `helm template`, in which mode Helm's `lookup` function returns empty — any chart-side `randAlphaNum` call would regenerate secrets on every sync. The chart-managed Secret path is **only** safe for `helm install` / `helm upgrade`.
--- a/deploy/charts/buzz/templates/_helpers.tpl
+++ b/deploy/charts/buzz/templates/_helpers.tpl
@@ -53,9 +53,13 @@ app.kubernetes.io/component: relay
 {{- end -}}

 {{- define "buzz.image" -}}
+{{- if .Values.image.digest -}}
+{{- printf "%s@%s" .Values.image.repository .Values.image.digest -}}
+{{- else -}}
 {{- $tag := default .Chart.AppVersion .Values.image.tag -}}
 {{- printf "%s:%s" .Values.image.repository $tag -}}
 {{- end -}}
+{{- end -}}

 {{/*
 Name of the chart-managed Secret holding relay-identity material and any
--- a/deploy/charts/buzz/tests/render_test.yaml
+++ b/deploy/charts/buzz/tests/render_test.yaml
@@ -195,6 +195,24 @@ tests:
          path: spec.template.spec.containers[0].args
        template: templates/deployment.yaml

+  - it: renders an immutable digest instead of a configured tag
+    set:
+      relayUrl: wss://buzz.example.com
+      ownerPubkey: "0000000000000000000000000000000000000000000000000000000000000000"
+      externalPostgresql.url: postgres://u:p@h:5432/d
+      externalRedis.url: redis://h:6379
+      s3.endpoint: http://minio:9000
+      s3.accessKey: a
+      s3.secretKey: s
+      image.repository: ghcr.io/block/buzz
+      image.tag: sha-deadbee
+      image.digest: sha256:aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
+    asserts:
+      - equal:
+          path: spec.template.spec.containers[0].image
+          value: ghcr.io/block/buzz@sha256:aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
+        template: templates/deployment.yaml
+
  - it: appends generic Pod extensions and overrides the relay command
    set:
      relayUrl: wss://buzz.example.com
--- a/deploy/charts/buzz/tests/validation_test.yaml
+++ b/deploy/charts/buzz/tests/validation_test.yaml
@@ -2,6 +2,16 @@ suite: validation
 templates:
  - templates/deployment.yaml
 tests:
+  - it: rejects a malformed image digest
+    set:
+      relayUrl: wss://buzz.example.com
+      ownerPubkey: "0000000000000000000000000000000000000000000000000000000000000000"
+      externalPostgresql.url: postgres://u:p@h:5432/d
+      image.digest: sha256:not-a-digest
+    asserts:
+      - failedTemplate:
+          errorPattern: "image.digest: Does not match pattern"
+
  - it: fails when relayUrl is missing
    set:
      relayUrl: ""
--- a/deploy/charts/buzz/values.schema.json
+++ b/deploy/charts/buzz/values.schema.json
@@ -15,6 +15,11 @@
      "properties": {
        "repository": { "type": "string", "minLength": 1 },
        "tag": { "type": "string" },
+        "digest": {
+          "type": "string",
+          "pattern": "^$|^sha256:[0-9a-f]{64}$",
+          "description": "Optional immutable OCI image digest. When set, the chart renders repository@digest and ignores tag."
+        },
        "pullPolicy": { "type": "string", "enum": ["Always", "IfNotPresent", "Never"] },
        "pullSecrets": {
          "type": "array",
--- a/deploy/charts/buzz/values.yaml
+++ b/deploy/charts/buzz/values.yaml
@@ -25,6 +25,7 @@ quickstart: false
 image:
  repository: ghcr.io/block/buzz
  tag: ""                        # empty → .Chart.AppVersion
+  digest: ""                     # optional sha256:...; when set, overrides tag
  pullPolicy: IfNotPresent
  pullSecrets: []

--- a/docs/deployment-identity.md
+++ b/docs/deployment-identity.md
@@ -0,0 +1,68 @@
+# Relay deployment identity
+
+Canonical relay images from `ghcr.io/block/buzz` carry two signed
+attestations:
+
+- SLSA build provenance maps the immutable image digest to the source commit
+  and Docker workflow run.
+- The Buzz deployment-eligibility predicate records the successful same-SHA
+  CI run and the exact Buzz Helm chart version from that source commit.
+
+The Docker workflow creates tagged multi-architecture manifests only after the
+same full source SHA has a successful `CI` push run on `main` or `release`.
+Architecture-specific build manifests may exist without tags while CI is
+running or after it fails; they do not receive the deployment-eligibility
+predicate and are not promotion inputs.
+
+Verify a canonical eligible digest with:
+
+```bash
+gh attestation verify \
+  oci://ghcr.io/block/buzz@sha256:<digest> \
+  --repo block/buzz \
+  --signer-workflow block/buzz/.github/workflows/docker.yml \
+  --predicate-type https://buzz.block.xyz/attestations/deployment-eligibility/v1 \
+  --source-ref refs/heads/main
+```
+
+The predicate's `helm_chart.compatible_version` is image-to-chart metadata. It
+does not describe database schema compatibility and does not relax Buzz's rule
+that migrations remain backwards compatible.
+
+The manual pre-merge workflow publishes only to
+`ghcr.io/block/buzz-staging-dev`. Those preview images are intentionally
+ineligible: they use a different package, may name non-main source, and do not
+receive the canonical deployment-eligibility predicate.
+
+## Runtime inspection
+
+The relay health listener exposes intrinsic build identity at `/_status`:
+
+```json
+{
+  "service": "buzz-relay",
+  "version": "0.2.1",
+  "uptime_seconds": 123,
+  "build": {
+    "source_sha": "<40-character-source-sha>",
+    "id": "github-actions:<run-id>:<attempt>",
+    "url": "https://github.com/block/buzz/actions/runs/<run-id>/attempts/<attempt>"
+  }
+}
+```
+
+Non-CI builds report stable `unknown` or `local` fallback values instead of
+claiming provenance they do not have.
+
+## Helm digest pinning
+
+Buzz chart `0.1.8` and newer accept an immutable image digest:
+
+```yaml
+image:
+  repository: ghcr.io/block/buzz
+  digest: sha256:<64-lowercase-hex-characters>
+```
+
+When `image.digest` is set, the chart renders `repository@digest` and ignores
+`image.tag`. Existing tag-only values remain backwards compatible.
--- a/scripts/create-deployment-eligibility-predicate.jq
+++ b/scripts/create-deployment-eligibility-predicate.jq
@@ -0,0 +1,26 @@
+{
+  predicate_version: 1,
+  eligible: true,
+  source: {
+    repository: $source_repository,
+    ref: $source_ref,
+    sha: $source_sha
+  },
+  build: {
+    workflow: $build_workflow,
+    run_id: $build_run_id,
+    run_attempt: $build_run_attempt,
+    run_url: $build_run_url
+  },
+  qualification: {
+    workflow: $qualification_workflow,
+    run_id: $qualification_run_id,
+    run_attempt: $qualification_run_attempt,
+    run_url: $qualification_run_url,
+    conclusion: "success"
+  },
+  helm_chart: {
+    name: "buzz",
+    compatible_version: $chart_version
+  }
+}
--- a/scripts/select-qualified-ci-run.jq
+++ b/scripts/select-qualified-ci-run.jq
@@ -0,0 +1,9 @@
+[
+  .workflow_runs[]
+  | select(.head_sha == $source_sha)
+  | select(.event == "push")
+  | select(.head_branch == "main" or .head_branch == "release")
+]
+| sort_by([.id, .run_attempt])
+| last // empty
+| select(.conclusion == "success")
--- a/scripts/test-relay-image-eligibility-workflow.sh
+++ b/scripts/test-relay-image-eligibility-workflow.sh
@@ -0,0 +1,108 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+repo_root=$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)
+workflow="$repo_root/.github/workflows/docker.yml"
+selector="$repo_root/scripts/select-qualified-ci-run.jq"
+predicate_builder="$repo_root/scripts/create-deployment-eligibility-predicate.jq"
+
+require_literal() {
+  local needle=$1
+  grep -Fq -- "$needle" "$workflow" || {
+    echo "relay image workflow is missing required delivery contract: $needle" >&2
+    exit 1
+  }
+}
+
+require_literal "  qualify:"
+require_literal "actions: read"
+require_literal "actions/workflows/ci.yml/runs"
+require_literal 'select-qualified-ci-run.jq'
+require_literal "needs: [build, qualify]"
+require_literal "https://buzz.block.xyz/attestations/deployment-eligibility/v1"
+require_literal "actions/attest@1e69f48acb82d1966a394da916b4c1698aa569d6"
+require_literal "if: matrix.variant == 'release'"
+require_literal "BUZZ_SOURCE_SHA"
+require_literal "BUZZ_BUILD_ID"
+require_literal "BUZZ_BUILD_URL"
+require_literal '- "deploy/charts/buzz/Chart.yaml"'
+require_literal '- "scripts/create-deployment-eligibility-predicate.jq"'
+require_literal '- "scripts/select-qualified-ci-run.jq"'
+require_literal '- "scripts/test-relay-image-eligibility-workflow.sh"'
+
+if grep -Fq "buzz-staging-dev" "$workflow"; then
+  echo "canonical relay image workflow references the preview-only image package" >&2
+  exit 1
+fi
+
+select_run() {
+  jq -r --arg source_sha aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa -f "$selector" | jq -r '.id // empty'
+}
+
+selected=$(select_run <<'JSON'
+{"workflow_runs":[
+  {"id":100,"run_attempt":1,"head_sha":"aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa","head_branch":"main","event":"push","status":"completed","conclusion":"failure"},
+  {"id":101,"run_attempt":1,"head_sha":"aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa","head_branch":"main","event":"push","status":"completed","conclusion":"success"}
+]}
+JSON
+)
+[[ "$selected" == "101" ]] || {
+  echo "latest successful same-SHA main run was not selected" >&2
+  exit 1
+}
+
+selected=$(select_run <<'JSON'
+{"workflow_runs":[
+  {"id":100,"run_attempt":1,"head_sha":"aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa","head_branch":"main","event":"push","status":"completed","conclusion":"success"},
+  {"id":101,"run_attempt":1,"head_sha":"aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa","head_branch":"main","event":"push","status":"completed","conclusion":"failure"}
+]}
+JSON
+)
+[[ -z "$selected" ]] || {
+  echo "stale successful run remained eligible after a newer failure" >&2
+  exit 1
+}
+
+selected=$(select_run <<'JSON'
+{"workflow_runs":[
+  {"id":102,"run_attempt":1,"head_sha":"bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb","head_branch":"main","event":"push","status":"completed","conclusion":"success"},
+  {"id":103,"run_attempt":1,"head_sha":"aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa","head_branch":"feature","event":"pull_request","status":"completed","conclusion":"success"}
+]}
+JSON
+)
+[[ -z "$selected" ]] || {
+  echo "wrong-SHA or pull-request CI run was accepted" >&2
+  exit 1
+}
+
+predicate=$(jq -n \
+  --arg source_repository "block/buzz" \
+  --arg source_ref "refs/heads/main" \
+  --arg source_sha "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa" \
+  --arg build_workflow ".github/workflows/docker.yml" \
+  --argjson build_run_id 200 \
+  --argjson build_run_attempt 2 \
+  --arg build_run_url "https://github.com/block/buzz/actions/runs/200/attempts/2" \
+  --arg qualification_workflow ".github/workflows/ci.yml" \
+  --argjson qualification_run_id 201 \
+  --argjson qualification_run_attempt 1 \
+  --arg qualification_run_url "https://github.com/block/buzz/actions/runs/201" \
+  --arg chart_version "0.1.8" \
+  -f "$predicate_builder")
+
+jq -e '
+  .predicate_version == 1 and
+  .eligible == true and
+  .source.sha == "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa" and
+  .build.run_id == 200 and
+  .qualification.run_id == 201 and
+  .qualification.conclusion == "success" and
+  .helm_chart == {"name":"buzz","compatible_version":"0.1.8"} and
+  (has("schema") | not) and
+  (.helm_chart | has("schema_compatibility") | not)
+' <<<"$predicate" >/dev/null || {
+  echo "deployment eligibility predicate has an invalid contract" >&2
+  exit 1
+}
+
+echo "relay image eligibility workflow contract passed"