ci: pass publish-server-image digests via GHCR handoff tags

Build jobs already push each architecture by digest. Tag those manifests
with ephemeral ci-${run_id}-${image}-${arch} refs instead of uploading
digest marker files to Actions artifact storage, which is blocked by the
account-wide quota.

Publish resolves handoff tags back into RUNNER_TEMP digest markers, then
assembles semver/edge tags and attestation as before. Handoff tags are
removed after publish with continue-on-error.

Co-authored-by: cynarAI <cynarAI@users.noreply.github.com>

.github/workflows/publish-server-image.yml

@@ -27,7 +27,7 @@ permissions:
 env:
   # docker/metadata-action otherwise truncates commit tags to seven collision-prone characters.
   DOCKER_METADATA_SHORT_SHA_LENGTH: 40
-  # build-push-action v6 uploads large *.dockerbuild records by default; publish only needs digest artifacts.
+  # build-push-action v6 uploads large *.dockerbuild records by default; publish reads digests from GHCR handoff tags.
   DOCKER_BUILD_RECORD_UPLOAD: false
 
 concurrency:
@@ -162,22 +162,15 @@ jobs:
           cache-to: type=gha,mode=max,scope=${{ matrix.name }}-${{ matrix.arch }}
           provenance: mode=max
           sbom: true
-      - name: Record the architecture digest
+      - name: Tag digest for publish job handoff
-        id: digest
         env:
           DIGEST: ${{ steps.build.outputs.digest }}
+          IMAGE: ghcr.io/${{ steps.ns.outputs.repo }}/${{ matrix.name }}
         run: |
           set -euo pipefail
-          digest_dir="${RUNNER_TEMP}/digest"
+          docker buildx imagetools create \
-          mkdir -p "$digest_dir"
+            -t "${IMAGE}:ci-${GITHUB_RUN_ID}-${{ matrix.name }}-${{ matrix.arch }}" \
-          touch "${digest_dir}/${DIGEST#sha256:}"
+            "${IMAGE}@${DIGEST}"
-          echo "dir=${digest_dir}" >> "$GITHUB_OUTPUT"
-      - uses: actions/upload-artifact@ea165f8d65b6e75b540449e92b4886f43607fa02 # v4
-        with:
-          name: digest-${{ matrix.name }}-${{ matrix.arch }}
-          path: ${{ steps.digest.outputs.dir }}/*
-          if-no-files-found: error
-          retention-days: 1
 
   publish:
     name: Publish ${{ matrix.name }} image
@@ -198,14 +191,6 @@ jobs:
           - name: updater
           - name: computer
     steps:
-      - name: Prepare an isolated digest directory
-        id: digest_dir
-        run: echo "path=${RUNNER_TEMP}/digests" >> "$GITHUB_OUTPUT"
-      - uses: actions/download-artifact@d3f86a106a0bac45b974a628896c90dbdf5c8093 # v4
-        with:
-          pattern: digest-${{ matrix.name }}-*
-          path: ${{ steps.digest_dir.outputs.path }}
-          merge-multiple: true
       - uses: docker/setup-buildx-action@8d2750c68a42422c14e847fe6c8ac0403b4cbd6f # v3.12.0
       - name: Log in to GHCR
         uses: docker/login-action@c94ce9fb468520275223c153574b00df6fe4bcc9 # v3.7.0
@@ -217,6 +202,21 @@ jobs:
         id: ns
         # GHCR rejects repository names with capitals; the GitHub repository slug has them.
         run: echo "repo=${GITHUB_REPOSITORY,,}" >> "$GITHUB_OUTPUT"
+      - name: Collect architecture digests from registry handoff tags
+        id: digest_dir
+        env:
+          IMAGE: ghcr.io/${{ steps.ns.outputs.repo }}/${{ matrix.name }}
+          IMAGE_NAME: ${{ matrix.name }}
+        run: |
+          set -euo pipefail
+          digest_dir="${RUNNER_TEMP}/digests"
+          mkdir -p "$digest_dir"
+          for arch in amd64; do
+            handoff="${IMAGE}:ci-${GITHUB_RUN_ID}-${IMAGE_NAME}-${arch}"
+            digest="$(docker buildx imagetools inspect "$handoff" --format '{{.Manifest.Digest}}')"
+            touch "${digest_dir}/${digest#sha256:}"
+          done
+          echo "path=${digest_dir}" >> "$GITHUB_OUTPUT"
       - id: meta
         uses: docker/metadata-action@c299e40c65443455700f0fdfc63efafe5b349051 # v5.10.0
         with:
@@ -280,3 +280,13 @@ jobs:
           subject-name: ghcr.io/${{ steps.ns.outputs.repo }}/${{ matrix.name }}
           subject-digest: ${{ steps.manifest.outputs.digest }}
           push-to-registry: true
+      - name: Remove CI handoff tags
+        continue-on-error: true
+        env:
+          IMAGE: ghcr.io/${{ steps.ns.outputs.repo }}/${{ matrix.name }}
+          IMAGE_NAME: ${{ matrix.name }}
+        run: |
+          set -euo pipefail
+          for arch in amd64; do
+            docker buildx imagetools rm "${IMAGE}:ci-${GITHUB_RUN_ID}-${IMAGE_NAME}-${arch}"
+          done

infra/updater/src/publish-workflow.test.ts

@@ -55,6 +55,13 @@ describe("server image publish workflow", () => {
     expect(workflowText).toContain("RUNNER_TEMP");
   });
 
+  it("passes build digests to publish through GHCR handoff tags, not Actions artifact storage", () => {
+    expect(workflowText).not.toContain("actions/upload-artifact@");
+    expect(workflowText).not.toContain("actions/download-artifact@");
+    expect(workflowText).toContain("Tag digest for publish job handoff");
+    expect(workflowText).toContain("ci-${GITHUB_RUN_ID}-");
+  });
+
   it("names every image under the lowercase repository namespace", () => {
     expect(workflowText).not.toContain(`ghcr.io/\${{ github.repository }}`);
     const references =