feat: split-base build pipeline (parallel, manual-trigger only)

Two-Dockerfile split-base build alongside the existing single-Dockerfile
pipeline. Goal: cut CI wall clock from ~165-180min to ~30-40min on
typical version-bump-only releases by reusing a base image across the
four variants.

Files added:
- Dockerfile.base       variant-independent layers (apt, locales, AWS
                        CLI, Node.js, mempalace, gitea-mcp, user setup,
                        chromadb prewarm, ENVs, entrypoints).
- Dockerfile.variant    FROMs ${BASE_IMAGE} and adds opencode / pi /
                        omos / Go installs gated by INSTALL_* args.
                        Each npm install -g uses NPM_CONFIG_PREFIX=/usr
                        per-RUN to keep baked binaries off the volume-
                        shadowed ~/.pi/npm-global path inherited from
                        base.
- .gitea/workflows/docker-publish-split.yml
                        workflow_dispatch-only pipeline:
                        base-decide -> build-base (conditional) ->
                        smoke-* (4 parallel) -> build-variant-*
                        (4 parallel) -> promote-base-latest ->
                        update-description. Hash-driven base reuse:
                        if base-<sha> already exists on Docker Hub,
                        the build is skipped entirely. Inputs:
                        release_tag (test tag suffix, default
                        v0.0.0-split-test) and promote_latest
                        (default false; gates latest-* aliases and
                        Hub description update).

Files unchanged:
- Dockerfile, docker-publish.yml, validate.yml all left in place so
  the production tag-push pipeline keeps working untouched.

Migration plan (in CHANGELOG Unreleased):
1. workflow_dispatch test run with promote_latest=false; verify the
   four variant images smoke-pass and have plausible sizes.
2. Compare manifest digests against the same-version output from the
   production pipeline (independent test run on the same commit).
3. Once verified across 1-2 release cycles, swap docker-publish-split.yml
   to on: push: tags: v* and retire docker-publish.yml.

AGENTS.md and CHANGELOG.md updated with file roles and the migration
plan. Production pipeline behavior is bit-for-bit unchanged on this
branch.

.gitea/workflows/docker-publish-split.yml

@@ -0,0 +1,576 @@
+name: Publish Docker Image (split-base)
+
+# Two-phase split-base build pipeline. Lives ALONGSIDE the original
+# docker-publish.yml during the migration window. Triggers only on
+# workflow_dispatch (manual) so it doesn't conflict with the production
+# tag-trigger pipeline.
+#
+# Once we've validated 1-2 successful runs and verified output
+# byte-for-byte against the original, this workflow takes over `on:
+# push: tags: v*` and the original is retired.
+#
+# Pipeline shape:
+#   1. base-decide      compute base hash from Dockerfile.base + rootfs/
+#                       + entrypoints; probe Docker Hub for existing tag.
+#   2. build-base       only if probe missed; multi-arch push of base-<hash>.
+#   3. smoke-* (×4)     amd64-only build of each variant FROMing the base
+#                       tag; runs scripts/smoke-test.sh.
+#   4. build-variant-*  multi-arch push of each variant tag (the user-
+#       (×4)            facing release tags, unchanged in shape).
+#   5. promote-base-latest  re-tag base-<hash> → base-latest with `crane copy`
+#                       (manifest copy, no rebuild).
+#   6. update-description   patch Docker Hub description (unchanged).
+
+on:
+  workflow_dispatch:
+    inputs:
+      release_tag:
+        description: 'Release tag to publish (e.g. v1.14.42-split). Pushed to Docker Hub as both the literal tag and `latest*`-aliases.'
+        required: true
+        default: 'v0.0.0-split-test'
+      promote_latest:
+        description: 'Update latest/latest-omos/latest-with-pi/latest-omos-with-pi aliases (set false for test runs)'
+        required: false
+        default: 'false'
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: false
+
+env:
+  BUILDKIT_PROGRESS: plain
+  IMAGE: ${{ vars.DOCKERHUB_USERNAME }}/opencode-devbox
+
+# ───────────────────────────────────────────────────────────────────
+# Reusable disk-reclaim snippet — strips catthehacker toolchains and
+# stale docker state. Identical to the production workflow's pattern.
+# ───────────────────────────────────────────────────────────────────
+
+jobs:
+  # ── Phase 1: decide whether base needs rebuilding ──────────────────
+  base-decide:
+    runs-on: ubuntu-latest
+    container:
+      image: catthehacker/ubuntu:act-latest
+    outputs:
+      base_tag: ${{ steps.compute.outputs.base_tag }}
+      need_build: ${{ steps.probe.outputs.need_build }}
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Compute base tag from Dockerfile.base + dependencies
+        id: compute
+        run: |
+          # Hash inputs that determine the base image's contents.
+          # Order is fixed via `find -print0 | sort -z` for reproducibility.
+          HASH=$(
+            {
+              cat Dockerfile.base
+              find rootfs -type f -print0 2>/dev/null | sort -z | xargs -0 cat 2>/dev/null
+              cat entrypoint.sh entrypoint-user.sh
+            } | sha256sum | cut -c1-12
+          )
+          BASE_TAG="base-${HASH}"
+          echo "base_tag=${BASE_TAG}" >> "$GITHUB_OUTPUT"
+          echo "Computed base tag: ${BASE_TAG}"
+
+      - name: Force IPv4 for Docker Hub
+        run: echo 'precedence ::ffff:0:0/96  100' >> /etc/gai.conf
+
+      - name: Probe Docker Hub for existing base tag
+        id: probe
+        run: |
+          set +e
+          docker manifest inspect "${IMAGE}:${{ steps.compute.outputs.base_tag }}" \
+            > /dev/null 2>&1
+          PROBE_RC=$?
+          set -e
+          if [ "${PROBE_RC}" = "0" ]; then
+            echo "need_build=false" >> "$GITHUB_OUTPUT"
+            echo "Base tag ${IMAGE}:${{ steps.compute.outputs.base_tag }} exists — skipping rebuild."
+          else
+            echo "need_build=true" >> "$GITHUB_OUTPUT"
+            echo "Base tag ${IMAGE}:${{ steps.compute.outputs.base_tag }} missing — will build."
+          fi
+
+  # ── Phase 2: build & push base (multi-arch), only when needed ──────
+  build-base:
+    needs: [base-decide]
+    if: needs.base-decide.outputs.need_build == 'true'
+    runs-on: ubuntu-latest
+    container:
+      image: catthehacker/ubuntu:act-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Force IPv4 for Docker Hub
+        run: echo 'precedence ::ffff:0:0/96  100' >> /etc/gai.conf
+
+      - name: Reclaim runner disk
+        run: |
+          set -x
+          df -h / || true
+          rm -rf \
+            /opt/hostedtoolcache /opt/microsoft /opt/az /opt/ghc \
+            /usr/local/.ghcup /usr/share/dotnet /usr/share/swift \
+            /usr/local/lib/android /usr/local/share/powershell \
+            /usr/local/share/chromium /usr/local/share/boost \
+            /usr/lib/jvm 2>/dev/null || true
+          apt-get clean || true
+          rm -rf /var/lib/apt/lists/* /tmp/* /var/tmp/* || true
+          docker system prune -af --volumes || true
+          docker builder prune -af || true
+          df -h / || true
+
+      - name: Set up QEMU
+        uses: docker/setup-qemu-action@v3
+        with:
+          platforms: arm64
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v4
+        with:
+          driver-opts: network=host
+
+      - name: Login to Docker Hub
+        uses: docker/login-action@v3
+        with:
+          username: ${{ vars.DOCKERHUB_USERNAME }}
+          password: ${{ secrets.DOCKERHUB_TOKEN }}
+
+      - name: Build and push base (multi-arch)
+        uses: docker/build-push-action@v7
+        with:
+          context: .
+          file: Dockerfile.base
+          platforms: linux/amd64,linux/arm64
+          push: true
+          tags: ${{ env.IMAGE }}:${{ needs.base-decide.outputs.base_tag }}
+          # Registry cache for faster repeat base rebuilds (e.g. Node bump).
+          cache-from: type=registry,ref=${{ env.IMAGE }}:base-buildcache
+          cache-to: type=registry,ref=${{ env.IMAGE }}:base-buildcache,mode=max
+
+  # ── Phase 3: amd64 smoke per variant (gates the multi-arch publish) ─
+  # Each smoke job builds amd64-only against the base tag and runs
+  # scripts/smoke-test.sh. base-decide.outputs.base_tag is always set;
+  # build-base may have been skipped (cache hit) but the tag exists either way.
+
+  smoke-base:
+    needs: [base-decide, build-base]
+    if: |
+      always() &&
+      needs.base-decide.result == 'success' &&
+      (needs.build-base.result == 'success' || needs.build-base.result == 'skipped')
+    runs-on: ubuntu-latest
+    container:
+      image: catthehacker/ubuntu:act-latest
+    steps:
+      - uses: actions/checkout@v4
+      - name: Force IPv4 for Docker Hub
+        run: echo 'precedence ::ffff:0:0/96  100' >> /etc/gai.conf
+      - name: Reclaim runner disk
+        run: |
+          rm -rf /opt/hostedtoolcache /opt/microsoft /opt/az /opt/ghc \
+            /usr/local/.ghcup /usr/share/dotnet /usr/share/swift \
+            /usr/local/lib/android /usr/local/share/powershell \
+            /usr/local/share/chromium /usr/local/share/boost \
+            /usr/lib/jvm 2>/dev/null || true
+          docker system prune -af --volumes || true
+          docker builder prune -af || true
+      - uses: docker/setup-buildx-action@v4
+        with: {driver-opts: network=host}
+      - uses: docker/login-action@v3
+        with:
+          username: ${{ vars.DOCKERHUB_USERNAME }}
+          password: ${{ secrets.DOCKERHUB_TOKEN }}
+      - name: Build amd64 variant for smoke
+        uses: docker/build-push-action@v7
+        with:
+          context: .
+          file: Dockerfile.variant
+          platforms: linux/amd64
+          push: false
+          load: true
+          tags: opencode-devbox:smoke-base
+          build-args: |
+            BASE_IMAGE=${{ env.IMAGE }}:${{ needs.base-decide.outputs.base_tag }}
+            INSTALL_OPENCODE=true
+            INSTALL_OMOS=false
+            INSTALL_PI=false
+      - name: Smoke test (amd64)
+        run: bash scripts/smoke-test.sh opencode-devbox:smoke-base --variant base
+
+  smoke-omos:
+    needs: [base-decide, build-base]
+    if: |
+      always() &&
+      needs.base-decide.result == 'success' &&
+      (needs.build-base.result == 'success' || needs.build-base.result == 'skipped')
+    runs-on: ubuntu-latest
+    container:
+      image: catthehacker/ubuntu:act-latest
+    steps:
+      - uses: actions/checkout@v4
+      - run: echo 'precedence ::ffff:0:0/96  100' >> /etc/gai.conf
+      - run: |
+          rm -rf /opt/hostedtoolcache /opt/microsoft /opt/az /opt/ghc \
+            /usr/local/.ghcup /usr/share/dotnet /usr/share/swift \
+            /usr/local/lib/android /usr/local/share/powershell \
+            /usr/local/share/chromium /usr/local/share/boost \
+            /usr/lib/jvm 2>/dev/null || true
+          docker system prune -af --volumes || true
+          docker builder prune -af || true
+      - uses: docker/setup-buildx-action@v4
+        with: {driver-opts: network=host}
+      - uses: docker/login-action@v3
+        with:
+          username: ${{ vars.DOCKERHUB_USERNAME }}
+          password: ${{ secrets.DOCKERHUB_TOKEN }}
+      - uses: docker/build-push-action@v7
+        with:
+          context: .
+          file: Dockerfile.variant
+          platforms: linux/amd64
+          push: false
+          load: true
+          tags: opencode-devbox:smoke-omos
+          build-args: |
+            BASE_IMAGE=${{ env.IMAGE }}:${{ needs.base-decide.outputs.base_tag }}
+            INSTALL_OPENCODE=true
+            INSTALL_OMOS=true
+            INSTALL_PI=false
+      - run: bash scripts/smoke-test.sh opencode-devbox:smoke-omos --variant omos
+
+  smoke-with-pi:
+    needs: [base-decide, build-base]
+    if: |
+      always() &&
+      needs.base-decide.result == 'success' &&
+      (needs.build-base.result == 'success' || needs.build-base.result == 'skipped')
+    runs-on: ubuntu-latest
+    container:
+      image: catthehacker/ubuntu:act-latest
+    steps:
+      - uses: actions/checkout@v4
+      - run: echo 'precedence ::ffff:0:0/96  100' >> /etc/gai.conf
+      - run: |
+          rm -rf /opt/hostedtoolcache /opt/microsoft /opt/az /opt/ghc \
+            /usr/local/.ghcup /usr/share/dotnet /usr/share/swift \
+            /usr/local/lib/android /usr/local/share/powershell \
+            /usr/local/share/chromium /usr/local/share/boost \
+            /usr/lib/jvm 2>/dev/null || true
+          docker system prune -af --volumes || true
+          docker builder prune -af || true
+      - uses: docker/setup-buildx-action@v4
+        with: {driver-opts: network=host}
+      - uses: docker/login-action@v3
+        with:
+          username: ${{ vars.DOCKERHUB_USERNAME }}
+          password: ${{ secrets.DOCKERHUB_TOKEN }}
+      - uses: docker/build-push-action@v7
+        with:
+          context: .
+          file: Dockerfile.variant
+          platforms: linux/amd64
+          push: false
+          load: true
+          tags: opencode-devbox:smoke-with-pi
+          build-args: |
+            BASE_IMAGE=${{ env.IMAGE }}:${{ needs.base-decide.outputs.base_tag }}
+            INSTALL_OPENCODE=true
+            INSTALL_OMOS=false
+            INSTALL_PI=true
+      - run: bash scripts/smoke-test.sh opencode-devbox:smoke-with-pi --variant with-pi
+
+  smoke-omos-with-pi:
+    needs: [base-decide, build-base]
+    if: |
+      always() &&
+      needs.base-decide.result == 'success' &&
+      (needs.build-base.result == 'success' || needs.build-base.result == 'skipped')
+    runs-on: ubuntu-latest
+    container:
+      image: catthehacker/ubuntu:act-latest
+    steps:
+      - uses: actions/checkout@v4
+      - run: echo 'precedence ::ffff:0:0/96  100' >> /etc/gai.conf
+      - run: |
+          rm -rf /opt/hostedtoolcache /opt/microsoft /opt/az /opt/ghc \
+            /usr/local/.ghcup /usr/share/dotnet /usr/share/swift \
+            /usr/local/lib/android /usr/local/share/powershell \
+            /usr/local/share/chromium /usr/local/share/boost \
+            /usr/lib/jvm 2>/dev/null || true
+          docker system prune -af --volumes || true
+          docker builder prune -af || true
+      - uses: docker/setup-buildx-action@v4
+        with: {driver-opts: network=host}
+      - uses: docker/login-action@v3
+        with:
+          username: ${{ vars.DOCKERHUB_USERNAME }}
+          password: ${{ secrets.DOCKERHUB_TOKEN }}
+      - uses: docker/build-push-action@v7
+        with:
+          context: .
+          file: Dockerfile.variant
+          platforms: linux/amd64
+          push: false
+          load: true
+          tags: opencode-devbox:smoke-omos-with-pi
+          build-args: |
+            BASE_IMAGE=${{ env.IMAGE }}:${{ needs.base-decide.outputs.base_tag }}
+            INSTALL_OPENCODE=true
+            INSTALL_OMOS=true
+            INSTALL_PI=true
+      - run: bash scripts/smoke-test.sh opencode-devbox:smoke-omos-with-pi --variant omos-with-pi
+
+  # ── Phase 4: multi-arch publish per variant ────────────────────────
+
+  build-variant-base:
+    needs: [base-decide, smoke-base]
+    runs-on: ubuntu-latest
+    container:
+      image: catthehacker/ubuntu:act-latest
+    steps:
+      - uses: actions/checkout@v4
+      - run: echo 'precedence ::ffff:0:0/96  100' >> /etc/gai.conf
+      - run: |
+          rm -rf /opt/hostedtoolcache /opt/microsoft /opt/az /opt/ghc \
+            /usr/local/.ghcup /usr/share/dotnet /usr/share/swift \
+            /usr/local/lib/android /usr/local/share/powershell \
+            /usr/local/share/chromium /usr/local/share/boost \
+            /usr/lib/jvm 2>/dev/null || true
+          docker system prune -af --volumes || true
+          docker builder prune -af || true
+      - uses: docker/setup-qemu-action@v3
+        with: {platforms: arm64}
+      - uses: docker/setup-buildx-action@v4
+        with: {driver-opts: network=host}
+      - uses: docker/login-action@v3
+        with:
+          username: ${{ vars.DOCKERHUB_USERNAME }}
+          password: ${{ secrets.DOCKERHUB_TOKEN }}
+      - name: Compute version-specific tags
+        id: tags
+        run: |
+          VERSION="${{ inputs.release_tag }}"
+          TAGS="${IMAGE}:${VERSION}"
+          if [ "${{ inputs.promote_latest }}" = "true" ]; then
+            TAGS="${TAGS}\n${IMAGE}:latest"
+          fi
+          echo -e "tags<<EOF\n${TAGS}\nEOF" >> "$GITHUB_OUTPUT"
+      - uses: docker/build-push-action@v7
+        with:
+          context: .
+          file: Dockerfile.variant
+          platforms: linux/amd64,linux/arm64
+          push: true
+          build-args: |
+            BASE_IMAGE=${{ env.IMAGE }}:${{ needs.base-decide.outputs.base_tag }}
+            INSTALL_OPENCODE=true
+            INSTALL_OMOS=false
+            INSTALL_PI=false
+          tags: ${{ steps.tags.outputs.tags }}
+
+  build-variant-omos:
+    needs: [base-decide, smoke-omos]
+    runs-on: ubuntu-latest
+    container:
+      image: catthehacker/ubuntu:act-latest
+    steps:
+      - uses: actions/checkout@v4
+      - run: echo 'precedence ::ffff:0:0/96  100' >> /etc/gai.conf
+      - run: |
+          rm -rf /opt/hostedtoolcache /opt/microsoft /opt/az /opt/ghc \
+            /usr/local/.ghcup /usr/share/dotnet /usr/share/swift \
+            /usr/local/lib/android /usr/local/share/powershell \
+            /usr/local/share/chromium /usr/local/share/boost \
+            /usr/lib/jvm 2>/dev/null || true
+          docker system prune -af --volumes || true
+          docker builder prune -af || true
+      - uses: docker/setup-qemu-action@v3
+        with: {platforms: arm64}
+      - uses: docker/setup-buildx-action@v4
+        with: {driver-opts: network=host}
+      - uses: docker/login-action@v3
+        with:
+          username: ${{ vars.DOCKERHUB_USERNAME }}
+          password: ${{ secrets.DOCKERHUB_TOKEN }}
+      - name: Compute version-specific tags
+        id: tags
+        run: |
+          VERSION="${{ inputs.release_tag }}"
+          TAGS="${IMAGE}:${VERSION}-omos"
+          if [ "${{ inputs.promote_latest }}" = "true" ]; then
+            TAGS="${TAGS}\n${IMAGE}:latest-omos"
+          fi
+          echo -e "tags<<EOF\n${TAGS}\nEOF" >> "$GITHUB_OUTPUT"
+      - uses: docker/build-push-action@v7
+        with:
+          context: .
+          file: Dockerfile.variant
+          platforms: linux/amd64,linux/arm64
+          push: true
+          build-args: |
+            BASE_IMAGE=${{ env.IMAGE }}:${{ needs.base-decide.outputs.base_tag }}
+            INSTALL_OPENCODE=true
+            INSTALL_OMOS=true
+            INSTALL_PI=false
+          tags: ${{ steps.tags.outputs.tags }}
+
+  build-variant-with-pi:
+    needs: [base-decide, smoke-with-pi]
+    runs-on: ubuntu-latest
+    container:
+      image: catthehacker/ubuntu:act-latest
+    steps:
+      - uses: actions/checkout@v4
+      - run: echo 'precedence ::ffff:0:0/96  100' >> /etc/gai.conf
+      - run: |
+          rm -rf /opt/hostedtoolcache /opt/microsoft /opt/az /opt/ghc \
+            /usr/local/.ghcup /usr/share/dotnet /usr/share/swift \
+            /usr/local/lib/android /usr/local/share/powershell \
+            /usr/local/share/chromium /usr/local/share/boost \
+            /usr/lib/jvm 2>/dev/null || true
+          docker system prune -af --volumes || true
+          docker builder prune -af || true
+      - uses: docker/setup-qemu-action@v3
+        with: {platforms: arm64}
+      - uses: docker/setup-buildx-action@v4
+        with: {driver-opts: network=host}
+      - uses: docker/login-action@v3
+        with:
+          username: ${{ vars.DOCKERHUB_USERNAME }}
+          password: ${{ secrets.DOCKERHUB_TOKEN }}
+      - name: Compute version-specific tags
+        id: tags
+        run: |
+          VERSION="${{ inputs.release_tag }}"
+          TAGS="${IMAGE}:${VERSION}-with-pi"
+          if [ "${{ inputs.promote_latest }}" = "true" ]; then
+            TAGS="${TAGS}\n${IMAGE}:latest-with-pi"
+          fi
+          echo -e "tags<<EOF\n${TAGS}\nEOF" >> "$GITHUB_OUTPUT"
+      - uses: docker/build-push-action@v7
+        with:
+          context: .
+          file: Dockerfile.variant
+          platforms: linux/amd64,linux/arm64
+          push: true
+          build-args: |
+            BASE_IMAGE=${{ env.IMAGE }}:${{ needs.base-decide.outputs.base_tag }}
+            INSTALL_OPENCODE=true
+            INSTALL_OMOS=false
+            INSTALL_PI=true
+          tags: ${{ steps.tags.outputs.tags }}
+
+  build-variant-omos-with-pi:
+    needs: [base-decide, smoke-omos-with-pi]
+    runs-on: ubuntu-latest
+    container:
+      image: catthehacker/ubuntu:act-latest
+    steps:
+      - uses: actions/checkout@v4
+      - run: echo 'precedence ::ffff:0:0/96  100' >> /etc/gai.conf
+      - run: |
+          rm -rf /opt/hostedtoolcache /opt/microsoft /opt/az /opt/ghc \
+            /usr/local/.ghcup /usr/share/dotnet /usr/share/swift \
+            /usr/local/lib/android /usr/local/share/powershell \
+            /usr/local/share/chromium /usr/local/share/boost \
+            /usr/lib/jvm 2>/dev/null || true
+          docker system prune -af --volumes || true
+          docker builder prune -af || true
+      - uses: docker/setup-qemu-action@v3
+        with: {platforms: arm64}
+      - uses: docker/setup-buildx-action@v4
+        with: {driver-opts: network=host}
+      - uses: docker/login-action@v3
+        with:
+          username: ${{ vars.DOCKERHUB_USERNAME }}
+          password: ${{ secrets.DOCKERHUB_TOKEN }}
+      - name: Compute version-specific tags
+        id: tags
+        run: |
+          VERSION="${{ inputs.release_tag }}"
+          TAGS="${IMAGE}:${VERSION}-omos-with-pi"
+          if [ "${{ inputs.promote_latest }}" = "true" ]; then
+            TAGS="${TAGS}\n${IMAGE}:latest-omos-with-pi"
+          fi
+          echo -e "tags<<EOF\n${TAGS}\nEOF" >> "$GITHUB_OUTPUT"
+      - uses: docker/build-push-action@v7
+        with:
+          context: .
+          file: Dockerfile.variant
+          platforms: linux/amd64,linux/arm64
+          push: true
+          build-args: |
+            BASE_IMAGE=${{ env.IMAGE }}:${{ needs.base-decide.outputs.base_tag }}
+            INSTALL_OPENCODE=true
+            INSTALL_OMOS=true
+            INSTALL_PI=true
+          tags: ${{ steps.tags.outputs.tags }}
+
+  # ── Phase 5: promote base-<hash> → base-latest (manifest copy only) ─
+  promote-base-latest:
+    needs:
+      - base-decide
+      - build-variant-base
+      - build-variant-omos
+      - build-variant-with-pi
+      - build-variant-omos-with-pi
+    if: inputs.promote_latest == 'true'
+    runs-on: ubuntu-latest
+    container:
+      image: catthehacker/ubuntu:act-latest
+    steps:
+      - uses: imjasonh/setup-crane@v0.4
+      - name: Login (crane)
+        run: |
+          crane auth login docker.io \
+            -u ${{ vars.DOCKERHUB_USERNAME }} \
+            -p "${{ secrets.DOCKERHUB_TOKEN }}"
+      - name: Re-tag base-<hash> as base-latest
+        run: |
+          crane copy \
+            ${{ env.IMAGE }}:${{ needs.base-decide.outputs.base_tag }} \
+            ${{ env.IMAGE }}:base-latest
+
+  # ── Phase 6: update Hub description (only on real release runs) ────
+  update-description:
+    needs:
+      - build-variant-base
+      - build-variant-omos
+      - build-variant-with-pi
+      - build-variant-omos-with-pi
+    if: inputs.promote_latest == 'true'
+    runs-on: ubuntu-latest
+    container:
+      image: catthehacker/ubuntu:act-latest
+    steps:
+      - uses: actions/checkout@v4
+      - name: Update Docker Hub description
+        run: |
+          TOKEN=$(curl -s -X POST https://hub.docker.com/v2/auth/token \
+            -H "Content-Type: application/json" \
+            -d '{"identifier":"${{ vars.DOCKERHUB_USERNAME }}","secret":"${{ secrets.DOCKERHUB_TOKEN }}"}' \
+            | jq -r .access_token)
+          if [ "$TOKEN" = "null" ] || [ -z "$TOKEN" ]; then
+            echo "::error::Failed to authenticate with Docker Hub API"
+            exit 1
+          fi
+          HTTP_CODE=$(jq -n \
+            --rawfile full DOCKER_HUB.md \
+            --arg short "Portable AI dev environment for opencode. Debian-based with git, Node.js, AWS CLI, and SSH support." \
+            '{"full_description": $full, "description": $short}' | \
+            curl -s -o /tmp/hub-response.txt -w "%{http_code}" -X PATCH \
+              "https://hub.docker.com/v2/repositories/${{ vars.DOCKERHUB_USERNAME }}/opencode-devbox/" \
+              -H "Authorization: Bearer $TOKEN" \
+              -H "Content-Type: application/json" \
+              -d @-)
+          if [ "$HTTP_CODE" != "200" ]; then
+            echo "Response body:"
+            cat /tmp/hub-response.txt
+            echo "::error::Docker Hub description update failed with HTTP $HTTP_CODE"
+            exit 1
+          fi