feat: add code image build to sandbox-image workflow

.github/workflows/sandbox-image.yml

@@ -8,25 +8,28 @@ on:
       - main
     paths:
       - "images/sandbox/**"
+      - "images/code/**"
   pull_request:
     paths:
       - "images/sandbox/**"
+      - "images/code/**"
   workflow_dispatch:
 
 # NOTE: GitHub Actions ignores `paths` filters on tag pushes, so every
 # v* tag triggers a build.  This is intentional — the sandbox image is
 # published alongside the CLI so consumers can pin both to the same
 # version.  Branch pushes and PRs still respect the paths filter.
 
-env:
-  IMAGE_NAME: ghcr.io/${{ github.repository_owner }}/fullsend-sandbox
-
 jobs:
-  build:
+  build-base:
     runs-on: ubuntu-latest
     permissions:
       contents: read
       packages: write
+    outputs:
+      image-ref: ${{ steps.ref.outputs.value }}
+    env:
+      BASE_IMAGE_NAME: ghcr.io/${{ github.repository_owner }}/fullsend-sandbox
     steps:
       - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
 
@@ -44,20 +47,83 @@ jobs:
         id: meta
         uses: docker/metadata-action@030e881283bb7a6894de51c315a6bfe6a94e05cf # v6
         with:
-          images: ${{ env.IMAGE_NAME }}
+          images: ${{ env.BASE_IMAGE_NAME }}
           tags: |
             type=semver,pattern={{version}}
             type=semver,pattern={{major}}.{{minor}}
             type=sha,prefix=
             type=raw,value=latest,enable={{is_default_branch}}
 
       - name: Build and push
+        id: push
         uses: docker/build-push-action@bcafcacb16a39f128d818304e6c9c0c18556b85f # v7
         with:
           context: images/sandbox
           file: images/sandbox/Containerfile
           push: ${{ github.event_name != 'pull_request' }}
           tags: ${{ steps.meta.outputs.tags }}
           labels: ${{ steps.meta.outputs.labels }}
-          cache-from: type=gha
-          cache-to: type=gha,mode=max
+          cache-from: type=gha,scope=sandbox
+          cache-to: type=gha,mode=max,scope=sandbox
+
+      # Compute a single image reference for the build-code job.
+      # On push: use the immutable digest from the pushed image.
+      # On PR: use the latest published image (the PR build validates
+      # the Containerfile compiles but doesn't push, so build-code
+      # needs an already-published base to FROM).
+      - name: Compute base image ref
+        id: ref
+        env:
+          DIGEST: ${{ steps.push.outputs.digest }}
+          IMAGE_NAME: ${{ env.BASE_IMAGE_NAME }}
+        run: |
+          if [ -n "$DIGEST" ]; then
+            echo "value=${IMAGE_NAME}@${DIGEST}" >> "$GITHUB_OUTPUT"
+          else
+            echo "value=${IMAGE_NAME}:latest" >> "$GITHUB_OUTPUT"
+          fi
+
+  build-code:
+    needs: build-base
+    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+      packages: write
+    env:
+      CODE_IMAGE_NAME: ghcr.io/${{ github.repository_owner }}/fullsend-code
+    steps:
+      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
+
+      - name: Log in to GitHub Container Registry
+        uses: docker/login-action@4907a6ddec9925e35a0a9e82d7399ccc52663121 # v4
+        with:
+          registry: ghcr.io
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@4d04d5d9486b7bd6fa91e7baf45bbb4f8b9deedd # v4
+
+      - name: Extract metadata
+        id: meta
+        uses: docker/metadata-action@030e881283bb7a6894de51c315a6bfe6a94e05cf # v6
+        with:
+          images: ${{ env.CODE_IMAGE_NAME }}
+          tags: |
+            type=semver,pattern={{version}}
+            type=semver,pattern={{major}}.{{minor}}
+            type=sha,prefix=
+            type=raw,value=latest,enable={{is_default_branch}}
+
+      - name: Build and push
+        uses: docker/build-push-action@bcafcacb16a39f128d818304e6c9c0c18556b85f # v7
+        with:
+          context: images/code
+          file: images/code/Containerfile
+          build-args: |
+            BASE_IMAGE=${{ needs.build-base.outputs.image-ref }}
+          push: ${{ github.event_name != 'pull_request' }}
+          tags: ${{ steps.meta.outputs.tags }}
+          labels: ${{ steps.meta.outputs.labels }}
+          cache-from: type=gha,scope=code
+          cache-to: type=gha,mode=max,scope=code

images/code/Containerfile

@@ -8,8 +8,8 @@
 # The base image already provides Claude Code, rsync, tirith, and LLM Guard.
 # See images/sandbox/Containerfile in fullsend-ai/fullsend for the base definition.
 #
-# This image is built AUTOMATICALLY by .github/workflows/build-images.yml
-# on every push to main that touches images/code/Containerfile.
+# This image is built AUTOMATICALLY by .github/workflows/sandbox-image.yml
+# (build-code job) on every push to main that touches images/code/.
 # You can also trigger it manually via workflow_dispatch.
 #
 # Published to: ghcr.io/fullsend-ai/fullsend-code:latest