From 8db75033c845caead889e7551aa7e32b9cda7372 Mon Sep 17 00:00:00 2001
From: owen <owen@gattaca.com>
Date: Fri, 4 Sep 2026 17:37:36 +0100
Subject: [PATCH] Build and publish a helix-builder image

Mirrors the existing relay, data-api and simulator jobs against the
builder.Dockerfile that was already in the tree.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
(cherry picked from commit 670c45a4fbb6a6dc04b231890d86b35729d872f2)
---
 .github/workflows/build.yml | 41 +++++++++++++++++++++++++++++++++++++
 1 file changed, 41 insertions(+)

diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 95e992f41..e6957fd1c 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -135,3 +135,44 @@ jobs:
             ghcr.io/${{ github.repository_owner }}/helix-simulator:${{ env.IMAGE_NAME }}
           cache-from: type=registry,ref=ghcr.io/${{ github.repository_owner }}/helix-simulator:buildcache
           cache-to: type=registry,ref=ghcr.io/${{ github.repository_owner }}/helix-simulator:buildcache,mode=max
+
+  build-builder:
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+
+      - name: Login to GitHub Container Registry
+        uses: docker/login-action@v3
+        with:
+          registry: ghcr.io
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Set IMAGE_NAME
+        run: |
+          if [[ "${{ github.event_name }}" == "pull_request" ]]; then
+            BRANCH=$(echo "${{ github.head_ref }}" | tr '[:upper:]' '[:lower:]' | tr '/' '-')
+            SHORT_SHA=$(echo "${{ github.sha }}" | cut -c1-7)
+            IMAGE_NAME="${BRANCH}_${SHORT_SHA}"
+          else
+            REF_BRANCH=$(echo "${{ github.ref_name }}" | tr '[:upper:]' '[:lower:]' | tr '/' '-')
+            IMAGE_NAME="${REF_BRANCH}"
+          fi
+          echo "IMAGE_NAME=$IMAGE_NAME" >> $GITHUB_ENV
+
+      - name: Build and push
+        uses: docker/build-push-action@v6
+        with:
+          context: .
+          push: true
+          file: ./builder.Dockerfile
+          tags: |
+            ghcr.io/${{ github.repository_owner }}/helix-builder:${{ env.IMAGE_NAME }}
+          cache-from: type=registry,ref=ghcr.io/${{ github.repository_owner }}/helix-builder:buildcache
+          cache-to: type=registry,ref=ghcr.io/${{ github.repository_owner }}/helix-builder:buildcache,mode=max