From 60132c4271eaaec553c5e157da23619cfdc0388f Mon Sep 17 00:00:00 2001
From: Mish Ushakov <10400064+mishushakov@users.noreply.github.com>
Date: Mon, 13 Jul 2026 18:52:09 +0200
Subject: [PATCH] ci: seed codegen image cache from main instead of per-PR
 scopes

The generated_files.yml workflow only runs on pull_request, so its
cache-to: type=gha,mode=max wrote buildkit blobs into per-PR scopes
that other PRs cannot read. Every new PR cold-built the codegen image
(235-365s in 11 of 17 runs last week), and ~6 GB of duplicate blobs
pushed the repo's Actions cache to 9.9/10 GB, evicting the Playwright
and pnpm caches.

Add codegen_image_cache.yml, which builds the image on pushes to main
that touch its inputs (codegen.Dockerfile, packages/connect-python)
and exports the cache to main's scope, readable by all PRs. Drop
cache-to from the PR-side build.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
---
 .github/workflows/codegen_image_cache.yml | 35 +++++++++++++++++++++++
 .github/workflows/generated_files.yml     |  4 ++-
 2 files changed, 38 insertions(+), 1 deletion(-)
 create mode 100644 .github/workflows/codegen_image_cache.yml

diff --git a/.github/workflows/codegen_image_cache.yml b/.github/workflows/codegen_image_cache.yml
new file mode 100644
index 0000000000..83e3584435
--- /dev/null
+++ b/.github/workflows/codegen_image_cache.yml
@@ -0,0 +1,35 @@
+name: Codegen image cache
+
+# Seeds the buildkit cache for codegen.Dockerfile from main so pull request
+# runs of generated_files.yml warm-start. PR-scoped cache writes are not
+# readable by other PRs, so main is the only scope worth writing to.
+on:
+  push:
+    branches: [main]
+    paths:
+      - 'codegen.Dockerfile'
+      - 'packages/connect-python/**'
+      - '.github/workflows/codegen_image_cache.yml'
+  workflow_dispatch:
+
+permissions:
+  contents: read
+
+jobs:
+  seed:
+    name: Seed codegen image cache
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+
+      - name: Build codegen image and export cache
+        uses: docker/build-push-action@v6
+        with:
+          context: .
+          file: codegen.Dockerfile
+          cache-from: type=gha
+          cache-to: type=gha,mode=max
diff --git a/.github/workflows/generated_files.yml b/.github/workflows/generated_files.yml
index 39d1a85dc7..772c48fda6 100644
--- a/.github/workflows/generated_files.yml
+++ b/.github/workflows/generated_files.yml
@@ -81,8 +81,10 @@ jobs:
           file: codegen.Dockerfile
           tags: codegen-env:latest
           load: true # makes the image available for `docker run`
+          # Cache is seeded from main by codegen_image_cache.yml. No cache-to
+          # here: PR-scoped writes are unreadable by other PRs and only fill
+          # the repo's 10 GB Actions cache, evicting other caches.
           cache-from: type=gha
-          cache-to: type=gha,mode=max
 
       - name: Run codegen
         run: CODEGEN_IMAGE=codegen-env:latest make codegen