Seed pre-commit cache from main builds

Author: bdice

.github/workflows/build.yaml

@@ -33,6 +33,20 @@ concurrency:
   cancel-in-progress: true
 permissions: {}
 jobs:
+  checks:
+    if: ${{ github.ref == 'refs/heads/main' }}
+    permissions:
+      actions: read
+      contents: read
+    uses: rapidsai/shared-workflows/.github/workflows/checks.yaml@main
+    with:
+      # Seed the default-branch pre-commit cache without running checks that only apply to PRs.
+      base-branch: main
+      enable_check_size: false
+      enable_check_generated_files: false
+      enable_check_pr_job_dependencies: false
+      enable_check_version_files_changed: false
+      enable_check_version_against_tag: false
   docs-build-matrix:
     permissions:
       contents: read

.github/workflows/pr.yaml

@@ -37,6 +37,9 @@ jobs:
     with:
       enable_check_generated_files: false
       ignored_pr_jobs: "telemetry-summarize"
+      # Main builds seed this cache. PR merge refs can restore it but should not create
+      # duplicate archives that are inaccessible to other PRs.
+      pre-commit-cache-read-only: true
     permissions:
       contents: read
   docs-build-matrix: