From 2820bc97de6c71ebb52fec5970f883f770d4d684 Mon Sep 17 00:00:00 2001
From: Thaddeus Crews <repiteo@outlook.com>
Date: Sun, 1 Mar 2026 16:06:54 -0600
Subject: [PATCH] CI: Determine if source files were changed before building

---
 .github/changed_files.yml           | 16 ++++++++++++++++
 .github/workflows/runner.yml        |  6 ++++++
 .github/workflows/static_checks.yml |  9 +++++++--
 3 files changed, 29 insertions(+), 2 deletions(-)
 create mode 100644 .github/changed_files.yml

diff --git a/.github/changed_files.yml b/.github/changed_files.yml
new file mode 100644
index 0000000000..cc279f48b4
--- /dev/null
+++ b/.github/changed_files.yml
@@ -0,0 +1,16 @@
+# We lack a convenient means of gathering *all* the changes when specializations are passed, so
+#  a catch-all variable is the easiest workaround.
+everything:
+  - "**"
+
+# Determines if build actions should occur after static checks are ran. Broadly speaking, these
+#  files changing would result in SCons rebuilding the engine, or are otherwise pertinent to the
+#  buildsystem itself.
+sources:
+  - .github/{actions,workflows}/*.yml
+  - "**/{SConstruct,SCsub,*.py}"
+  - "**/*.{h,hpp,hh,hxx,c,cpp,cc,cxx,m,mm,inc,glsl}"
+  - modules/mono/**/*.{cs,csproj,sln,props,targets}
+  - platform/android/java/{gradle*,**/*.{jar,java,kt,gradle}}
+  - platform/web/{package{,-lock}.json,js/**/*.js}
+  - tests/**
diff --git a/.github/workflows/runner.yml b/.github/workflows/runner.yml
index 7499988b48..e1d3ee6a7d 100644
--- a/.github/workflows/runner.yml
+++ b/.github/workflows/runner.yml
@@ -18,16 +18,19 @@ jobs:
   android-build:
     name: 🤖 Android
     needs: static-checks
+    if: needs.static-checks.outputs.sources-changed == 'true' || github.event_name != 'pull_request'
     uses: ./.github/workflows/android_builds.yml
 
   ios-build:
     name: 🍏 iOS
     needs: static-checks
+    if: needs.static-checks.outputs.sources-changed == 'true' || github.event_name != 'pull_request'
     uses: ./.github/workflows/ios_builds.yml
 
   linux-build:
     name: 🐧 Linux
     needs: static-checks
+    if: needs.static-checks.outputs.sources-changed == 'true' || github.event_name != 'pull_request'
     uses: ./.github/workflows/linux_builds.yml
     with:
       changed-files: ${{ needs.static-checks.outputs.changed-files }}
@@ -35,14 +38,17 @@ jobs:
   macos-build:
     name: 🍎 macOS
     needs: static-checks
+    if: needs.static-checks.outputs.sources-changed == 'true' || github.event_name != 'pull_request'
     uses: ./.github/workflows/macos_builds.yml
 
   windows-build:
     name: 🏁 Windows
     needs: static-checks
+    if: needs.static-checks.outputs.sources-changed == 'true' || github.event_name != 'pull_request'
     uses: ./.github/workflows/windows_builds.yml
 
   web-build:
     name: 🌐 Web
     needs: static-checks
+    if: needs.static-checks.outputs.sources-changed == 'true' || github.event_name != 'pull_request'
     uses: ./.github/workflows/web_builds.yml
diff --git a/.github/workflows/static_checks.yml b/.github/workflows/static_checks.yml
index 69c4fb40df..0900f4a398 100644
--- a/.github/workflows/static_checks.yml
+++ b/.github/workflows/static_checks.yml
@@ -5,6 +5,9 @@ on:
       changed-files:
         description: A list of changed files.
         value: ${{ jobs.static-checks.outputs.changed-files }}
+      sources-changed:
+        description: Determines if any source files were changed.
+        value: ${{ jobs.static-checks.outputs.sources-changed }}
   workflow_dispatch:
 
 jobs:
@@ -13,7 +16,8 @@ jobs:
     runs-on: ubuntu-24.04
     timeout-minutes: 30
     outputs:
-      changed-files: '"${{ steps.changed-files.outputs.all_changed_files }}"' # Wrap with quotes to bookend internal quote separators.
+      changed-files: '"${{ steps.changed-files.outputs.everything_all_changed_files }}"' # Wrap with quotes to bookend internal quote separators.
+      sources-changed: ${{ steps.changed-files.outputs.sources_any_changed }}
     steps:
       - name: Checkout
         uses: actions/checkout@v6
@@ -33,10 +37,11 @@ jobs:
           safe_output: false # Output passed to environment variable to avoid command injection.
           separator: '" "' # To account for paths with spaces, ensure our items are split by quotes internally.
           skip_initial_fetch: true
+          files_yaml_from_source_file: .github/changed_files.yml
 
       - name: Style checks via pre-commit
         uses: pre-commit/action@v3.0.1
         env:
-          CHANGED_FILES: '"${{ steps.changed-files.outputs.all_changed_files }}"' # Wrap with quotes to bookend internal quote separators.
+          CHANGED_FILES: '"${{ steps.changed-files.outputs.everything_all_changed_files }}"' # Wrap with quotes to bookend internal quote separators.
         with:
           extra_args: --files ${{ env.CHANGED_FILES }}