From 14b1137f5c0f7aa65ad207e1162ddbc20538004d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bart=C5=82omiej=20Kozak?= <bartlomiejkozak@proton.me>
Date: Fri, 28 Aug 2026 13:38:55 +0200
Subject: [PATCH] Skip CI build/test jobs on doc-only changes

Add a `changes` gate (dorny/paths-filter) that checks whether a push/PR
touches actual code (**/*.scala, project.scala, .scalafmt.conf, or ci.yml
itself). Scalafmt, Test and Compile are gated behind it with a job-level
`if`, so a PR that only touches README.md/renovate.json/.github/sync.yml
etc. no longer spins up the full build+test matrix.

A skipped job reports "Success" and satisfies a required status check, but
skipping a *matrix* job at the top level leaves its required inner checks
("Test (scala-js)", "Test (scala-native)") pending forever instead
(actions/runner#952). So test-cross-platform is split into two plain jobs,
test-scala-js and test-scala-native, that can be individually skipped.
`compile` stays a matrix (its per-platform checks aren't required, so a
top-level skip there is harmless).

Required status check names are unchanged: Scalafmt, Test,
Test (scala-js), Test (scala-native).

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_019awuXm5QZgXajLw3PvGo1s
---
 .github/workflows/ci.yml | 75 ++++++++++++++++++++++++++++++++--------
 1 file changed, 60 insertions(+), 15 deletions(-)

diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 42b5641..2de8f7b 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -7,8 +7,33 @@ on:
     branches: [ master ]
 
 jobs:
+  # Gate the build/test jobs so doc-only changes (README, renovate.json,
+  # sync config, …) don't run the suite. The gated jobs keep their names as
+  # required status checks; skipped via a job-level `if` they report Success.
+  # `test-cross-platform` is split into one job per platform on purpose:
+  # skipping a *matrix* job leaves its required inner checks pending forever
+  # (actions/runner#952).
+  changes:
+    name: Detect code changes
+    runs-on: ubuntu-latest
+    outputs:
+      code: ${{ steps.filter.outputs.code }}
+    steps:
+      - uses: actions/checkout@v7
+      - uses: dorny/paths-filter@v3
+        id: filter
+        with:
+          filters: |
+            code:
+              - '**/*.scala'
+              - 'project.scala'
+              - '.scalafmt.conf'
+              - '.github/workflows/ci.yml'
+
   lint:
     name: Scalafmt
+    needs: changes
+    if: ${{ needs.changes.outputs.code == 'true' }}
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v7
@@ -20,6 +45,8 @@ jobs:
 
   test:
     name: Test
+    needs: changes
+    if: ${{ needs.changes.outputs.code == 'true' }}
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v7
@@ -51,6 +78,8 @@ jobs:
 
   compile:
     name: Compile (${{ matrix.platform }})
+    needs: changes
+    if: ${{ needs.changes.outputs.code == 'true' }}
     runs-on: ubuntu-latest
     strategy:
       fail-fast: false
@@ -77,19 +106,15 @@ jobs:
       - name: Compile
         run: scala-cli --power compile . --platform ${{ matrix.platform }} ${{ matrix.args }}
 
-  # JVM is covered by the `test` job above (with coverage/docs); this just runs
-  # the same suite on the other targets to catch platform-specific regressions.
-  test-cross-platform:
-    name: Test (${{ matrix.platform }})
+  # JVM is covered by the `test` job above (with coverage/docs); these two just
+  # run the same suite on the other targets to catch platform-specific
+  # regressions. Kept as separate jobs (not a matrix) so they can be skipped
+  # individually without hanging their required checks.
+  test-scala-js:
+    name: Test (scala-js)
+    needs: changes
+    if: ${{ needs.changes.outputs.code == 'true' }}
     runs-on: ubuntu-latest
-    strategy:
-      fail-fast: false
-      matrix:
-        include:
-          - platform: scala-js
-            args: "--js-version 1.22.0"
-          - platform: scala-native
-            args: "--native-version 0.5.12"
     steps:
       - uses: actions/checkout@v7
       - name: Setup coursier cache
@@ -98,9 +123,29 @@ jobs:
         uses: actions/cache@v6
         with:
           path: .scala-build
-          key: scala-build-${{ matrix.platform }}-${{ hashFiles('project.scala', '**/*.scala') }}
+          key: scala-build-scala-js-${{ hashFiles('project.scala', '**/*.scala') }}
           restore-keys: |
-            scala-build-${{ matrix.platform }}-
+            scala-build-scala-js-
+      - uses: VirtusLab/scala-cli-setup@v1
+      - name: Run tests
+        run: scala-cli --power test . --platform scala-js --js-version 1.22.0
+
+  test-scala-native:
+    name: Test (scala-native)
+    needs: changes
+    if: ${{ needs.changes.outputs.code == 'true' }}
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v7
+      - name: Setup coursier cache
+        uses: coursier/cache-action@v8.1
+      - name: Cache scala-cli/Bloop incremental build
+        uses: actions/cache@v6
+        with:
+          path: .scala-build
+          key: scala-build-scala-native-${{ hashFiles('project.scala', '**/*.scala') }}
+          restore-keys: |
+            scala-build-scala-native-
       - uses: VirtusLab/scala-cli-setup@v1
       - name: Run tests
-        run: scala-cli --power test . --platform ${{ matrix.platform }} ${{ matrix.args }}
+        run: scala-cli --power test . --platform scala-native --native-version 0.5.12