ADFA-5244: Make CI able to catch the Spotless/source-tree failure

.github/workflows/debug.yml

@@ -197,12 +197,22 @@ jobs:
         run: |
           flox activate -d flox/base -- ./gradlew :plugin-api:apiCheck --no-daemon
 
-      - name: Run spotlessCheck
+      # Combined with a compile task on purpose: spotlessCheck alone never pulls a
+      # source-tree-writing task into the graph, so the implicit-dependency failure ADFA-5244 fixed
+      # cannot reproduce in a standalone run. Without this step a regression of that exclude is
+      # invisible to CI and shows up only on a developer's machine at push time.
+      - name: Run spotlessCheck alongside a compile task
         run: |
-          flox activate -d flox/base -- ./gradlew spotlessCheck --no-daemon || {
-            echo "::error::Spotless found formatting violations in this branch. Run './gradlew spotlessApply' locally, then commit and push the formatted files."
-            exit 1
-          }
+          # Two tasks, so two possible causes: the message must not name one of them. Blaming
+          # Spotless for a compile error is the exact misdiagnosis this step exists to catch.
+          set +e
+          flox activate -d flox/base -- ./gradlew :common:compileV8DebugKotlin spotlessCheck --no-daemon
+          status=$?
+          set -e
+          if [ "$status" -ne 0 ]; then
+            echo "::error::Gradle failed on ':common:compileV8DebugKotlin spotlessCheck'. If the output above shows formatting violations, run './gradlew spotlessApply' locally and commit the result; if it shows a compile error, spotlessApply will not help. The Gradle output says which."
+            exit "$status"
+          fi
 
       - name: Install advancecomp (advzip, used by recompressApk)
         run: |

.gitignore

@@ -110,6 +110,12 @@ sentry.properties
 
 /app/google-services.json
 
+# Written by the gradle-plugin tests, not by a Gradle task: writeInitScript() in
+# gradle-plugin/src/test/.../utils.kt resolves FileProvider.testHomeDir() and creates
+# .cg/init/androidide.init.gradle there on every run. ADFA-5263 deleted copyToTestDir, so the
+# model.jar entry that used to sit beside this one is dead, but the directory still fills up.
+tests/test-home
+
 # Kotlin build files
 .kotlin/
 

build.gradle.kts

@@ -179,9 +179,12 @@ spotless {
 	// Spotless's auto-prune of .git/.gradle/build, so restore them. flox is the
 	// ADFA-4816 fix: its /nix/store symlinks (millions of files) made
 	// spotlessCheck take 12+ minutes.
-	// Bare dir names required: Gradle prunes a subtree only when an exclude
-	// matches the dir node itself; `dir/**` matches contents and forces a
-	// descend-and-filter (no pruning).
+	// The pattern must match the directory node itself, because Gradle prunes a subtree only then;
+	// `dir/**` matches the contents instead and forces a descend-and-filter. Bare names are
+	// root-anchored: "flox" prunes only rootDir/flox, so anything that has to match at depth needs
+	// the `**/` prefix the three entries below carry. Dropping it -- reading "**/.gradle" as
+	// equivalent to ".gradle" -- would stop pruning every per-project cache dir and bring back the
+	// ADFA-4816 12-minute spotlessCheck.
 	val traversalExcludes =
 		arrayOf(
 			"flox",