Use more defined scope for post-submit task scheduling.

app_dart/lib/src/service/scheduler.dart

@@ -134,37 +134,37 @@ class Scheduler {
       return;
     }
 
-    final branch = pr.base!.ref!;
     final sha = pr.mergeCommitSha!;
-
-    // TODO(matanlurey): Remove carvout for legacy branch after 3.29 is archived.
-    // https://github.com/flutter/flutter/issues/167821
-    var markAllTasksSkipped = false;
-    if (isReleaseCandidateBranch(branchName: branch) &&
-        branch != 'flutter-3.29-candidate.0') {
-      markAllTasksSkipped = true;
-      log.info(
-        '[release-candidate-postsubmit-skip] For merged PR ${pr.number}, SHA=$sha, skipping all post-submit tasks',
-      );
-    }
-
-    final mergedCommit = fs.Commit.fromGithubPullRequest(pr);
-    if (await _commitExistsInFirestore(sha: mergedCommit.sha)) {
+    if (await _commitExistsInFirestore(sha: sha)) {
       log.debug('$sha already exists in Firestore. Scheduling skipped.');
       return;
     }
 
     log.debug('Scheduling $sha via GitHub webhook');
-    await _addCommit(mergedCommit, skipAllTasks: markAllTasksSkipped);
+    final mergedCommit = fs.Commit.fromGithubPullRequest(pr);
+    await _addCommit(mergedCommit);
   }
 
   /// Processes postsubmit tasks.
-  Future<void> _addCommit(fs.Commit commit, {bool skipAllTasks = false}) async {
+  Future<void> _addCommit(fs.Commit commit) async {
     if (!_config.supportedRepos.contains(commit.slug)) {
       log.debug('Skipping ${commit.sha} as repo is not supported');
       return;
     }
 
+    final _TaskCommitScheduling scheduling;
+    if (isReleaseCandidateBranch(branchName: commit.branch)) {
+      // TODO(matanlurey): Remove carvout for legacy branch after 3.29 is archived.
+      // https://github.com/flutter/flutter/issues/167821
+      if (commit.branch == 'flutter-3.29-candidate.0') {
+        scheduling = _TaskCommitScheduling.legacyImmediatelyRunGuaranteedPolicy;
+      } else {
+        scheduling = _TaskCommitScheduling.releaseCandidateSkipTasksByDefault;
+      }
+    } else {
+      scheduling = _TaskCommitScheduling.defaultUseTargetSchedulingPolicy;
+    }
+
     final ciYaml = await _ciYamlFetcher.getCiYamlByCommit(
       commit.toRef(),
       postsubmit: true,
@@ -189,21 +189,15 @@ class Scheduler {
     final toBeScheduled = <PendingTask>[];
     for (var target in targets) {
       final task = tasks.singleWhere((task) => task.taskName == target.name);
-      var policy = target.schedulerPolicy;
-
-      // TODO(matanlurey): Clean up the logic below, we actually do *not* want
-      // release branches to run every task automatically, and instead defer to
-      // manual scheduling.
-      //
-      // See https://github.com/flutter/flutter/issues/163896.
-      if (skipAllTasks) {
+      if (scheduling.skipPostsubmitTasks) {
         task.setStatus(TaskStatus.skipped);
         continue;
       }
-
-      // Release branches should run every task
-      if (Config.defaultBranch(commit.slug) != commit.branch) {
+      final SchedulerPolicy policy;
+      if (scheduling.forceGuaranteedPolicy) {
         policy = const GuaranteedPolicy();
+      } else {
+        policy = target.schedulerPolicy;
       }
       final priority = await policy.triggerPriority(
         taskName: task.taskName,
@@ -1611,3 +1605,26 @@ enum _FlutterRepoTestsToRun {
   /// No tests.
   frameworkFlutterAnalyzeOnly,
 }
+
+enum _TaskCommitScheduling {
+  /// Schedule according to how [Target.schedulerPolicy] is computed.
+  defaultUseTargetSchedulingPolicy,
+
+  /// Release candidate where tasks are skipped to be manually run either.
+  releaseCandidateSkipTasksByDefault,
+
+  /// Legacy handling for `3.29-candidate.0`.
+  ///
+  /// Remove after https://github.com/flutter/flutter/issues/167821.
+  legacyImmediatelyRunGuaranteedPolicy;
+
+  /// Whether postsubmit tasks should be initially skipped.
+  bool get skipPostsubmitTasks {
+    return this == releaseCandidateSkipTasksByDefault;
+  }
+
+  /// Whether to default to [GuaranteedPolicy] regardless of target settings.
+  bool get forceGuaranteedPolicy {
+    return this == legacyImmediatelyRunGuaranteedPolicy;
+  }
+}

app_dart/test/service/scheduler_test.dart

@@ -43,6 +43,13 @@ import '../src/utilities/entity_generators.dart';
 import '../src/utilities/mocks.dart';
 import '../src/utilities/webhook_generators.dart';
 
+const String otherBranchCiYaml = r'''
+enabled_branches:
+  - ios-experimental
+targets:
+  - name: Linux A
+''';
+
 const String singleCiYaml = r'''
 enabled_branches:
   - master
@@ -508,6 +515,39 @@ void main() {
         );
       });
 
+      // Regression test for https://github.com/flutter/flutter/issues/168738.
+      test('marks all tasks as new for non-release/non-master', () async {
+        ciYamlFetcher.setCiYamlFrom(otherBranchCiYaml, engine: fusionCiYaml);
+
+        final mergedPr = generatePullRequest(
+          repo: 'flutter',
+          branch: 'ios-experimental',
+        );
+        await scheduler.addPullRequest(mergedPr);
+
+        expect(
+          firestore,
+          existsInStorage(fs.Commit.metadata, [
+            isCommit
+                .hasRepositoryPath('flutter/flutter')
+                .hasSha('abc')
+                .hasBranch('ios-experimental')
+                .hasCreateTimestamp(1)
+                .hasAuthor('dash')
+                .hasAvatar('dashatar')
+                .hasMessage('example message'),
+          ]),
+        );
+
+        expect(
+          firestore,
+          existsInStorage(
+            fs.Task.metadata,
+            everyElement(isTask.hasStatus(TaskStatus.waitingForBackfill)),
+          ),
+        );
+      });
+
       test('run all tasks if legacy release candidate branch', () async {
         ciYamlFetcher.setCiYamlFrom(singleCiYaml, engine: fusionCiYaml);