diff --git a/.github/workflows/macos-latest.yml b/.github/workflows/macos-latest.yml
index a46ff0d26..bacbaccc2 100644
--- a/.github/workflows/macos-latest.yml
+++ b/.github/workflows/macos-latest.yml
@@ -20,6 +20,7 @@ on:
   push:
     branches:
       - main
+      - 'release/v*'
 
 jobs:
   macos-latest:
diff --git a/.github/workflows/windows-latest.yml b/.github/workflows/windows-latest.yml
index 71400c71a..f959369e9 100644
--- a/.github/workflows/windows-latest.yml
+++ b/.github/workflows/windows-latest.yml
@@ -20,6 +20,7 @@ on:
   push:
     branches:
       - main
+      - 'release/v*'
 
 jobs:
   windows-latest:
diff --git a/build/Build.CI.GitHubActions.cs b/build/Build.CI.GitHubActions.cs
index ddb849f52..83f7fa61a 100644
--- a/build/Build.CI.GitHubActions.cs
+++ b/build/Build.CI.GitHubActions.cs
@@ -1,15 +1,17 @@
 using Fallout.Common.CI.GitHubActions;
 using Fallout.Components;
 
-// macOS and Windows runs are reserved for main-branch validation (post-merge
-// and release pipelines). PRs and feature-branch pushes get Linux-only for
-// fast, cheap feedback.
+// macOS and Windows runs are reserved for post-merge validation on the
+// long-lived branches (main and release/vN). PRs and feature-branch pushes
+// get Linux-only for fast, cheap feedback. Cross-platform regressions on a
+// release branch surface as a red commit on release/v* — same fail-fast
+// model as main.
 [GitHubActions(
     "macos-latest",
     GitHubActionsImage.MacOsLatest,
     FetchDepth = 0,
     Submodules = GitHubActionsSubmodules.Recursive,
-    OnPushBranches = new[] { MainBranch },
+    OnPushBranches = new[] { MainBranch, ReleaseBranchPattern },
     InvokedTargets = new[] { nameof(ITest.Test), nameof(IPack.Pack) },
     PublishArtifacts = false)]
 [GitHubActions(
@@ -17,7 +19,7 @@
     GitHubActionsImage.WindowsLatest,
     FetchDepth = 0,
     Submodules = GitHubActionsSubmodules.Recursive,
-    OnPushBranches = new[] { MainBranch },
+    OnPushBranches = new[] { MainBranch, ReleaseBranchPattern },
     InvokedTargets = new[] { nameof(ITest.Test), nameof(IPack.Pack) },
     PublishArtifacts = false)]
 // pull_request only — same-repo branches would otherwise fire both push and