diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index db204d9..105e557 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -30,7 +30,8 @@ concurrency:
   cancel-in-progress: ${{ github.event_name == 'pull_request' }}
 
 # Jobs that only need Node/pnpm/bash use [self-hosted, evoo-ci] so macOS runners (air, mini)
-# can share load. Linux-only work keeps the Linux label (Docker, xvfb, local Postgres :5433).
+# can share load. Linux-only work keeps the Linux label (Docker, xvfb, local Postgres :5433,
+# Homebrew ffmpeg with libass/subtitles filter for media unit tests).
 
 jobs:
   changes:
@@ -193,7 +194,7 @@ jobs:
     name: Unit tests
     needs: changes
     if: needs.changes.outputs.product == 'true'
-    runs-on: [self-hosted, evoo-ci]
+    runs-on: [self-hosted, evoo-ci, Linux]
     steps:
       - uses: actions/checkout@v5
         with:
diff --git a/apps/web/src/lib/heute-brief.test.ts b/apps/web/src/lib/heute-brief.test.ts
index f376f89..90c5a65 100644
--- a/apps/web/src/lib/heute-brief.test.ts
+++ b/apps/web/src/lib/heute-brief.test.ts
@@ -91,7 +91,8 @@ function run(overrides: Partial<RunActivityRow> = {}): RunActivityRow {
 describe("isToday", () => {
   it("matches same calendar day", () => {
     expect(isToday("2026-09-22T08:30:00.000Z", now)).toBe(true);
-    expect(isToday("2026-09-21T23:59:00.000Z", now)).toBe(false);
+    // Midday UTC on the previous day stays the previous calendar day in UTC+14…UTC-12.
+    expect(isToday("2026-09-21T12:00:00.000Z", now)).toBe(false);
   });
 });