diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index b1e02c0e..78bc3230 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -126,10 +126,14 @@ jobs:
         run: cd client && npm run lint:pages
 
       - name: Run tests
-        # Coverage is intentionally NOT collected in CI: the v8 coverage report
-        # phase (source-map remapping over 150+ files) runs out of memory even
-        # with a 12 GB heap, while the tests themselves pass within the default
-        # heap. Run coverage locally with `npm run test:coverage`.
+        # Two separate OOM sources, both avoided here:
+        #  1) The v8 coverage report phase (source-map remapping over 150+ files)
+        #     OOMs even with a 12 GB heap, so coverage is NOT collected in CI.
+        #  2) Each forks worker runs ~38 files and jsdom/MSW state accumulates
+        #     past Node's default ~4 GB, so workers get extra heap.
+        # Run coverage locally with `npm run test:coverage`.
         # TODO(#1258): re-enable coverage in CI via test sharding or the istanbul
         # provider, then restore the artifact upload.
+        env:
+          NODE_OPTIONS: --max-old-space-size=8192
         run: cd client && npm run test