ci: cancel superseded documentation browser checks

.github/workflows/browser.yml

@@ -5,6 +5,12 @@ on:
     branches: [main]
 permissions:
   contents: read
+
+# Stop testing superseded revisions without cancelling other PRs or main.
+concurrency:
+  group: browser-${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
 jobs:
   browser:
     runs-on: ubuntu-latest

docs/README.md

@@ -6,3 +6,8 @@ checks its rendered title. Run the production build, install Chromium with
 `pnpm exec e2e-web install chromium`, then run the package’s `test:e2e` script.
 It makes no model calls, uses no account credentials, and does not replace
 the project’s native/CLI integration tests. Browser traces remain in `.e2e/`.
+
+CI runs the full browser suite on every pull request and on pushes to `main`.
+New runs cancel older runs for the same ref, so superseded revisions do not
+consume runners while the latest revision waits. Different PRs and `main`
+remain independent.