Prevent storage E2E retries from canceling CI

[brandonpayton]

Why this change is needed

@adamziel reported that flaky end-to-end tests were causing more CI jobs to be
canceled.

The canceled jobs shared the same pattern: one storage test failed late in a
Playwright serial group, so Playwright retried the whole group from its first
test. In one case, a 33-test storage group restarted more than once and the job
reached the existing 30-minute limit before it could finish. The OPFS tests had
the same retry behavior.

Adding another ordinary shard would not help because Playwright keeps a serial
group together. Increasing the timeout or reducing the three retries would
also leave the whole-group replay in place.

Examples:

• https://github.com/WordPress/wordpress-playground/actions/runs/30863319632/job/91858108020
• https://github.com/WordPress/wordpress-playground/actions/runs/30860081972/job/91848066181

Why this approach

The storage tests must not run at the same time because they share browser
storage. A dedicated storage lane with one worker preserves that isolation.
Using Playwright's default test mode inside that lane means a failure retries
only the failed test instead of replaying every earlier test in its group.

This directly addresses the cancellation pattern while keeping the existing
30-minute job timeout and three retries.

What this changes

• Changes the OPFS tests and default-storage tests from serial mode to default
  mode, allowing Playwright to retry one failed test.
• Adds @storage to the top-level OPFS suite and the default-storage group.
  CI routes tests only by this tag, so it does not need file-path rules.
• Keeps three ordinary shards per browser and excludes storage tests from them.
• Adds one unsharded storage lane per browser with workers: 1.
• Runs the Nx CI-style target as two sequential groups: ordinary tests use the
  normal three workers, then storage tests use one worker. Missing or unsupported
  group values produce a clear error.
• Gives only the three storage matrix entries a storage test group. Entries
  without a group use the ordinary-test behavior, so the matrix does not repeat
  a regular label nine times.
• Adds a -storage suffix only to storage artifacts. Ordinary artifact names
  remain unchanged.

The tradeoff is three additional install/build runners, one per browser. This
is the same job-count increase as changing from three to four ordinary shards,
but it removes the whole-group retry amplification that caused the cancellations.

Verification

• Collected all Chromium tests with the tag-only selector and confirmed that
  each test is in exactly one lane: 182 ordinary tests and 59 storage tests.
  The ordinary shards contain 61, 61, and 60 tests.
• Confirmed the top-level OPFS suite contributes all 26 tagged tests.
• Confirmed the Nx target resolves to two sequential commands with explicit
  groups, and a missing or unsupported group exits with a clear error.
• Ran all 59 Chromium storage tests locally with one worker; all passed.
• The full CI run passed for Chromium, Firefox, and WebKit storage lanes.
• Ran the Chromium storage lane two more times after it first passed. All three
  attempts passed. Two attempts had one flaky ZIP-import test, and Playwright
  retried only that test instead of restarting the storage suite. This confirms
  the new retry scope works as intended.
• Confirmed the simplified matrix has 12 entries: 9 without a group and 3 with
  the storage group.
• Ran the website typecheck, lint, formatting checks, YAML parsing, and workflow
  validation.

The repetitions also exposed a separate race in two ZIP-import tests. PR #4213
addresses that underlying race. It remains separate so this PR stays focused on
making retries safe and preventing CI cancellations.

[Copilot]

Pull request overview

Note

Copilot was unable to run its full agentic suite in this review.

Adjusts Playwright CI sharding so storage-sensitive E2E tests run in a dedicated single-worker lane, allowing retries to re-run only failed tests (instead of replaying full serial groups) and reducing CI cancellations caused by late failures.

Changes:

• Adds CI test-group routing (regular vs storage) via PLAYWRIGHT_TEST_GROUP, with workers: 1 for the storage lane.
• Marks default-storage tests with @storage and switches storage suites from serial to Playwright’s default mode.
• Updates the GitHub Actions matrix to add one storage lane per browser and to suffix storage artifacts.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 2 comments.

File	Description
packages/playground/website/playwright/playwright.ci.config.ts	Adds PLAYWRIGHT_TEST_GROUP-based grep/grepInvert and workers: 1 to separate storage vs regular runs.
packages/playground/website/playwright/e2e/website-ui.spec.ts	Tags the default-storage suite as @storage and switches it off serial.
packages/playground/website/playwright/e2e/opfs.spec.ts	Switches OPFS tests from serial to default mode and updates comments.
.github/workflows/ci.yml	Adds per-browser storage matrix entries, passes PLAYWRIGHT_TEST_GROUP, and updates step/artifact naming.

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[brandonpayton]

I think all the changes in the file from here down are the result of whitespace-only changes (indentation) that led to formatting changes.

[brandonpayton]

This looks good to go. Let's merge.