ci: pre-warm Namespace cache for unit/component-view test shards

[tommasini]

Summary

Introduces a `prepare-ci-js-deps` job and a `setup-ci-js-deps` composite action to eliminate redundant `yarn install` + `yarn setup:github-ci --node` across 13 CI shards (10 unit-test + 2 component-view + 1 merge job).

What changed

New job `prepare-ci-js-deps` (`ci.yml`)
Runs before `unit-tests`, `component-view-tests`, and `merge-unit-and-component-view-tests` and installs dependencies once on behalf of all consumers.

• Namespace runners: mounts the persistent cache volume and runs install only when the volume is cold (yarn.lock changed in the pool). Consumers restore from the same volume — install is skipped entirely on a warm cache.
• Non-Namespace runners (current default for all PRs): runs install, then packs `node_modules` + generated files into a gzipped tarball (`ci-js-deps.tar.gz`) and uploads it as a workflow-run artifact. Consumers download and extract the tarball instead of running their own install.

TEMP: The tarball artifact path is a temporary fallback while Namespace is on trial. Once Namespace becomes the default runner, the pack/upload steps in the producer and the download/extract steps in each consumer can be deleted. The `setup-ci-js-deps` composite action requires no changes.

New composite action `.github/actions/setup-ci-js-deps`
Shared setup sequence used by the producer and all three consumer jobs:

1. Mount Namespace cache (Namespace only)
2. `actions/setup-node`
3. File-based freshness check (`node_modules` dir + `termsOfUseContent.ts`)
4. `yarn install --immutable` + `yarn setup:github-ci --node` — only if step 3 finds files missing

On non-Namespace consumers, step 3 finds the tarball already extracted, so step 4 is skipped.

Consumer jobs (`unit-tests`, `component-view-tests`, `merge-unit-and-component-view-tests`)
Each job's setup block is replaced with:

• TEMP: download + extract `ci-js-deps.tar.gz` (non-Namespace only; tar preserves permissions so no separate restore step is needed)
• Call to `setup-ci-js-deps` (which skips install when files are already present)

`check-all-jobs-pass`
`prepare-ci-js-deps` added to the gate.

Not changed

• `setup-node-modules.yml` — untouched
• E2E jobs — untouched (Phase 2 scope)

Estimated impact

Lane	Shards	Before	After (non-Namespace)	After (Namespace)
`unit-tests`	10	~2 min install each	~30s download+extract	~10s cache hit
`component-view-tests`	2	~2 min install each	~30s download+extract	~10s cache hit
`merge-unit-and-component-view-tests`	1	~2 min install	~30s download+extract	~10s cache hit
Saved per run			~22 runner-min	~26 runner-min

Removal guide (when Namespace passes trial)

Search for `# TEMP` in `ci.yml` — there are exactly 4 clearly marked blocks:

1. `Pack CI JS deps` + `Upload CI JS deps artifact` in `prepare-ci-js-deps`
2. `Download CI JS deps artifact` + `Extract CI JS deps` in each of the 3 consumer jobs

Delete those blocks. No changes needed to `setup-ci-js-deps/action.yml`.

Manual testing steps

```gherkin
Given a pull request runs CI on a non-Namespace runner (ubuntu-latest)
When prepare-ci-js-deps completes
Then a ci-js-deps.tar.gz artifact is uploaded
And each unit-tests and component-view-tests shard downloads and extracts it
And all shards skip yarn install and pass

Given a pull request runs CI on a Namespace runner
When prepare-ci-js-deps completes on a warm cache volume
Then all consumer shards mount the cache volume and skip yarn install
And all shards pass

Given the Namespace cache volume is cold (yarn.lock changed)
When prepare-ci-js-deps runs
Then it installs dependencies and warms the volume
And all consumer shards hit the warm volume and skip install
```

References

• ADR: `docs/ci-dependency-setup-reuse-adr.md`
• Related action: `.github/actions/restore-node-modules-permissions`

---

Note

Medium Risk
Changes CI job dependencies and dependency-caching behavior for unit/component-view shards; misconfiguration could cause flaky installs or missing artifacts, but impact is limited to CI execution.

Overview
Reduces redundant JS dependency setup across CI test shards. Adds a new composite action setup-ci-js-deps that configures Namespace cache, sets up Node, and conditionally runs yarn install --immutable + yarn setup:github-ci --node based on workspace freshness.

Introduces a prepare-ci-js-deps job that runs once before unit-tests, component-view-tests, and merge-unit-and-component-view-tests to warm Namespace shared cache; for non-Namespace runners it packs and uploads a short-lived ci-js-deps artifact that consumer shards download/extract to skip their own installs.

Updates test/merge jobs to depend on prepare-ci-js-deps, replaces their inline dependency setup with the new action + temporary artifact restore steps, tightens if conditions to require successful get_requirements, and adds prepare-ci-js-deps to the check-all-jobs-pass gate.

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[github-actions]

🔍 Smart E2E Test Selection

• Selected E2E tags: None (no tests recommended)
• Selected Performance tags: None (no tests recommended)
• Risk Level: low
• AI Confidence: 95%

click to see 🤖 AI reasoning details

E2E Test Selection:
The two changed files are purely CI infrastructure changes with no impact on application code or E2E test logic:

1. .github/actions/setup-ci-js-deps/action.yml - A NEW composite GitHub Action that centralizes JS dependency setup (Namespace cache config, Node.js setup, yarn install with retry, project setup). This is a pure CI refactoring.

2. .github/workflows/ci.yml - Refactors the CI pipeline to:

   • Add a new prepare-ci-js-deps job that installs dependencies once and either warms the Namespace shared cache volume or uploads a tarball artifact for non-Namespace runners
   • Update unit-tests, component-view-tests, and merge-unit-and-component-view-tests jobs to use the new composite action and download the artifact instead of each installing independently
   • Improve if conditions with !cancelled() and result == 'success' patterns
   • Add prepare-ci-js-deps to the final status check

These changes are a CI optimization/refactoring to reduce redundant dependency installations across parallel jobs. No application source code, E2E test files, test page objects, test fixtures, or app functionality was modified. Running E2E tests would not validate these CI infrastructure changes and would be wasteful. No performance tests are needed either since no app code was changed.

Performance Test Selection:
No application code was changed. These are pure CI infrastructure changes affecting how JS dependencies are installed and cached across CI jobs. No performance impact on the app itself.

View GitHub Actions results

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[Cal-L]

LGTM