feat(ui-test): Playwright ui tests foundation stage 0

[cjlg-soloio]

Description

Adds the Stage 0 foundation for Playwright page-level E2E testing of the kagent UI, running against a mocked backend with no cluster required.

The suite targets the one gap nothing else covers — multi-step user flows across components:

Tool	Covers
Storybook / Chromatic	Component render states
Jest	Logic
Cypress	Page-load smoke
Playwright (this PR)	Cross-component user flows

The core design challenge: the UI fetches data server-side via Next.js server actions, so browser-level page.route("**/api/**") intercepts nothing. Instead, this PR boots a dependency-free stub backend and redirects Next's server-side fetch to it via BACKEND_INTERNAL_URL — which getBackendUrl() in ui/src/lib/utils.ts already honors. Playwright's webServer block starts both the stub (:8899) and next dev (:8001) automatically.

This is foundation-only: config, stub backend, shared fixture, CI workflow, and a single smoke test. The helper/driver library and per-test scenarios land in Stage 1; feature flows in Stage 3 (see ui/playwright/README.md).

Files

New

File	Purpose
ui/playwright.config.ts	Boots stub + dev server; chromium project; CI-aware retries/workers; trace & screenshot on failure
ui/playwright/mocks/server.mjs	Dependency-free stub backend (Node http only); serves happy-path payloads mirroring src/types/index.ts; exposes /__mock/health & /__mock/reset
ui/playwright/mocks/data.ts	Typed spec-side data builders mirroring the stub's shapes
ui/playwright/fixtures/test.ts	Shared test/expect fixture; resets stub per test and bypasses first-run onboarding
ui/playwright/tests/smoke.spec.ts	Stage 0 smoke test — asserts the Agents list renders against the mock
ui/playwright/tsconfig.json	Extends UI tsconfig with node + Playwright types
ui/playwright/README.md	Test strategy, mocking rationale, conventions, roadmap
.github/workflows/ui-playwright.yaml	Standalone CI workflow (paths-filtered to ui/**); installs chromium, runs test:pw, uploads report

Modified

• ui/package.json — @playwright/test dev dep + test:pw / test:pw:ui / test:pw:debug scripts
• ui/package-lock.json — lockfile updates
• ui/.gitignore — ignores playwright-report, playwright/test-results, playwright/.cache

Testing

cd ui
npm install
npx playwright install chromium   # first time only
npm run test:pw

Playwright starts the stub backend and dev server automatically. The smoke test passes when the home page renders the Agents, no "Error Encountered" state appears, and no uncaught page errors occur. CI runs the same on any ui/** change.

Change type

test / ci — new test infrastructure and CI workflow. No product or runtime code changed.

Changelog

Stage 1 of 3 playwright tests for ui

[Copilot]

Pull request overview

Introduces a foundational Playwright E2E test setup for the UI, including a dependency-free stub backend and CI workflow, to enable end-to-end coverage of multi-step user flows against mocked API responses.

Changes:

• Added Playwright configuration, fixtures, and an initial smoke spec to validate the app loads against a stubbed backend.
• Implemented a standalone Node HTTP stub backend plus typed mock builders for specs.
• Wired Playwright into UI scripts, gitignore, and a dedicated GitHub Actions workflow.

Reviewed changes

Copilot reviewed 10 out of 11 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
ui/playwright/tsconfig.json	Adds Playwright-local TS config extending the UI tsconfig.
ui/playwright/tests/smoke.spec.ts	Adds initial Stage 0 smoke test asserting Agents page loads without error state/page errors.
ui/playwright/README.md	Documents Playwright scope, mocking approach, layout, and conventions.
ui/playwright/mocks/server.mjs	Adds dependency-free stub backend serving /api/* responses used by server actions.
ui/playwright/mocks/data.ts	Adds typed mock builders for assertions and future scenario plumbing.
ui/playwright/fixtures/test.ts	Adds shared fixture to reset stub and bypass onboarding via localStorage init script.
ui/playwright.config.ts	Adds Playwright runner config including webServer boot of stub + next dev.
ui/package.json	Adds Playwright test scripts and @playwright/test dev dependency.
ui/package-lock.json	Locks @playwright/test and updates Playwright packages.
ui/.gitignore	Ignores Playwright report/output directories.
.github/workflows/ui-playwright.yaml	Adds CI workflow to run Playwright tests on UI changes and upload reports.

Files not reviewed (1)

• ui/package-lock.json: Generated file

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[mesutoezdil]

dco is red

[Charlesthebird]

Looks good overall, just a few requests before merging:

• The package-lock diff due to node version not matching .nvmrc should be resolved.
• Cypress can be removed here.
• There should be a playwright video output.

[Charlesthebird]

Thanks for the updates!

[peterj]

@cjlg-soloio there are some CI failures: https://github.com/kagent-dev/kagent/actions/runs/29391678324/job/87276477369?pr=2180

[cjlg-soloio]

Superseded by #2262. This PR's branch name contained parentheses (feat(ui)--...) which broke the Docker buildx cache-scope shell interpolation in CI (/bin/sh: Syntax error: "(" unexpected), failing all build/e2e/upgrade jobs. Reopened from a paren-free branch (cjlg-soloio/playwrightTestsStage1) in #2262 with the same changes plus the ui-tests lint fix.