Summary

Enhance the Playwright UI testing infrastructure to improve test resilience, developer experience, and alignment with the recommended docker-compose testing stack.

Problem

1. Endpoint mismatch: Default test target (localhost:8000) didn't match the recommended docker-compose nginx endpoint (localhost:8080)
2. Auth brittleness: Tests failed when admin credentials didn't match the running gateway, with no fallback mechanism
3. Poor preflight guidance: No validation or guidance before running tests, leading to confusing failures
4. Test data collisions: Hardcoded server names caused conflicts when tests ran multiple times
5. Missing artifact capture: No always-on screenshot/video targets for debugging intermittent failures

Changes

Configuration & Defaults

• Default TEST_BASE_URL changed from localhost:8000 to localhost:8080 (docker-compose nginx)
• Added playwright-preflight target that validates gateway availability and shows helpful guidance
• Made TEST_BASE_URL configurable via environment variable for all make targets

Authentication Resilience

• Added JWT cookie fallback (_set_admin_jwt_cookie()) when UI login fails with unknown credentials
• Fallback uses _create_jwt_token() to seed a valid admin JWT, bypassing form login
• Fallback can be disabled via PLAYWRIGHT_DISABLE_JWT_FALLBACK=true
• Auth tests now skip gracefully instead of failing when credentials are invalid

Test Stability

• Fixed admin page URL from /admin to /admin/ for consistent navigation
• Added UUID suffix to test server names to prevent naming collisions
• Improved login flow handling with better status detection

Artifact Capture

• Added make test-ui-screenshots for always-on screenshot capture
• Enhanced make test-ui-record to capture both videos and screenshots
• Updated .gitignore for test-results/, reports/, videos/, screenshots/

Documentation

• Updated TESTING.md with preflight guidance and new targets
• Updated tests/playwright/README.md with docker-compose workflow
• Clarified artifact storage locations

Technical Details

Testing

# Start the recommended stack
make testing-up

# Run tests with new defaults
make test-ui-headless

# Override endpoint if needed
TEST_BASE_URL=http://localhost:8000 make test-ui

Related Issues

• Parent Epic: [EPIC][TESTING][UI]: Comprehensive Playwright E2E Test Suite for MCP Gateway Admin UI #2519 ([EPIC][TESTING][UI]: Comprehensive Playwright E2E Test Suite)
• Related: [BUG][TESTING]: Playwright tests not updated to use admin email/password login credentials #2136 (Playwright tests not updated to use admin email/password login credentials)
• Related: [CHORE]: Implement comprehensive Playwright test automation for the entire MCP Gateway Admin UI with Makefile targets and GitHub Actions #255 (Implement comprehensive Playwright test automation)