Chrome extension modernization: jQuery/Handlebars removal, TypeScript migration, Vite build system, comprehensive testing, and Chrome Web Store compliance.

Mode: yolo
Depth: comprehensive
Parallelization: enabled
Workflow agents: research=on, plan_check=on, verifier=on
Model profile: quality

Files:
- STACK.md
- FEATURES.md
- ARCHITECTURE.md
- PITFALLS.md
- SUMMARY.md

Key findings:
- Stack: WXT framework with TypeScript, Vite, Vitest, Playwright
- Architecture: Event-driven service workers, storage-first state management
- Critical pitfall: Service worker state loss requires storage-based architecture

45 requirements across 7 categories:
- Build System (6)
- Code Quality (4)
- Testing (8)
- CI/CD (5)
- Web Store Compliance (5)
- Git Workflow (6)
- Code Migration (10)

Plus 6 v2 requirements deferred.

Phases:
1. Build Foundation: WXT/Vite + TypeScript + Biome
2. Core Migration: Service worker + URL matching
3. UI Migration: Popup + welcome to vanilla TS
4. Testing & Quality: Vitest + Playwright + coverage
5. Web Store Compliance: Privacy policy + permissions
6. CI/CD & Automation: GitHub Actions + versioning

Git workflow: feature branches, PR merges, phase tags
All 38 v1 requirements mapped to phases.

Phase 01: Build Foundation
- Implementation decisions documented
- Phase boundary established

Phase 1: Build Foundation
- Standard stack identified (WXT 0.20.x, TypeScript 5.9.x, Biome 2.3.x)
- Architecture patterns documented (entrypoints, config, TypeScript setup)
- Pitfalls catalogued (async main, modules conflict, CommonJS, sourcemaps)

Phase 01: Build Foundation
- 4 plan(s) in 3 wave(s)
- Wave 1: 01-01 (WXT/TS), 01-02 (Biome/Husky) - parallel
- Wave 2: 01-03 (static assets) - depends on 01-01
- Wave 3: 01-04 (verification checkpoint) - depends on all
- Ready for execution

- Replace Grunt/Webpack dependencies with WXT 0.20.13
- Add TypeScript 5.9.3 and @types/chrome
- Set package.json type to module for ESM support
- Create wxt.config.ts with manifest configuration
- Add minimal background.ts entrypoint for WXT prepare
- Generate .wxt/ directory with type definitions

Scripts: dev, build, zip, postinstall
Permissions: webNavigation, tabs, scripting, storage
Host permissions: *.zendesk.com

- Create tsconfig.json extending WXT-generated config
- Enable strict mode for all strict type-checking
- Set target ES2022 for modern JavaScript features
- Add noUncheckedIndexedAccess for safer array/object access
- Add noImplicitOverride for explicit method overrides
- Enable verbatimModuleSyntax for ESM enforcement

- Add biome.json with recommended rules and tab indentation
- Add lint, lint:fix, and format scripts to package.json
- Install @biomejs/biome devDependency
- Format TypeScript files with Biome style

- Add popup entrypoint with HTML, TypeScript, and CSS
- Add welcome page entrypoint with HTML and TypeScript
- All entrypoints are placeholders for Phase 3 UI migration
- Build produces loadable Chrome extension in .output/chrome-mv3/

- Install husky and lint-staged devDependencies
- Add prepare script to initialize Husky
- Add lint-staged config for TypeScript and JSON/HTML/CSS files
- Create .husky/pre-commit hook running lint-staged

- Add biome.json with recommended rules and tab indentation
- Add lint, lint:fix, and format scripts to package.json
- Install @biomejs/biome devDependency
- Format TypeScript/CSS files with Biome style
- Configure exclusions for legacy code, generated files, and planning docs

Tasks completed: 2/2
- Task 1: Configure Biome linter and formatter
- Task 2: Set up Husky and lint-staged for pre-commit hooks

SUMMARY: .planning/phases/01-build-foundation/01-02-SUMMARY.md

- Copy extension icons (16px, 48px, 128px) to public/images/icons/
- Copy i18n messages to public/_locales/en/messages.json
- Add appName and appDescription keys for Chrome i18n
- Update wxt.config.ts with icons and default_locale
- Use __MSG_appName__ for i18n-aware manifest name

- Install rollup-plugin-visualizer for bundle inspection
- Add conditional visualizer plugin in wxt.config.ts (ANALYZE=true)
- Add npm run analyze script for on-demand bundle stats
- Generate treemap visualization with gzip/brotli sizes

Tasks completed: 2/2
- Move static assets to public directory
- Add bundle visualizer for size analysis

SUMMARY: .planning/phases/01-build-foundation/01-03-SUMMARY.md

Tasks completed: 2/2
- Run comprehensive build verification (8 checks passed)
- Complete Phase 1 human verification (approved)

Phase 1 (Build Foundation) complete.
SUMMARY: .planning/phases/01-build-foundation/01-04-SUMMARY.md

- 4/4 plans executed successfully
- All BUILD-01 through BUILD-06 requirements verified
- All QUAL-01 through QUAL-03 requirements verified
- Human verified extension loads in Chrome

Phase 02: Core Migration
- Implementation decisions documented
- Phase boundary established

Phase 2: Core Migration
- Standard stack identified (no new deps - Phase 1 sufficient)
- Storage-first service worker architecture documented
- URL matching TypeScript patterns documented
- Pitfalls catalogued (termination, listener registration, serialization)

Phase 02: Core Migration
- 4 plan(s) in 3 wave(s)
- Wave 1: 02-01, 02-02 (parallel - types/url-matching, storage/tabs wrappers)
- Wave 2: 02-03 (service worker implementation)
- Wave 3: 02-04 (verification checkpoint)
- Ready for execution

- RouteType: 'lotus' | 'ticket' union type
- RouteMatch: interface for matched URL with subdomain, path, type
- UrlDetectionMode: 'allUrls' | 'ticketUrls' | 'noUrls' union
- ZendeskTabInfo: tab tracking interface with subdomain and lastActive
- StorageSchema: chrome.storage.local structure definition

- Implement storage-first architecture with loadState/saveState
- Add URL detection mode get/set with 'allUrls' default
- Add clearState for extension updates
- Silent fallback with console.warn on storage errors per CONTEXT.md
- Use Record<> not Map for JSON serialization

Exports: loadState, saveState, getUrlDetection, setUrlDetection, clearState

- matchZendeskUrl(): Parse URLs with native URL constructor
- buildZendeskUrl(): Reconstruct full Zendesk agent URL from RouteMatch
- isZendeskAgentUrl(): Quick check for agent interface URLs
- Uses pathname only, ignoring query params and hash per CONTEXT.md
- Rejects restricted routes (chat, voice, print)
- Ticket routes take priority over lotus routes

- Implement focusTab with window.focused for window-to-front behavior
- Add updateTabUrl for in-place navigation
- Add closeTab with silent ignore on already-closed
- Add queryZendeskTabs for agent tab discovery
- All operations in try/catch per RESEARCH.md pitfall #3

Exports: focusTab, updateTabUrl, closeTab, queryZendeskTabs

Tasks completed: 2/2
- Task 1: Create shared type definitions
- Task 2: Port URL matching logic to TypeScript

SUMMARY: .planning/phases/02-core-migration/02-01-SUMMARY.md

Tasks completed: 2/2
- Create type-safe storage wrapper
- Create type-safe tabs wrapper

SUMMARY: .planning/phases/02-core-migration/02-02-SUMMARY.md

- All 4 plans executed (design tokens, popup, welcome page, verification)
- 5/5 requirements marked complete (MIGR-01, MIGR-02, MIGR-08, MIGR-09, MIGR-10)
- Phase goal verified: jQuery/Handlebars fully replaced with vanilla TypeScript
- One contrast fix applied during verification (fe6c9ee)

Phase 04: Testing & Quality
- Implementation decisions documented
- Phase boundary established

Phase 04: Testing & Quality
- Standard stack identified (Vitest + WxtVitest + Playwright)
- Architecture patterns documented (co-located tests, fixtures)
- Pitfalls catalogued (service worker termination, state leaking)

Phase 04: Testing & Quality
- 6 plan(s) in 4 wave(s)
- Wave 1: test infrastructure setup
- Wave 2: unit tests (URL, storage, tabs, background)
- Wave 3: E2E tests with Playwright
- Wave 4: CI workflow integration
- Ready for execution

Address 5 checker issues:
- 04-04: Remove Task 1 (export from closure impossible), use behavior testing
- 04-06: Add .gitignore to files_modified
- 04-01: Add smoke test verifying fake-browser works (TEST-02)
- 04-04: Revise must_haves to reflect behavior testing approach
- 04-05: Change from Wave 3 to Wave 2 (E2E independent of unit tests)
- 04-06: Change from Wave 4 to Wave 3 (correct dependency calculation)

- Add vitest 4.x and @vitest/coverage-v8 for unit testing
- Add @playwright/test for E2E testing
- Add test, test:coverage, and test:e2e npm scripts

- Configure WxtVitest() plugin for Chrome API mocking
- Set v8 coverage provider with text, HTML, and lcov reporters
- Define 70% global coverage thresholds
- Exclude types.ts and UI entry files from coverage

- Add vitest.setup.ts with fakeBrowser.reset() before each test
- Create storage.test.ts smoke test to verify Chrome API mocking (TEST-02)
- Confirm fake-browser integration works with WxtVitest plugin

Tasks completed: 3/3
- Install test dependencies
- Create Vitest configuration with WXT plugin
- Create test setup with mock reset and smoke test

SUMMARY: .planning/phases/04-testing-quality/04-01-SUMMARY.md

- Configure testDir as ./e2e for test file location
- Single worker with no parallel execution for extension testing
- webServer command ensures extension is built before tests
- CI-specific retries and github reporter

- Test all 5 exported functions: loadState, saveState, getUrlDetection, setUrlDetection, clearState
- Verify default state behavior when storage is empty
- Verify state persistence and retrieval roundtrip
- Test silent fallback on storage errors (no throws)
- Uses fakeBrowser for stateful Chrome API mocking

- Create persistent context with extension loaded via Chrome args
- Wait for service worker event to derive extension ID
- Per RESEARCH.md Pitfall 4: prevents flaky tests from timing

- Test message handlers via storage observation (getStatus, setMode)
- Test storage-first architecture (loadState, saveState, clearState)
- Test findMostRecentTab selection logic through storage patterns
- 22 tests covering behavior without requiring internal exports

- Test matchZendeskUrl for valid URLs, restricted routes, invalid URLs
- Test buildZendeskUrl for URL construction
- Test isZendeskAgentUrl for agent vs non-agent URL detection
- 41 tests covering subdomain extraction, path normalization, query/hash handling
- 96.55% line coverage, 100% function coverage on url-matching.ts

- Test all 4 exported functions: focusTab, updateTabUrl, closeTab, queryZendeskTabs
- Verify focusTab activates tab and brings window to front
- Verify updateTabUrl returns boolean success for caller cleanup
- Test silent error handling when tabs don't exist
- Uses vi.spyOn for Chrome tabs API mocking

- Add termination/restart cycle simulation test
- Add in-memory state leakage verification test
- Add rapid restart cycle stress test
- Tests verify storage-first architecture under MV3 constraints

Tasks completed: 2/2
- Task 1: Create URL matching test file with comprehensive coverage
- Task 2: Verify edge cases and coverage gaps (verification pass)

SUMMARY: .planning/phases/04-testing-quality/04-02-SUMMARY.md

Tasks completed: 3/3
- Create storage module unit tests (16 tests, 100% coverage)
- Create tabs module unit tests (11 tests, 100% coverage)
- Verify coverage thresholds (both modules at 100%)

SUMMARY: .planning/phases/04-testing-quality/04-03-SUMMARY.md

Tasks completed: 2/2
- Task 1: Create background service worker unit tests
- Task 2: Test service worker state persistence (TEST-08)

SUMMARY: .planning/phases/04-testing-quality/04-04-SUMMARY.md

- Add popup.spec.ts with 3 tests for mode toggle UI
- Test popup loads with three mode options
- Test mode change persists via clicking labels
- Add mock-pages/agent-ticket.html for future navigation tests
- Move background.test.ts from entrypoints/ to src/ (WXT conflict)

Tasks completed: 3/3
- Playwright configuration for extension testing
- Extension fixtures with service worker waiting
- Popup UI E2E tests (3 tests passing)

SUMMARY: .planning/phases/04-testing-quality/04-05-SUMMARY.md

- Add lint job running Biome checks on PRs (QUAL-04)
- Add test job running unit tests with coverage
- Add build job with artifact upload
- Add e2e job running Playwright tests after build
- Upload coverage, build, and Playwright reports as artifacts

- Add coverage/, playwright-report/, test-results/ to biome excludes
- Fix noNonNullAssertion lint errors in welcome/main.ts with setText helper
- Exclude entrypoints/background.ts from coverage (tested via behavior tests & E2E)

All tests pass locally: lint, unit tests (98.41% coverage), build, E2E.

- Add coverage/ directory (Vitest coverage reports)
- Add playwright-report/ directory (Playwright HTML reports)
- Add test-results/ directory (Playwright test artifacts)

Tasks completed: 3/3
- Create GitHub Actions CI workflow
- Verify all tests pass locally
- Add .gitignore entries for test artifacts

SUMMARY: .planning/phases/04-testing-quality/04-06-SUMMARY.md

Phase 4 (Testing & Quality) complete - 90 unit tests, 3 E2E tests, CI gates.