Migrate build system from Webpack to WXT

[skid-dev]

Summary

• Replace Webpack 5 + hand-authored src/manifest.json with WXT: manifest is now generated from wxt.config.ts + entrypoint discovery in src/entrypoints/.
• Background, popup, and all 9 dynamically-injected content scripts are now WXT entrypoints. Output paths are preserved (background.js, popup.html, launcher_homepage.js, etc.) so existing chrome.scripting.executeScript({ files: [...] }) and insertCSS call sites in src/background/events/injects/** keep working without changes.
• CSS assets moved into public/ for verbatim copy at the same root paths.
• Build output moved from dist/ → .output/chrome-mv3/. bun run zip produces a Web-Store-ready zip at .output/<name>-<version>-chrome.zip.

The migration is intentionally minimal — chrome.* globals are left in place (WXT runs them as-is), src/storage/ is unchanged, and React isn't pulled into the popup. All of those can be follow-ups.

What changed

Area	Before	After
Build system	webpack.config.cjs (5+ loaders, 8 deps)	wxt.config.ts (~25 lines)
Manifest	static src/manifest.json	generated from wxt.config.ts + entrypoints
Background	top-level chrome.*.addListener(...) calls	inside defineBackground(() => { ... })
Content scripts	bundled by Webpack, copied to dist/	defineUnlistedScript(() => { ... }) in src/entrypoints/*.ts
CSS	CopyWebpackPlugin patterns	public/**/*.css
Dev workflow	bun run dev → Webpack watch	bun run dev → Vite + HMR + auto-launched browser
Firefox	not supported	bun run build:firefox works for free

Code review cleanups (from /simplify)

• Extract show_detection_banner() helper used by detect_domain and detect_rss_feed (kills ~22 lines of duplicate banner code per file).
• Switch detect_domain / detect_rss_feed to use set_setting() instead of inlining chrome.storage.sync.get → mutate → set.
• Split set_setting() into its own file so content-script entrypoints don't transitively pull in poll_feed / fast-xml-parser. This saves ~63 kB per detect_* bundle (detect_schooltape.js: 64.74 kB → 1.37 kB).
• Collapse mirrored addedNodes/removedNodes branches in detect_schooltape.ts into a handle_stylesheet_change() helper.
• Trim verbose web_accessible_resources list to glob patterns.
• Drop redundant compile npm script.
• Remove duplicated "Load unpacked" steps in README.

Total bundle size went from 548 kB (post-naive-migration) to 485 kB after the cleanup — actually smaller than what Webpack was producing, because the set_setting split also fixes a pre-existing transitive-import bloat in detect_schooltape.js.

Test plan

• bun run typecheck passes
• bun run build produces all 11 expected JS entries + 9 CSS files + popup.html + manifest.json
• bun run zip produces .output/schoolbox-chrome-extension-1.3.0-chrome.zip
• Manual: load .output/chrome-mv3/ as unpacked extension in Chrome
• Manual: verify popup opens from toolbar icon
• Manual: verify Ctrl+K launcher works on LMS homepage
• Manual: verify news-search autocomplete still works
• Manual: verify post-history diffs render on edited posts
• Manual: verify SchoolTape detection toggles schooltape_compatibility when SchoolTape installs/removes its stylesheet

The migration plan and full WXT reference are saved in ~/.claude/plans/pure-bouncing-cat.md.

🤖 Generated with Claude Code