Aging Tabs

Browser extension that auto-closes inactive tabs with visual aging feedback. Inspired by the original Aging Tabs (Dao Gottwald, ~2008) that died with Firefox 57.

The Problem

Growing tab count causes decision paralysis — you keep tabs open "just in case" and never close them. Hard auto-close loses information. Aging Tabs solves both: tabs visually fade as they age, then close with a safety net.

How It Works

1. Visual aging — inactive tab favicons progressively desaturate. Optional title prefix shows emoji indicators. At the final stage, the title blinks as a last warning
2. Auto-close — tabs inactive beyond a configurable timeout (default 30 min) are closed. Alternative: discard mode unloads from memory without closing
3. Graveyard — every auto-closed tab is saved to a searchable list with one-click restore. Sort by recent, domain, or alphabetically. Export/import as JSON
4. Smart immunity — pinned tabs, locked tabs, audible tabs, grouped tabs, whitelisted domains, and the active tab are never closed
5. Idle awareness — aging pauses when you're away from the computer and resumes when you return
6. Notification + undo — browser notification on close with click-to-restore

Features

• Favicon dimming: 5-stage progressive grayscale (0% → 25% → 50% → 75% → 100%)
• Title prefix: optional emoji indicators (off by default)
• Title blink warning before close
• Searchable graveyard popup with sort (Recent / By domain / A-Z)
• Badge count on extension icon
• Lock tab: right-click → Lock (prevent auto-close without pinning)
• Keyboard shortcut: Alt+L to lock/unlock current tab
• Domain whitelist
• Minimum tab count floor (0 = no floor, active tab always protected)
• Close empty tabs (about:blank, new tab)
• Tab groups protection (Firefox 138+ / Chrome)
• Discard mode: unload from memory instead of closing
• Grace period on fresh install
• Idle pause: aging only during active work time
• JSON export/import for graveyard backup (unlimited history with size = 0)
• Light/dark theme (follows browser)
• i18n: English + Russian
• Cross-browser: Chrome + Firefox (Manifest V3)
• Privacy-first: all data stays in browser, no external services

Install

From source

npm install
npm run build

Chrome: chrome://extensions → Developer mode → Load unpacked → select dist/chrome/

Firefox: about:debugging#/runtime/this-firefox → Load Temporary Add-on → select dist/firefox/manifest.json

Development

npm run watch                        # auto-rebuild on changes
npm test                             # run 104 unit + property-based tests
npx vitest run --coverage            # coverage report (98.7% stmts)
node scenarios/aging-tabs.spec.mjs   # run 19 e2e holdout scenarios
npm run package:firefox              # create .zip for AMO submission
npm run package:chrome               # create .zip for Chrome Web Store
npm run package:source               # create source .zip for AMO review

Tech Stack

• TypeScript (strict mode, zero type errors)
• esbuild for bundling
• webextension-polyfill for cross-browser compat
• vitest + fast-check for testing (104 unit/property tests)
• Code coverage: 98.7% statements, 100% functions (pure logic)
• Stryker mutation testing: 94.4% kill rate
• 19 e2e holdout scenarios via Playwright (100% satisfaction)
• Security audited (SSRF protection, message sender validation, CSP, input sanitization)
• Adversarial review: 8/8 bugs found and fixed

Note

While Aging Tabs includes multiple safety nets (graveyard, notifications, lock, whitelist), we recommend pinning or locking your most important tabs. Closed tab data is stored locally and may be lost if you clear browser data or uninstall the extension.

Privacy

All data stays in your browser. No accounts, no servers, no tracking, no network requests. See PRIVACY_POLICY.md.

License

MIT. See LICENSE.