README

Tab Count Chrome Extension
==========================

Tab Count shows the number of open tabs in Chrome's toolbar and provides a
keyboard-accessible list for switching to and closing tabs. The badge and list
can each show the current window or all windows.

Chrome Web Store: <https://chromewebstore.google.com/detail/tab-count/cfokcacdaonnckdmopmcgeanhkebeaio>

Development
-----------

Requires Chrome 121+ and Node 22+ for development. No runtime dependencies or
bundling step. Run `npm run check` for behavioral tests and JavaScript syntax
checks. Run `npm run package` to validate and produce the upload ZIP in `dist/`.
The packaging script requires the `zip` command (available on macOS and Linux).

To test manually, open chrome://extensions, enable Developer mode, choose
Load unpacked, and select `dist/extension` after packaging. Use a disposable
Chrome profile, especially when testing automatic closing. Reload the extension
after changing its files. See STORE.md for release and reviewer instructions.

Manifest V3 behavior
--------------------

All worker event listeners register synchronously. Chrome may stop the worker
when idle; no feature depends on an in-memory timer or activity-history object.

- `chrome.alarms` runs the optional unused-tab check hourly. The alarm is checked
  on every worker start and removed when the setting is turned off.
- Unused-tab closing uses Chrome's `tabs.Tab.lastAccessed` timestamp (Chrome
  121+) rather than maintaining a separate browsing record. It never closes
  active, pinned, playing, loading, incognito, or browser-internal tabs. Unknown
  or invalid timestamps are kept. The state is checked again before closing.
- Duplicate detection compares exact HTTP(S) URLs, supports more than two
  matches, and skips incognito tabs. Pending actions live in session storage so
  they survive worker suspension. Clicking a notification or its first button
  switches to the existing tab and closes the unchanged duplicate. Dismissing
  it or choosing Keep both keeps both tabs. Buttons depend on OS support; the
  notification body is also actionable.
- Settings apply immediately without reloading the extension. Old MV2 settings
  migrate when the popup or options page is first opened, preserving newer
  preferences. Legacy auto-close is left off until explicitly enabled again.

Privacy and permissions
-----------------------

Tab information stays in the browser. No network requests, remote favicons,
analytics, content scripts, or host permissions. `tabs` supplies titles, URLs,
and state for the list and optional management features; `storage` saves local
preferences and session notification actions; `alarms` supports the hourly
check; `notifications` displays opt-in duplicate prompts. Both optional features
are off by default. Auto-close may lose unsaved work in otherwise eligible tabs.

See PRIVACY.md for the published privacy policy and STORE.md for the store's
single-purpose statement, permission justifications, and release procedure.

Related contributions
---------------------

Duplicate detection and unused-tab closing were originally contributed by
rgluga. lordvorp's PR #16 also identified service-worker lifecycle and legacy
storage migration problems: <https://github.com/developerish/tab-count/pull/16>.
This release addresses those problems in the existing js/background.js layout,
using Chrome's own last-accessed timestamps and adding regression coverage.