Better Tab Session Manager

A fork of sienori/Tab-Session-Manager that exports your sessions to disk on a schedule, so a corrupted profile or a full disk can't take your tabs with it.

Upstream can only write a backup once, when the browser starts. If you leave your browser running for days, that backup never happens. This fork adds a real scheduler.

Upstream is excellent software, and this fork exists only to scratch one specific itch. The original README is preserved at readme-original.md.

The ifBackup setting upstream fires exactly one alarm, from onStartup:

browser.alarms.create("backupSessions", { delayInMinutes: 0.5 });

That is the whole backup story. Related upstream reports:

A "Back up on a schedule" option, on by default, that runs the existing Export Sessions routine at a time you pick.

The controls, in the order they appear:

• Frequency: every hour, day, or week.
• Time: wall-clock time in your own timezone. 06:00 means 06:00 where you are.
• Day of the week, for weekly schedules.
• Run missed backups on startup. If the browser was closed at 06:00, back up shortly after the next launch. Without this, "every day at 6am" silently never runs for anyone who isn't at their desk at 6am.
• Back up when the browser starts, which is upstream's original behaviour, now a toggle.

Weekly, every Monday at 03:30:

Hourly, dark theme:

In context on the options page:

With Individual backup enabled (the default), each run only writes sessions whose lastEditedTime is newer than the last run. An unchanged session costs nothing.

Files land under your browser download folder, in the folder named by the Save location setting. Paths, filenames, and overwrite behaviour match upstream's export. Nothing about the on-disk format changed, so these files import back into stock Tab Session Manager.

Two of them, both because data loss is the entire point of the fork:

A fresh install therefore starts backing up to ~/Downloads/TabSessionManager - Backup/ without being asked. If you'd rather it didn't, flip ifBackup back to false in src/settings/defaultSettings.js. Existing installs are unaffected either way, since initSettings() only fills in keys that are missing.

Scheduling uses one-shot alarms that re-arm after each run, rather than a repeating periodInMinutes: 1440. A fixed 24-hour period drifts off the wall clock every time DST shifts. Recomputing the next occurrence from a local Date keeps 06:00 at 06:00 year-round:

across spring-forward  ->  absolute elapsed: 20h, wall clock still 06:00
across fall-back       ->  absolute elapsed: 22h, wall clock still 06:00

No new permissions are needed. alarms and downloads were already in the manifest.

Everything reuses backupSessions(). The scheduler only triggers the existing export path, so incremental logic, folder naming, chunking for large session sets, and blob cleanup all behave as they do upstream.

New code lives in src/background/scheduledBackup.js. The rest is wiring in background.js, onInstalledListener.js, defaultSettings.js, OptionContainer.js (which gains a time input type), and _locales/en/messages.json.

npm install
npm run build          # dist/  packaged zips for Chrome and Firefox
npx webpack --config webpack.config.dev.js   # dev/chrome, dev/firefox  unpacked

Load dev/chrome via chrome://extensions, then "Load unpacked".

Cloud sync needs src/credentials.js exporting clientId and clientSecret. That file is gitignored and not in this repo. Without it every other feature builds and runs, and only Google Drive sync is unavailable.

npm test          # scheduling maths, no browser needed
npm run test:e2e  # loads the built extension in real Chromium

npm test transpiles the real scheduledBackup.js and injects mocks. It covers next-run computation across hour, day and week frequencies, month and year rollovers, malformed time input, DST boundaries, alarm re-arming, and the missed-backup catch-up. Run it under several zones:

for tz in Asia/Tokyo America/New_York Europe/London UTC; do TZ=$tz npm test; done

npm run test:e2e drives a real MV3 service worker. It asserts the defaults, reads chrome.alarms.getAll() to confirm the alarm lands on the right wall-clock time, toggles every control through the options UI, then fires the schedule and verifies the actual chrome.downloads.download calls. That includes checking that an unchanged second run exports nothing while an edited session does get re-exported.

Set CHROME_BIN to use a specific browser binary. npm run screenshots regenerates the images in this README.

Not planned. Judging by upstream's history, features tend to get absorbed and reimplemented rather than merged. Of 71 external pull requests, 29 were merged, and roughly a dozen of the closures were some version of "thanks, I implemented it myself." That is a legitimate way to run a project with 2.4k stars and one maintainer. It does mean a fork is the honest path for a personal itch. If sienori wants any of this, the code is MPL-2.0 like the original and they're welcome to it.

MPL-2.0, same as upstream. Modified upstream files stay MPL-2.0. See the original copyright in LICENSE.