Track and highlight visited and watched* fanfiction links across the following sites: AlternateHistory*, DarkLordPotter*, QuestionableQuesting*, SpaceBattles*, SufficientVelocity*, FanFiction, HPFanfiction, PatronusCharm, also highlight them in some old subreddits.
Track and highlight visited and watched links on these sites:
- visited & watched (Xenforo only): AlternateHistory, DarkLordPotter, QuestionableQuesting, SpaceBattles, SufficientVelocity
- visited: (m.)fanfiction.net, hpfanfiction.org, patronuscharm.net.
- Old reddit: no tracking, but highlights visited links in a few subs (hardcoded for efficiency).

Tested on Firefox|Edge, on desktop|mobile, with ViolentMonkey|TamperMonkey.
Note: Not recommended for FFN since I never use this site. If it interacts badly with other scripts, you can delete @include fanfiction.net above the code.
Modes: Auto/Manual mode footer toggle on the left (persists between updates).
- Auto mode: links are marked visited when you click on them.
- Manual mode (default): you must click the top title inside the thread.
It used to default to Auto, but I often want to peek at a thread without marking it seen, so manual marking is a lot more convenient.
Features:
• When a link is clicked, add its {id} and Xenforo {name}* to plugin storage.
• Highlight visited threads in purple (by id).
• Highlight names visited on another forum in pink (across some Xenforo).
• Highlight watched threads in yellow (looks for the native Xenforo watched bell icon) Note: Icon not present in Search only Forum view.
• Add TXT export Backup/Restore buttons at the bottom of the page, and Remove latest highlight with 20s name+link popup.
• Turn the main title into a self-referential link (allows self-visiting in Manual mode).
• Multiple tab support, cache safe (no corruption from stale GM storage on back-forward navigation), live concurrent updates.
Note: My score script comes with a Xenforo-exclusive footer toggle to hide seen threads.
Also recommended:
- Jump button: Instantly scroll up to click the title, useful in [Manual mode] on mobile.
- Bookmarks list: See Xenforo bookmarks better, useful to mark for later or jump back in a watched thread.
Optional (Paid) feature:
For Backblaze B2 owners, you can set up auto-upload to stop worrying about backups or loosing your phone. Simply create a bucket + application key for this script, then long press this script's Backup button 4s and paste this JSON to activate the feature: {"AUTH_TYPE":"B2","KEY_ID":"...","APP_KEY":"...","BUCKET_ID":"..."}. It will push a GZIP of the TXT backup to the bucket on each change. Only tested in Manual mode, as you need to wait a second after tapping the title. Expect a longer wait every 24h to reacquire the bucket.