Reading Progress & Re-read History

Codex tracks two separate things about what you read, and it helps to know which is which:

	Holds	Changed by
Reading progress	where you are right now in a book	reading, marking read/unread
Read history	every time you have finished a book	finishing a book, or clearing history

Progress is current state. History is a permanent log. Marking a book unread resets the first and leaves the second alone, which is what lets you re-read a favourite series without pretending you never read it.

Reading progress

Your position is saved as you read, and syncs across devices and clients:

• The Continue button on a book, and the Keep Reading and On Deck rows on the home page, all come from this.
• A book counts as read when you reach the last page, or when you use Mark as Read.
• Mark as Unread discards your position entirely, putting the book back to never-opened.

Progress arriving from a Komga-compatible app, a KOReader device or an external tracker sync is treated exactly the same as progress from the built-in reader.

Underneath, your position is worked out from a log of reading sessions rather than stored as a single number. That is what stops a device syncing late after being offline from dragging you backwards: sessions are ordered by when the reading happened, not by when they reached the server. If you are building a client, see Reading Sessions for the contract.

Read history

Every time you finish a book, Codex records the completion: when that pass started and when it finished. Book and series pages show the result:

You've finished this book 2 times, last on 5 Mar 2025

Expand the section to see each read-through with its dates. The section is hidden entirely on anything you have never finished, so it only appears once there is something to show.

What counts as finishing again

A new entry is recorded when you finish a book after marking it unread. Marking unread is the signal that a new read-through has started.

That distinction matters because of what it excludes:

• Tapping back a page and forward again does not count twice. Turning back from the last page technically un-finishes the book, and turning forward finishes it again, but it is obviously the same read-through and Codex treats it as one.
• Re-sending "completed" does not count twice. Some clients re-assert the read state on every sync; that never inflates the count.
• Re-reading without marking unread is not counted. If you scroll back to page 1 while your progress is still there, Codex cannot tell that apart from browsing backwards through a long volume, so it stays one read-through. Mark the book unread first if you want the re-read recorded.

Series history

A series counts as read once every book in it has been read. So the series count is the lowest count across its volumes, not the highest:

• Read all six volumes: the series has been read once.
• Re-read volume 1 only: still once, because volumes 2-6 have only had one pass.
• Re-read all six: twice.

Each series entry spans from the earliest volume start of that pass to the last volume finish, so it describes when you were reading the series as a whole.

Adding a new volume to a series you had finished drops the series count to zero, and the history section disappears from the series page. That is intended: with an unread volume in it, the series is no longer one you have read from end to end, so there is no completed pass to report.

Nothing is deleted. Every volume keeps its own read-throughs on its own page, and the series count returns as soon as you finish the new volume. Only the series-level view goes quiet in the meantime, which for an ongoing series is most of the time.

Clearing history

History can be cleared at three scopes. None of them touch your reading progress: books stay read or unread exactly as they are.

Scope	Where	Clears
One book	the history section on a book page	that book's completions
One series	the history section on a series page	every book in that series
Everything	Settings → Profile → Account → Reading History	your whole library

Each asks for confirmation first. Clearing is per-user: it never affects anyone else's history, and no user can see or clear another's.

Removing a single read-through

Clearing is the blunt instrument. If one entry is simply wrong (a re-read recorded that never happened, or a duplicate from an app re-asserting a completion), expand the history on the book page and remove that entry alone. The rest of the book's history stays.

Series history has no per-entry removal, because a series read-through is not a stored record: it is worked out from its books, and counts as one pass only once every volume has been finished that many times. Removing the entry from whichever book is holding the count up updates the series straight away. Since the series number is the lowest count across its books, it only moves if that book was the one setting it.

What is not recorded

• Abandoned reads leave no trace. Marking a book unread at page 50 without finishing records nothing. A completion log should not contain "gave up at page 50".
• Nothing appears on library grid cards. Re-read counts show on book and series detail pages only, so browsing a library does not have to compute them for every card.
• Read lists have no completion count. History is tracked for books, and rolled up to series.

For existing libraries

Books you had already finished before this feature existed are counted: the first upgrade records one completion for every book currently marked read, dated from its completion time where that was stored and from its last-updated time otherwise. You do not need to re-read anything to get a starting count.