[BUG] when LM fails to create hardlinks, it copies and deletes original file

[kyleviloria]

What happened?

with Use hard links (same file system) checked, Library Manager copies and deletes the original downloaded file when hard linking fails

Expected behavior

LM should create a hardlink in library folder from downloaded file in downloads folder; if it fails, state why and allow user to address it

Steps to reproduce

1. download book into watched folder (Enable Watch Folder checked, folder mounted appropriately in compose file)
2. scan/process files

Environment

• Version: v0.9.0-beta.134
• Platform: Docker
• Library size: ~20 books

Logs

[library-manager] 
2026-04-17 18:26:51,431 - INFO - [LAYER 1] OpenLibrary matched: Joseph Lam - Creation Stories of the Ancient World
[library-manager] 
2026-04-17 18:26:52,852 - INFO - OpenLibrary found: Joseph Lam - Creation Stories of the Ancient World
[library-manager] 
2026-04-17 18:26:55,554 - INFO - Watch folder: Identified as Joseph Lam - Creation Stories of the Ancient World
[library-manager] 
2026-04-17 18:26:55,660 - WARNING - Hard link failed, copy+delete: 01 - Opening Credits.mp3
[library-manager] 
2026-04-17 18:26:55,747 - WARNING - Hard link failed, copy+delete: 02 - About Joseph Lam.mp3
[library-manager] 
2026-04-17 18:26:55,845 - WARNING - Hard link failed, copy+delete: 03 - Lecture 1 Creation Stories and Why They Matter.mp3
[library-manager] 
2026-04-17 18:26:57,528 - WARNING - Hard link failed, copy+delete: 04 - Lecture 2 Reading Metaphor in Creation Stories.mp3
[library-manager] 
2026-04-17 18:26:59,630 - WARNING - Hard link failed, copy+delete: 05 - Lecture 3 Mesopotamian Creation Enuma elish.mp3
[library-manager] 
2026-04-17 18:27:01,195 - WARNING - Hard link failed, copy+delete: 06 - Lecture 4 The Mesopotamian Flood The Atrahasis Epic.mp3
[library-manager] 
2026-04-17 18:27:02,904 - WARNING - Hard link failed, copy+delete: 07 - Lecture 5 Egyptian Gods of Creation.mp3
[library-manager] 
2026-04-17 18:27:04,453 - WARNING - Hard link failed, copy+delete: 08 - Lecture 6 Egyptian Approaches to Creation.mp3
[library-manager] 
2026-04-17 18:27:05,970 - WARNING - Hard link failed, copy+delete: 09 - Lecture 7 The Storm God's Supremacy in the Baal Cycle.mp3
[library-manager] 
2026-04-17 18:27:07,637 - WARNING - Hard link failed, copy+delete: 10 - Lecture 8 Hittite Creation in the Kumarbi Cycle.mp3
[library-manager] 
2026-04-17 18:27:09,221 - WARNING - Hard link failed, copy+delete: 11 - Lecture 9 Greek Creation in Hesiod's Theogony.mp3
[library-manager] 
2026-04-17 18:27:10,735 - WARNING - Hard link failed, copy+delete: 12 - Lecture 10 Seven Days of Creation in Genesis.mp3
[library-manager] 
2026-04-17 18:27:12,416 - WARNING - Hard link failed, copy+delete: 13 - Lecture 11 The Garden of Eden in Genesis.mp3
[library-manager] 
2026-04-17 18:27:13,913 - WARNING - Hard link failed, copy+delete: 14 - Lecture 12 Creation Stories and the Present.mp3
[library-manager] 
2026-04-17 18:27:15,462 - WARNING - Hard link failed, copy+delete: Creation Stories of the Ancient World.jpg
[library-manager] 
2026-04-17 18:27:15,524 - WARNING - Hard link failed, copy+delete: Creation Stories of the Ancient World.pdf

Screenshots

[deucebucket]

Fix merged in beta.147 (#210 → develop, commit 7864dcf).

Live-tested against the maintainer's running Library Manager instance (1193-book library) with three scenarios:

Scenario	Config	Result
Cross-fs + hardlinks (your bug)	watch on one volume, output on another, watch_use_hard_links=true	✅ Clean error in log, source file untouched in watch folder, nothing written to the target library
Same-fs + hardlinks	both on same volume, hardlinks on	✅ True hardlink created (same inode, nlink=2 on both paths)
Non-hardlinks	hardlinks off	✅ Normal move, source removed, dest has nlink=1

Log output from your exact failure mode now reads:

ERROR - Watch folder: Failed to move Test Author - Hardlink Cross FS Test:
Hard link failed: watch folder and library are on different filesystems.
Hard links require both paths on the same volume. Move your library to the
same volume as the watch folder, or disable 'Use hard links' in Settings.
Source files were not modified.

Once beta.147 is published, your watch folder will stop copy+deleting. Two ways you can fix the underlying setup:

1. Recommended: mount your library volume and watch folder on the same filesystem in docker-compose (e.g. both under /data).
2. Alternative: uncheck Use hard links (same file system) in Settings — LM will fall back to moving files (which always works, but consumes disk in the library and removes the original from your watch folder).

@kyleviloria — please confirm once you've pulled beta.147 and verified your own downloads behave correctly. Leaving this open until you confirm on your side.

[deucebucket]

Fix is in — #210 merged to develop as beta.147, release PR to main up at #212. Once that merges :latest will rebuild with the fix. If you want it right now, ghcr.io/deucebucket/library-manager:develop has it.

What was actually happening on your end: your watch folder and library were on different filesystems (different Docker volume mounts), so os.link() was failing with EXDEV. Old code caught that and fell back to copy+delete — which is exactly the wrong thing to do. New code checks st_dev up front, refuses if they don't match, and leaves your source files alone with a clear error.

If you want hard links to actually work, mount your watch folder and library on the same volume in your compose file. Otherwise just uncheck Use hard links in Settings and it'll move files normally.

Appreciate the report with full logs — made this easy to track down.