willmiao-ComfyUI-Lora-Manager/docs/library-switching.md

Preview Routes

Multi-library support and library switching have been removed. On upgrade, all configured library folder paths are merged into the active library, and the libraries / active_library keys are removed from settings.json. Legacy library-named caches are migrated to the default cache namespace. Multiple folder roots within that single library remain fully supported.

The preview thumbnails shown in the UI are served through a dynamic endpoint that resolves files against the currently configured folders at request time. This keeps previews available when model roots change without touching the aiohttp router.

How the dynamic preview endpoint works

• config.get_preview_static_url() now returns /api/lm/previews?path=<encoded>&v=<mtime_ns> for any preview path. The raw filesystem location is URL encoded so that it can be passed through the query string without leaking directory structure in the route itself. The v parameter carries the preview file's modification time so a rewritten preview (e.g. delete + recreate an LM-managed workflow) produces a fresh URL that bypasses the browser's day-long cache; the handler ignores it.【F:py/config.py†L398-L404】 Because the URL no longer ends with the media extension, clients must not pick between <img> and <video> with a suffix check: derive the extension from the decoded path value (static/js/utils/mediaTypes.js for the web UI, web/comfyui/mediaTypes.js for the ComfyUI widgets).
• PreviewRoutes exposes the /api/lm/previews handler which validates the decoded path against the directories registered for the current library. The request is rejected if it falls outside those roots or if the file does not exist.【F:py/routes/preview_routes.py†L5-L21】【F:py/routes/handlers/preview_handlers.py†L9-L48】
• Config keeps an up-to-date cache of allowed preview roots. Every time a library is applied the cache is rebuilt using the declared LoRA, checkpoint and embedding directories (including symlink targets). The validation logic checks preview requests against this cache.【F:py/config.py†L51-L68】【F:py/config.py†L180-L248】【F:py/config.py†L332-L346】

Both the ComfyUI runtime (LoraManager.add_routes) and the standalone launcher (StandaloneLoraManager.add_routes) register the preview routes instead of mounting a static directory per root. Preview URLs therefore continue to resolve correctly when the configured roots change.【F:py/lora_manager.py†L21-L82】【F:standalone.py†L302-L315】