Refactor database architecture: dirty tracking, UUIDs, ghost files

[RetricSu]

No description provided.

[gemini-code-assist]

Code Review

This pull request transitions the library identification system from path-based to hash-based uniqueness and changes track keys from integers to UUID strings. It introduces a "dirty" flag mechanism for optimized database persistence and improves picture loading performance by eliminating N+1 queries. Feedback points out that resetting dirty flags before a successful transaction commit could lead to data loss. Additionally, the use of blocking I/O in LibraryItem::new during database loading is inefficient, and the non-deterministic UUID fallback for file hashes may cause duplicate entries if metadata retrieval fails.

[Copilot]

Pull request overview

This PR refactors the library/playlist persistence layer to reduce unnecessary DB writes (“dirty” tracking), switch identifiers to UUID strings, and improve library load performance by avoiding N+1 picture queries—aiming to address “ghost file” behavior and scalability concerns.

Changes:

• Introduces dirty flags for LibraryItem and Playlist to skip DB writes when nothing changed.
• Switches LibraryItem keys from usize to UUID String and propagates API changes across services/UI.
• Updates DB schema (adds file_hash, adds pictures index) and refactors picture loading to batch-fetch.

Reviewed changes

Copilot reviewed 16 out of 17 changed files in this pull request and generated 7 comments.

Show a summary per file

File	Description
src/lib/services/library_import.rs	Sends boxed LibraryItem commands to the app layer.
src/lib/playlist.rs	Adds playlist dirty tracking; updates key lookups to string keys; save now early-returns if clean.
src/lib/library.rs	Adds item dirty tracking + UUID keys + file_hash; batches picture loading.
src/app/services/player_service.rs	Updates removed-track return type to UUID string key.
src/app/services/persistence_service.rs	Makes library mutable during save so dirty flags can be reset.
src/app/services/lyrics_service.rs	Updates lyrics update path to use string keys and new library API.
src/app/services/library_service.rs	Adjusts LibraryCommand::AddItem to box/unbox library items.
src/app/services/db_persistence.rs	Allows Library::save_to_db to mutate/reset dirty flags.
src/app/db.rs	Bumps schema version, adds file_hash column and pictures index.
src/app/core.rs	Threads updated key types + mutable library into persistence/lyrics flows.
src/app/components/playlist_table/services.rs	Updates clear-lyrics action to use string keys.
src/app/components/playlist_table/columns.rs	Updates lyrics column API to use string keys.
src/app/components/playlist_table/actions.rs	Stores pending clear-lyrics actions as string keys.
src/app/components/player_component.rs	Updates playlist removal path to use string key lookup.
docs/DATABASE_ISSUES.md	Updates/shortens DB-issues documentation.
Cargo.toml	Adds uuid dependency.
Cargo.lock	Locks new dependency graph (uuid + transitive updates).

Comments suppressed due to low confidence (1)

docs/DATABASE_ISSUES.md:42

• This doc section removal is misleading: the code in Database::initialize_schema still drops all tables whenever schema_version changes, and this PR bumps SCHEMA_VERSION again. Either keep the warning/issue documented here, or (preferably) implement a non-destructive migration and update the doc to reflect the new behavior.

• Impact: Relying on SQLite's implicit type conversion (from TEXT to i64) can cause unexpected query failures, index misses, and potential panics if a generated usize exceeds i64::MAX.
• Solution: Use standardized unique identifiers (such as ULIDs or UUIDs), store them strictly as TEXT, and query them as strings.

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