Update yt-dlp to 2026.07.04 and refresh the bundled macOS runtime plus engine locks.
Route every non-media download through aria2 by removing the native HTTP fallback path, native GID handling, and the old direct-download harness.
Retry transient aria2 startup/RPC failures before failing, then show the real last error in the download row and Properties modal so Windows failures are diagnosable instead of silent.
Refresh docs and tests around the aria2-only file-download contract, and advance the Firefox extension submodule to its published wording cleanup.
- Update 'fetch_metadata' to detect 'Accept-Ranges' HTTP header
- Persist 'resumable' flag in DownloadItem across backend and frontend
- Add confirmation dialog when pausing non-resumable downloads (single and bulk actions)
- Improve UI for start/pause/options buttons by adopting the application accent color on hover
- Add backendRegisteredIds and backendDispatchPromises for single dispatch enforcement
- Add detach_download_for_reconfigure to safely modify properties of active downloads
- Add applyProperties logic handling completed, failed, paused, and active queues
- Add extractValidDownloadUrls and fix multi-url paste handling
- Setup vitest and add useDownloadStore unit tests for backend registration lifecycle
This commit replaces the frontend-imperative download dispatcher with a centralized backend `QueueManager`. It acts as the sole concurrency gatekeeper using a single `tokio::sync::Semaphore` across all download paths (aria2 RPC, native HTTP, yt-dlp media).
Backend Changes:
- **queue**: Added `QueueManager` to manage an ordered `VecDeque` of tasks, semaphore permits, and retirement debt (CAS resize).
- **commands**: Replaced direct start commands with `enqueue_download`, `enqueue_many`, `move_in_queue`, and `remove_from_queue`.
- **ipc**: Exported `DownloadStateEvent` and `QueueDirection` to the frontend.
- **tests**: Added 11 integration tests covering idle-parking, idempotent releases, CAS underflow prevention, and gid-completion races.
Frontend Changes:
- **store**: Made `useDownloadStore` reactive to the backend via the `download-state` event.
- **store**: Removed `processQueue` and introduced `pendingOrder` to track the accurate sequence of queued items.
- **ui**: Updated `DownloadItem` with queue visuals (clock icon, position badge).
- **ui**: Added Move Up/Down controls to interact with the backend queue reordering API.
NimBold