- Bind cancel context to all extension HTTP calls (fetch, httpGet, httpPost,
httpRequest, fileDownload, authExchangeCodeWithPKCE) so in-flight requests
are aborted when user cancels a download
- Make initDownloadCancel idempotent: return existing context if entry already
exists and preserve pre-cancelled state
- Force SAF output filename to match actual file extension when extension
returns a different format than requested (e.g. FLAC requested but M4A produced)
- Map ALAC/AAC quality to .m4a instead of falling through to default .flac