The latter. 1. The client POSTs, this allocates a unique Location which the server returns and 2. the client saves this (e.g. in localStorage) along with loca

The latter. 1. The client POSTs, this allocates a unique Location which the server returns and 2. the client saves this (e.g. in localStorage) along with local file identifiers so it can be looked up later and can 3. query that URL to check how many bytes were already received, and then 4. PATCH the remaining bytes Repeat step 3 & 4 on failures/resumes.