Put Chunk

Append one chunk to the staging file at offset index * chunk_size.

Each chunk PUT is at most CHUNK_SIZE_BYTES of body — small enough to slip under any HTTP proxy cap, so a 1 GB upload arrives as many small requests instead of one big one. The sidecar {token}.meta.json records which indices have arrived so a client that drops mid-upload can resume from the last successful chunk.

The final=1 chunk is the last one for the file. After its bytes are written, this route flips the token state from pending to uploaded so the existing finalize_upload path works unchanged regardless of whether the file arrived in one request or many.