We support server-side filter generation today (sparse:oid, blob:none, etc.) but don’t implement the promisor-remote contract for partial clones beyond basic filter application. A promisor remote can be asked later for missing objects.

Scope

• Serve GET /objects/<sha> lazy-fetch requests.
• Advertise partial-clone capability correctly.
• Integrate with existing filter code so a client can clone blob:none, then later lazy-fetch a blob on demand.

Acceptance

• git clone --filter=blob:none <url> followed by git cat-file -p <blob-sha> succeeds (lazy fetch transparent).
• git fsck on the partial clone passes with promisor semantics.