Function obj_find_unique 

#[unsafe(no_mangle)]
pub unsafe extern "C" fn obj_find_unique(
    txn: *mut obj_read_txn_t,
    collection: *const c_char,
    index_name: *const c_char,
    key: *const u8,
    key_len: usize,
    out_id: *mut u64,
    out_payload: *mut *mut u8,
    out_payload_len: *mut usize,
) -> obj_error_t

Look up a single doc by index key on a Unique index. The caller pre-encodes key_bytes per M7’s order-preserving scheme. Returns OBJ_ERR_NOT_FOUND when no doc matches.

Safety

• txn must be live.
• collection, index_name, key follow the usual pointer rules; key may be NULL when key_len == 0.
• out_id, out_payload, out_payload_len must be writable.