nx_blob_store.nx

nx_blob_store.nx -- content-addressed blob store (L0 storage substrate). ST-1 milestone of NISHI_STORAGE_SUBSTRATE_ROADMAP.md. Foundation of the 6-layer storage stack; every higher layer (journal, K/V, schema registry, peer sync, mount adapter) ultimately stores bytes here keyed by SHA-256. V1 model: put_blob(bytes, len) -> 32-byte hash Compute SHA-256 over the input bytes. If hash already present, return existing hash (DEDUP). Otherwise allocate a private copy of the bytes + add an entry. get_blob(hash, out_buf, max_len) -> actual_len Linear-scan entries for the matching hash. If found: assert blob_len <= max_len; copy to out_buf; return blob_len. If not found OR oversized: return -1. has_blob(hash) -> 0/1 V1 scope: - In-memory store only (file-backed deferred to ST-2) - Fixed maximum entries (NX_BLOB_STORE_CAPACITY) to keep allocation deterministic - Linear-scan index (O(n) per lookup); hash-table queued for ST-2 - Hash representation: 4 i64 fields (32 bytes total, LE-packed) to avoid u8[32] in struct (NishiLang convention is i64 fields) Deferred per roadmap: - File-backed persistence (ST-2) - Open-addressing hash table for O(1) lookup (ST-2) - Content-defined chunking for large blobs (ST-2.5) - Free-list management; current store is APPEND-ONLY (Cardinal 13 -- "tombstoned" blobs would compose via L1 journal entries marking them is_current=0 rather than actually freeing) - Concurrent access (multi-thread / multi-process) (ST-4+) genealogy_id: git_loose_objects_2005 + nix_store_2003 + ipfs_2015 + cardinal_2026-05-20_storage_substrate