Module mmap 

CSR graph mmap cache (format v1).

The file .brain/graph.mmap is compiled from SQLite by CsrCompiler and read by CsrMmapGraph. It enables fast neighborhood expansion for agent context without re-querying SQLite for every hop.

Full layout: repository docs/MMAP_FORMAT.md.

Design notes

• All multi-byte integers are little-endian.
• Sections are size-validated before any access.
• Neighbor/vector accessors use explicit from_le_bytes loads (no unaligned from_raw_parts casts) — correct on all platforms and free of UB under mmap base-alignment variance.
• Publish path is write temp + rename for crash safety.

Structs

CsrCompiler

Compiler that bakes nodes, edges, and optional vectors into graph.mmap.

CsrMmapGraph

Memory-mapped CSR graph reader with safe unaligned loads.

Constants

FLAG_HAS_IDS

Flag bit: id string table is present after the vector matrix.

HEADER_SIZE

Header size in bytes.

MAGIC_BYTES

Magic bytes: RBRNMAP1

MMAP_VERSION

On-disk format version for graph.mmap.