Module binary 

The compiled binary form of .faf — FAFb v2 (re-export of faf-fafb).

Modules

canon

The canonical chunk table — FAFb v2 is CLOSED CANONICAL.

compile

Compile/decompile API for .faf ↔ .fafb conversion — FAFb v2, closed canonical.

error

FAFB Error Types

flags

FAFB Feature Flags

header

FAFB Header Implementation

identity

Content ID and file digest — computed, never stored.

priority

FAFB Priority System

section

FAFB Section Entry and Section Table

string_table

FAFb v2 String Table

Structs

CanonicalChunk

One canonical chunk: name, classification, default priority.

CompileOptions

Options for compilation

DecompiledFafb

A decompiled .fafb file with header, section table, string table, and raw data

FafbHeader

The 32-byte FAFB file header

Flags

Helper struct for working with flags

Priority

Priority level with semantic meaning

SectionEntry

A single section entry in the section table

SectionTable

The section table containing all section entries

StringTable

A string table mapping u8 indices to UTF-8 names

Enums

ChunkClassification

Chunk classification, stored in bits 0–1 of SectionEntry.flags.

FafbError

Errors that can occur when working with .fafb files

TruncationTier

Spec truncation tiers, dropped from the tail in this order.

Constants

CANONICAL_CHUNKS

The canonical chunk table — the complete, closed set of FAFb v2 section names, in serialization order. This IS the format: there is no chunk 14.

CLASSIFICATION_MASK

Classification mask for the low 2 bits of section flags.

FLAG_COMPRESSED

Content is zstd compressed

FLAG_EMBEDDINGS

Contains pre-computed embeddings

FLAG_MEMBERS

Carries __members__ (spec 2.0 structural; this crate does not write it)

FLAG_MODEL_HINTS

Contains model-specific hints

FLAG_PROVENANCE

Carries __provenance__ (spec 2.0 structural; this crate does not write it)

FLAG_RESOLVED

File is output of chain resolution (enterprise)

FLAG_SIGNED

Contains cryptographic signature

FLAG_STRING_TABLE

Contains a string table (always set in unified format)

FLAG_TOKENIZED

Contains token boundaries

FLAG_WEIGHTED

Contains attention weights

HEADER_SIZE

Header size in bytes

MAGIC

Magic number identifying FAFB files: “FAFB” in ASCII

MAGIC_U32

Magic number as u32 (little-endian)

MAX_FILE_SIZE

Maximum allowed file size (DoS protection): 10MB

MAX_SECTIONS

Maximum allowed section count (DoS protection)

PRIORITY_CRITICAL

Critical priority - never truncate (name, version)

PRIORITY_HIGH

High priority - truncate last (key_files, tech_stack)

PRIORITY_LOW

Low priority - truncate first (verbose context)

PRIORITY_MEDIUM

Medium priority - normal truncation (architecture, commands)

PRIORITY_OPTIONAL

Optional priority - can be omitted entirely

SECTION_ENTRY_SIZE

Size of a single section entry in bytes

STRUCTURAL_CHUNKS

Structural (__-prefixed) chunk names closed for spec 2.0.

VERSION

Library version

VERSION_MAJOR

Format major version

VERSION_MINOR

Current format minor version (additive changes)

Functions

canonical_chunk

Look up a canonical chunk by name.

canonical_rendering

Canonical text rendering: concatenation of content-chunk payloads in canonical table order. Each payload already begins with name:\n.

compile

Compile a .faf YAML source string into .fafb v2 binary bytes.

content_id

Content ID of a compiled .fafb.

content_id_of

Content ID from an already-decompiled file.

decompile

Decompile .fafb v2 binary bytes into a structured representation.

file_digest

File digest: SHA-256 over every byte of the file.

hex_sha256

SHA-256 as 64 lowercase hex characters, no 0x prefix.

is_canonical

Is this top-level key part of the canonical chunk set?

is_known_structural

True when name is on the closed structural list.

is_structural_name

True when name is structural (leading __), whether or not it is on the closed list. Structural chunks are excluded from the Content ID.

is_valid_member_path

__members__ paths are POSIX, relative to the root brick, and MUST NOT contain ...

source_date_epoch

Honour SOURCE_DATE_EPOCH when it is a valid u64. Spec MUST.

truncated_rendering

Canonical rendering after dropping whole priority tiers from the tail.

Type Aliases

FafbResult

Result type for FAFB operations