Module ecc_segment 

ECC RVF segment type definitions (WEFT-508).

Upstream rvf-types::SegmentType covers vector/index/federation codes (0x00–0x36). WeftOS ECC structures need domain-local discriminants that do not collide with:

• rvf-types (≤ 0x36)
• context-router research reservations (0x40–0x42)

We allocate the 0x50–0x5F block for ECC persistence payloads. Each variant wraps a CBOR (preferred) or JSON body; this module defines the type table + encode/decode helpers. Full migration of on-disk chain blobs onto these segments is follow-up work (see migration notes).

Segment table

Code	Name	Payload
0x50	CausalEdge	CausalEdge
0x51	CausalNode	CausalNode
0x52	Impulse	Impulse
0x53	CalibrationProfile	JSON profile blob (calibration / democritus)
0x54	CrossRef	CrossRef
0x55	SpectralCheckpoint	λ₂ / eigenvalue snapshot
0x56	CausalGraphSnap	Whole-graph snapshot envelope

Migration plan

1. Today: ad-hoc JSON / ExoChain CBOR events remain authoritative.
2. Writers may dual-write ECC segments alongside chain events.
3. Readers prefer ECC segments when present; fall back to legacy.
4. After one release cycle, stop writing legacy-only forms for new events.

Structs

CalibrationProfileSegment

Calibration profile payload (opaque JSON-friendly map for now).

EccSegment

Framed ECC segment: type byte + codec + payload bytes.

SpectralCheckpoint

Spectral checkpoint payload (λ₂ snapshot).

Enums

EccSegmentCodec

Codec for ECC segment payloads.

EccSegmentError

Errors for ECC segment codec.

EccSegmentType

WeftOS ECC segment discriminants (RVF type byte, domain 0x50–0x5F).

Functions

decode_ecc_segment

Decode payload bytes into T.

encode_ecc_segment

Encode a serializable payload as an EccSegment.

segment_from_wire

Parse wire bytes produced by segment_to_wire.

segment_to_wire

Wire bytes: [type:u8][codec:u8][payload...].