Module interfaces 

Pithy interface contracts — FROZEN at Phase 0.

This module defines the trait and type contracts that every other crate in the workspace depends on. Semver commitment: any breaking change to these types or traits requires a major-version bump and coordinated release across all consumers.

Copyright (c) 2026 Mikko Parkkola. All rights reserved. Licensed under PolyForm Noncommercial 1.0 + Pithy Attribution Rider.

Structs

Compressed

Output of a single compression operation.

CostEntry

Cost translation for a single record.

Integrity

Cryptographic fields of a signed record. Phase 1 must populate BOTH ed25519 and ML-DSA signatures (Day-1 PQC).

QualityScore

Optional quality measurement attached to a Record when the proxy ran a shadow comparison between the compressed and the prose arm at sample rate.

Record

A single signed measurement record. Wire format frozen at v0.1.

RecordId

Opaque id for a stored record.

StreamDelta

Per-stream delta between uncompressed and compressed.

Enums

FallbackReason

Reason the encoder fell back to a less aggressive format.

Format

One of the four compression formats defined by the Pithy specification.

LogError

Error type for the measurement log.

Model

The upstream LLM whose tokenizer rules the measurement.

SignerError

Error type from the signer.

TokenizerError

Error from the measurer path. Kept narrow so downstream code can fall back.

Traits

Encoder

A pass-through encoder interface. Implementors MUST preserve semantic fidelity of the compressed output at or above the Phase-0 kill-switch threshold (≥0.90 cosine similarity under the target LLM’s response).

MeasurementLog

Log of signed measurement records. Append-only; tampering detectable via merkle.

Measurer

Count real tokens for the target model. No estimation, no synthetic fallback.

Signer

Dual-signing facade. Implementations sign with BOTH ed25519 and ML-DSA.