Code Contracts

Code contracts define the canonical spreading-code behavior for supported GNSS signal families. Acquisition, tracking, validation, and synthetic generation must consume these implementations instead of carrying parallel code truth.

Code Ownership Flow

flowchart LR
    family["signal family<br/>assignment and constants"]
    generator["code generator"]
    sampler["sampling helper"]
    proof["reference and correlation tests"]
    consumers["receiver validation<br/>synthetic workflows"]

    family --> generator --> sampler --> proof --> consumers

Published Guarantees

guarantee	owned by signal	downstream limit
canonical primary-code generation	code-family modules	receiver does not reimplement code truth
family assignments and constants	assignment tables and public constants	hidden table layout stays private
sampling helpers	sample_ca_code, L2C, L5, Galileo, BeiDou, and GLONASS samplers	receiver decides search and tracking policy
secondary-code helpers	family-specific secondary-code modules	nav owns decoded data semantics
reference catalogs	test fixtures and support modules	tests consume proof without becoming production API

Change Gates

• Add reference or correlation proof before documenting broader signal support.
• Keep a new family grouped by constellation and code family.
• Expose through the public API facade only when a downstream crate needs the public contract.
• Keep receiver ranking, ambiguity, lock, and reacquisition policy out of code contracts.

First Proof Check

Start with the signal code-family guide, code-family source, and public API facade. Then confirm behavior through the GPS C/A reference test, GPS L2C multiplex test, GPS L5 reference test, and Galileo E5 reference test.