api contract shapes

Contract shapes

Purpose

Contract shapes define the JSON and command payloads shared by Rust and TypeScript. They keep backend workflows, browser mode, desktop mode, and frontend state aligned.

Main contracts

Contract	Rust source	TypeScript source
File load response	`src/presentation/responses.rs`	`frontend/src/types/api.ts`
Mapping request/response	`src/backend/requests.rs`, `src/presentation/responses.rs`	`frontend/src/types/api.ts`
Compare request/response	`src/backend/requests.rs`, `src/presentation/responses.rs`	`frontend/src/types/api.ts`
Pair-order selection	`src/backend/requests.rs`	`frontend/src/types/api.ts`
Snapshot load response	`src/backend/requests.rs`	`frontend/src/types/api.ts`
Error body	`src/backend/error.rs`	`frontend/src/services/http.ts`, `frontend/src/services/tauri.ts`

Shape rules

Rust uses serde snake_case for most wire fields. Frontend types in frontend/src/types/api.ts mirror those names rather than converting them to camelCase. This keeps transport helpers simple and reduces accidental field drift.

Key source files

File	Purpose
`src/backend/requests.rs`	Request DTOs and validation errors.
`src/presentation/responses.rs`	Response DTOs and conversions.
`src/backend/error.rs`	Error DTO shape and status mapping.
`frontend/src/types/api.ts`	Frontend wire types.
`tests/response_contracts.rs`	Contract regression tests.