# ADR-004: Works Square Owns The Desktop Authentication Lifecycle Boundary

## Status

Accepted and implemented on 2026-08-19.

## Context

The desktop client obtained tokens from Works Square but refreshed them directly against the custom identity service with an embedded OAuth client secret. That mixed issuer/client boundary made rotation dependent on two independently configured clients and could turn an otherwise valid persisted session into `invalid_grant`, returning the user to the login page hours later.

## Decision

- Renderer sends authentication operations only to Electron Main.
- Electron Main owns access/refresh tokens, encrypted persistence, refresh rotation, terminal failure cleanup, and the seven-day inactivity policy.
- Desktop login, mobile login, refresh, and logout use fixed Works Square `/api/auth/*` endpoints.
- Works Square owns the confidential upstream OAuth client configuration and proxies the lifecycle to the identity service.
- The desktop bundle must not contain an OAuth client secret or call the custom identity service directly.

## Consequences

- The matching Works Square server endpoints must be deployed before this client is released.
- OAuth credential rotation or upstream endpoint changes are server-side configuration changes rather than desktop releases.
- A terminal refresh `400` or `401` still fails closed and clears the local session; transient failures preserve the established retry behavior.

## Evidence

- Source commit: `dc776ff`
- Integration merge: `f52c2c8`
- Feature verification: 2,190 client tests passed, typecheck passed, Vite build passed, and lint reported no errors.