# 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.
- Optional remembered username/password data is a separate Electron Main record. Packaged builds encrypt it with OS-protected storage; it is never Renderer-persisted or stored by Works Square.
- 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.
- Logout and mobile login preserve remembered-password data. A successful password login with the option cleared removes the previous record; unavailable secure storage disables the option.

## 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.
- Remembered-password persistence is convenience behavior rather than session authority. Its failure must not grant authentication or move password persistence to Works Square/Renderer.
- Packaged Windows and signed macOS still require a smoke covering save, restart restore, unchecked-login clear, and the absence of a development Keychain prompt.

## Evidence

- Source commit: `dc776ff`
- Integration merge: `f52c2c8`
- Feature verification: 2,190 client tests passed, typecheck passed, Vite build passed, and lint reported no errors.
- Remember-password source/integration: `990639f` / `2b9f84e`; 79 focused tests, typecheck, scoped lint, and Renderer/Main/Preload/utility build passed.