The desktop chat store was dropping the previous assistant draft when a new user turn began because streaming text was cleared before it was flushed into message history. At the same time, the desktop OAuth flow was using an unregistered /api/haha-oauth/callback redirect URI, which caused provider authorization failures. This change flushes visible assistant drafts before starting a new turn, restores the OAuth redirect to the registered localhost callback, and adds a root callback handler while keeping the legacy API callback path compatible.
Constraint: The OAuth provider only accepts the registered localhost /callback redirect URI
Rejected: Keep the desktop-specific /api/haha-oauth/callback path | provider rejects unsupported redirect URIs
Rejected: Rely on message_complete to persist visible assistant text | next user turn can begin before that event arrives
Confidence: high
Scope-risk: moderate
Directive: Any UI-visible assistant draft must be flushed into messages before a new user turn resets streaming state
Tested: bun test src/server/__tests__/haha-oauth-service.test.ts src/server/__tests__/haha-oauth-api.test.ts src/server/__tests__/conversation-service.test.ts
Tested: cd desktop && bun run test src/stores/chatStore.test.ts
Tested: cd desktop && bun run lint
Not-tested: Manual end-to-end desktop OAuth login after reinstall