Drop legacy runtime paths and role assignments across backend/frontend, and add upgrade-safe DB migration for existing installs. This aligns config, docs, tests, and UI to the agent-first architecture with codex as the only alternate engine.
Comprehensive 838-line design specification covering architecture,
provider types, database schema, API endpoints, encryption strategy,
frontend wireframes, and migration plan for the pluggable multi-provider
LLM system.
Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-opencode)