Update implementation_plan.md with a detailed refactor plan that splits
`chatInitActor` into two independent actors (`loadQuotaActor` +
`loadHistoryActor`) and redesigns the history loading flow to follow
local → network → save semantics so the UI sees local data first,
then network data.
Key changes outlined in the plan:
- Add new events: `ChatQuotaLoaded`, `ChatHistoryLocalLoaded`,
`ChatHistoryNetworkLoaded`, `ChatHistorySyncDone`
- Remove dead-code `ChatInit` event
- Extend `ChatState` with `quotaLoaded` and `historyLoaded` flags
- Use an `always` barrier in `guestSession.initializing` and
`userSession.initializing` so both tasks must complete before
transitioning to `ready`
- Guest init runs `loadQuota` + `loadHistory` in parallel; non-guest
init runs `chatWebSocket` + `loadHistory` as independent tasks
Also adds `implementation_plan` to .gitignore.
Move new AuthPlatform(provider).signIn() out of UI components and into
the auth state machine. UI now dispatches AuthGoogle/FacebookLoginSubmitted
events; a new oauthSignIn actor inside the machine calls next-auth/react's
signIn(provider). Errors and the OAuth redirect window are exposed via
the existing state.isLoading / state.errorMessage surface, removing the
local busy / error state in auth-facebook-panel.
Co-Authored-By: Claude <noreply@anthropic.com>