Move session cache initialization from per-request _build_app_context to
startup lifespan handler. The session cache type is now decided once at app
startup based on settings, making _build_app_context pure (read-only).
Changes:
- Move cache initialization logic to new _update_session_cache() in main.py
- Call _update_session_cache() during lifespan startup to initialize cache
- Remove three if/elif/elif branches mutating state.session_cache from _build_app_context
- Add cache swap logic to set_runtime_settings() in runtime_state.py to handle
runtime settings changes (e.g., setup wizard updates)
- Keep app.state.session_cache initialization in create_app() for test compatibility
This ensures:
- _build_app_context is pure and doesn't mutate app state on each request
- Session cache configuration decisions are centralized at startup
- Settings changes during runtime (via setup wizard) also trigger cache swap
- Cache initialization logic is isolated in one place
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
