Breaking Changes

• SettingsManager persistence semantics changed for SDK consumers. Setters now update in-memory state immediately and queue disk writes. Code that requires durable on-disk settings must call await settingsManager.flush().
• AuthStorage constructor is no longer public. Use static factories (AuthStorage.create(...), AuthStorage.fromStorage(...), AuthStorage.inMemory(...)). This breaks code that used new AuthStorage(...) directly.

Added

• Added SettingsManager.drainErrors() for caller-controlled settings I/O error handling without manager-side console output.
• Added auth storage backends (FileAuthStorageBackend, InMemoryAuthStorageBackend) and AuthStorage.fromStorage(...) for storage-first auth persistence wiring.
• Added Anthropic claude-sonnet-4-6 model fallback entry to generated model definitions.

Changed

• SettingsManager now uses scoped storage abstraction with per-scope locked read/merge/write persistence for global and project settings.

Fixed

• Fixed project settings persistence to preserve unrelated external edits via merge-on-write, while still applying in-memory changes for modified keys.
• Fixed auth credential persistence to preserve unrelated external edits to auth.json via locked read/merge/write updates.
• Fixed auth load/persist error surfacing by buffering errors and exposing them via AuthStorage.drainErrors().