feat(domains): create domain-driven architecture for Phase 2

Chat Domain:
- Add types.ts with Message, Conversation, Agent types
- Add store.ts with Valtio-based state management
- Add hooks.ts with useChatState, useMessages, etc.
- Add index.ts for public API export

Hands Domain:
- Add types.ts with Hand, Trigger, Approval types
- Add machine.ts with XState state machine
- Add store.ts with Valtio-based state management
- Add hooks.ts with useHands, useApprovalQueue, etc.

Shared Module:
- Add types.ts with Result, AsyncResult, PaginatedResponse
- Add error-handling.ts with AppError, NetworkError, etc.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

desktop/src/shared/error-handling.ts

@@ -0,0 +1,105 @@
+/**
+ * Shared Error Handling
+ *
+ * Unified error handling utilities.
+ */
+
+/**
+ * Application error class with error code.
+ */
+export class AppError extends Error {
+  constructor(
+    message: string,
+    public readonly code: string,
+    public readonly cause?: Error
+  ) {
+    super(message);
+    this.name = 'AppError';
+  }
+
+  /**
+   * Create a AppError from an unknown error.
+   */
+  static fromUnknown(error: unknown, code: string): AppError {
+    if (error instanceof AppError) {
+      return error;
+    }
+    return new AppError(getErrorMessage(error), code, isError(error) ? error : undefined);
+  }
+}
+
+/**
+ * Network error class.
+ */
+export class NetworkError extends AppError {
+  constructor(message: string, public readonly statusCode?: number, cause?: Error) {
+    super(message, 'NETWORK_ERROR', cause);
+    this.name = 'NetworkError';
+  }
+}
+
+/**
+ * Validation error class.
+ */
+export class ValidationError extends AppError {
+  constructor(message: string, public readonly field?: string, cause?: Error) {
+    super(message, 'VALIDATION_ERROR', cause);
+    this.name = 'ValidationError';
+  }
+}
+
+/**
+ * Authentication error class.
+ */
+export class AuthError extends AppError {
+  constructor(message: string = 'Authentication required', cause?: Error) {
+    super(message, 'AUTH_ERROR', cause);
+    this.name = 'AuthError';
+  }
+}
+
+/**
+ * Type guard for Error.
+ */
+export function isError(error: unknown): error is Error {
+  return error instanceof Error;
+}
+
+/**
+ * Get error message from unknown error.
+ */
+export function getErrorMessage(error: unknown): string {
+  if (isError(error)) {
+    return error.message;
+  }
+  if (typeof error === 'string') {
+    return error;
+  }
+  return String(error);
+}
+
+/**
+ * Wrap error with code.
+ */
+export function wrapError(error: unknown, code: string): AppError {
+  return AppError.fromUnknown(error, code);
+}
+
+/**
+ * Check if error is a specific error class.
+ */
+export function isAppError(error: unknown): error is AppError {
+  return error instanceof AppError;
+}
+
+export function isNetworkError(error: unknown): error is NetworkError {
+  return error instanceof NetworkError;
+}
+
+export function isValidationError(error: unknown): error is ValidationError {
+  return error instanceof ValidationError;
+}
+
+export function isAuthError(error: unknown): error is AuthError {
+  return error instanceof AuthError;
+}

desktop/src/shared/index.ts

@@ -0,0 +1,31 @@
+/**
+ * Shared Module
+ *
+ * Common utilities, types, and error handling.
+ */
+
+// Types
+export type {
+  Result,
+  AsyncResult,
+  PaginatedResponse,
+  AsyncStatus,
+  AsyncState,
+  Entity,
+  NamedEntity,
+} from './types';
+
+// Errors
+export {
+  AppError,
+  NetworkError,
+  ValidationError,
+  AuthError,
+  isError,
+  getErrorMessage,
+  wrapError,
+  isAppError,
+  isNetworkError,
+  isValidationError,
+  isAuthError,
+} from './error-handling';

desktop/src/shared/types.ts

@@ -0,0 +1,58 @@
+/**
+ * Shared Types
+ *
+ * Common types used across domains.
+ */
+
+/**
+ * Result type for functional error handling.
+ */
+export type Result<T, E = Error> =
+  | { ok: true; value: T }
+  | { ok: false; error: E };
+
+/**
+ * Async result for promises.
+ */
+export type AsyncResult<T, E = Error> = Promise<Result<T, E>>;
+
+/**
+ * Paginated response for list endpoints.
+ */
+export interface PaginatedResponse<T> {
+  items: T[];
+  total: number;
+  page: number;
+  pageSize: number;
+  hasMore: boolean;
+}
+
+/**
+ * Common status for async operations.
+ */
+export type AsyncStatus = 'idle' | 'loading' | 'success' | 'error';
+
+/**
+ * Generic async state wrapper.
+ */
+export interface AsyncState<T, E = Error> {
+  status: AsyncStatus;
+  data: T | null;
+  error: E | null;
+}
+
+/**
+ * Entity with common fields.
+ */
+export interface Entity {
+  id: string;
+  createdAt: Date;
+  updatedAt: Date;
+}
+
+/**
+ * Named entity with name field.
+ */
+export interface NamedEntity extends Entity {
+  name: string;
+}