feat(renderer): command store (action registry for menu/shortcut/toolbar)

- useCommandStore: register/unregister/registerMany/dispatch/get
- keyed by id (e.g. 'file.open', 'view.toggleSidebar')
- TDD: 10 unit tests covering register, dispatch, unregister, batch
- foundation for Phase 6 native menu + toolbar wiring

src/renderer/stores/command-store.ts

@@ -0,0 +1,35 @@
+import { create } from 'zustand';
+
+export type CommandId = string;
+
+export type CommandHandler = (args?: unknown) => void | Promise<void>;
+
+interface CommandState {
+  handlers: Record<string, CommandHandler>;
+  register: (id: CommandId, handler: CommandHandler) => void;
+  registerMany: (handlers: Record<string, CommandHandler>) => void;
+  unregister: (id: CommandId) => void;
+  dispatch: (id: CommandId, args?: unknown) => void;
+  get: (id: CommandId) => CommandHandler | undefined;
+}
+
+export const useCommandStore = create<CommandState>((set, get) => ({
+  handlers: {},
+  register: (id, handler) =>
+    set((s) => ({ handlers: { ...s.handlers, [id]: handler } })),
+  registerMany: (handlers) =>
+    set((s) => ({ handlers: { ...s.handlers, ...handlers } })),
+  unregister: (id) =>
+    set((s) => {
+      const next = { ...s.handlers };
+      delete next[id];
+      return { handlers: next };
+    }),
+  dispatch: (id, args) => {
+    const handler = get().handlers[id];
+    if (handler) {
+      void handler(args);
+    }
+  },
+  get: (id) => get().handlers[id],
+}));

tests/unit/stores/command-store.test.ts

@@ -0,0 +1,80 @@
+import { describe, it, expect, beforeEach, vi } from 'vitest';
+import { useCommandStore, CommandHandler } from '@/stores/command-store';
+
+describe('useCommandStore', () => {
+  beforeEach(() => {
+    useCommandStore.setState({ handlers: {} });
+  });
+
+  it('register stores a handler keyed by id', () => {
+    const handler = vi.fn();
+    useCommandStore.getState().register('file.open', handler);
+    expect(useCommandStore.getState().handlers['file.open']).toBe(handler);
+  });
+
+  it('register overwrites any existing handler for the same id', () => {
+    const a = vi.fn();
+    const b = vi.fn();
+    useCommandStore.getState().register('file.open', a);
+    useCommandStore.getState().register('file.open', b);
+    expect(useCommandStore.getState().handlers['file.open']).toBe(b);
+  });
+
+  it('dispatch invokes the registered handler with the provided args', () => {
+    const handler = vi.fn();
+    useCommandStore.getState().register('file.save', handler);
+    useCommandStore.getState().dispatch('file.save', { path: '/x.md' });
+    expect(handler).toHaveBeenCalledWith({ path: '/x.md' });
+  });
+
+  it('dispatch with no args calls the handler with undefined', () => {
+    const handler = vi.fn();
+    useCommandStore.getState().register('view.toggleSidebar', handler);
+    useCommandStore.getState().dispatch('view.toggleSidebar');
+    expect(handler).toHaveBeenCalledWith(undefined);
+  });
+
+  it('dispatch on an unregistered id is a no-op (no throw)', () => {
+    expect(() => useCommandStore.getState().dispatch('does.not.exist')).not.toThrow();
+  });
+
+  it('unregister removes a handler', () => {
+    const handler = vi.fn();
+    useCommandStore.getState().register('file.open', handler);
+    useCommandStore.getState().unregister('file.open');
+    expect(useCommandStore.getState().handlers['file.open']).toBeUndefined();
+    useCommandStore.getState().dispatch('file.open');
+    expect(handler).not.toHaveBeenCalled();
+  });
+
+  it('unregister on a missing id is a no-op', () => {
+    expect(() => useCommandStore.getState().unregister('does.not.exist')).not.toThrow();
+  });
+
+  it('get returns the handler or undefined', () => {
+    const handler: CommandHandler = () => {};
+    useCommandStore.getState().register('file.open', handler);
+    expect(useCommandStore.getState().get('file.open')).toBe(handler);
+    expect(useCommandStore.getState().get('does.not.exist')).toBeUndefined();
+  });
+
+  it('registerMany registers multiple handlers in one call', () => {
+    const a = vi.fn();
+    const b = vi.fn();
+    useCommandStore.getState().registerMany({
+      'file.open': a,
+      'file.save': b,
+    });
+    expect(useCommandStore.getState().handlers['file.open']).toBe(a);
+    expect(useCommandStore.getState().handlers['file.save']).toBe(b);
+  });
+
+  it('registerMany does not clear handlers that were already registered', () => {
+    const existing = vi.fn();
+    const added = vi.fn();
+    useCommandStore.getState().register('file.open', existing);
+    useCommandStore.getState().registerMany({ 'file.save': added });
+    expect(useCommandStore.getState().handlers['file.open']).toBe(existing);
+    expect(useCommandStore.getState().handlers['file.save']).toBe(added);
+  });
+});