feat(commands): add app state dispatcher foundation

editor/index.ts

@@ -1 +1,4 @@
 export type { AppState, EditorState, SelectionState, ViewportState } from "./state";
+export { createInitialAppState, initialEditorState } from "./initial-state";
+export type { AppStore, StateListener } from "./store";
+export { createAppStore } from "./store";

editor/initial-state.ts

@@ -0,0 +1,26 @@
+import type { AppState, EditorState } from "./state";
+
+export const initialEditorState: EditorState = {
+  viewport: {
+    center: { x: 0, y: 0 },
+    zoom: 1,
+    rotation: 0,
+    size: { w: 0, h: 0 },
+  },
+  selection: {
+    layerIds: [],
+  },
+};
+
+export function createInitialAppState(name = "Untitled"): AppState {
+  return {
+    document: {
+      id: crypto.randomUUID(),
+      name,
+      version: 1,
+      artboards: [],
+      assets: [],
+    },
+    editor: initialEditorState,
+  };
+}

editor/store.ts

@@ -0,0 +1,39 @@
+import type { CommandDispatcher } from "@commands/dispatcher";
+import { createCommandDispatcher } from "@commands/dispatcher";
+import type { CommandRegistry } from "@commands/registry";
+import type { AppState } from "./state";
+
+export type StateListener = (state: AppState) => void;
+
+export type AppStore = {
+  getState(): AppState;
+  subscribe(listener: StateListener): () => void;
+  dispatch: CommandDispatcher["dispatch"];
+};
+
+export function createAppStore(initialState: AppState, registry: CommandRegistry): AppStore {
+  let state = initialState;
+  const listeners = new Set<StateListener>();
+
+  const emit = () => {
+    for (const listener of listeners) listener(state);
+  };
+
+  const dispatcher = createCommandDispatcher({
+    registry,
+    getState: () => state,
+    setState: (nextState) => {
+      state = nextState;
+      emit();
+    },
+  });
+
+  return {
+    getState: () => state,
+    subscribe(listener) {
+      listeners.add(listener);
+      return () => listeners.delete(listener);
+    },
+    dispatch: dispatcher.dispatch,
+  };
+}