feat(history): add undo redo stack

commands/history.ts

@@ -0,0 +1,42 @@
+import type { Command } from "./command";
+import { commandIds } from "./ids";
+
+export const historyUndoCommand: Command = {
+  id: commandIds.historyUndo,
+  name: "Undo",
+  execute({ state }) {
+    const previous = state.history.past.at(-1);
+    if (!previous) return state;
+
+    return {
+      ...state,
+      document: previous.document,
+      editor: previous.editor,
+      history: {
+        past: state.history.past.slice(0, -1),
+        future: [{ document: state.document, editor: state.editor }, ...state.history.future],
+      },
+    };
+  },
+};
+
+export const historyRedoCommand: Command = {
+  id: commandIds.historyRedo,
+  name: "Redo",
+  execute({ state }) {
+    const next = state.history.future[0];
+    if (!next) return state;
+
+    return {
+      ...state,
+      document: next.document,
+      editor: next.editor,
+      history: {
+        past: [...state.history.past, { document: state.document, editor: state.editor }],
+        future: state.history.future.slice(1),
+      },
+    };
+  },
+};
+
+export const historyCommands = [historyUndoCommand, historyRedoCommand] satisfies Command<unknown>[];