perf(history): batch transform drag undo

commands/command.ts

@@ -4,8 +4,14 @@ export type CommandContext = {
   state: AppState;
 };
 
+export type CommandHistoryPolicy =
+  | { mode: "auto" }
+  | { mode: "ignore" }
+  | { mode: "deferred"; phase: "begin" | "update" | "commit" };
+
 export type Command<TPayload = void> = {
   id: string;
   name: string;
+  history?: CommandHistoryPolicy;
   execute(context: CommandContext, payload: TPayload): AppState;
 };

commands/dispatcher.ts

@@ -1,6 +1,5 @@
 import type { AppState, HistorySnapshot } from "@editor/state";
-import type { CommandContext } from "./command";
-import { commandIds } from "./ids";
+import type { CommandContext, CommandHistoryPolicy } from "./command";
 import type { CommandId, CommandPayloads } from "./payloads";
 import type { CommandRegistry } from "./registry";
 
@@ -15,6 +14,8 @@ export function createCommandDispatcher(options: {
   getState: () => AppState;
   setState: (state: AppState) => void;
 }): CommandDispatcher {
+  let deferredHistory: { snapshot: HistorySnapshot; changed: boolean } | undefined;
+
   return {
     dispatch(commandId, payload) {
       const command = options.registry.get(commandId);
@@ -23,28 +24,89 @@ export function createCommandDispatcher(options: {
       }
 
       const currentState = options.getState();
+      const historyPolicy = command.history ?? defaultHistoryPolicy;
+      const deferredSnapshot = historyPolicy.mode === "deferred" && historyPolicy.phase === "begin" ? snapshot(currentState) : undefined;
       const context: CommandContext = { state: currentState };
       const executedState = command.execute(context, payload);
       if (executedState === currentState) {
+        if (historyPolicy.mode === "deferred" && historyPolicy.phase === "commit") deferredHistory = undefined;
         return currentState;
       }
-      const nextState = shouldRecordHistory(commandId, currentState, executedState) ? recordHistory(currentState, executedState) : executedState;
+
+      const nextState = applyHistoryPolicy({
+        currentState,
+        nextState: executedState,
+        historyPolicy,
+        deferredSnapshot,
+        getDeferredHistory: () => deferredHistory,
+        setDeferredHistory: (nextDeferredHistory) => {
+          deferredHistory = nextDeferredHistory;
+        },
+      });
       options.setState(nextState);
       return nextState;
     },
   };
 }
 
-function shouldRecordHistory(commandId: CommandId, currentState: AppState, nextState: AppState) {
-  if (commandId === commandIds.historyUndo || commandId === commandIds.historyRedo) return false;
+const defaultHistoryPolicy: CommandHistoryPolicy = { mode: "auto" };
+
+function applyHistoryPolicy(options: {
+  currentState: AppState;
+  nextState: AppState;
+  historyPolicy: CommandHistoryPolicy;
+  deferredSnapshot?: HistorySnapshot;
+  getDeferredHistory: () => { snapshot: HistorySnapshot; changed: boolean } | undefined;
+  setDeferredHistory: (nextDeferredHistory: { snapshot: HistorySnapshot; changed: boolean } | undefined) => void;
+}): AppState {
+  if (options.historyPolicy.mode === "ignore") {
+    options.setDeferredHistory(undefined);
+    return options.nextState;
+  }
+
+  if (options.historyPolicy.mode === "deferred") {
+    return applyDeferredHistoryPolicy(options);
+  }
+
+  return shouldRecordHistory(options.currentState, options.nextState) ? recordHistory(snapshot(options.currentState), options.nextState) : options.nextState;
+}
+
+function applyDeferredHistoryPolicy(options: {
+  currentState: AppState;
+  nextState: AppState;
+  historyPolicy: Extract<CommandHistoryPolicy, { mode: "deferred" }>;
+  deferredSnapshot?: HistorySnapshot;
+  getDeferredHistory: () => { snapshot: HistorySnapshot; changed: boolean } | undefined;
+  setDeferredHistory: (nextDeferredHistory: { snapshot: HistorySnapshot; changed: boolean } | undefined) => void;
+}): AppState {
+  switch (options.historyPolicy.phase) {
+    case "begin":
+      options.setDeferredHistory(options.deferredSnapshot ? { snapshot: options.deferredSnapshot, changed: false } : undefined);
+      return options.nextState;
+    case "update": {
+      const deferredHistory = options.getDeferredHistory();
+      if (deferredHistory && options.currentState.document !== options.nextState.document) {
+        options.setDeferredHistory({ ...deferredHistory, changed: true });
+      }
+      return options.nextState;
+    }
+    case "commit": {
+      const deferredHistory = options.getDeferredHistory();
+      options.setDeferredHistory(undefined);
+      return deferredHistory?.changed ? recordHistory(deferredHistory.snapshot, options.nextState) : options.nextState;
+    }
+  }
+}
+
+function shouldRecordHistory(currentState: AppState, nextState: AppState) {
   return currentState.document !== nextState.document;
 }
 
-function recordHistory(currentState: AppState, nextState: AppState): AppState {
+function recordHistory(historySnapshot: HistorySnapshot, nextState: AppState): AppState {
   return {
     ...nextState,
     history: {
-      past: [...currentState.history.past, snapshot(currentState)].slice(-100),
+      past: [...nextState.history.past, historySnapshot].slice(-100),
       future: [],
     },
   };

commands/history.test.ts

@@ -5,8 +5,9 @@ import { documentAddArtboardCommand } from "./document";
 import { historyCommands } from "./history";
 import { commandIds } from "./ids";
 import { createCommandRegistry } from "./registry";
+import { transformCommands } from "./transform";
 
-const registry = createCommandRegistry([documentAddArtboardCommand, ...historyCommands]);
+const registry = createCommandRegistry([documentAddArtboardCommand, ...historyCommands, ...transformCommands]);
 
 describe("history commands", () => {
   test("records document changes and undoes/redoes them", () => {
@@ -26,4 +27,81 @@ describe("history commands", () => {
 
     expect(store.getState().document.artboards.map((artboard) => artboard.id)).toEqual(["a1"]);
   });
+
+  test("records one history entry for a transform drag", () => {
+    const store = createAppStore(artboardState(), registry);
+
+    store.dispatch(commandIds.transformBegin, {
+      target: { type: "artboard", id: "a1" },
+      handle: "body",
+      point: { x: 0, y: 0 },
+      initialBounds: { x: 0, y: 0, w: 100, h: 80 },
+    });
+    store.dispatch(commandIds.transformUpdate, { point: { x: 5, y: 10 } });
+    store.dispatch(commandIds.transformUpdate, { point: { x: 10, y: 20 } });
+    store.dispatch(commandIds.transformUpdate, { point: { x: 15, y: 25 } });
+
+    expect(store.getState().document.artboards[0]?.bounds).toEqual({ x: 15, y: 25, w: 100, h: 80 });
+    expect(store.getState().history.past).toHaveLength(0);
+
+    store.dispatch(commandIds.transformEnd, undefined);
+
+    expect(store.getState().editor.transformSession).toBeUndefined();
+    expect(store.getState().history.past).toHaveLength(1);
+    expect(store.getState().history.past[0]?.document.artboards[0]?.bounds).toEqual({ x: 0, y: 0, w: 100, h: 80 });
+    expect(store.getState().history.past[0]?.editor.transformSession).toBeUndefined();
+
+    store.dispatch(commandIds.historyUndo, undefined);
+
+    expect(store.getState().document.artboards[0]?.bounds).toEqual({ x: 0, y: 0, w: 100, h: 80 });
+    expect(store.getState().editor.transformSession).toBeUndefined();
+    expect(store.getState().history.future).toHaveLength(1);
+  });
+
+  test("keeps direct transform bounds edits normally undoable", () => {
+    const store = createAppStore(artboardState(), registry);
+
+    store.dispatch(commandIds.transformSetBounds, { target: { type: "artboard", id: "a1" }, bounds: { x: 12, y: 24, w: 120, h: 90 } });
+
+    expect(store.getState().document.artboards[0]?.bounds).toEqual({ x: 12, y: 24, w: 120, h: 90 });
+    expect(store.getState().history.past).toHaveLength(1);
+
+    store.dispatch(commandIds.historyUndo, undefined);
+
+    expect(store.getState().document.artboards[0]?.bounds).toEqual({ x: 0, y: 0, w: 100, h: 80 });
+  });
+
+  test("does not record history for transform update or end without a session", () => {
+    const store = createAppStore(artboardState(), registry);
+
+    store.dispatch(commandIds.transformUpdate, { point: { x: 10, y: 20 } });
+    store.dispatch(commandIds.transformEnd, undefined);
+
+    expect(store.getState().document.artboards[0]?.bounds).toEqual({ x: 0, y: 0, w: 100, h: 80 });
+    expect(store.getState().history.past).toHaveLength(0);
+    expect(store.getState().history.future).toHaveLength(0);
+  });
+
+  test("does not record history for a transform session with no document update", () => {
+    const store = createAppStore(artboardState(), registry);
+
+    store.dispatch(commandIds.transformBegin, {
+      target: { type: "artboard", id: "a1" },
+      handle: "body",
+      point: { x: 0, y: 0 },
+      initialBounds: { x: 0, y: 0, w: 100, h: 80 },
+    });
+    store.dispatch(commandIds.transformEnd, undefined);
+
+    expect(store.getState().editor.transformSession).toBeUndefined();
+    expect(store.getState().document.artboards[0]?.bounds).toEqual({ x: 0, y: 0, w: 100, h: 80 });
+    expect(store.getState().history.past).toHaveLength(0);
+  });
 });
+
+function artboardState() {
+  return documentAddArtboardCommand.execute(
+    { state: createInitialAppState("Test") },
+    { id: "a1", name: "Artboard", bounds: { x: 0, y: 0, w: 100, h: 80 } },
+  );
+}

commands/history.ts

@@ -4,6 +4,7 @@ import { commandIds } from "./ids";
 export const historyUndoCommand: Command = {
   id: commandIds.historyUndo,
   name: "Undo",
+  history: { mode: "ignore" },
   execute({ state }) {
     const previous = state.history.past.at(-1);
     if (!previous) return state;
@@ -23,6 +24,7 @@ export const historyUndoCommand: Command = {
 export const historyRedoCommand: Command = {
   id: commandIds.historyRedo,
   name: "Redo",
+  history: { mode: "ignore" },
   execute({ state }) {
     const next = state.history.future[0];
     if (!next) return state;

commands/transform.ts

@@ -24,6 +24,7 @@ export type TransformSetBoundsPayload = {
 export const transformBeginCommand: Command<TransformBeginPayload> = {
   id: commandIds.transformBegin,
   name: "Begin transform",
+  history: { mode: "deferred", phase: "begin" },
   execute({ state }, payload) {
     return {
       ...state,
@@ -43,6 +44,7 @@ export const transformBeginCommand: Command<TransformBeginPayload> = {
 export const transformUpdateCommand: Command<TransformUpdatePayload> = {
   id: commandIds.transformUpdate,
   name: "Update transform",
+  history: { mode: "deferred", phase: "update" },
   execute({ state }, payload) {
     const session = state.editor.transformSession;
     if (!session) return state;
@@ -78,6 +80,7 @@ export const transformSetBoundsCommand: Command<TransformSetBoundsPayload> = {
 export const transformEndCommand: Command = {
   id: commandIds.transformEnd,
   name: "End transform",
+  history: { mode: "deferred", phase: "commit" },
   execute({ state }) {
     if (!state.editor.transformSession) return state;