fix(studio): drain pending edits before reload

packages/studio/src/hooks/useEditorSave.test.tsx

@@ -0,0 +1,168 @@
+// @vitest-environment happy-dom
+import { act } from "react";
+import { createRoot } from "react-dom/client";
+import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
+import { useEditorSave, type EditorSaveHandle } from "./useEditorSave";
+import { StudioFileConflictError } from "../utils/studioSaveDiagnostics";
+
+(globalThis as unknown as { IS_REACT_ACT_ENVIRONMENT: boolean }).IS_REACT_ACT_ENVIRONMENT = true;
+
+describe("useEditorSave pending work", () => {
+  beforeEach(() => {
+    vi.stubGlobal(
+      "requestAnimationFrame",
+      vi.fn(() => 41),
+    );
+    vi.stubGlobal("cancelAnimationFrame", vi.fn());
+  });
+
+  afterEach(() => vi.unstubAllGlobals());
+
+  it("exposes and flushes the latest rAF-buffered source candidate", async () => {
+    const writeProjectFile = vi.fn(async () => undefined);
+    const captured: { handle: EditorSaveHandle | null } = { handle: null };
+
+    function Probe() {
+      captured.handle = useEditorSave({
+        editingPathRef: { current: "index.html" },
+        projectIdRef: { current: "project-a" },
+        readProjectFile: vi.fn(async () => "before"),
+        writeProjectFile,
+        recordEdit: vi.fn(async () => undefined),
+        domEditSaveTimestampRef: { current: 0 },
+        setRefreshKey: vi.fn(),
+        showToast: vi.fn(),
+      });
+      return null;
+    }
+
+    const root = createRoot(document.createElement("div"));
+    await act(async () => root.render(<Probe />));
+    act(() => captured.handle?.handleContentChange("studio candidate"));
+
+    expect(captured.handle?.getPendingCandidate()).toEqual({
+      projectId: "project-a",
+      path: "index.html",
+      content: "studio candidate",
+    });
+    await expect(captured.handle?.flushPendingSave()).resolves.toEqual({ status: "clean" });
+    expect(writeProjectFile).toHaveBeenCalledWith("index.html", "studio candidate", "before");
+
+    await act(async () => root.unmount());
+  });
+
+  it("joins an in-flight source save instead of writing the frozen candidate twice", async () => {
+    let frame: FrameRequestCallback | null = null;
+    vi.stubGlobal(
+      "requestAnimationFrame",
+      vi.fn((callback: FrameRequestCallback) => {
+        frame = callback;
+        return 42;
+      }),
+    );
+    let finishWrite!: () => void;
+    const writeProjectFile = vi
+      .fn()
+      .mockImplementationOnce(
+        () =>
+          new Promise<void>((resolve) => {
+            finishWrite = resolve;
+          }),
+      )
+      .mockResolvedValue(undefined);
+    const captured: { handle: EditorSaveHandle | null } = { handle: null };
+    function Probe() {
+      captured.handle = useEditorSave({
+        editingPathRef: { current: "index.html" },
+        projectIdRef: { current: "project-a" },
+        readProjectFile: vi.fn(async () => "before"),
+        writeProjectFile,
+        recordEdit: vi.fn(async () => undefined),
+        domEditSaveTimestampRef: { current: 0 },
+        setRefreshKey: vi.fn(),
+        showToast: vi.fn(),
+      });
+      return null;
+    }
+    const root = createRoot(document.createElement("div"));
+    await act(async () => root.render(<Probe />));
+    act(() => captured.handle?.handleContentChange("candidate"));
+    act(() => frame?.(0));
+    await vi.waitFor(() => expect(writeProjectFile).toHaveBeenCalledOnce());
+
+    const drained = captured.handle?.flushPendingSave();
+    expect(writeProjectFile).toHaveBeenCalledOnce();
+    finishWrite();
+    await expect(drained).resolves.toEqual({ status: "clean" });
+    expect(writeProjectFile).toHaveBeenCalledOnce();
+    await act(async () => root.unmount());
+  });
+
+  it("preserves conflict details when flushing a buffered source candidate", async () => {
+    const conflict = new StudioFileConflictError({
+      filePath: "index.html",
+      currentVersion: "external-v2",
+      currentContent: "external",
+      attemptedContent: "studio candidate",
+    });
+    const captured: { handle: EditorSaveHandle | null } = { handle: null };
+
+    function Probe() {
+      captured.handle = useEditorSave({
+        editingPathRef: { current: "index.html" },
+        projectIdRef: { current: "project-a" },
+        readProjectFile: vi.fn(async () => "before"),
+        writeProjectFile: vi.fn(async () => {
+          throw conflict;
+        }),
+        recordEdit: vi.fn(async () => undefined),
+        domEditSaveTimestampRef: { current: 0 },
+        setRefreshKey: vi.fn(),
+        showToast: vi.fn(),
+      });
+      return null;
+    }
+
+    const root = createRoot(document.createElement("div"));
+    await act(async () => root.render(<Probe />));
+    act(() => captured.handle?.handleContentChange("studio candidate"));
+
+    await expect(captured.handle?.flushPendingSave()).resolves.toEqual({
+      status: "conflict",
+      error: conflict,
+    });
+
+    await act(async () => root.unmount());
+  });
+
+  it("discards an rAF-buffered candidate without persisting it", async () => {
+    const writeProjectFile = vi.fn(async () => undefined);
+    const captured: { handle: EditorSaveHandle | null } = { handle: null };
+
+    function Probe() {
+      captured.handle = useEditorSave({
+        editingPathRef: { current: "index.html" },
+        projectIdRef: { current: "project-a" },
+        readProjectFile: vi.fn(async () => "before"),
+        writeProjectFile,
+        recordEdit: vi.fn(async () => undefined),
+        domEditSaveTimestampRef: { current: 0 },
+        setRefreshKey: vi.fn(),
+        showToast: vi.fn(),
+      });
+      return null;
+    }
+
+    const root = createRoot(document.createElement("div"));
+    await act(async () => root.render(<Probe />));
+    act(() => captured.handle?.handleContentChange("discard me"));
+    act(() => captured.handle?.discardPendingSave());
+
+    expect(captured.handle?.getPendingCandidate()).toBeNull();
+    await expect(captured.handle?.flushPendingSave()).resolves.toEqual({ status: "clean" });
+    expect(writeProjectFile).not.toHaveBeenCalled();
+    expect(cancelAnimationFrame).toHaveBeenCalledWith(41);
+
+    await act(async () => root.unmount());
+  });
+});

packages/studio/src/hooks/useEditorSave.ts

@@ -2,6 +2,10 @@ import { useCallback, useRef } from "react";
 import { saveProjectFilesWithHistory } from "../utils/studioFileHistory";
 import type { EditHistoryKind } from "../utils/editHistory";
 import { trackStudioEvent } from "../utils/studioTelemetry";
+import {
+  StudioFileConflictError,
+  type StudioSaveDrainResult,
+} from "../utils/studioSaveDiagnostics";
 
 interface RecordEditInput {
   label: string;
@@ -21,6 +25,25 @@ interface UseEditorSaveOptions {
   showToast: (message: string, tone?: "error" | "info") => void;
 }
 
+export interface EditorSaveCandidate {
+  projectId: string;
+  path: string;
+  content: string;
+}
+
+export type EditorSaveDrainResult = StudioSaveDrainResult;
+
+export interface EditorSaveHandle {
+  saveRafRef: React.MutableRefObject<number | null>;
+  handleContentChange: (content: string) => void;
+  /** Read by the external-reload reconciliation introduced in stack PR #2993. */
+  getPendingCandidate: () => EditorSaveCandidate | null;
+  /** Wired into the external-reload drain by stack PR #2993. */
+  flushPendingSave: () => Promise<EditorSaveDrainResult>;
+  /** Used by PR #2993 when the external version wins. */
+  discardPendingSave: () => void;
+}
+
 export function useEditorSave({
   editingPathRef,
   projectIdRef,
@@ -30,12 +53,70 @@ export function useEditorSave({
   domEditSaveTimestampRef,
   setRefreshKey,
   showToast,
-}: UseEditorSaveOptions) {
+}: UseEditorSaveOptions): EditorSaveHandle {
   const saveRafRef = useRef<number | null>(null);
   const refreshRafRef = useRef<number | null>(null);
   // One error toast per burst of failures — every keystroke retries the save,
   // and error toasts persist until dismissed, so don't stack duplicates.
   const lastFailureToastAtRef = useRef(0);
+  const pendingCandidateRef = useRef<EditorSaveCandidate | null>(null);
+  const inFlightRef = useRef<Promise<EditorSaveDrainResult> | null>(null);
+  const inFlightCandidateRef = useRef<EditorSaveCandidate | null>(null);
+
+  const reportFailure = useCallback(
+    (path: string, error: unknown) => {
+      trackStudioEvent("save_failure", {
+        source: "code_editor",
+        error_message: error instanceof Error ? error.message : "unknown",
+      });
+      const now = Date.now();
+      if (now - lastFailureToastAtRef.current > 5000) {
+        lastFailureToastAtRef.current = now;
+        showToast(
+          `Couldn't save ${path} — your latest edits are NOT persisted. Check the preview server; editing again retries the save.`,
+          "error",
+        );
+      }
+    },
+    [showToast],
+  );
+
+  const persistCandidate = useCallback(
+    (candidate: EditorSaveCandidate): Promise<EditorSaveDrainResult> => {
+      const task = saveProjectFilesWithHistory({
+        projectId: candidate.projectId,
+        label: "Edit source",
+        kind: "source",
+        coalesceKey: `source:${candidate.path}`,
+        files: { [candidate.path]: candidate.content },
+        readFile: readProjectFile,
+        writeFile: writeProjectFile,
+        recordEdit,
+      })
+        .then<EditorSaveDrainResult>(() => {
+          if (pendingCandidateRef.current === candidate) pendingCandidateRef.current = null;
+          if (refreshRafRef.current != null) cancelAnimationFrame(refreshRafRef.current);
+          refreshRafRef.current = requestAnimationFrame(() => setRefreshKey((k) => k + 1));
+          return { status: "clean" };
+        })
+        .catch<EditorSaveDrainResult>((error: unknown) => {
+          reportFailure(candidate.path, error);
+          return error instanceof StudioFileConflictError
+            ? { status: "conflict", error }
+            : { status: "failed", error };
+        })
+        .finally(() => {
+          if (inFlightRef.current === task) {
+            inFlightRef.current = null;
+            inFlightCandidateRef.current = null;
+          }
+        });
+      inFlightRef.current = task;
+      inFlightCandidateRef.current = candidate;
+      return task;
+    },
+    [readProjectFile, recordEdit, reportFailure, setRefreshKey, writeProjectFile],
+  );
 
   const handleContentChange = useCallback(
     (content: string) => {
@@ -44,53 +125,46 @@ export function useEditorSave({
       const path = editingPathRef.current;
       if (!path) return;
 
+      const candidate = { projectId: pid, path, content };
+      pendingCandidateRef.current = candidate;
+
       if (saveRafRef.current != null) cancelAnimationFrame(saveRafRef.current);
       saveRafRef.current = requestAnimationFrame(() => {
+        saveRafRef.current = null;
         domEditSaveTimestampRef.current = Date.now();
-        saveProjectFilesWithHistory({
-          projectId: pid,
-          label: "Edit source",
-          kind: "source",
-          coalesceKey: `source:${path}`,
-          files: { [path]: content },
-          readFile: readProjectFile,
-          writeFile: writeProjectFile,
-          recordEdit,
-        })
-          .then(() => {
-            if (refreshRafRef.current != null) cancelAnimationFrame(refreshRafRef.current);
-            refreshRafRef.current = requestAnimationFrame(() => setRefreshKey((k) => k + 1));
-          })
-          .catch((error) => {
-            trackStudioEvent("save_failure", {
-              source: "code_editor",
-              error_message: error instanceof Error ? error.message : "unknown",
-            });
-            const now = Date.now();
-            if (now - lastFailureToastAtRef.current > 5000) {
-              lastFailureToastAtRef.current = now;
-              showToast(
-                `Couldn't save ${path} — your latest edits are NOT persisted. Check the preview server; editing again retries the save.`,
-                "error",
-              );
-            }
-          });
+        void persistCandidate(candidate);
       });
     },
-    [
-      domEditSaveTimestampRef,
-      editingPathRef,
-      projectIdRef,
-      readProjectFile,
-      recordEdit,
-      setRefreshKey,
-      showToast,
-      writeProjectFile,
-    ],
+    [domEditSaveTimestampRef, editingPathRef, projectIdRef, persistCandidate],
   );
 
+  const flushPendingSave = useCallback(async (): Promise<EditorSaveDrainResult> => {
+    if (saveRafRef.current != null) {
+      cancelAnimationFrame(saveRafRef.current);
+      saveRafRef.current = null;
+    }
+    const candidate = pendingCandidateRef.current;
+    if (candidate && candidate === inFlightCandidateRef.current && inFlightRef.current) {
+      return inFlightRef.current;
+    }
+    if (candidate) {
+      domEditSaveTimestampRef.current = Date.now();
+      return persistCandidate(candidate);
+    }
+    return (await inFlightRef.current) ?? { status: "clean" };
+  }, [domEditSaveTimestampRef, persistCandidate]);
+
+  const discardPendingSave = useCallback(() => {
+    if (saveRafRef.current != null) cancelAnimationFrame(saveRafRef.current);
+    saveRafRef.current = null;
+    pendingCandidateRef.current = null;
+  }, []);
+
   return {
     saveRafRef,
     handleContentChange,
+    getPendingCandidate: () => pendingCandidateRef.current,
+    flushPendingSave,
+    discardPendingSave,
   };
 }