fix(studio-server): undoing a change takes the media ledger back with the film

packages/studio-server/src/history/historyLog.ts

@@ -40,10 +40,11 @@ export interface HistoryLog {
   baseline: Manifest;
   entries: HistoryEntry[];
   pins: Set<string>;
+  keepsLedger?: boolean;
 }
 
 export type LogRecord =
-  | { type: "baseline"; files: Record<string, string> }
+  | { type: "baseline"; files: Record<string, string>; keepsLedger?: boolean }
   | { type: "entry"; entry: HistoryEntry }
   | { type: "pin"; id: string; pinned: boolean };
 
@@ -74,8 +75,10 @@ export function readLog(file: string, onUnreadable: (line: number) => void): His
 }
 
 function applyRecord(log: HistoryLog, record: LogRecord): void {
-  if (record.type === "baseline") log.baseline = new Map(Object.entries(record.files));
-  else if (record.type === "entry") log.entries.push(record.entry);
+  if (record.type === "baseline") {
+    log.baseline = new Map(Object.entries(record.files));
+    log.keepsLedger = record.keepsLedger === true;
+  } else if (record.type === "entry") log.entries.push(record.entry);
   else if (record.pinned) log.pins.add(record.id);
   else log.pins.delete(record.id);
 }
@@ -99,7 +102,11 @@ export function saveRecord(file: string, log: HistoryLog, record: LogRecord): vo
 
 export function writeLog(file: string, log: HistoryLog): void {
   const records: LogRecord[] = [
-    { type: "baseline", files: Object.fromEntries(log.baseline) },
+    {
+      type: "baseline",
+      files: Object.fromEntries(log.baseline),
+      ...(log.keepsLedger && { keepsLedger: true }),
+    },
     ...log.entries.map((entry) => ({ type: "entry" as const, entry })),
     ...[...log.pins].map((id) => ({ type: "pin" as const, id, pinned: true })),
   ];

packages/studio-server/src/history/projectHistory.test.ts

@@ -71,6 +71,19 @@ async function project(files: Record<string, string | Buffer>, options = {}) {
 }
 
 /** Undoes the newest change still in effect, whoever made it; Cmd+Z steps only over the caller's own. */
+/** What 0.8.123 leaves: a log whose baseline never names the media ledger and carries no marker. */
+function asWrittenBy0_8_123(logFile: string) {
+  const lines = readFileSync(logFile, "utf-8")
+    .trim()
+    .split("\n")
+    .map((line) => JSON.parse(line));
+  for (const record of lines.filter((line) => line.type === "baseline")) {
+    delete record.files[".media/manifest.jsonl"];
+    delete record.keepsLedger;
+  }
+  writeFileSync(logFile, lines.map((record) => JSON.stringify(record)).join("\n") + "\n");
+}
+
 async function undoNewest(history: ProjectHistory) {
   const newest = [...history.list()].reverse().find((entry) => !entry.undoes && !entry.undone);
   return history.undo(newest!.id, { who: you });
@@ -201,6 +214,73 @@ describe("openProjectHistory", () => {
     expect(reopened.next("forward", you)).toBeUndefined();
   });
 
+  it("a log 0.8.123 wrote without the media ledger takes it in, so the first Undo undoes the edit", async () => {
+    const { history, write, read, projectDir, historyRoot } = await project({
+      "index.html": "A",
+      ".media/manifest.jsonl": "{}\n",
+    });
+    await change(history, you, "Your edit", () => write("index.html", "B"));
+    await history.close();
+    asWrittenBy0_8_123(join(historyRoot, history.projectId, "log.jsonl"));
+    const reopened = await open(projectDir, historyRoot);
+    expect(await reopened.step("back", you)).toMatchObject({ ok: true });
+    expect([read("index.html"), read(".media/manifest.jsonl")]).toEqual(["A", "{}\n"]);
+  });
+
+  // Windows needs a privilege to create symlinks.
+  it.skipIf(process.platform === "win32")(
+    "a log 0.8.123 wrote never takes in a ledger behind a link",
+    async () => {
+      const { history, projectDir, historyRoot } = await project(
+        { "index.html": "A" },
+        { quietMs: 30 },
+      );
+      await history.close();
+      asWrittenBy0_8_123(join(historyRoot, history.projectId, "log.jsonl"));
+      const outside = tempDir("hf-history-linked-");
+      writeFileSync(join(outside, "manifest.jsonl"), "{}\n");
+      symlinkSync(outside, join(projectDir, ".media"), "dir");
+      const reopened = await open(projectDir, historyRoot, { quietMs: 30 });
+      await reopened.flush();
+      expect(reopened.list()).toEqual([]);
+    },
+  );
+
+  it("a ledger made while the project was closed is a change like any file, once a log keeps the ledger", async () => {
+    const { history, write, read, has, projectDir, historyRoot } = await project(
+      { "index.html": "A" },
+      { quietMs: 30 },
+    );
+    await history.close();
+    write("index.html", "B");
+    write(".media/manifest.jsonl", "{}\n");
+    const reopened = await open(projectDir, historyRoot, { quietMs: 30 });
+    await reopened.flush();
+    const [outside] = reopened.list();
+    expect(outside!.files.map((file) => file.path).sort()).toEqual([
+      ".media/manifest.jsonl",
+      "index.html",
+    ]);
+    expect((await reopened.undo(outside!.id, { who: you })).ok).toBe(true);
+    expect([read("index.html"), has(".media/manifest.jsonl")]).toEqual(["A", false]);
+  });
+
+  it("takes the media ledger back with the film when a change is undone", async () => {
+    const { history, write, read } = await project({
+      "index.html": "<h1>Hello</h1>",
+      ".media/manifest.jsonl": "{}\n",
+    });
+    const cutout = await change(history, agent, "Cut out the logo", () => {
+      write("index.html", "<h1>Hello</h1><img src='logo.png'>");
+      write(".media/manifest.jsonl", '{}\n{"id":"logo"}\n');
+      write(".media/images/logo.png", "png");
+      write(".tools/manifest.jsonl", "{}\n");
+    });
+    expect(cutout.files.map((file) => file.path)).toEqual([".media/manifest.jsonl", "index.html"]);
+    expect((await history.undo(cutout.id, { who: you })).ok).toBe(true);
+    expect(read(".media/manifest.jsonl")).toBe("{}\n");
+  });
+
   it("never files a hidden file name as a change, but keeps Studio's two manifests", async () => {
     const { history, write } = await project({ "index.html": "<h1>Hello</h1>" }, { quietMs: 30 });
     const turn = await history.beginWindow(agent, "Agent turn");

packages/studio-server/src/history/projectHistory.ts

@@ -203,9 +203,12 @@ const statKey = (file: { size: number; mtimeMs: number; ctimeMs: number }, swept
     ? ""
     : `${file.size}:${file.mtimeMs}:${file.ctimeMs}`;
 
-/** A hidden name anywhere in a path (a tool's own record, .DS_Store) is nobody's work, except Studio's manifests. */
+const MEDIA_LEDGER = ".media/manifest.jsonl";
+const KEPT_HIDDEN_PATHS = new Set<string>([...STUDIO_SIGNATURE_MANIFEST_PATHS, MEDIA_LEDGER]);
+
+/** A hidden name anywhere in a path (a tool's own record, .DS_Store) is nobody's work, except the kept ones above. */
 function isHistoryPath(path: string): boolean {
-  if ((STUDIO_SIGNATURE_MANIFEST_PATHS as readonly string[]).includes(path)) return true;
+  if (KEPT_HIDDEN_PATHS.has(path)) return true;
   return !path.split("/").some((segment) => segment.startsWith("."));
 }
 
@@ -403,6 +406,7 @@ class Engine {
     );
     if (!log) return this.firstOpen();
     this.log = withoutHiddenPaths(log);
+    if (!this.log.keepsLedger) await this.takeInUnnamedLedger();
     const cache = this.readStatCache();
     const last = this.log.entries.at(-1)?.id ?? START;
     for (const [path, hash] of manifestAt(this.log, last) ?? []) {
@@ -462,6 +466,19 @@ class Engine {
     this.windows.push({ id, who, label, startedAt, lastWriteAt, idleMs, changes: new Map() });
   }
 
+  async takeInUnnamedLedger(): Promise<void> {
+    const named = (path: string) =>
+      this.log.entries.some((entry) => entry.files.some((file) => file.path === path));
+    const listed = () => historyFiles(this.dir).some((file) => file.path === MEDIA_LEDGER);
+    const hash =
+      this.log.baseline.has(MEDIA_LEDGER) || named(MEDIA_LEDGER) || !listed()
+        ? null
+        : await this.storeIfPresent(MEDIA_LEDGER);
+    if (hash !== null) this.log.baseline.set(MEDIA_LEDGER, hash);
+    this.log.keepsLedger = true;
+    this.persistLog();
+  }
+
   async firstOpen(): Promise<void> {
     const sweptAt = this.now();
     for (const file of historyFiles(this.dir)) {
@@ -470,6 +487,7 @@ class Engine {
       if (hash !== null) this.tracked.set(file.path, { hash, stat: statKey(file, sweptAt) });
     }
     this.log.baseline = this.manifest();
+    this.log.keepsLedger = true;
     this.persistLog();
     this.saveStatCache();
   }