fix(web): harden WhatsApp creds persistence

src/web/session.test.ts

@@ -1,5 +1,6 @@
 import { EventEmitter } from "node:events";
 import fsSync from "node:fs";
+import path from "node:path";
 import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
 import { resetLogger, setLoggerOverride } from "../logging.js";
 import {
@@ -43,6 +44,7 @@ describe("web session", () => {
     ).saveCreds;
     // trigger creds.update listener
     sock.ev.emit("creds.update", {});
+    await new Promise<void>((resolve) => setImmediate(resolve));
     expect(saveCreds).toHaveBeenCalled();
   });
 
@@ -107,4 +109,129 @@ describe("web session", () => {
     expect(formatError(err)).toContain("Request Time-out");
     expect(formatError(err)).toContain("QR refs attempts ended");
   });
+
+  it("does not clobber creds backup when creds.json is corrupted", async () => {
+    const credsSuffix = path.join(".clawdis", "credentials", "creds.json");
+
+    const copySpy = vi
+      .spyOn(fsSync, "copyFileSync")
+      .mockImplementation(() => {});
+    const existsSpy = vi.spyOn(fsSync, "existsSync").mockImplementation((p) => {
+      if (typeof p !== "string") return false;
+      return p.endsWith(credsSuffix);
+    });
+    const statSpy = vi.spyOn(fsSync, "statSync").mockImplementation((p) => {
+      if (typeof p === "string" && p.endsWith(credsSuffix)) {
+        return { isFile: () => true, size: 12 } as never;
+      }
+      throw new Error(`unexpected statSync path: ${String(p)}`);
+    });
+    const readSpy = vi.spyOn(fsSync, "readFileSync").mockImplementation((p) => {
+      if (typeof p === "string" && p.endsWith(credsSuffix)) {
+        return "{" as never;
+      }
+      throw new Error(`unexpected readFileSync path: ${String(p)}`);
+    });
+
+    await createWaSocket(false, false);
+    const sock = getLastSocket();
+    const saveCreds = (
+      await baileys.useMultiFileAuthState.mock.results[0].value
+    ).saveCreds;
+
+    sock.ev.emit("creds.update", {});
+    await new Promise<void>((resolve) => setImmediate(resolve));
+
+    expect(copySpy).not.toHaveBeenCalled();
+    expect(saveCreds).toHaveBeenCalled();
+
+    copySpy.mockRestore();
+    existsSpy.mockRestore();
+    statSpy.mockRestore();
+    readSpy.mockRestore();
+  });
+
+  it("serializes creds.update saves to avoid overlapping writes", async () => {
+    let inFlight = 0;
+    let maxInFlight = 0;
+    let release: (() => void) | null = null;
+    const gate = new Promise<void>((resolve) => {
+      release = resolve;
+    });
+
+    const saveCreds = vi.fn(async () => {
+      inFlight += 1;
+      maxInFlight = Math.max(maxInFlight, inFlight);
+      await gate;
+      inFlight -= 1;
+    });
+    baileys.useMultiFileAuthState.mockResolvedValueOnce({
+      state: { creds: {}, keys: {} },
+      saveCreds,
+    });
+
+    await createWaSocket(false, false);
+    const sock = getLastSocket();
+
+    sock.ev.emit("creds.update", {});
+    sock.ev.emit("creds.update", {});
+
+    await new Promise<void>((resolve) => setImmediate(resolve));
+    expect(inFlight).toBe(1);
+
+    release?.();
+
+    // let both queued saves complete
+    await new Promise<void>((resolve) => setImmediate(resolve));
+    await new Promise<void>((resolve) => setImmediate(resolve));
+
+    expect(saveCreds).toHaveBeenCalledTimes(2);
+    expect(maxInFlight).toBe(1);
+    expect(inFlight).toBe(0);
+  });
+
+  it("rotates creds backup when creds.json is valid JSON", async () => {
+    const credsSuffix = path.join(".clawdis", "credentials", "creds.json");
+    const backupSuffix = path.join(".clawdis", "credentials", "creds.json.bak");
+
+    const copySpy = vi
+      .spyOn(fsSync, "copyFileSync")
+      .mockImplementation(() => {});
+    const existsSpy = vi.spyOn(fsSync, "existsSync").mockImplementation((p) => {
+      if (typeof p !== "string") return false;
+      return p.endsWith(credsSuffix);
+    });
+    const statSpy = vi.spyOn(fsSync, "statSync").mockImplementation((p) => {
+      if (typeof p === "string" && p.endsWith(credsSuffix)) {
+        return { isFile: () => true, size: 12 } as never;
+      }
+      throw new Error(`unexpected statSync path: ${String(p)}`);
+    });
+    const readSpy = vi.spyOn(fsSync, "readFileSync").mockImplementation((p) => {
+      if (typeof p === "string" && p.endsWith(credsSuffix)) {
+        return "{}" as never;
+      }
+      throw new Error(`unexpected readFileSync path: ${String(p)}`);
+    });
+
+    await createWaSocket(false, false);
+    const sock = getLastSocket();
+    const saveCreds = (
+      await baileys.useMultiFileAuthState.mock.results[0].value
+    ).saveCreds;
+
+    sock.ev.emit("creds.update", {});
+    await new Promise<void>((resolve) => setImmediate(resolve));
+
+    expect(copySpy).toHaveBeenCalledTimes(1);
+    const args = copySpy.mock.calls[0] ?? [];
+    expect(String(args[0] ?? "")).toContain(credsSuffix);
+    expect(String(args[1] ?? "")).toContain(backupSuffix);
+    expect(saveCreds).toHaveBeenCalled();
+
+    copySpy.mockRestore();
+    existsSpy.mockRestore();
+    statSpy.mockRestore();
+    readSpy.mockRestore();
+  });
 });