Fix invalid Gmail message dates

src/lib/google/gmail.test.ts

@@ -0,0 +1,39 @@
+import { describe, expect, it, vi } from "vitest";
+
+vi.mock("./account", () => ({ googleFetch: vi.fn() }));
+
+import { readMessage } from "./gmail";
+
+const message = (overrides: { internalDate?: string; date?: string } = {}) => ({
+  id: "message-id",
+  threadId: "thread-id",
+  ...(overrides.internalDate === undefined ? {} : { internalDate: overrides.internalDate }),
+  payload: {
+    mimeType: "text/plain",
+    headers: overrides.date === undefined ? [] : [{ name: "Date", value: overrides.date }],
+    body: { data: Buffer.from("Message body").toString("base64url") },
+  },
+});
+
+describe("readMessage", () => {
+  it("uses the current time when internalDate and the Date header are missing", () => {
+    const before = Date.now();
+    const result = readMessage(message());
+    const after = Date.now();
+
+    expect(result.date.getTime()).toBeGreaterThanOrEqual(before);
+    expect(result.date.getTime()).toBeLessThanOrEqual(after);
+  });
+
+  it("uses the Date header when internalDate is malformed", () => {
+    const result = readMessage({ ...message({ internalDate: " 1793253600000 ", date: "Thu, 29 Oct 2026 06:00:00 GMT" }) });
+
+    expect(result.date.toISOString()).toBe("2026-10-29T06:00:00.000Z");
+  });
+
+  it("uses the internal millisecond timestamp when it is valid", () => {
+    const result = readMessage(message({ internalDate: "1793253600000", date: "Thu, 29 Oct 2026 06:00:00 GMT" }));
+
+    expect(result.date.toISOString()).toBe("2026-10-29T06:00:00.000Z");
+  });
+});

src/lib/google/gmail.ts

@@ -85,7 +85,10 @@ export function readMessage(json: unknown): ReadMail {
   const html = plain ? null : findPart(payload, "text/html");
   const text = plain ? decodeBody(plain.body!.data!) : html ? htmlToText(decodeBody(html.body!.data!)) : message.snippet;
   const dateHeader = header(payload, "Date");
-  const date = message.internalDate ? new Date(Number(message.internalDate)) : new Date(dateHeader);
+  const internalDate = message.internalDate;
+  const parsedDate =
+    internalDate && /^\d+$/.test(internalDate) ? new Date(Number(internalDate)) : new Date(dateHeader);
+  const date = Number.isNaN(parsedDate.getTime()) ? new Date() : parsedDate;
   return {
     id: message.id,
     threadId: message.threadId,
@@ -95,7 +98,7 @@ export function readMessage(json: unknown): ReadMail {
     subject: decodeHeader(header(payload, "Subject")),
     messageId: header(payload, "Message-ID") || header(payload, "Message-Id"),
     references: header(payload, "References"),
-    date: Number.isNaN(date.getTime()) ? new Date() : date,
+    date,
     text,
   };
 }