Fix: Log-Zeitstempel in lokaler Zeit (mit Offset) statt UTC

User-Report: Logs zeigten z.B. "17:29:43" obwohl es lokal 19:29:43 war (CEST/UTC+2), weil
alle Logger `new Date().toISOString()` (UTC "...Z") nutzten. Neuer Helper logTimestamp()
formatiert lokale Zeit mit explizitem Offset (ISO 8601, z.B. "2026-05-31T19:29:43.605+02:00")
— menschlich lokal UND weiterhin eindeutig/Date.parse-bar. Angewandt auf alle Log-Zeilen-
Writer: item-log, logger (rd_downloader.log), audit-log, rename-log, session-log,
package-log, account-rotation-log, trace-log. Interne/API-/Dateinamen-Zeitstempel
(debug-server, support-bundle, trace autoDisableAt-Config) bleiben absichtlich UTC.

Test: tests/log-timestamp.test.ts (Format + Round-Trip zum selben Instant + lokale Stunde,
TZ-unabhaengig). 650 Tests gruen, tsc 9, Build sauber.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/main/account-rotation-log.ts

@@ -1,4 +1,5 @@
 import fs from "node:fs";
+import { logTimestamp } from "./log-timestamp";
 import path from "node:path";
 import { AsyncLocalStorage } from "node:async_hooks";
 import type { RotationEvent } from "../shared/types";
@@ -181,7 +182,7 @@ export function initAccountRotationLog(baseDir: string): void {
     }
     fs.appendFileSync(
       rotationLogPath,
-      `=== Account-Rotation Log Start: ${new Date().toISOString()} ===\n`,
+      `=== Account-Rotation Log Start: ${logTimestamp()} ===\n`,
       "utf8"
     );
   } catch {
@@ -213,7 +214,7 @@ export function logAccountRotation(
     if (!fs.existsSync(rotationLogPath)) {
       fs.writeFileSync(rotationLogPath, "", "utf8");
     }
-    const head = `${new Date().toISOString()} [${level}] ${provider} | ${accountLabel} | ${event}`;
+    const head = `${logTimestamp()} [${level}] ${provider} | ${accountLabel} | ${event}`;
     fs.appendFileSync(rotationLogPath, `${head}${formatFields(fields)}\n`, "utf8");
   } catch {
     // ignore write errors
@@ -234,7 +235,7 @@ export function shutdownAccountRotationLog(): void {
   try {
     fs.appendFileSync(
       rotationLogPath,
-      `=== Account-Rotation Log Ende: ${new Date().toISOString()} ===\n`,
+      `=== Account-Rotation Log Ende: ${logTimestamp()} ===\n`,
       "utf8"
     );
   } catch {

src/main/audit-log.ts

@@ -1,4 +1,5 @@
 import fs from "node:fs";
+import { logTimestamp } from "./log-timestamp";
 import path from "node:path";
 
 type AuditLevel = "INFO" | "WARN" | "ERROR";
@@ -78,7 +79,7 @@ export function initAuditLog(baseDir: string): void {
     if (!fs.existsSync(auditLogPath)) {
       fs.writeFileSync(auditLogPath, "", "utf8");
     }
-    fs.appendFileSync(auditLogPath, `=== Audit-Log Start: ${new Date().toISOString()} ===\n`, "utf8");
+    fs.appendFileSync(auditLogPath, `=== Audit-Log Start: ${logTimestamp()} ===\n`, "utf8");
   } catch {
     auditLogPath = null;
   }
@@ -95,7 +96,7 @@ export function logAuditEvent(level: AuditLevel, message: string, fields?: Recor
     }
     fs.appendFileSync(
       auditLogPath,
-      `${new Date().toISOString()} [${level}] ${message}${formatFields(fields)}\n`,
+      `${logTimestamp()} [${level}] ${message}${formatFields(fields)}\n`,
       "utf8"
     );
   } catch {
@@ -115,7 +116,7 @@ export function shutdownAuditLog(): void {
     return;
   }
   try {
-    fs.appendFileSync(auditLogPath, `=== Audit-Log Ende: ${new Date().toISOString()} ===\n`, "utf8");
+    fs.appendFileSync(auditLogPath, `=== Audit-Log Ende: ${logTimestamp()} ===\n`, "utf8");
   } catch {
     // ignore
   }

src/main/item-log.ts

@@ -1,4 +1,5 @@
 import fs from "node:fs";
+import { logTimestamp } from "./log-timestamp";
 import path from "node:path";
 import crypto from "node:crypto";
 
@@ -166,7 +167,7 @@ export function ensureItemLog(meta: ItemLogMeta): string | null {
     }
     if (!initializedThisProcess.has(normalizedItemId)) {
       initializedThisProcess.add(normalizedItemId);
-      const startedAt = new Date().toISOString();
+      const startedAt = logTimestamp();
       fs.appendFileSync(
         logPath,
         `=== Item-Log Start: ${startedAt} | itemId=${sanitizeFieldValue(String(meta.itemId || ""))} | logKey=${normalizedItemId} | fileName=${sanitizeFieldValue(meta.fileName)} ===\n`,
@@ -174,7 +175,7 @@ export function ensureItemLog(meta: ItemLogMeta): string | null {
       );
       fs.appendFileSync(
         logPath,
-        `${new Date().toISOString()} [INFO] Item-Kontext initialisiert${formatFields({
+        `${logTimestamp()} [INFO] Item-Kontext initialisiert${formatFields({
           packageId: meta.packageId,
           packageName: meta.packageName,
           fileName: meta.fileName,
@@ -199,7 +200,7 @@ export function logItemEvent(
   if (!logPath) {
     return;
   }
-  const line = `${new Date().toISOString()} [${level}] ${message}${formatFields(fields)}\n`;
+  const line = `${logTimestamp()} [${level}] ${message}${formatFields(fields)}\n`;
   appendLine(itemId, line);
 }
 
@@ -223,7 +224,7 @@ export function shutdownItemLogs(): void {
       continue;
     }
     try {
-      fs.appendFileSync(logPath, `=== Item-Log Ende: ${new Date().toISOString()} ===\n`, "utf8");
+      fs.appendFileSync(logPath, `=== Item-Log Ende: ${logTimestamp()} ===\n`, "utf8");
     } catch {
       // ignore
     }

src/main/log-timestamp.ts

@@ -0,0 +1,22 @@
+/**
+ * Zeitstempel für Log-Dateien in LOKALER Zeit mit explizitem UTC-Offset
+ * (ISO 8601, z. B. "2026-05-31T19:29:43.605+02:00").
+ *
+ * Vorher nutzten alle Logger `new Date().toISOString()` → UTC ("...Z"). Auf einem
+ * CEST-Server (UTC+2) las der User dadurch z. B. "17:29:43" statt der erwarteten
+ * lokalen "19:29:43". Lokale Zeit MIT Offset bleibt eindeutig + maschinell parsebar
+ * (Date.parse versteht den Offset), zeigt dem User aber die Uhrzeit seiner Zeitzone.
+ */
+export function logTimestamp(date: Date = new Date()): string {
+  const pad = (value: number, length = 2): string => String(value).padStart(length, "0");
+  // getTimezoneOffset() liefert Minuten, die man zur LOKALEN Zeit ADDIEREN muss, um
+  // UTC zu erhalten — also negiert = Offset der lokalen Zone gegenüber UTC.
+  const offsetMinutes = -date.getTimezoneOffset();
+  const sign = offsetMinutes >= 0 ? "+" : "-";
+  const absOffset = Math.abs(offsetMinutes);
+  const offset = `${sign}${pad(Math.floor(absOffset / 60))}:${pad(absOffset % 60)}`;
+  return (
+    `${date.getFullYear()}-${pad(date.getMonth() + 1)}-${pad(date.getDate())}` +
+    `T${pad(date.getHours())}:${pad(date.getMinutes())}:${pad(date.getSeconds())}.${pad(date.getMilliseconds(), 3)}${offset}`
+  );
+}

src/main/logger.ts

@@ -1,4 +1,5 @@
 import fs from "node:fs";
+import { logTimestamp } from "./log-timestamp";
 import path from "node:path";
 
 let logFilePath = path.resolve(process.cwd(), "rd_downloader.log");
@@ -209,7 +210,7 @@ function ensureExitHook(): void {
 
 function write(level: "INFO" | "WARN" | "ERROR", message: string): void {
   ensureExitHook();
-  const line = `${new Date().toISOString()} [${level}] ${message}\n`;
+  const line = `${logTimestamp()} [${level}] ${message}\n`;
   pendingLines.push(line);
   pendingChars += line.length;
 

src/main/package-log.ts

@@ -1,4 +1,5 @@
 import fs from "node:fs";
+import { logTimestamp } from "./log-timestamp";
 import path from "node:path";
 import crypto from "node:crypto";
 
@@ -165,7 +166,7 @@ export function ensurePackageLog(meta: PackageLogMeta): string | null {
     }
     if (!initializedThisProcess.has(normalizedPackageId)) {
       initializedThisProcess.add(normalizedPackageId);
-      const startedAt = new Date().toISOString();
+      const startedAt = logTimestamp();
       fs.appendFileSync(
         logPath,
         `=== Paket-Log Start: ${startedAt} | packageId=${sanitizeFieldValue(String(meta.packageId || ""))} | logKey=${normalizedPackageId} | name=${sanitizeFieldValue(meta.name)} ===\n`,
@@ -173,7 +174,7 @@ export function ensurePackageLog(meta: PackageLogMeta): string | null {
       );
       fs.appendFileSync(
         logPath,
-        `${new Date().toISOString()} [INFO] Paket-Kontext initialisiert${formatFields({
+        `${logTimestamp()} [INFO] Paket-Kontext initialisiert${formatFields({
           name: meta.name,
           outputDir: meta.outputDir,
           extractDir: meta.extractDir
@@ -197,7 +198,7 @@ export function logPackageEvent(
   if (!logPath) {
     return;
   }
-  const line = `${new Date().toISOString()} [${level}] ${message}${formatFields(fields)}\n`;
+  const line = `${logTimestamp()} [${level}] ${message}${formatFields(fields)}\n`;
   appendLine(packageId, line);
 }
 
@@ -221,7 +222,7 @@ export function shutdownPackageLogs(): void {
       continue;
     }
     try {
-      fs.appendFileSync(logPath, `=== Paket-Log Ende: ${new Date().toISOString()} ===\n`, "utf8");
+      fs.appendFileSync(logPath, `=== Paket-Log Ende: ${logTimestamp()} ===\n`, "utf8");
     } catch {
       // ignore
     }

src/main/rename-log.ts

@@ -1,4 +1,5 @@
 import fs from "node:fs";
+import { logTimestamp } from "./log-timestamp";
 import path from "node:path";
 
 type RenameLogLevel = "INFO" | "WARN" | "ERROR";
@@ -78,7 +79,7 @@ export function initRenameLog(baseDir: string): void {
     if (!fs.existsSync(renameLogPath)) {
       fs.writeFileSync(renameLogPath, "", "utf8");
     }
-    fs.appendFileSync(renameLogPath, `=== Rename-Log Start: ${new Date().toISOString()} ===\n`, "utf8");
+    fs.appendFileSync(renameLogPath, `=== Rename-Log Start: ${logTimestamp()} ===\n`, "utf8");
   } catch {
     renameLogPath = null;
   }
@@ -95,7 +96,7 @@ export function logRenameEvent(level: RenameLogLevel, message: string, fields?:
     }
     fs.appendFileSync(
       renameLogPath,
-      `${new Date().toISOString()} [${level}] ${message}${formatFields(fields)}\n`,
+      `${logTimestamp()} [${level}] ${message}${formatFields(fields)}\n`,
       "utf8"
     );
   } catch {
@@ -115,7 +116,7 @@ export function shutdownRenameLog(): void {
     return;
   }
   try {
-    fs.appendFileSync(renameLogPath, `=== Rename-Log Ende: ${new Date().toISOString()} ===\n`, "utf8");
+    fs.appendFileSync(renameLogPath, `=== Rename-Log Ende: ${logTimestamp()} ===\n`, "utf8");
   } catch {
     // ignore
   }

src/main/session-log.ts

@@ -1,4 +1,5 @@
 import fs from "node:fs";
+import { logTimestamp } from "./log-timestamp";
 import path from "node:path";
 import { setLogListener } from "./logger";
 
@@ -86,7 +87,7 @@ export function initSessionLog(baseDir: string): void {
   const timestamp = formatTimestamp();
   sessionLogPath = path.join(sessionLogsDir, `session_${timestamp}.txt`);
 
-  const isoTimestamp = new Date().toISOString();
+  const isoTimestamp = logTimestamp();
   try {
     fs.writeFileSync(sessionLogPath, `=== Session gestartet: ${isoTimestamp} ===\n`, "utf8");
   } catch {
@@ -116,7 +117,7 @@ export function shutdownSessionLog(): void {
   flushPending();
 
   // Write closing line
-  const isoTimestamp = new Date().toISOString();
+  const isoTimestamp = logTimestamp();
   try {
     fs.appendFileSync(sessionLogPath, `=== Session beendet: ${isoTimestamp} ===\n`, "utf8");
   } catch {

src/main/trace-log.ts

@@ -1,4 +1,5 @@
 import fs from "node:fs";
+import { logTimestamp } from "./log-timestamp";
 import path from "node:path";
 import { addLogListener, removeLogListener } from "./logger";
 import type { SupportTraceConfig } from "../shared/types";
@@ -189,10 +190,10 @@ function disableTraceDueToExpiry(): void {
     ...traceConfig,
     enabled: false,
     autoDisableAt: null,
-    updatedAt: new Date().toISOString()
+    updatedAt: logTimestamp()
   });
   persistTraceConfig();
-  appendTraceLine(`${new Date().toISOString()} [INFO] [trace] Support-Trace automatisch deaktiviert | reason=expired\n`);
+  appendTraceLine(`${logTimestamp()} [INFO] [trace] Support-Trace automatisch deaktiviert | reason=expired\n`);
 }
 
 function scheduleAutoDisable(): void {
@@ -230,7 +231,7 @@ export function initTraceLog(baseDir: string): void {
     }
     traceConfig = loadTraceConfig();
     persistTraceConfig();
-    fs.appendFileSync(traceLogPath, `=== Trace-Log Start: ${new Date().toISOString()} ===\n`, "utf8");
+    fs.appendFileSync(traceLogPath, `=== Trace-Log Start: ${logTimestamp()} ===\n`, "utf8");
   } catch {
     traceLogPath = null;
     traceConfigPath = null;
@@ -263,11 +264,11 @@ export function updateTraceConfig(patch: Partial<SupportTraceConfig>): SupportTr
   traceConfig = normalizeTraceConfig({
     ...traceConfig,
     ...patch,
-    updatedAt: new Date().toISOString()
+    updatedAt: logTimestamp()
   });
   persistTraceConfig();
   scheduleAutoDisable();
-  appendTraceLine(`${new Date().toISOString()} [INFO] [trace] Konfiguration aktualisiert${formatFields(traceConfig as unknown as Record<string, unknown>)}\n`);
+  appendTraceLine(`${logTimestamp()} [INFO] [trace] Konfiguration aktualisiert${formatFields(traceConfig as unknown as Record<string, unknown>)}\n`);
   return getTraceConfig();
 }
 
@@ -276,7 +277,7 @@ export function setTraceEnabled(enabled: boolean, note = "", durationMs: number
     ? new Date(Date.now() + durationMs).toISOString()
     : null;
   const next = updateTraceConfig({ enabled, autoDisableAt });
-  appendTraceLine(`${new Date().toISOString()} [INFO] [trace] Support-Trace ${enabled ? "aktiviert" : "deaktiviert"}${formatFields({ note, autoDisableAt })}\n`);
+  appendTraceLine(`${logTimestamp()} [INFO] [trace] Support-Trace ${enabled ? "aktiviert" : "deaktiviert"}${formatFields({ note, autoDisableAt })}\n`);
   return next;
 }
 
@@ -292,7 +293,7 @@ export function logTraceEvent(
   if (category === "audit" && !traceConfig.includeAudit) {
     return;
   }
-  appendTraceLine(`${new Date().toISOString()} [${level}] [${category}] ${message}${formatFields(fields)}\n`);
+  appendTraceLine(`${logTimestamp()} [${level}] [${category}] ${message}${formatFields(fields)}\n`);
 }
 
 export function shutdownTraceLog(): void {
@@ -307,7 +308,7 @@ export function shutdownTraceLog(): void {
   }
   flushPending();
   try {
-    fs.appendFileSync(traceLogPath, `=== Trace-Log Ende: ${new Date().toISOString()} ===\n`, "utf8");
+    fs.appendFileSync(traceLogPath, `=== Trace-Log Ende: ${logTimestamp()} ===\n`, "utf8");
   } catch {
     // ignore
   }

tests/log-timestamp.test.ts

@@ -0,0 +1,28 @@
+import { describe, expect, it } from "vitest";
+import { logTimestamp } from "../src/main/log-timestamp";
+
+describe("logTimestamp", () => {
+  it("formats local time with an explicit UTC offset (ISO 8601), not a UTC 'Z' string", () => {
+    const instant = new Date("2026-05-31T17:29:43.605Z");
+    const formatted = logTimestamp(instant);
+
+    // Shape: YYYY-MM-DDTHH:MM:SS.mmm±HH:MM
+    expect(formatted).toMatch(/^\d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}\.\d{3}[+-]\d{2}:\d{2}$/);
+    // The whole point: NOT the old UTC "...Z" format that showed 17:29 instead of 19:29.
+    expect(formatted.endsWith("Z")).toBe(false);
+  });
+
+  it("is parseable back to the exact same instant (offset keeps it unambiguous)", () => {
+    const instant = new Date("2026-05-31T17:29:43.605Z");
+    // Date.parse must still recover the identical instant (trace-log autoDisableAt etc.).
+    expect(new Date(logTimestamp(instant)).getTime()).toBe(instant.getTime());
+  });
+
+  it("shows the LOCAL wall-clock hour (machine-timezone-independent assertion)", () => {
+    const instant = new Date("2026-05-31T17:29:43.605Z");
+    const formatted = logTimestamp(instant);
+    // Hour segment must equal the local getHours() of the same instant — i.e. the
+    // user's wall clock, whatever the server timezone is.
+    expect(formatted.slice(11, 13)).toBe(String(instant.getHours()).padStart(2, "0"));
+  });
+});