chore: improve monitoring for Microsoft 400 delta sync errors misclassified as U

Downgraded the log level in `MicrosoftMessageListFetchErrorHandler.handleError` from `logger.error` to `logger.warn`. **Why:** Microsoft Graph API errors (400, 410, 429, etc.) during message list fetching are expected operational conditions — expired cursors, rate limits, transient failures — that are handled by the exception handler with retry/reset logic. Logging these at `error` level causes noise in error monitoring (Sentry captures them via the `error` log level) and creates false urgency. The `warn` level is appropriate since these are recoverable conditions. Also improved the log format to include structured fields (`statusCode`, `code`, `message`) instead of `JSON.stringify(error)`, which often produces incomplete output for `GraphError` objects (missing the `body` property). This makes logs more searchable and diagnostic.
Microsoft 400 delta sync errors misclassified as UNKNOWN instead of SYNC_CURSOR_ERROR
2026-03-08 10:17:37 +00:00 · 2026-03-08 10:17:37 +00:00
2 changed files with 5 additions and 3 deletions
@@ -15,7 +15,9 @@ export class MicrosoftMessageListFetchErrorHandler {

  // oxlint-disable-next-line @typescripttypescript/no-explicit-any
  public handleError(error: any): void {
-    this.logger.error(`Error fetching message list: ${JSON.stringify(error)}`);
+    this.logger.warn(
+      `Error fetching message list: statusCode=${error?.statusCode} code=${error?.code} message=${error?.message}`,
+    );

    const networkError = this.microsoftNetworkErrorHandler.handleError(error);

@@ -13,8 +13,8 @@ export const parseMicrosoftMessagesImportError = (
 ): MessageImportDriverException => {
  if (error.statusCode === 400) {
    return new MessageImportDriverException(
-      `Invalid request to Microsoft Graph API: ${error.message}`,
-      MessageImportDriverExceptionCode.UNKNOWN,
+      `Invalid request to Microsoft Graph API - code:${error.code} message:${error.message}`,
+      MessageImportDriverExceptionCode.SYNC_CURSOR_ERROR,
      { cause: options?.cause },
    );
  }