YARA-1056

src/captcha/captcha-challenge.service.ts

@@ -32,12 +32,17 @@ export class CaptchaChallengeService {
       this.captchaService.normalizeAnswer(generated.text),
     );
 
+    // expireAt is the MongoDB TTL sentinel. The TTL reaper fires every ~60 s, so
+    // setting it equal to expiresAt means Mongo can delete the document up to 60 s
+    // BEFORE the application-level expiry check runs — causing the intermittent
+    // "captchaId not found" error under load. Adding a 120 s grace buffer ensures
+    // the document is always present when verify() runs its own expiresAt check.
     await this.captchaChallengeDbService.create({
       captchaId,
       answerHash,
       image: generated.image,
       expiresAt: generated.expiresAt,
-      expireAt: new Date(generated.expiresAt),
+      expireAt: new Date(generated.expiresAt + 120_000),
       usedAt: null,
     });