Data export does not include other users' private messages

Data portability (GDPR Art. 20) entitles users to their own data — not other users' data. An export query that fetches entire conversation threads by conversation ID rather than by participant ID will return messages the requesting user received from, or in group threads containing, other users who did not request the export. This is a direct CWE-285 (improper authorization) and CWE-200 (information exposure) violation, and a data breach reportable under GDPR Art. 33 if it reaches the requesting user's device.

Filter the message export query strictly to rows where the requesting user is sender or recipient — never by conversation ID alone. In your data export job (src/jobs/generateDataExport.ts):

const messages = await db.message.findMany({
  where: {
    OR: [
      { senderId: userId },
      { recipientId: userId }
    ]
  },
  select: {
    id: true, content: true, sentAt: true,
    senderId: true, recipientId: true
  }
});
// Do NOT query by conversationId — that pulls all participants' messages

Code-review the export job whenever the message schema changes to ensure new join tables or group-chat expansions don't reintroduce the over-fetch pattern.