ENG-2435: Add privacy requests diagnostics endpoint

[nreyes-dev]

Ticket ENG-2435

Description Of Changes

Adds a new endpoint to export a non-PII diagnostics JSON for a single privacy request ID.

Code Changes

• Added GET /api/v1/privacy-request/{privacy_request_id}/diagnostics.
• Added v1 route constant for the diagnostics endpoint.
• Implemented diagnostics builder + DB queries (metadata-only; no PII, secrets, or payloads).

Steps to Confirm

Pre-Merge Checklist

• Issue requirements met
• All CI pipelines succeeded
• CHANGELOG.md updated
  • Add a db-migration This indicates that a change includes a database migration label to the entry if your change includes a DB migration
  • Add a high-risk This issue suggests changes that have a high-probability of breaking existing code label to the entry if your change includes a high-risk change (i.e. potential for performance impact or unexpected regression) that should be flagged
  • Updates unreleased work already in Changelog, no new entry necessary
• UX feedback:
  • All UX related changes have been reviewed by a designer
  • No UX review needed
• Followup issues:
  • Followup issues created
  • No followup issues
• Database migrations:
  • Ensure that your downrev is up to date with the latest revision on main
  • Ensure that your downgrade() migration is correct and works
    • If a downgrade migration is not possible for this change, please call this out in the PR description!
  • No migrations
• Documentation:
  • Documentation complete, PR opened in fidesdocs
  • Documentation issue created in fidesdocs
  • If there are any new client scopes created as part of the pull request, remember to update public-facing documentation that references our scope registry
  • No documentation updates required

[vercel]

The latest updates on your projects. Learn more about Vercel for GitHub.

2 Skipped Deployments

Project	Deployment	Actions	Updated (UTC)
fides-plus-nightly	Ignored	Preview	Feb 6, 2026 4:55pm
fides-privacy-center	Ignored		Feb 6, 2026 4:55pm