fix: Validate authentication security and prevent identity spoofing

[paradyo]

Description

1 final security validation must confirm that identity spoofing through client provided headers is no longer possible after the authentication refactor. Manual header manipulation attempts must be tested to verify the backend rejects them and only accepts identity derived from validated authentication tokens. Documentation explaining the authentication flow must be prepared and the validated implementation merged into the main branch after review.

Ownership, Timeline, and Effort

Owner: @cenkerenozbek
Given Date: 04-03-2026
Deadline: 08-03-2026 24:00 (end of day, explicitly stated)
Hours: 1
Value: 1
Week: 10

Deliverables

• Security validation tests confirming identity spoofing attempts fail.
• Test results demonstrating backend rejection of manipulated identity headers.
• Documentation describing the authentication flow and identity validation mechanism.
• Pull request containing final security validation updates and documentation merged into the main branch.

Scope Definition

In Scope

• Perform security validation of authentication and identity verification mechanisms.
• Attempt identity spoofing using manual header manipulation.
• Confirm backend rejects requests attempting identity injection.
• Verify identity resolution occurs only through validated authentication tokens.
• Document the authentication flow and identity validation process.
• Submit pull request including documentation and any required security fixes.

Out of Scope

• Implementation of new authentication mechanisms.
• Role based authorization or permission systems.
• Frontend authentication interface changes.
• Security penetration testing beyond authentication validation.
• Changes to unrelated backend services.

Acceptance Criteria

• Identity spoofing attempts using manual request headers are rejected.
• Backend ignores client provided identity headers.
• Authenticated identity is derived exclusively from validated tokens.
• Security validation tests demonstrate correct backend behavior.
• Authentication flow documentation is completed and shared.
• Pull request including documentation and validation results is merged into the main branch.

Domain Specific Notes

Engineering considerations:

• Identity validation must rely exclusively on the Clerk token verification middleware.
• Manual identity headers must not influence backend identity resolution.

Assumption: Authentication middleware and token validation mechanisms have already been implemented and integrated into protected endpoints.

Validation and Review Requirements

• Reviewer confirms identity spoofing attempts are rejected.
• Reviewer verifies backend ignores manually injected identity headers.
• Reviewer reviews authentication flow documentation.
• Reviewer confirms pull request includes all validation results and documentation.
• Issue is considered Done only when the pull request is merged into the main branch after successful review.