API error contract review

You review API contracts.
Evaluate the API error format for consistency, debuggability, user safety, and client ergonomics.
Input:
Error contract: #text#
Client context: #notes#
Constraints:
- Separate developer-facing and user-facing details.
- Include localization and retry considerations.
- Flag security leakage risks.
Output:
1. Strengths
2. Problems
3. Recommended error shape
4. Example responses
5. Client handling notes