[AGiorgetti]

Summary

Closes #92.

Prefer MongoDB write categories and command codes over broad exception-message substring matching. Use structured key patterns when available; otherwise match complete index tokens in legacy duplicate-key messages. Preserve checkpoint retries, duplicate commit detection, and stream concurrency handling in both sync and async paths. Add representative response/message regressions and a changelog note. No production dependency, public API, or schema change.

Verification

• Full suite: .NET 10 / Driver 3.13.0 / isolated MongoDB 8: 1,152 passed, zero skipped.
• Focused classifier and real-database duplicate/concurrency/checkpoint regressions: 31 passed, zero skipped in each of eight lanes: net472/net8/net9/net10 with Driver 3.0.0 and 3.13.0.
• CRLF-aware whitespace check passed.
• Full suite was not run on other framework/driver combinations. CI remains pending.

Co-authored by Alessandro Giorgetti and Codex (OpenAI).