Nexent backend changes

Repository paths below are relative to the root; reference links resolve from this skill directory.

1. Identify the affected boundary and inspect existing callers and contracts. Apps handle HTTP, services orchestrate business logic, and database modules own persistence.
2. Read only the references matching the work. For end-to-end changes, read each affected layer before editing.

Work	Reference
HTTP routes, validation, identity, response/error mapping	HTTP layer
Business orchestration and domain errors	Services
Relational schema design, models, keys/indexes, queries, transactions, SQL migrations	Database
Environment configuration and SDK configuration parameters	Configuration
Threads, worker pools, blocking calls, background loops, streaming resource lifetime	Thread lifecycle

3. Preserve public contracts. Apply conventions to the changed scope; do not refactor unrelated legacy behavior merely to satisfy a rule.
4. Verify affected success and failure behavior. For Python unit tests, use nexent-python-tests linked from root AGENTS.md. Unit-test mocks do not establish live-integration acceptance.
5. Report references consulted, affected contracts, and verification results. Resolve material contract conflicts using concrete evidence; routine implementation choices do not require additional permission.