Summary

Hardens the user CRUD routes with missing input validation, duplicate-entry handling, and correct HTTP semantics.

Schema validation (app/schema.py):

• email fields now use Pydantic EmailStr (leverages email-validator already in requirements) instead of bare str
• name fields are stripped of surrounding whitespace and rejected if empty
• password on UserCreate requires a minimum length of 6 characters

Route-level error handling (main.py):

• POST /users/ returns 201 Created instead of 200
• Both POST /users/ and PUT /users/{user_id} check for duplicate emails before committing, returning 409 Conflict if the email is already taken
• IntegrityError is caught with a db.rollback() as a safety net against race conditions on the unique email constraint
• Renamed misleading handler functions (get_user_by_email → get_user, etc.) since they operate on user_id, not email

Review & Testing Checklist for Human

• Duplicate email on create/update: Manually POST a user, then POST again with the same email — confirm you get 409. Do the same with PUT targeting a different user's ID.
• Password minimum length: Confirm POST /users/ with a 5-char password returns a 422 validation error, and a 6-char password succeeds. Decide if 6 is the right threshold for your use case.
• Whitespace-only name: POST or PUT with "name": " " — confirm it's rejected. Also confirm leading/trailing whitespace is stripped from valid names (e.g. " Alice " → "Alice").
• Email format validation: Confirm malformed emails like "not-an-email" return 422.
• End-to-end smoke test: Run the app with uvicorn main:app --reload (using Python 3.10 — pydantic v1 is incompatible with 3.12) and exercise all five CRUD endpoints to confirm nothing regressed.

Notes

• No automated test suite exists in this repo, so all verification is manual.
• The pre-existing Python 3.12 + pydantic v1 incompatibility is unrelated to this PR (the project targets Python 3.10 per the Dockerfile).

Link to Devin session: https://app.devin.ai/sessions/384a73385f864e4396f60815e484395a
Requested by: @SoySoy4444