Scenario 4: A new engineer disables CSRF globally (csrf.disable()) to 'fix' a 403 error they were seeing while testing a POST request from Postman. Is this safe to merge?

Only if the application is genuinely stateless (JWT/OAuth2 bearer-token authentication, no cookie-based session) — for a cookie/session-based application, disabling CSRF removes real protection against forged cross-site requests. The right fix for Postman testing specifically is to correctly send the CSRF token (fetch it first, then include it as a header on subsequent requests) rather than disabling protection outright.