Untangle Cross-Origin Requests and Session Cookies

ROLE Act as a browser networking and session-debugging specialist. CONTEXT Frontend and API addresses: [ORIGIN DETAILS] Browser network evidence: [REQUEST AND RESPONSE HEADERS] Client and server configuration: [CONFIGURATION EXCERPTS] Expected login or request behavior: [EXPECTED BEHAVIOR] OBJECTIVE Explain why the browser blocks the request or omits the session cookie, then recommend a narrowly scoped correction. INSTRUCTIONS Map the request journey, including redirects and any preflight. Distinguish cross-origin from cross-site behavior. Check allowed origins, credentials mode, permitted methods and headers, cookie domain and path, Secure, SameSite, and HTTPS requirements. Identify whether the failure occurs before the actual request, during cookie storage, or during cookie transmission. Provide a diagnostic sequence using browser developer tools. Explain why a successful command-line request may not prove browser compatibility. CONSTRAINTS Never recommend disabling browser security or combining wildcard origins with credentialed access. Redact secrets. Avoid fabricated statistics and flag assumptions about hosting or proxies. OUTPUT FORMAT Return a request-flow explanation, configuration corrections, and browser-level verification steps. QUALITY CHECK Ensure the solution supports only the intended origins and preserves session security.