CORS wildcard origin silently breaks authenticated requests after deployment

Short summary

A developer shares a debugging story where React + Express auth worked locally but silently failed after deployment. The root cause was CORS configured with origin '*' which breaks credential-based requests in browsers. The fix: set an explicit origin, enable credentials, and align cookie SameSite/Secure attributes.

• •CORS wildcard origin silently breaks authenticated requests in production
• •Local same-origin behavior masks CORS, cookie, and credential misconfigurations
• •Fix: explicit CORS origin, credentials:true, and correct SameSite/Secure cookie attributes

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