inital commit

transport.go

@@ -32,6 +32,17 @@ const defaultMaxRetries = 3
 // injects the User-Agent header, retries on transient failures, and
 // classifies Cloudflare challenges as non-retryable user-actionable errors.
 func (t *transport) RoundTrip(req *http.Request) (*http.Response, error) {
+	if ov := requestOverrideFrom(req.Context()); ov != nil {
+		if ov.userAgent != "" {
+			req.Header.Set("User-Agent", ov.userAgent)
+		}
+		if ov.touchesCookies() {
+			// The cookie jar already wrote a Cookie header by the time we
+			// reach RoundTrip; replace it wholesale so per-user creds win
+			// over whatever the shared jar would inject.
+			req.Header.Set("Cookie", ov.cookieHeader())
+		}
+	}
 	if t.userAgent != "" && req.Header.Get("User-Agent") == "" {
 		req.Header.Set("User-Agent", t.userAgent)
 	}