chore: import upstream snapshot with attribution

pkg/http/transport/bearer.go

@@ -0,0 +1,40 @@
+package transport
+
+import (
+	"net/http"
+	"strings"
+
+	ghcontext "github.com/github/github-mcp-server/pkg/context"
+	headers "github.com/github/github-mcp-server/pkg/http/headers"
+)
+
+type BearerAuthTransport struct {
+	Transport http.RoundTripper
+	Token     string
+
+	// TokenProvider, when non-nil, supplies the bearer token for each request
+	// and takes precedence over Token. It backs OAuth, where the token is
+	// obtained after the client is built and is refreshed over the session's
+	// lifetime. It may return an empty string before authorization completes.
+	TokenProvider func() string
+}
+
+func (t *BearerAuthTransport) RoundTrip(req *http.Request) (*http.Response, error) {
+	req = req.Clone(req.Context())
+	token := t.Token
+	if t.TokenProvider != nil {
+		token = t.TokenProvider()
+	}
+	// Before OAuth authorization completes the token is empty; send an
+	// unauthenticated request rather than an empty "Bearer " header.
+	if token != "" {
+		req.Header.Set(headers.AuthorizationHeader, "Bearer "+token)
+	}
+
+	// Check for GraphQL-Features in context and add header if present
+	if features := ghcontext.GetGraphQLFeatures(req.Context()); len(features) > 0 {
+		req.Header.Set(headers.GraphQLFeaturesHeader, strings.Join(features, ", "))
+	}
+
+	return t.Transport.RoundTrip(req)
+}