feat(auth): add support for managing custom headers in auth files

Closes #2457

sdk/cliproxy/auth/custom_headers.go

@@ -0,0 +1,68 @@
+package auth
+
+import "strings"
+
+func ExtractCustomHeadersFromMetadata(metadata map[string]any) map[string]string {
+	if len(metadata) == 0 {
+		return nil
+	}
+	raw, ok := metadata["headers"]
+	if !ok || raw == nil {
+		return nil
+	}
+
+	out := make(map[string]string)
+	switch headers := raw.(type) {
+	case map[string]string:
+		for key, value := range headers {
+			name := strings.TrimSpace(key)
+			if name == "" {
+				continue
+			}
+			val := strings.TrimSpace(value)
+			if val == "" {
+				continue
+			}
+			out[name] = val
+		}
+	case map[string]any:
+		for key, value := range headers {
+			name := strings.TrimSpace(key)
+			if name == "" {
+				continue
+			}
+			rawVal, ok := value.(string)
+			if !ok {
+				continue
+			}
+			val := strings.TrimSpace(rawVal)
+			if val == "" {
+				continue
+			}
+			out[name] = val
+		}
+	default:
+		return nil
+	}
+
+	if len(out) == 0 {
+		return nil
+	}
+	return out
+}
+
+func ApplyCustomHeadersFromMetadata(auth *Auth) {
+	if auth == nil || len(auth.Metadata) == 0 {
+		return
+	}
+	headers := ExtractCustomHeadersFromMetadata(auth.Metadata)
+	if len(headers) == 0 {
+		return
+	}
+	if auth.Attributes == nil {
+		auth.Attributes = make(map[string]string)
+	}
+	for name, value := range headers {
+		auth.Attributes["header:"+name] = value
+	}
+}

sdk/cliproxy/auth/custom_headers_test.go

@@ -0,0 +1,50 @@
+package auth
+
+import (
+	"reflect"
+	"testing"
+)
+
+func TestExtractCustomHeadersFromMetadata(t *testing.T) {
+	meta := map[string]any{
+		"headers": map[string]any{
+			" X-Test ": " value ",
+			"":         "ignored",
+			"X-Empty":  "   ",
+			"X-Num":    float64(1),
+		},
+	}
+
+	got := ExtractCustomHeadersFromMetadata(meta)
+	want := map[string]string{"X-Test": "value"}
+	if !reflect.DeepEqual(got, want) {
+		t.Fatalf("ExtractCustomHeadersFromMetadata() = %#v, want %#v", got, want)
+	}
+}
+
+func TestApplyCustomHeadersFromMetadata(t *testing.T) {
+	auth := &Auth{
+		Metadata: map[string]any{
+			"headers": map[string]string{
+				"X-Test":  "new",
+				"X-Empty": "   ",
+			},
+		},
+		Attributes: map[string]string{
+			"header:X-Test": "old",
+			"keep":          "1",
+		},
+	}
+
+	ApplyCustomHeadersFromMetadata(auth)
+
+	if got := auth.Attributes["header:X-Test"]; got != "new" {
+		t.Fatalf("header:X-Test = %q, want %q", got, "new")
+	}
+	if _, ok := auth.Attributes["header:X-Empty"]; ok {
+		t.Fatalf("expected header:X-Empty to be absent, got %#v", auth.Attributes["header:X-Empty"])
+	}
+	if got := auth.Attributes["keep"]; got != "1" {
+		t.Fatalf("keep = %q, want %q", got, "1")
+	}
+}