Simplify codebase per audit of 8b89f14

internal/mcp/server.go

@@ -17,6 +17,35 @@ type Tool struct {
 	Rich        func(ctx context.Context, args json.RawMessage) Result
 }
 
+func decode[A any](raw json.RawMessage) (A, error) {
+	args := *new(A)
+	err := json.Unmarshal(raw, &args)
+	if err != nil {
+		return args, fmt.Errorf("malformed call: %w", err)
+	}
+	return args, nil
+}
+
+func Typed[A any](run func(ctx context.Context, args A) (string, error)) func(ctx context.Context, raw json.RawMessage) (string, error) {
+	return func(ctx context.Context, raw json.RawMessage) (string, error) {
+		args, err := decode[A](raw)
+		if err != nil {
+			return "", err
+		}
+		return run(ctx, args)
+	}
+}
+
+func TypedRich[A any](run func(ctx context.Context, args A) Result) func(ctx context.Context, raw json.RawMessage) Result {
+	return func(ctx context.Context, raw json.RawMessage) Result {
+		args, err := decode[A](raw)
+		if err != nil {
+			return TextResult(err.Error(), true)
+		}
+		return run(ctx, args)
+	}
+}
+
 type Content struct {
 	Type     string `json:"type"`
 	Text     string `json:"text"`