diff --git a/plugins/template-function-response/src/index.ts b/plugins/template-function-response/src/index.ts
index 884c4c7d..dcf85295 100644
--- a/plugins/template-function-response/src/index.ts
+++ b/plugins/template-function-response/src/index.ts
@@ -72,6 +72,10 @@ export const plugin: PluginDefinition = {
           name: 'header',
           label: 'Header Name',
           async dynamic(ctx, args) {
+            // Dynamic form config also runs during send-time rendering.
+            // Keep this preview-only to avoid side-effect request sends.
+            if (args.purpose !== 'preview') return null;
+
             const response = await getResponse(ctx, {
               requestId: String(args.values.request || ''),
               purpose: args.purpose,
@@ -146,6 +150,10 @@ export const plugin: PluginDefinition = {
           label: 'JSONPath or XPath',
           placeholder: '$.books[0].id or /books[0]/id',
           dynamic: async (ctx, args) => {
+            // Dynamic form config also runs during send-time rendering.
+            // Keep this preview-only to avoid side-effect request sends.
+            if (args.purpose !== 'preview') return null;
+
             const resp = await getResponse(ctx, {
               requestId: String(args.values.request || ''),
               purpose: 'preview',