diff --git a/ui/src/core/components/template-param-form.tsx b/ui/src/core/components/template-param-form.tsx
index 00539c9f..22f62a5f 100644
--- a/ui/src/core/components/template-param-form.tsx
+++ b/ui/src/core/components/template-param-form.tsx
@@ -139,7 +139,7 @@ export function TemplateParamForm({
   errors,
 }: TemplateParamFormProps) {
   const paramEntries = useMemo(
-    () => Object.entries(template.parameters),
+    () => Object.entries(template.parameters ?? {}),
     [template.parameters]
   );
 
diff --git a/ui/src/core/page-components/agent-detail/modals/edit-control/edit-control-content.tsx b/ui/src/core/page-components/agent-detail/modals/edit-control/edit-control-content.tsx
index e45ffca9..96fc60c5 100644
--- a/ui/src/core/page-components/agent-detail/modals/edit-control/edit-control-content.tsx
+++ b/ui/src/core/page-components/agent-detail/modals/edit-control/edit-control-content.tsx
@@ -55,7 +55,7 @@ import { applyApiErrorsToForms } from './utils';
 
 function isTemplateBacked(control: Control): boolean {
   const def = control.control as Record<string, unknown> | undefined;
-  return def?.template != null && def?.template_values != null;
+  return def?.template != null;
 }
 
 const EVALUATOR_CONFIG_HEIGHT = 450;
diff --git a/ui/src/core/page-components/agent-detail/modals/edit-control/template-edit-content.tsx b/ui/src/core/page-components/agent-detail/modals/edit-control/template-edit-content.tsx
index 384913f6..aeeb3e7e 100644
--- a/ui/src/core/page-components/agent-detail/modals/edit-control/template-edit-content.tsx
+++ b/ui/src/core/page-components/agent-detail/modals/edit-control/template-edit-content.tsx
@@ -45,6 +45,10 @@ type TemplateEditContentProps = {
 
 type EditorMode = 'params' | 'json';
 
+function isRecord(value: unknown): value is Record<string, unknown> {
+  return typeof value === 'object' && value !== null && !Array.isArray(value);
+}
+
 /**
  * Editor for template-backed controls. Shows the parameter form by default,
  * with a toggle to edit the full template JSON.
@@ -58,7 +62,18 @@ export function TemplateEditContent({
   // Access template fields via cast — these exist at runtime but aren't in the
   // generated API types yet. Will be cleaned up after type regeneration.
   const definitionRaw = control.control as Record<string, unknown>;
-  const template = definitionRaw.template as TemplateControlInput['template'];
+  const template = useMemo(() => {
+    const rawControl = control.control as Record<string, unknown>;
+    const templateRaw = isRecord(rawControl.template)
+      ? rawControl.template
+      : {};
+    return {
+      ...templateRaw,
+      parameters: isRecord(templateRaw.parameters)
+        ? templateRaw.parameters
+        : {},
+    } as TemplateControlInput['template'];
+  }, [control.control]);
   const storedValues = definitionRaw.template_values as
     | Record<string, TemplateValue>
     | undefined;
@@ -116,12 +131,12 @@ export function TemplateEditContent({
   // Dynamically extract parameter names from the current JSON text so
   // completions update as the user edits the parameters block.
   const templateParameterNames = useMemo(() => {
-    if (editorMode !== 'json') return Object.keys(template.parameters);
+    if (editorMode !== 'json') return Object.keys(template.parameters ?? {});
     try {
       const parsed = JSON.parse(jsonText) as TemplateControlInput;
       return Object.keys(parsed?.template?.parameters ?? {});
     } catch {
-      return Object.keys(template.parameters);
+      return Object.keys(template.parameters ?? {});
     }
   }, [editorMode, jsonText, template.parameters]);
 
diff --git a/ui/tests/control-templates.spec.ts b/ui/tests/control-templates.spec.ts
index d374b5b5..cd0c48db 100644
--- a/ui/tests/control-templates.spec.ts
+++ b/ui/tests/control-templates.spec.ts
@@ -134,6 +134,29 @@ test.describe('Control Templates', () => {
       ).toBeVisible();
     });
 
+    test('opens unrendered template controls without rendered fields', async ({
+      mockedPage,
+    }) => {
+      await mockRoutes.agent(mockedPage, {
+        controls: { data: mockData.controlsWithUnrenderedTemplate },
+      });
+      await mockRoutes.controlRenderTemplate(mockedPage);
+
+      await mockedPage.goto(
+        getAgentRoute(agentId, {
+          tab: 'controls',
+          query: { modal: 'edit', controlId: '11' },
+        })
+      );
+
+      const dialog = mockedPage.getByRole('dialog');
+      await expect(dialog.getByText('Template Parameters')).toBeVisible();
+      await expect(
+        dialog.getByText('This template has no configurable parameters.')
+      ).toBeVisible();
+      await expect(dialog.getByText('Something went wrong')).not.toBeVisible();
+    });
+
     test('can toggle to Full JSON mode and see template JSON', async ({
       mockedPage,
     }) => {
diff --git a/ui/tests/fixtures.ts b/ui/tests/fixtures.ts
index 099df7c6..313d651a 100644
--- a/ui/tests/fixtures.ts
+++ b/ui/tests/fixtures.ts
@@ -188,6 +188,32 @@ const templateBackedControl: Control = {
   } as Control['control'],
 };
 
+const unrenderedTemplateControl = {
+  id: 11,
+  name: 'Unrendered Template Guard',
+  control: {
+    enabled: false,
+    template: {
+      description: 'Template without supplied values',
+      definition_template: {
+        description: 'Deny when input matches pattern',
+        execution: 'server',
+        scope: {
+          stages: ['pre'],
+        },
+        condition: {
+          selector: { path: 'input' },
+          evaluator: {
+            name: 'regex',
+            config: { pattern: '\\bsecret\\b' },
+          },
+        },
+        action: { decision: 'deny' },
+      },
+    },
+  },
+} as unknown as Control;
+
 const controlsList: Control[] = [
   {
     id: 1,
@@ -258,6 +284,11 @@ const controlsWithTemplateList: Control[] = [
   templateBackedControl,
 ];
 
+const controlsWithUnrenderedTemplateList: Control[] = [
+  ...controlsList,
+  unrenderedTemplateControl,
+];
+
 const controlsResponse: AgentControlsResponse = {
   controls: controlsList,
 };
@@ -266,6 +297,10 @@ const controlsWithTemplateResponse: AgentControlsResponse = {
   controls: controlsWithTemplateList,
 };
 
+const controlsWithUnrenderedTemplateResponse: AgentControlsResponse = {
+  controls: controlsWithUnrenderedTemplateList,
+};
+
 // Control summaries for GET /api/v1/controls (list all controls)
 const controlSummariesList: (ControlSummary & {
   used_by_agent?: { agent_name: string } | null;
@@ -621,7 +656,9 @@ export const mockData = {
   agentWithSteps: agentWithStepsResponse,
   controls: controlsResponse,
   controlsWithTemplate: controlsWithTemplateResponse,
+  controlsWithUnrenderedTemplate: controlsWithUnrenderedTemplateResponse,
   templateControl: templateBackedControl,
+  unrenderedTemplateControl,
   listControls: listControlsResponse,
   templateControlSummary: templateControlSummary,
   evaluators: evaluatorsResponse,