diff --git a/src/cli/primitives/PolicyPrimitive.ts b/src/cli/primitives/PolicyPrimitive.ts
index 950416ef8..c3be8a233 100644
--- a/src/cli/primitives/PolicyPrimitive.ts
+++ b/src/cli/primitives/PolicyPrimitive.ts
@@ -9,7 +9,14 @@ import type { RemovalPreview, SchemaChange } from '../operations/remove/types';
 import { runCliCommand, withCommandRunTelemetry } from '../telemetry/cli-command-run.js';
 import { PolicyValidationMode, standardize } from '../telemetry/schemas/common-shapes.js';
 import { requireTTY } from '../tui/guards/tty';
-import { type PolicyEffect, authorizationPhaseForEffect, defaultDataPathForEffect } from '../tui/screens/policy/types';
+import {
+  FILTERS_BY_CATEGORY,
+  type GuardrailCategoryType,
+  type PolicyEffect,
+  authorizationPhaseForEffect,
+  defaultDataPathForEffect,
+  invalidFiltersForCategory,
+} from '../tui/screens/policy/types';
 import { BasePrimitive } from './BasePrimitive';
 import { SOURCE_CODE_NOTE } from './constants';
 import type { AddResult, AddScreenComponent, RemovableResource } from './types';
@@ -408,6 +415,15 @@ export class PolicyPrimitive extends BasePrimitive<AddPolicyOptions, RemovablePo
                 const policyEffect = effect as PolicyEffect;
                 const filters = cliOptions.formFilters.split(',').map(s => s.trim());
 
+                const category = cliOptions.formCategory as GuardrailCategoryType;
+                const invalidFilters = invalidFiltersForCategory(category, filters);
+                if (invalidFilters.length > 0) {
+                  throw new ValidationError(
+                    `Invalid filter(s) for category '${category}': ${invalidFilters.join(', ')}. ` +
+                      `Allowed: ${FILTERS_BY_CATEGORY[category].join(', ')}`
+                  );
+                }
+
                 let resolvedGatewayArn: string | undefined;
                 let resolvedTargetName: string | undefined = cliOptions.target;
                 if (cliOptions.gateway) {
@@ -446,7 +462,7 @@ export class PolicyPrimitive extends BasePrimitive<AddPolicyOptions, RemovablePo
 
                 const statement = synthesizeCedar(
                   {
-                    category: cliOptions.formCategory as 'contentFilter' | 'promptAttack' | 'sensitiveInformation',
+                    category,
                     filters,
                     effect: policyEffect,
                     dataPath: cliOptions.formDataPath ?? defaultDataPathForEffect(policyEffect),
diff --git a/src/cli/tui/screens/policy/__tests__/synthesize-cedar.test.ts b/src/cli/tui/screens/policy/__tests__/synthesize-cedar.test.ts
index 3f4324f2c..84b09a2ea 100644
--- a/src/cli/tui/screens/policy/__tests__/synthesize-cedar.test.ts
+++ b/src/cli/tui/screens/policy/__tests__/synthesize-cedar.test.ts
@@ -30,6 +30,12 @@ describe('synthesizeCedar', () => {
     expect(result).toContain('[context.input.prompt]');
   });
 
+  it('generates a policy with the INSULTS content filter (canonical plural name)', () => {
+    const form: GuardrailFormConfig = { ...baseForm, filters: ['INSULTS'] };
+    const result = synthesizeCedar(form);
+    expect(result).toContain('["INSULTS"]');
+  });
+
   it('generates permit policy with single filter using lessThanOrEqual', () => {
     const form: GuardrailFormConfig = { ...baseForm, effect: 'permit' };
     const result = synthesizeCedar(form);
diff --git a/src/cli/tui/screens/policy/__tests__/types.test.ts b/src/cli/tui/screens/policy/__tests__/types.test.ts
new file mode 100644
index 000000000..28cd47ca1
--- /dev/null
+++ b/src/cli/tui/screens/policy/__tests__/types.test.ts
@@ -0,0 +1,19 @@
+import { invalidFiltersForCategory } from '../types.js';
+import { describe, expect, it } from 'vitest';
+
+describe('invalidFiltersForCategory', () => {
+  it('returns an empty array when every filter is valid for the category', () => {
+    expect(invalidFiltersForCategory('contentFilter', ['VIOLENCE', 'INSULTS'])).toEqual([]);
+    expect(invalidFiltersForCategory('promptAttack', ['JAILBREAK'])).toEqual([]);
+    expect(invalidFiltersForCategory('sensitiveInformation', ['EMAIL', 'PHONE'])).toEqual([]);
+  });
+
+  it('rejects an unknown filter value', () => {
+    expect(invalidFiltersForCategory('contentFilter', ['VIOLENCE', 'NOTAREAL'])).toEqual(['NOTAREAL']);
+  });
+
+  it('rejects the legacy singular INSULT (regression guard for #1571)', () => {
+    expect(invalidFiltersForCategory('contentFilter', ['INSULT'])).toEqual(['INSULT']);
+    expect(invalidFiltersForCategory('contentFilter', ['INSULTS'])).toEqual([]);
+  });
+});
diff --git a/src/cli/tui/screens/policy/types.ts b/src/cli/tui/screens/policy/types.ts
index b1bceaf5b..7b94045c7 100644
--- a/src/cli/tui/screens/policy/types.ts
+++ b/src/cli/tui/screens/policy/types.ts
@@ -12,7 +12,7 @@ export type PolicySourceMethod = 'file' | 'inline' | 'generate' | 'form';
 
 export type GuardrailCategoryType = 'contentFilter' | 'promptAttack' | 'sensitiveInformation';
 
-export const CONTENT_FILTER_FILTERS = ['VIOLENCE', 'HATE', 'SEXUAL', 'MISCONDUCT', 'INSULT'] as const;
+export const CONTENT_FILTER_FILTERS = ['VIOLENCE', 'HATE', 'SEXUAL', 'MISCONDUCT', 'INSULTS'] as const;
 export type ContentFilterCategory = (typeof CONTENT_FILTER_FILTERS)[number];
 
 export const PROMPT_ATTACK_FILTERS = ['JAILBREAK', 'PROMPT_INJECTION', 'PROMPT_LEAKAGE'] as const;
@@ -81,6 +81,25 @@ export const GUARDRAIL_CATEGORY_OPTIONS: {
   },
 ];
 
+/**
+ * Valid filters per guardrail category. Single source of truth for both the TUI options
+ * and client-side validation of the non-interactive `--form-filters` flag.
+ */
+export const FILTERS_BY_CATEGORY: Record<GuardrailCategoryType, readonly string[]> = {
+  contentFilter: CONTENT_FILTER_FILTERS,
+  promptAttack: PROMPT_ATTACK_FILTERS,
+  sensitiveInformation: SENSITIVE_INFO_FILTERS,
+};
+
+/**
+ * Returns the filter values that are not valid for the given category.
+ * An empty array means every supplied filter is valid.
+ */
+export function invalidFiltersForCategory(category: GuardrailCategoryType, filters: string[]): string[] {
+  const allowed = FILTERS_BY_CATEGORY[category];
+  return filters.filter(f => !allowed.includes(f));
+}
+
 export type PolicyEffect = 'permit' | 'forbid' | 'suppressOutput';
 
 /**