fix: report AgentExecutionBlocked in non-interactive programmatic modes (#26262)

packages/core/src/agent/event-translator.test.ts

@@ -378,7 +378,7 @@ describe('translateEvent', () => {
       expect(err.type).toBe('error');
       expect(err.fatal).toBe(false);
       expect(err._meta?.['code']).toBe('AGENT_EXECUTION_BLOCKED');
-      expect(err.message).toBe('Agent execution blocked: Policy violation');
+      expect(err.message).toBe('Policy violation');
     });
 
     it('uses systemMessage in the final error message when available', () => {
@@ -393,9 +393,7 @@ describe('translateEvent', () => {
       };
       const result = translateEvent(event, state);
       const err = result[0] as AgentEvent<'error'>;
-      expect(err.message).toBe(
-        'Agent execution blocked: Blocked by policy hook',
-      );
+      expect(err.message).toBe('Blocked by policy hook');
     });
   });
 

packages/core/src/agent/event-translator.ts

@@ -210,7 +210,7 @@ export function translateEvent(
       out.push(
         makeEvent('error', state, {
           status: 'PERMISSION_DENIED',
-          message: `Agent execution blocked: ${event.value.systemMessage?.trim() || event.value.reason}`,
+          message: event.value.systemMessage?.trim() || event.value.reason,
           fatal: false,
           _meta: { code: 'AGENT_EXECUTION_BLOCKED' },
         }),

packages/core/src/agent/legacy-agent-session.test.ts

@@ -647,7 +647,7 @@ describe('LegacyAgentSession', () => {
           e.type === 'error' && e._meta?.['code'] === 'AGENT_EXECUTION_BLOCKED',
       );
       expect(blocked?.fatal).toBe(false);
-      expect(blocked?.message).toBe('Agent execution blocked: Blocked by hook');
+      expect(blocked?.message).toBe('Blocked by hook');
 
       const messages = events.filter(
         (e): e is AgentEvent<'message'> =>