feat: add structured silent output contract

src/output-suppression.test.ts

@@ -1,6 +1,10 @@
 import { describe, expect, it } from 'vitest';
 
-import { classifySuppressTokenOutput } from './output-suppression.js';
+import {
+  buildStructuredOutputPrompt,
+  classifySuppressTokenOutput,
+  parseStructuredOutputEnvelope,
+} from './output-suppression.js';
 
 describe('classifySuppressTokenOutput', () => {
   it('treats the current turn suppress token as exact', () => {
@@ -38,4 +42,34 @@ describe('classifySuppressTokenOutput', () => {
       ),
     ).toBe('mixed');
   });
+
+  it('treats the exact structured silent envelope as exact silent output', () => {
+    expect(
+      classifySuppressTokenOutput('{"ejclaw":{"visibility":"silent"}}', undefined),
+    ).toBe('exact');
+  });
+});
+
+describe('parseStructuredOutputEnvelope', () => {
+  it('parses the exact silent envelope', () => {
+    expect(
+      parseStructuredOutputEnvelope('{"ejclaw":{"visibility":"silent"}}'),
+    ).toEqual({ visibility: 'silent' });
+  });
+
+  it('parses a public envelope', () => {
+    expect(
+      parseStructuredOutputEnvelope(
+        '{"ejclaw":{"visibility":"public","text":"hello"}}',
+      ),
+    ).toEqual({ visibility: 'public', text: 'hello' });
+  });
+});
+
+describe('buildStructuredOutputPrompt', () => {
+  it('prepends the structured output control block', () => {
+    expect(buildStructuredOutputPrompt('hello')).toContain(
+      'If you have no user-visible content to send for this turn, output exactly this JSON and nothing else: {"ejclaw":{"visibility":"silent"}}',
+    );
+  });
 });