fix: Bound the two uncapped in-memory buffers in the agent run

src/lib/__tests__/agent-interface.test.ts

@@ -1,4 +1,5 @@
 import { runAgent, createStopHook } from '@lib/agent/agent-interface';
+import { AgentOutputSignals } from '@lib/agent/output-signals';
 import type { WizardRunOptions } from '@utils/types';
 import type { SpinnerHandle } from '@ui';
 import {
@@ -393,26 +394,29 @@ describe('createStopHook', () => {
   });
 
   it('allows stop immediately on API error (401)', () => {
-    const collectedText = [
+    const signals = new AgentOutputSignals();
+    signals.push(
       'Failed to authenticate. API Error: 401 {"detail":"Authentication required"}',
-    ];
-    const hook = createStopHook([AdditionalFeature.LLM], collectedText);
+    );
+    const hook = createStopHook([AdditionalFeature.LLM], signals);
 
     const result = hook(hookInput);
     expect(result).toEqual({});
   });
 
   it('allows stop immediately on generic API error', () => {
-    const collectedText = ['API Error: 500 Internal Server Error'];
-    const hook = createStopHook([AdditionalFeature.LLM], collectedText);
+    const signals = new AgentOutputSignals();
+    signals.push('API Error: 500 Internal Server Error');
+    const hook = createStopHook([AdditionalFeature.LLM], signals);
 
     const result = hook(hookInput);
     expect(result).toEqual({});
   });
 
-  it('proceeds normally when collectedText has no API error', () => {
-    const collectedText = ['Some normal agent output'];
-    const hook = createStopHook([], collectedText);
+  it('proceeds normally when output has no API error', () => {
+    const signals = new AgentOutputSignals();
+    signals.push('Some normal agent output'); // dropped: carries no signal
+    const hook = createStopHook([], signals);
 
     // First call → remark prompt (normal behavior)
     const first = hook(hookInput);

src/lib/agent/__tests__/output-signals.test.ts

@@ -0,0 +1,66 @@
+import { AgentOutputSignals } from '@lib/agent/output-signals';
+
+describe('AgentOutputSignals', () => {
+  it('drops prose but detects each signal marker', () => {
+    const signals = new AgentOutputSignals();
+    signals.push('Thinking about the integration plan...'); // prose, dropped
+    signals.push('Reading files and editing config'); // prose, dropped
+    signals.push('Hit a wall. API Error: 401 unauthorized');
+    signals.push('[ERROR-MCP-MISSING] could not reach MCP');
+
+    expect(signals.hasApiError()).toBe(true);
+    expect(signals.hasApiErrorStatus(401)).toBe(true);
+    expect(signals.hasApiErrorStatus(429)).toBe(false);
+    expect(signals.has('MCP_MISSING')).toBe(true);
+    expect(signals.has('RESOURCE_MISSING')).toBe(false);
+    expect(signals.hasYaraViolation()).toBe(false);
+    expect(signals.remark()).toBeUndefined();
+  });
+
+  it('treats the API error status as a parameter, not a fixed marker', () => {
+    const signals = new AgentOutputSignals();
+    signals.push('API Error: 503 service unavailable');
+
+    expect(signals.hasApiError()).toBe(true); // generic match via the prefix
+    expect(signals.hasApiErrorStatus(503)).toBe(true);
+    expect(signals.hasApiErrorStatus(500)).toBe(false);
+  });
+
+  it('detects YARA violations from either marker', () => {
+    const critical = new AgentOutputSignals();
+    critical.push('[YARA CRITICAL] prompt injection detected');
+    expect(critical.hasYaraViolation()).toBe(true);
+
+    const scannerErr = new AgentOutputSignals();
+    scannerErr.push('[YARA] Scanner error: failed to load rules');
+    expect(scannerErr.hasYaraViolation()).toBe(true);
+  });
+
+  it('extracts only the API Error lines for the message', () => {
+    const signals = new AgentOutputSignals();
+    signals.push('Some prose before the error');
+    signals.push('Request failed: API Error: 429 rate limited, retry later');
+
+    expect(signals.hasApiErrorStatus(429)).toBe(true);
+    expect(signals.apiErrorMessage()).toBe(
+      'API Error: 429 rate limited, retry later',
+    );
+  });
+
+  it('extracts the trimmed remark after the marker', () => {
+    const signals = new AgentOutputSignals();
+    signals.push(
+      'Done. [WIZARD-REMARK] The MCP schema was larger than expected.',
+    );
+
+    expect(signals.remark()).toBe('The MCP schema was larger than expected.');
+  });
+
+  it('returns undefined extractions when no matching lines were retained', () => {
+    const signals = new AgentOutputSignals();
+    signals.push('Nothing interesting here');
+
+    expect(signals.apiErrorMessage()).toBeUndefined();
+    expect(signals.remark()).toBeUndefined();
+  });
+});