Fix agent output summary for pipeline steps (#812)

* Changes from fix/agent-output-summary-for-pipeline-steps

* feat: Optimize pipeline summary extraction and fix regex vulnerability

* fix: Use fallback summary for pipeline steps when extraction fails

* fix: Strip follow-up session scaffold from pipeline step fallback summaries

apps/server/tests/unit/services/pipeline-orchestrator-prompts.test.ts

@@ -0,0 +1,57 @@
+import { describe, it, expect, vi } from 'vitest';
+import { PipelineOrchestrator } from '../../../src/services/pipeline-orchestrator.js';
+import type { Feature } from '@automaker/types';
+
+describe('PipelineOrchestrator Prompts', () => {
+  const mockFeature: Feature = {
+    id: 'feature-123',
+    title: 'Test Feature',
+    description: 'A test feature',
+    status: 'in_progress',
+    createdAt: new Date().toISOString(),
+    updatedAt: new Date().toISOString(),
+    tasks: [],
+  };
+
+  const mockBuildFeaturePrompt = (feature: Feature) => `Feature: ${feature.title}`;
+
+  it('should include mandatory summary requirement in pipeline step prompt', () => {
+    const orchestrator = new PipelineOrchestrator(
+      null as any, // eventBus
+      null as any, // featureStateManager
+      null as any, // agentExecutor
+      null as any, // testRunnerService
+      null as any, // worktreeResolver
+      null as any, // concurrencyManager
+      null as any, // settingsService
+      null as any, // updateFeatureStatusFn
+      null as any, // loadContextFilesFn
+      mockBuildFeaturePrompt,
+      null as any, // executeFeatureFn
+      null as any // runAgentFn
+    );
+
+    const step = {
+      id: 'step1',
+      name: 'Code Review',
+      instructions: 'Review the code for quality.',
+    };
+
+    const prompt = orchestrator.buildPipelineStepPrompt(
+      step as any,
+      mockFeature,
+      'Previous work context',
+      { implementationInstructions: '', playwrightVerificationInstructions: '' }
+    );
+
+    expect(prompt).toContain('## Pipeline Step: Code Review');
+    expect(prompt).toContain('Review the code for quality.');
+    expect(prompt).toContain(
+      '**CRITICAL: After completing the instructions, you MUST output a summary using this EXACT format:**'
+    );
+    expect(prompt).toContain('<summary>');
+    expect(prompt).toContain('## Summary: Code Review');
+    expect(prompt).toContain('</summary>');
+    expect(prompt).toContain('The <summary> and </summary> tags MUST be on their own lines.');
+  });
+});