feat(observer): обогащение primary_rationale из router-state (Task 3)

- parseTranscript получает третий параметр options = {}
- options.routerStateBaseDir пробрасывается в readRouterState
- recommended_node: router-state переопределяет classification-map
- новые поля: recommended_chain, chain_progress, chain_completed
- 2 новых теста (enrich + fallback), 538/538 tools GREEN

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

tools/observer-transcript-parser.test.mjs

@@ -1,4 +1,7 @@
 import { describe, it, expect } from 'vitest';
+import { mkdtempSync, writeFileSync, rmSync } from 'node:fs';
+import { tmpdir } from 'node:os';
+import { join } from 'node:path';
 import {
   parseTranscript,
   extractEnvironment,
@@ -1655,3 +1658,59 @@ describe('parseTranscript v3 fields', () => {
     expect(typeof hookEvent.scripts).toBe('object');
   });
 });
+
+describe('parseTranscript — router-state enrichment (Task 3)', () => {
+  function makeTranscript(sessionId) {
+    return [
+      JSON.stringify({
+        type: 'user',
+        message: { role: 'user', content: 'добавь новый endpoint /api/bar' },
+        timestamp: '2026-05-24T10:00:00Z',
+        uuid: 'u-t3-1',
+        sessionId,
+      }),
+      JSON.stringify({
+        type: 'assistant',
+        message: { role: 'assistant', content: [{ type: 'text', text: 'делаю' }] },
+        timestamp: '2026-05-24T10:00:01Z',
+        uuid: 'u-t3-2',
+        sessionId,
+      }),
+    ].join('\n');
+  }
+
+  it('enriches primary_rationale from router-state file when present', () => {
+    const dir = mkdtempSync(join(tmpdir(), 'router-state-test-'));
+    const sessionId = 'test-session-t3-enrich';
+    const state = {
+      classification: { recommendedNode: '#42', recommendedChain: 'L13' },
+      chainProgress: ['step-a', 'step-b'],
+      chainCompleted: false,
+    };
+    writeFileSync(join(dir, `router-state-${sessionId}.json`), JSON.stringify(state));
+    try {
+      const ep = parseTranscript(makeTranscript(sessionId), sessionId, { routerStateBaseDir: dir });
+      expect(ep.primary_rationale.recommended_node).toBe('#42');
+      expect(ep.primary_rationale.recommended_chain).toBe('L13');
+      expect(ep.primary_rationale.chain_progress).toEqual(['step-a', 'step-b']);
+      expect(ep.primary_rationale.chain_completed).toBe(false);
+    } finally {
+      rmSync(dir, { recursive: true, force: true });
+    }
+  });
+
+  it('falls back gracefully when router-state file is absent', () => {
+    const dir = mkdtempSync(join(tmpdir(), 'router-state-test-'));
+    const sessionId = 'test-session-t3-missing';
+    try {
+      const ep = parseTranscript(makeTranscript(sessionId), sessionId, { routerStateBaseDir: dir });
+      // recommended_node falls back to classification-map result (direct episode → feature → #19)
+      expect(ep.primary_rationale.recommended_node).toBe('#19');
+      expect(ep.primary_rationale.recommended_chain).toBeNull();
+      expect(ep.primary_rationale.chain_progress).toEqual([]);
+      expect(ep.primary_rationale.chain_completed).toBe(false);
+    } finally {
+      rmSync(dir, { recursive: true, force: true });
+    }
+  });
+});