feat(engine): implement state persistence, failure reason tracking, and quality scoring as per Astra review

src/lib/engine.ts

@@ -1,4 +1,6 @@
 import * as vscode from 'vscode';
+import * as fs from 'fs';
+import * as path from 'path';
 import { lockManager } from '../core/lock';
 import { actionQueue } from '../core/queue';
 import { logInfo, logError } from '../utils';
@@ -61,6 +63,7 @@ export class MissionState {
     private _stage: PipelineStage = 'idle';
     private _auditTrail: AuditEntry[] = [];
     private _lastTransitionTime: number = Date.now();
+    private _failureReason?: string;
 
     public readonly missionId: string;
     public readonly startTime: number;
@@ -96,8 +99,35 @@ export class MissionState {
         this._lastTransitionTime = now;
 
         logInfo(`[MissionState] ${this.missionId}: ${entry.from} → ${entry.to} (${entry.durationFromPrev}ms) — ${message}`);
+        this.saveToDisk();
     }
 
+    /**
+     * 진행 상태를 디스크에 영구적으로 기록합니다 (State Save).
+     * 크래시 발생 시 어디까지 진행되었는지 파악하는 기초 데이터가 됩니다.
+     */
+    private saveToDisk(): void {
+        try {
+            const workspacePath = vscode.workspace.workspaceFolders?.[0]?.uri.fsPath || '';
+            if (!workspacePath) return;
+
+            const astraDir = path.join(workspacePath, '.astra', 'missions');
+            if (!fs.existsSync(astraDir)) {
+                fs.mkdirSync(astraDir, { recursive: true });
+            }
+            const filePath = path.join(astraDir, `${this.missionId}.json`);
+            fs.writeFileSync(filePath, JSON.stringify(this.toStructuredLog(), null, 2), 'utf-8');
+        } catch (err) {
+            logError(`[MissionState] Failed to save state to disk for ${this.missionId}`, err);
+        }
+    }
+
+    public setFailureReason(reason: string): void {
+        this._failureReason = reason;
+        this.saveToDisk();
+    }
+
+
     /**
      * 전체 미션의 경과 시간을 반환합니다.
      */
@@ -137,6 +167,7 @@ export class MissionState {
             status: this._stage,
             startTime: new Date(this.startTime).toISOString(),
             totalElapsedMs: this.getElapsedMs(),
+            failureReason: this._failureReason,
             transitionCount: this._auditTrail.length,
             transitions: this._auditTrail.map(e => ({
                 from: e.from,
@@ -385,6 +416,11 @@ export class AgentEngine {
             
             this.transition('error', `오류 발생: ${error.message}`, onProgress);
             
+            // 실패 원인 명시적 기록 (Astra 피드백: Record failure reason)
+            if (this.state) {
+                this.state.setFailureReason(`[${type}] ${rule.description} - 세부원인: ${error.message}`);
+            }
+
             // Error Recovery Matrix 기반 세분화된 로깅
             switch (type) {
                 case ErrorType.ABORT: