# Task ID: 99

**Title:** Add Cache Key with Stage File Hash

**Status:** done

**Dependencies:** 98 ✓

**Priority:** medium

**Description:** Include the stage file hash in cache keys so cached artifacts are automatically invalidated when stage code changes.

**Details:**

Modify `src/mcplocal/src/proxymodel/executor.ts`:

```typescript
import { readFile, stat } from 'fs/promises';
import { createHash } from 'crypto';
import { join } from 'path';

const STAGES_DIR = join(process.env.HOME ?? '', '.mcpctl', 'stages');
const stageFileHashes: Map<string, string> = new Map();

async function getStageFileHash(stageName: string): Promise<string> {
  // Check if custom stage file exists
  const filePath = join(STAGES_DIR, `${stageName}.ts`);
  try {
    const content = await readFile(filePath, 'utf-8');
    const hash = createHash('sha256').update(content).digest('hex').slice(0, 8);
    stageFileHashes.set(stageName, hash);
    return hash;
  } catch {
    // Built-in stage, use version-based hash or fixed value
    return 'builtin-v1';
  }
}

// In executePipeline, compute cache key:
const stageHash = await getStageFileHash(stageConfig.type);
const cacheKey = [
  'stage',
  stageConfig.type,
  stageHash,
  cache.hash(currentContent),
  cache.hash(JSON.stringify(stageConfig.config ?? {})),
].join(':');

// Use pipeline-level cache wrapping:
if (proxyModel.spec.cacheable) {
  const cached = await cache.get(cacheKey);
  if (cached) {
    currentContent = cached;
    continue; // Skip stage execution
  }
}
```

**Test Strategy:**

Unit tests: changing stage file content changes the hash, built-in stages have stable hash, cache miss when stage file changes, cache hit when stage file unchanged.