# Task ID: 78

**Title:** Create ProxyModel YAML Schema and Loader

**Status:** done

**Dependencies:** 71 ✓

**Priority:** high

**Description:** Define the YAML schema for proxymodel definitions and implement the loader that reads from ~/.mcpctl/proxymodels/ and merges with built-ins.

**Details:**

Create `src/mcplocal/src/proxymodel/schema.ts`:

```typescript
import { z } from 'zod';

export const ProxyModelSchema = z.object({
  kind: z.literal('ProxyModel'),
  metadata: z.object({
    name: z.string(),
  }),
  spec: z.object({
    controller: z.string().optional().default('gate'),
    controllerConfig: z.record(z.unknown()).optional(),
    stages: z.array(z.object({
      type: z.string(),
      config: z.record(z.unknown()).optional(),
    })),
    appliesTo: z.array(z.enum(['prompts', 'toolResults', 'resource'])).optional(),
    cacheable: z.boolean().optional().default(true),
  }),
});

export type ProxyModelDefinition = z.infer<typeof ProxyModelSchema>;
```

Create `src/mcplocal/src/proxymodel/loader.ts`:

```typescript
import { readdir, readFile } from 'fs/promises';
import { join } from 'path';
import { parse as parseYaml } from 'yaml';
import { ProxyModelSchema, type ProxyModelDefinition } from './schema';
import { getBuiltInProxyModels } from './built-in-models';

const PROXYMODELS_DIR = join(process.env.HOME ?? '', '.mcpctl', 'proxymodels');

export async function loadProxyModels(): Promise<Map<string, ProxyModelDefinition>> {
  const models = new Map<string, ProxyModelDefinition>();
  
  // Load built-ins first
  for (const [name, model] of getBuiltInProxyModels()) {
    models.set(name, model);
  }
  
  // Load local (overrides built-ins)
  try {
    const files = await readdir(PROXYMODELS_DIR);
    for (const file of files.filter(f => f.endsWith('.yaml') || f.endsWith('.yml'))) {
      const content = await readFile(join(PROXYMODELS_DIR, file), 'utf-8');
      const parsed = parseYaml(content);
      const validated = ProxyModelSchema.parse(parsed);
      models.set(validated.metadata.name, validated);
    }
  } catch (e) {
    // Directory doesn't exist or can't be read - use built-ins only
  }
  
  return models;
}
```

**Test Strategy:**

Unit tests: valid YAML parses correctly, invalid YAML throws validation error, local models override built-ins with same name, missing directory doesn't throw. Create test fixtures for various YAML configurations.