feat(core): expand RequestDefinition and implement writeHttpFile

  Add optional description, bodyFile, formData, and directives fields to
  RequestDefinition so plugin-authored requests can be serialized via
  serializeDocument(). Implement the writeHttpFile CLI context method
  using the new serializer, replacing the previous stub.

Author: andrewmelchor

packages/app/src/cli.ts

@@ -45,9 +45,14 @@ function createPluginCommand(
           const resolved = nodePath.resolve(projectRoot, path);
           await fs.writeFile(resolved, content, 'utf-8');
         },
-        writeHttpFile: async (_name: string, _requests) => {
-          // Simplified implementation
-          throw new Error('writeHttpFile not implemented in CLI context');
+        writeHttpFile: async (name: string, requests) => {
+          const fs = await import('node:fs/promises');
+          const nodePath = await import('node:path');
+          const { serializeDocument } = await import('@t-req/core');
+          const resolved = nodePath.resolve(projectRoot, name);
+          const content = serializeDocument({ requests });
+          await fs.mkdir(nodePath.dirname(resolved), { recursive: true });
+          await fs.writeFile(resolved, content, 'utf-8');
         },
         parseCollection: async () => {
           throw new Error('parseCollection not implemented in CLI context');

packages/core/src/plugin/types.ts

@@ -1,6 +1,6 @@
 import type { z } from 'zod';
 import type { EngineEvent } from '../runtime/types';
-import type { ParsedRequest } from '../types';
+import type { FileReference, FormField, ParsedRequest } from '../types';
 
 // ============================================================================
 // Plugin Permissions
@@ -538,10 +538,14 @@ export interface CommandContext {
  */
 export interface RequestDefinition {
   name?: string;
+  description?: string;
   method: string;
   url: string;
   headers?: Record<string, string>;
   body?: string;
+  bodyFile?: FileReference;
+  formData?: FormField[];
+  directives?: Array<{ name: string; value: string }>;
 }
 
 /**