fix(coding): close PI-100 review findings

electron/api/routes/coding-files.ts

@@ -2,33 +2,22 @@ import type { IncomingMessage, ServerResponse } from 'node:http';
 import type { HostApiContext } from '../context';
 import { CodingProductHostError } from '../coding-product-services';
 import { sendJson } from '../route-utils';
+import { sendFixedCodingError } from './coding-route-errors';
 
 function unavailable(res: ServerResponse): void {
-  sendJson(res, 503, {
-    success: false,
-    code: 'CODING_PRODUCT_TOOLS_UNAVAILABLE',
-    error: 'Coding product tools are unavailable',
-  });
+  sendFixedCodingError(res, 503, 'CODING_PRODUCT_TOOLS_UNAVAILABLE');
 }
 
 function serviceError(res: ServerResponse, error: unknown): void {
   if (error instanceof CodingProductHostError) {
-    sendJson(res, error.status, {
-      success: false,
-      code: error.code,
-      error: error.message,
-    });
+    sendFixedCodingError(res, error.status, error.code);
     return;
   }
   const code = error && typeof error === 'object' && 'code' in error
     ? String(error.code)
     : '';
   if (code === 'ENOENT') {
-    sendJson(res, 404, {
-      success: false,
-      code: 'CODING_FILE_NOT_FOUND',
-      error: 'Project file does not exist',
-    });
+    sendFixedCodingError(res, 404, 'CODING_FILE_NOT_FOUND');
     return;
   }
   const message = error instanceof Error ? error.message : '';
@@ -44,18 +33,10 @@ function serviceError(res: ServerResponse, error: unknown): void {
     'Project file is not valid UTF-8 text',
   ]);
   if (knownInputError.has(message)) {
-    sendJson(res, 400, {
-      success: false,
-      code: 'CODING_FILE_REQUEST_INVALID',
-      error: message,
-    });
+    sendFixedCodingError(res, 400, 'CODING_FILE_REQUEST_INVALID');
     return;
   }
-  sendJson(res, 500, {
-    success: false,
-    code: 'CODING_PRODUCT_TOOL_FAILED',
-    error: 'Coding product request failed',
-  });
+  sendFixedCodingError(res, 500, 'CODING_PRODUCT_TOOL_FAILED');
 }
 
 export async function handleCodingFileRoutes(