feat: support await in $B js and eval commands

Auto-wrap await expressions in async IIFE context so
$B js "await fetch(...)" works without SyntaxError.

- hasAwait() strips comments before detection
- js: expression wrapping (async()=>(expr))()
- eval: smart wrapping — single-line=expression, multi-line=block
- 6 new unit tests covering async, false-positive, and return semantics

browse/src/read-commands.ts

@@ -11,6 +11,12 @@ import type { Page } from 'playwright';
 import * as fs from 'fs';
 import * as path from 'path';
 
+/** Detect await keyword, ignoring comments. Accepted risk: await in string literals triggers wrapping (harmless). */
+function hasAwait(code: string): boolean {
+  const stripped = code.replace(/\/\/.*$/gm, '').replace(/\/\*[\s\S]*?\*\//g, '');
+  return /\bawait\b/.test(stripped);
+}
+
 // Security: Path validation to prevent path traversal attacks
 const SAFE_DIRECTORIES = ['/tmp', process.cwd()];
 
@@ -118,7 +124,8 @@ export async function handleReadCommand(
     case 'js': {
       const expr = args[0];
       if (!expr) throw new Error('Usage: browse js <expression>');
-      const result = await page.evaluate(expr);
+      const wrapped = hasAwait(expr) ? `(async()=>(${expr}))()` : expr;
+      const result = await page.evaluate(wrapped);
       return typeof result === 'object' ? JSON.stringify(result, null, 2) : String(result ?? '');
     }
 
@@ -128,6 +135,13 @@ export async function handleReadCommand(
       validateReadPath(filePath);
       if (!fs.existsSync(filePath)) throw new Error(`File not found: ${filePath}`);
       const code = fs.readFileSync(filePath, 'utf-8');
+      if (hasAwait(code)) {
+        const trimmed = code.trim();
+        const isSingleExpr = trimmed.split('\n').length === 1;
+        const wrapped = isSingleExpr ? `(async()=>(${trimmed}))()` : `(async()=>{\n${code}\n})()`;
+        const result = await page.evaluate(wrapped);
+        return typeof result === 'object' ? JSON.stringify(result, null, 2) : String(result ?? '');
+      }
       const result = await page.evaluate(code);
       return typeof result === 'object' ? JSON.stringify(result, null, 2) : String(result ?? '');
     }