Bug Description

The patch tool intermittently corrupts the await keyword when applying changes to TypeScript/TSX files, replacing it with ***.

Reproduction

This has occurred multiple times in our Next.js project when patching React components:

Example 1

File: apps/web/app/[locale]/dashboard/blog/new/page.tsx

• Before patch: const token = await getToken();
• After patch: const token=*** getToken();

Example 2

File: apps/web/app/[locale]/dashboard/blog/[id]/edit/page.tsx

• Before patch: const token = await getToken();
• After patch: const token=*** getToken();

Both instances:

• Used the same patch tool with mode: replace
• Targeted lines containing await keyword
• Resulted in corrupted syntax that broke the build

Environment

• OS: Linux (containerized environment)
• File types affected: .tsx, .ts
• Hermes Agent version: Latest (as of March 2026)
• Project: Next.js 14 + TypeScript

Impact

• Silent failures: The patch reports success, but the file is corrupted
• Build breaks: TypeScript compilation fails with cryptic errors
• Time loss: Requires manual investigation and fix

Workaround

After any patch operation on files containing await, manually verify the file content:

# Check for corruption
grep -n "\*\*\*" apps/web/app/**/*.tsx

Suggested Fix

The patch tool should:

1. Validate output is valid TypeScript/JavaScript syntax before reporting success
2. Add a pre-flight check for common keyword corruption patterns
3. Consider using AST-aware patching for code files instead of text replacement

Additional Context

The corruption appears related to how the tool handles special characters or encoding around async/await keywords. This is a critical reliability issue for automated code editing workflows.