Grep Tool Fails to Find Existing Patterns

Bug Description
Confirmed: Grep Tool Bug

Yes, this appears to be a Claude Code Grep tool bug! Here's the evidence:

Working vs Broken:

• ✅ Bash tool: grep works perfectly
• ❌ Grep tool: Always returns "No matches found" even for content that definitely exists

Tested Multiple Patterns:

• val_results - exists but Grep tool doesn't find it
• import pandas - exists but Grep tool doesn't find it
• Same file, same working directory

Should You Restart Claude Code?

It might help! This could be:

1. Tool state issue - The Grep tool might be in a bad state
2. File handle issue - The tool might not be reading the current file version
3. Permission issue - Though Bash tool works fine

Try restarting Claude Code first. If the Grep tool still fails after restart, then we know it's a more fundamental tool issue.

Workaround for now: I'll use the Bash tool for all grep operations since it works reliably:

bash: grep -n "pattern" filename.py

This is definitely a tool bug, not a file or search strategy issue. Good catch!

Environment Info

• Platform: linux
• Terminal: vscode
• Version: 1.0.80
• Feedback ID: 16862fc8-0d5d-4881-9a16-ebfb351ebda1

Errors

[{"error":"Error: Language not supported while highlighting code, falling back to markdown: \n    at _V (/$bunfs/root/claude:1638:1192)\n    at map (native:1:11)\n    at qQ (/$bunfs/root/claude:1638:905)\n    at $oG (/$bunfs/root/claude:2213:5239)\n    at zE (/$bunfs/root/claude:188:19860)\n    at Uy (/$bunfs/root/claude:190:42827)\n    at Ay (/$bunfs/root/claude:190:38350)\n    at ER (/$bunfs/root/claude:190:38278)\n    at kE (/$bunfs/root/claude:190:38132)\n    at fK (/$bunfs/root/claude:190:35195)","timestamp":"2025-08-14T02:52:54.604Z"},{"error":"Error: Language not supported while highlighting code, falling back to markdown: \n    at _V (/$bunfs/root/claude:1638:1192)\n    at map (native:1:11)\n    at qQ (/$bunfs/root/claude:1638:905)\n    at $oG (/$bunfs/root/claude:2213:5239)\n    at zE (/$bunfs/root/claude:188:19860)\n    at Uy (/$bunfs/root/claude:190:42827)\n    at Ay (/$bunfs/root/claude:190:38350)\n    at ER (/$bunfs/root/claude:190:38278)\n    at kE (/$bunfs/root/claude:190:38132)\n    at fK (/$bunfs/root/claude:190:35195)","timestamp":"2025-08-14T02:52:54.617Z"},{"error":"Error: Language not supported while highlighting code, falling back to markdown: \n    at _V (/$bunfs/root/claude:1638:1192)\n    at map (native:1:11)\n    at qQ (/$bunfs/root/claude:1638:905)\n    at $oG (/$bunfs/root/claude:2213:5239)\n    at zE (/$bunfs/root/claude:188:19860)\n    at Uy (/$bunfs/root/claude:190:42827)\n    at Ay (/$bunfs/root/claude:190:38350)\n    at ER (/$bunfs/root/claude:190:38278)\n    at kE (/$bunfs/root/claude:190:38132)\n    at fK (/$bunfs/root/claude:190:35195)","timestamp":"2025-08-14T02:52:54.674Z"},{"error":"Error: Language not supported while highlighting code, falling back to markdown: \n    at _V (/$bunfs/root/claude:1638:1192)\n    at map (native:1:11)\n    at qQ (/$bunfs/root/claude:1638:905)\n    at $oG (/$bunfs/root/claude:2213:5239)\n    at zE (/$bunfs/root/claude:188:19860)\n    at Uy (/$bunfs/root/claude:190:42827)\n    at Ay (/$bunfs/root/claude:190:38350)\n    at ER (/$bunfs/root/claude:190:38278)\n    at kE (/$bunfs/root/claude:190:38132)\n    at fK (/$bunfs/root/claude:190:35195)","timestamp":"2025-08-14T02:52:54.676Z"},{"error":"Error: Language not supported while highlighting code, falling back to markdown: \n    at _V (/$bunfs/root/claude:1638:1192)\n    at map (native:1:11)\n    at qQ (/$bunfs/root/claude:1638:905)\n    at $oG (/$bunfs/root/claude:2213:5239)\n    at zE (/$bunfs/root/claude:188:19860)\n    at Uy (/$bunfs/root/claude:190:42827)\n    at Ay (/$bunfs/root/claude:190:38350)\n    at ER (/$bunfs/root/claude:190:38278)\n    at kE (/$bunfs/root/claude:190:38132)\n    at fK (/$bunfs/root/claude:190:35195)","timestamp":"2025-08-14T02:52:54.769Z"},{"error":"Error: Language not supported while highlighting code, falling back to markdown: \n    at _V (/$bunfs/root/claude:1638:1192)\n    at map (native:1:11)\n    at qQ (/$bunfs/root/claude:1638:905)\n    at $oG (/$bunfs/root/claude:2213:5239)\n    at zE (/$bunfs/root/claude:188:19860)\n    at Uy (/$bunfs/root/claude:190:42827)\n    at Ay (/$bunfs/root/claude:190:38350)\n    at ER (/$bunfs/root/claude:190:38278)\n    at kE (/$bunfs/root/claude:190:38132)\n    at fK (/$bunfs/root/claude:190:35195)","timestamp":"2025-08-14T02:52:54.795Z"},{"error":"Error: Language not supported while highlighting code, falling ba

Note: Error logs were truncated.