[BUG] Opus 4.5 hangs 5-6+ minutes on first prompt in new repo when MCP memory check returns empty

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

When using Opus 4.5 with the memory MCP server and a skill that instructs Claude to "check memory at session start," the first prompt in a new repository (where no memory exists) causes a 5-6+ minute hang showing ↓ 0 tokens. Subsequent prompts in the same session are fast once memory is established.

Opus 4.5 appears to enter an extended thinking spiral when memory MCP returns empty/no results. The UI shows ✶ Meandering… (esc to interrupt · 5m 52s · ↓ 0 tokens) with no visible progress.

Environment:

Claude Code version: 2.0.76
OS: macOS (Homebrew cask installation)
Model: Default Opus 4.5
MCP servers: @modelcontextprotocol/server-memory, @modelcontextprotocol/server-sequential-thinking

What Should Happen?

Empty memory results should return quickly, allowing Claude to proceed without extended delay.

Error Messages/Logs

MCP servers connect successfully (~400-550ms)
Stream started - received first chunk appears in logs
No errors logged
Tokens never increment during the hang

Steps to Reproduce

Reproduction steps:

Configure memory and sequential-thinking MCP servers
Create a skill that includes instruction: "Check memory at session start for relevant prior context"
Navigate to a git repository that has never been used with Claude Code before
Submit prompt
Observe hang at 0 tokens for 5-6+ minutes
Eventually completes
Subsequent prompts are fast

Claude Model

Opus

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

2.0.76

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_