[BUG] SendMessage does not appear -- NOT STALE (yes: duplicate but still broken)

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?

Other users have already reported this issue -- It has been marked as stale -- It is NOT STALE. Ongoing issue, needs fixing.

• Agent tool documentation explicitly references SendMessage as the mechanism for continuing held agents
• SendMessage doesn't appear in tools, deferred-tools, or ToolSearch
• Every long-running coordination workflow has been silently doing fresh spawns with full-context-in-prompt
• Impact: doubled context loading, dead-pointer references in artifacts, lost "stop and resume" pattern

Two separate Max 20x subscriptions. Multiple days. Model: Opus 4.7 xhigh effort. Claude Code CLI/Terminal on MacBook Pro M5 and M4 Pro.

What Should Happen?

SendMessage needs to appear.

Error Messages/Logs

Steps to Reproduce

1. Try to spawn any agent and instruct to SendMessage.
2. Output: 'response has ended with "use SendMessage with to: <id>". But SendMessage isn't in my tool list, isn't in the deferred-tool list, and ToolSearch returns "No matching deferred tools found."

Claude Model

Opus

Is this a regression?

Yes, this worked in a previous version

Last Working Version

Opus 4.6

Claude Code Version

v2.1.133

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_