Agent fails with 'classifyHandoffIfNeeded is not defined'

Bug Report: Agent fails with 'classifyHandoffIfNeeded is not defined'

Product: Claude Code CLI
Version: 2.1.31
Platform: macOS Darwin 24.6.0

Description

Task tool agents consistently fail with the error classifyHandoffIfNeeded is not defined. This has occurred 5+ times today across different agent types (technical-writer, general-purpose).

Steps to Reproduce

1. Start a Claude Code session
2. Use the Task tool to launch an agent with subagent_type: "technical-writer" (or other agent types)
3. Agent starts working, makes progress (reads files, processes content)
4. Agent abruptly fails with error: classifyHandoffIfNeeded is not defined

Error Message

Agent "Rewrite rioolheffing design doc" failed: classifyHandoffIfNeeded is not defined

Observed Behavior

• Agent launches successfully
• Agent makes significant progress (in this case, ~430KB of output, 18+ tool calls, 79,959+ tokens used)
• Agent suddenly terminates with the classifyHandoffIfNeeded is not defined error
• No work is saved/committed
• User must redo the entire task manually

Expected Behavior

Agent should complete its task or fail gracefully with a meaningful error that allows recovery.

Impact

• Severity: High - blocks delegated work entirely
• Frequency: 5+ occurrences in a single day
• Workaround: None - must do work manually instead of delegating to agents

Session Context

• Multiple failed agent IDs in same session: ad023bf, a79fff4, a8128cf, a21ddb8
• All failed with same error
• Session ID: eaf7e734-d8d9-4c6c-81d0-ee289627a7d1

Additional Notes

The error appears to be an internal JavaScript/TypeScript error where a function classifyHandoffIfNeeded is called but not defined in scope. This suggests a missing import, incorrect bundling, or a race condition in the agent execution environment.