bug: AskUserQuestion tool not available when using Claude Channel feature

Bug Description

The AskUserQuestion built-in tool is not injected into the session when using the Claude Channel feature. The tool is completely absent from the available tool list, making it impossible to use interactive select prompts.

Reproduction Steps

1. Start a Claude Code session with a Channel connected
2. Attempt to use AskUserQuestion tool
3. The tool is not found in the session's available tools

Expected Behavior

AskUserQuestion should be available as a built-in tool regardless of whether a Channel is connected, as it is in standard terminal sessions.

Actual Behavior

AskUserQuestion is not present in the tool list at all when a Channel is active. No error is thrown — the tool simply doesn't exist in the session.

Environment

• Claude Code version: 2.1.87
• OS: macOS 26.4 (Darwin 25.4.0 arm64)
• Terminal: iTerm2 with tmux

Related Issues

• #29889 — AskUserQuestion returns empty answers without waiting for user input
• #39677 — feat(channels): Allow toggling channels on/off within a running session