Bug Description

The /stop command and typing "stop" do not reliably interrupt a running agent on the CLI. When an agent is in a long-running task or queued operation, there is no effective way to halt execution.

Steps to Reproduce

1. Start a long-running task (e.g., file operations, web automation, multi-step coding)
2. Type /stop or "stop" while the agent is running
3. Observe that the agent continues executing regardless
4. Try Ctrl+C or other interrupt signals
5. Agent keeps running, consuming tokens and executing tools

Expected Behavior

• /stop should immediately halt the current agent run
• Typing "stop" in busy/queue mode should cancel the pending operation
• There should be a reliable keyboard interrupt (Ctrl+C) that kills the agent loop
• The TUI and classic CLI should both respect stop commands consistently

Actual Behavior

• /stop is ignored or queued behind other operations
• "stop" typed during execution is not recognized as an interrupt
• The agent continues running tool calls, API requests, and subagent spawns
• No way to force-quit without killing the entire Hermes process
• This is especially bad with subagents and delegate_task — they spawn children that also can't be stopped

Environment

• OS: macOS
• Hermes: latest (May 2026)
• Terminal: both classic CLI and TUI
• Model: various (OpenAI, Kimi, MiniMax)

Impact

This makes Hermes CLI effectively unusable for real work. When an agent goes off-track or gets stuck in a loop, the user has no recourse except to kill the terminal window. This wastes API credits, time, and creates a frustrating experience where the user feels they have lost control of their own machine.

Additional Context

• The issue happens in both queue mode and when the agent is actively executing tools
• Subagent delegate_task calls are particularly bad — they spawn independent processes that the parent can't kill
• There should be an emergency brake that works at every level: agent loop, tool execution, subagent dispatch
• Consider: SIGINT handler, a dedicated stop thread, or a process group kill mechanism