kiro-sub-agent

name	kiro-sub-agent
description	Launch Kiro CLI as a headless sub-agent in a tmux pane and monitor its completion. Use when delegating a well-defined coding task to a Kiro agent subprocess. Triggers include "run kiro agent", "delegate to kiro", "kiro sub-agent", or any request to run kiro-cli headlessly.

Kiro Sub-Agent Skill

Launch kiro-cli chat as a headless sub-agent in a tmux pane.

When to use

• Delegating a scoped task to Kiro CLI running autonomously
• Parallel execution alongside other sub-agents (claude, gemini, pi)
• Running Ralph or Bart loops via Kiro instead of Claude CLI
• When you want to use Kiro's tool ecosystem (AWS, code intelligence, etc.)

Key differences from Claude CLI

Aspect	Claude CLI	Kiro CLI
Structured output	--output-format stream-json (JSONL)	None — ANSI terminal output only
Non-interactive	--print + --no-session-persistence	--no-interactive
Tool trust	--dangerously-skip-permissions	-a / --trust-all-tools
Prompt input	-p @/path/to/file.md or -p "text"	Positional argument "text"
Model selection	--model haiku|sonnet|opus	--model <model>
Completion signal	{"type":"result"} in JSONL	Process exit (exit code 0)
Cost tracking	total_cost_usd in result event	Not available in output

Non-interactive invocation

kiro-cli chat \
  --trust-all-tools \
  --no-interactive \
  --model <model> \
  "Your prompt here"

Reading prompt from file

Kiro CLI doesn't support @file syntax. Use command substitution:

kiro-cli chat -a --no-interactive "$(cat /tmp/task-prompt.md)"

Or for very long prompts (argument length limits), use a heredoc wrapper:

cat > /tmp/launch-kiro.sh << 'SCRIPT'
#!/bin/bash
cd /path/to/worktree
kiro-cli chat -a --no-interactive "$(cat /tmp/ralph-task.md)" \
  > /tmp/kiro-task.log 2>&1
echo "EXIT_CODE: $?"
SCRIPT
chmod +x /tmp/launch-kiro.sh

Monitoring

Since Kiro doesn't produce JSONL, monitoring is process-based:

Check if still running

# From tmux pane scraping
tmux capture-pane -t "$PANE" -p | tail -5

Check completion

# Look for the credits/time line that signals end of response
tmux capture-pane -t "$PANE" -p | grep -q "Credits:.*Time:" && echo "DONE"

Log-based monitoring

# If output is redirected to a file
tail -f /tmp/kiro-task.log | grep --line-buffered "Credits:"

Launch template (for dispatch.py)

#!/bin/bash
cd {worktree}
kiro-cli chat -a --no-interactive "$(cat {prompt})" \
  > {logfile} 2>&1
echo "KIRO_EXIT: $?" >> {logfile}

Completion detection

Unlike Claude's JSONL result event, detect Kiro completion by:

1. Process exit — the kiro-cli chat process terminates
2. Log marker — look for Credits: and Time: in output
3. Exit code file — append echo "KIRO_EXIT: $?" after the command

Limitations

• No structured output — cannot extract cost, turn count, or tool calls programmatically
• No session persistence control beyond --no-interactive
• Prompt size limited by shell argument length (getconf ARG_MAX, typically 2MB on Linux)
• ANSI escape codes in output require stripping for clean log analysis
• No --append-system-prompt equivalent — persona must be included in the prompt text

Integration with agent-mux

In dispatch.py, Kiro uses a different launch template:

AGENT_CONFIG = {
    "ralph": {
        "runner": "kiro",
        "model": None,  # uses default
        "logfile": "/tmp/kiro-ralph-{id}.log",
    },
}

The dispatch script writes the prompt to a file and launches via:

cd <worktree> && kiro-cli chat -a --no-interactive "$(cat <prompt>)" > <logfile> 2>&1