feat: add cli-ui-tester agent and tmux helper scripts

[brandonkachen]

Summary

Adds a cli-ui-tester agent for testing CLI UI functionality via tmux, along with helper scripts and a fix for spawnerPrompt in agent-runtime.

Changes

• .agents/cli-ui-tester.ts - Programmatic agent that:

  • Spawns tmux sessions to test CLI functionality
  • Captures terminal output with ANSI colors
  • Validates visual rendering and behavior
  • Saves session logs to debug/tmux-sessions/

• scripts/tmux/ - Helper scripts for tmux session management:

  • tmux-start.sh - Start a new tmux session with CLI
  • tmux-send.sh - Send input to tmux session (handles bracketed paste)
  • tmux-capture.sh - Capture terminal output with YAML logging
  • tmux-stop.sh - Stop and cleanup tmux session
  • tmux-cli.sh - Convenience wrapper for CLI interaction

• cli/tmux.knowledge.md - Documentation for tmux testing workflow

• packages/agent-runtime/src/templates/strings.ts - Fix to include spawnerPrompt in parent agent instructions

• packages/agent-runtime/src/templates/__tests__/strings.test.ts - Tests for template string generation

Usage

Spawn from Buffy:

@cli-ui-tester Test that the help command displays correctly

Testing

• ✅ Typecheck passes
• ✅ New tests for template strings pass