field-agent: dispatch a field agent and keep it

Before you use this skill, check that HERDR_ENV=1. If it is not 1, tell the user that you do not run inside a herdr pane. Then stop.

Run herdr --skill for the command surface, then read the herdr skill for the semantics it leaves out. Several field agents on one theme is the field-handler skill.

<skill_dir> below is this skill's own directory (the Base directory for this skill: path above). It holds field.py, the ledger tool, whose state lives in ~/.claude/field/.

The model

You are the handler. Each agent you start is a field agent.

A handler does four things. All four are required.