Ponytail

📦 GitHub

Why. Prevents over-engineering by injecting lazy senior dev rules into every session. Saves code, dependencies, and complexity. YAGNI, stdlib-first, one-line ladder.

How it works. Installed as a project package via packages in .pi/settings.json. Cloned to .pi/git/github.com/DietrichGebert/ponytail/. Symlinked into .pi/extensions/ponytail/ for pi auto-discovery and supervisor sub-agent resolution. Hooks before_agent_start to inject rules into system prompt. Registers /ponytail commands and skill aliases (/ponytail-review, /ponytail-audit, etc.).

Location: .pi/extensions/ponytail/ (symlink to .pi/git/github.com/DietrichGebert/ponytail/pi-extension/)

Why use it

Agents default to over-building — interfaces before they’re needed, factories for one product, dependencies for what stdlib covers. Ponytail counteracts this by embedding a decision ladder into the agent’s reasoning:

Does this need to exist at all? (YAGNI)
Does stdlib do it? Use it.
Does native platform cover it? Use it.
Does an installed dependency solve it? Use it.
Can it be one line? One line.
Only then: minimum code.

Commands

Command	Effect
`/ponytail` or `/ponytail full`	Full ladder enforced. Default
`/ponytail lite`	Build what’s asked, name lazier alt
`/ponytail ultra`	YAGNI extremist
`/ponytail off`	Disable ponytail for session
`/ponytail status`	Show current + default mode
`/ponytail review`	Run ponytail-review skill
`/ponytail-audit`	Whole-repo bloat scan

Deactivate with stop ponytail or normal mode. Resume with /ponytail.

Skills

Ponytail ships 6 skills for manual invocation:

Skill	Trigger	Purpose
ponytail	`/skill:ponytail`	Lazy mode instructions
ponytail-review	`/skill:ponytail-review`	Diff-level over-engineering review
ponytail-audit	`/skill:ponytail-audit`	Whole-repo bloat scan
ponytail-debt	`/skill:ponytail-debt`	Track deliberate shortcuts
ponytail-gain	`/skill:ponytail-gain`	Measured-impact scoreboard
ponytail-help	`/skill:ponytail-help`	Reference card

Agent integration

Ponytail is active for the main interactive session by default. Supervisor sub-agents only get ponytail when listed in their frontmatter extensions: field:

developer — ponytail in extensions (YAGNI during implementation)
auditor — ponytail in extensions (over-engineering review mindset)

Architect, researcher, and test-designer do not include ponytail — their roles conflict with lazy-mode thinking.

Details

Architecture

package ponytail (cloned to .pi/git/github.com/DietrichGebert/ponytail/)
├── pi-extension/
│   └── index.js          # Extension entry: hooks + commands
├── hooks/
│   ├── ponytail-config.js        # Mode resolution, persistence
│   └── ponytail-instructions.js  # Prompt generation from SKILL.md
└── skills/
    ├── ponytail/                 # Lazy mode skill
    ├── ponytail-review/          # Over-engineering review skill
    ├── ponytail-audit/           # Whole-repo audit skill
    ├── ponytail-debt/            # Shortcut ledger skill
    ├── ponytail-gain/            # Impact scoreboard skill
    └── ponytail-help/            # Reference card skill

Prompt Injection

Via before_agent_start hook. Reads skills/ponytail/SKILL.md from the cloned repo, filters by current intensity level (lite/full/ultra), appends to system prompt. No injection when mode is off.

Mode Persistence

Mode is persisted to session entries (ponytail-mode custom entry). Survives session restarts. Default defined by config file or env var PONYTAIL_DEFAULT_MODE.

Deactivation Monitoring

The input hook watches for deactivation phrases (stop ponytail, normal mode) and switches to off automatically.