plugin-dev

A development agent for building and maintaining the gutt-pro plugin, an add-on made of agents, skills, commands, hooks, and configuration files.

In plain words
What is it for?
Writing hooks, agents, skills, manifests, configuration, and tests; debugging hook failures; and understanding how the plugin components fit together.
Why use it?
It provides a single place to handle the plugin's development tasks and its cross-platform structure.

Agent for Claude Code

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add agents/ibrain-bvba/gutt-claude-code-plugin/plugin-dev
Clone the repo
git clone --depth 1 https://github.com/iBrain-BVBA/gutt-claude-code-plugin

Made for: Claude Code.

Per session 41 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 2,816 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00041 $0.02816
Opus 5 $0.00020 $0.01408
Sonnet 5 $0.00008 $0.00563
Haiku 4.5 $0.00004 $0.00282

Measured yesterday against content hash 98740bc90966, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

plugin-dev scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured yesterday.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

.claude/agents/plugin-dev.md · 293 lines

How it starts

The opening of the file, as written. The whole thing — 293 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Plugin Dev Agent

The go-to agent for all development work on the gutt-pro plugin. Has deep knowledge of the plugin architecture, hook system, agent/skill definitions, manifest structure, testing patterns, and cross-platform requirements.

Trigger

Invoke this agent when:

  • Writing or modifying hook scripts (.cjs files in hooks/)
  • Creating or updating shared libraries (hooks/lib/*.cjs)
  • Adding new agent definitions (agents/*.md)
  • Adding new skill definitions (skills/*/SKILL.md)
  • Updating plugin manifests (.claude-plugin/, .cursor-plugin/)
  • Writing or updating tests (tests/)
  • Debugging hook execution failures
  • Understanding how the plugin architecture fits together
  • Registering hooks in hooks.json or .claude/settings.json
  • Modifying config.json or package.json

Plugin Architecture

gutt-claude-code-plugin/
├── agents/*.md              # Agent definitions (frontmatter + markdown)
├── commands/                # Command definitions (setup, start, reset-counters)
├── hooks/*.cjs              # Hook scripts (CommonJS, ~15 hooks)
│   └── lib/*.cjs            # Shared utilities (~17 files)
├── skills/*/SKILL.md        # Skill definitions (4 skills)
├── tests/                   # Unit + integration tests
├── .claude-plugin/          # Claude Code manifest (plugin.json, marketplace.json)
├── .cursor-plugin/          # Cursor manifest (plugin.json, hooks.json)
├── .claude/settings.json    # Plugin-level permissions + hook registration
├── config.json              # Runtime config (group_id, statusline)
├── package.json             # type: "module", Node>=18
└── eslint.config.js         # ESLint v9 flat config

Critical Rules

Hooks MUST be CommonJS (.cjs)

The project uses ES modules ("type": "module" in package.json), but hooks MUST use .cjs extension with CommonJS syntax. This is required for synchronous IDE execution.

Hooks MUST consume stdin

Every hook receives JSON via stdin. Even if the hook does not need the input, it MUST read stdin to avoid broken pipe errors. Use this standard pattern:

Read the full file on GitHub · 293 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. yesterday First seen · 293 lines · 41 tokens per session scan A 98740bc90966

Subscribe to this mod's changes

plugin-dev is an agent published in the GitHub repository iBrain-BVBA/gutt-claude-code-plugin (4 stars, last pushed 11d ago), licensed MIT. It adds 41 tokens to every session and 2,816 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

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