Claude Code Plugin Reference (night-market edition)

A field-verified reference for how Claude Code manifests, skills, commands, agents, and hooks actually behave — for plugin authors and debuggers.

Dev & CodingAdvanced★ 327⑂ 35AI score 8/10Last updated: Aug 12, 2026

What it does

Collects the mechanical contracts you need when authoring or debugging Claude Code plugins:

Field-by-field contract for .claude-plugin/plugin.json, metadata.json, and openpackage.yml
SKILL.md frontmatter rules (160-char description cap, role taxonomy, hub-and-spoke progressive loading)
Decision tables for command vs. skill vs. agent, plus $ARGUMENTS and extends usage
The hook chapter: register only in hooks/hooks.json, read the payload from stdin JSON (never CLAUDE_TOOL_* env vars), always exit 0 with a JSON verdict on stdout, and use only allow|deny|ask for PreToolUse
Host Python 3.9 landmines (no datetime.UTC, mandatory from __future__ import annotations, guarded third-party imports) and cache-dir execution rules (no relative paths)
Marketplace registration, version lockstep bumping, and a block of shell commands to re-verify every claim

Who it's for

Developers building Claude Code plugins, skills, or lifecycle hooks
Anyone chasing a hook that runs but silently does nothing
Teams modeling an internal plugin ecosystem on the claude-night-market layout

Examples

Dead hook: the script reads CLAUDE_TOOL_NAME; swap in the stdin-JSON read pattern and confirm echo not-json | python3 hook.py; echo $? prints 0.
"Duplicate hooks file" at session start: remove ./hooks/hooks.json from the manifest hooks array and rely on auto-loading.
New skill won't resolve: verify it is listed in plugin.json skills, its description is ≤160 chars, and it has an ## Exit Criteria section so the drift ratchets pass.

· · · Install guide · · ·

Try it now, no install

Paste this into Claude to use the skill without installing anything.

Read the instructions in this file and follow them to help me:
https://raw.githubusercontent.com/athola/claude-night-market/HEAD/.claude/skills/claude-code-plugin-reference/SKILL.md

What I want: (describe your task here)

If Claude can't open the link, open it yourself and paste the contents instead.

↓ If it works for you, download the ZIP below and install it. Then it runs on its own — no pasting each time.

Install in the Claude app (no terminal)

Download the ZIP with the button below.
In Claude, open Settings → Capabilities and turn on 'Code execution and file creation'. (one time)
Go to Customize → Skills → + → 'Upload a skill' and upload the ZIP.

↓ Download ZIP

Install in Claude Code

Let Claude do it — paste this into Claude Code

Install the skill I found on Claude Skill Mart.
Copy the .claude/skills/claude-code-plugin-reference folder from the GitHub repo athola/claude-night-market into my ~/.claude/skills/claude-code-plugin-reference/.
When it's done, tell me in one line what this skill can do.

Install with a command instead

git clone https://github.com/athola/claude-night-market.git /tmp/claude-night-market && mkdir -p ~/.claude/skills && cp -r /tmp/claude-night-market/.claude/skills/claude-code-plugin-reference ~/.claude/skills/

⚠ This is a third-party skill. Check the source repository before installing.

Open a terminal in a scratch directory.
Clone the repository: git clone https://github.com/athola/claude-night-market.git
Create the skills directory if needed: mkdir -p ~/.claude/skills
Copy the skill in: cp -r claude-night-market/.claude/skills/claude-code-plugin-reference ~/.claude/skills/
Restart Claude Code and ask something like "what is the hook payload contract?" to trigger loading.
(Optional) Keep the cloned repo around — the document frequently cites files under plugins/... as exemplars.
(Optional) To install the repo's actual plugins, run /plugin marketplace add athola/claude-night-market inside Claude Code.

View source on GitHub ↗License: MIT