Claude Code skills

Personal skills marketplace for Claude Code.

Install on a new machine

/plugin marketplace add johnfink8/skill-repo
/plugin install johnfink-skills@johnfink

(Replace the GitHub slug if you fork.)

Verify with /plugin — you should see the johnfink-skills plugin and its skills will appear in skill listings as johnfink-skills:<skill-name>.

Skills

• trial-data-discipline — empirical trials, evals, fixtures: where to put data, how to separate capture from analysis.
• commit-preferences — terse, informal, hint-don't-restate commit messages. No trailers.
• pytest-methodology — how to write Python tests that stay useful.
• e2e-testing — when e2e is right, selector strategy, anti-flake discipline.
• type-safety — TypeScript / Python typing. The rules around as / # type: ignore / any.
• formatting-standards — formatter-as-source-of-truth, defaults per language.
• agentic-llm — building LLM-in-a-loop systems: queue inputs, bound the loop, errors-as-results, tool UX.
• autonomy — don't punt verification to the user; plan browser automation and CLI access from the first commit.
• shell-discipline — cache session state, avoid permission-prompt thrash, surface persistent env problems with a fix.

Always-on rules (no skill triggering required)

A SessionStart hook injects plugins/johnfink-skills/rules/house-rules.md into context at the start of every session. These are the rules that apply regardless of task — transparency about shortcuts, comment hygiene, how to respond to "why did you do X this way?" — and live as a hook because their trigger condition is "always," not "matches description."

Why a hook instead of CLAUDE.md?

CLAUDE.md isn't plugin-able. Marketplaces ship skills, hooks, agents, and commands — not CLAUDE.md content. Even if they could, CLAUDE.md often holds per-machine configuration that shouldn't be clobbered: things like "you're in a Docker container, don't try to spawn Docker", "pyright lives at this nonstandard path", or project-specific facts that don't belong in a portable marketplace. A SessionStart hook ships the always-on rules without touching CLAUDE.md, so portable guidance and local config coexist cleanly.

Hook-enforced anti-patterns

A PreToolUse hook on the Bash tool injects a warning into Claude's context (model-visible via additionalContext, non-blocking) when it spots a string-as-code anti-pattern — a script piped into a language interpreter instead of being written to a real file:

• A heredoc piped to a language interpreter (python <<EOF, node <<EOF, ruby <<-EOF, perl <<EOF, php <<EOF) when the command runs 30+ newlines. Smaller heredocs are tolerated. Heredocs into non-interpreters (cat, psql, tee, bash) are always fine at any length.
• An inline -c / -e script in a language interpreter (python -c, node -e, etc.) with substantial content (multi-line or >120 chars).

The warning carries a transferable why — the piped script skips your formatter and linter, isn't somewhere you (or the user) can diff or re-run — and each form cross-references the other so the natural pivot ("just use -c instead") is preempted. The remedy is always: use the Write tool to create a real script file and invoke that.

This is the enforcement half of a rule that lives advisorily in the autonomy and trial-data-discipline skills. Skills tell Claude what should happen; hooks catch when it doesn't.

Lives at plugins/johnfink-skills/hooks/bash-anti-patterns.py; test cases in test_bash_anti_patterns.py.

Updating

Edit the SKILL.md files in plugins/johnfink-skills/skills/, commit, push. Bump version in plugins/johnfink-skills/.claude-plugin/plugin.json for meaningful changes.

On other machines:

1. /plugin marketplace update johnfink — refresh the marketplace listing.
2. Then update the installed plugin. There's no one-shot CLI for this:
   • Easiest: open /plugin, go to the Installed tab, update from there.
   • Or: /plugin uninstall johnfink-skills@johnfink then /plugin install johnfink-skills@johnfink.
   • Or: enable auto-update on the marketplace (/plugin → Marketplaces tab) so future versions pull at startup.

Layout

.claude-plugin/marketplace.json   # marketplace manifest
plugins/johnfink-skills/
  .claude-plugin/plugin.json      # plugin manifest
  skills/<skill-name>/SKILL.md    # one skill per dir (lazy-loaded)
  hooks/hooks.json                # SessionStart + PreToolUse hook config
  hooks/bash-anti-patterns.py     # PreToolUse: warn on ephemeral scripts
  rules/house-rules.md            # always-on rules injected by SessionStart