utk2103 Lean Help
Display this reference card when invoked. One-shot only — do NOT change
mode, write flag files, touch ~/.claude/.lean-active, or persist state of
any kind. If the user wants to switch modes, point them at the trigger.
Levels at a glance
| Level | Trigger | Rule of thumb | Diff shape |
|---|---|---|---|
| Lite | /prompt-studio:lean lite |
Build what's asked. Name the lazier alternative in one line. | Requested code + 1-line footnote. |
| Full | /prompt-studio:lean (default) |
The ladder: YAGNI → reuse → stdlib → native → installed dep → one line → minimum. | Shortest working diff. ≤3 lines of prose. |
| Ultra | /prompt-studio:lean ultra |
YAGNI extremist. Deletion beats addition. Challenges the requirement before building. | Often zero code + a question back. |
Level sticks until you change it or the session ends. Persisted in
~/.claude/.lean-active so it survives across turns.
Same task, three levels
Task: "Add a cache for these API responses."
| Level | Response |
|---|---|
| Lite | Custom TTLCache class as asked. Note: functools.lru_cache(maxsize=1000) covers it in one line. |
| Full | @lru_cache(maxsize=1000) on the fetch function. Skipped custom cache, add when lru_cache measurably falls short. |
| Ultra | Do these responses actually re-fetch? Show me a hot path. If yes: @lru_cache. If not: skip. |
Skills
| Skill | Trigger | What it does |
|---|---|---|
| lean | /prompt-studio:lean [lite|full|ultra] |
Lazy mode itself. Shortest solution that actually works. |
| compress | /prompt-studio:compress FILE |
Compress a memory file (CLAUDE.md, todos, prefs) into Lean shorthand. Backup at FILE.original.md. |
| lean-audit | /prompt-studio:lean-audit |
Whole-repo over-engineering audit. Ranked list of what to delete/simplify across the codebase. |
| lean-commit | /prompt-studio:lean-commit |
Generate a terse Conventional Commits message for staged changes. Message only — never runs git. |
| lean-debt | /prompt-studio:lean-debt |
Harvest lean: comments into a debt ledger so deferrals get tracked, not forgotten. |
| lean-gain | /prompt-studio:lean-gain |
Measured impact scoreboard — less code, more speed (no cost claim). |
| lean-review | /prompt-studio:lean-review |
Review a diff for over-engineering only. One line per finding: what to cut, what replaces it. |
| lean-help | /prompt-studio:lean-help |
This card. |
Codex users: @lean, @compress, @lean-audit, @lean-commit, @lean-debt, @lean-gain, @lean-review, @lean-help. OpenCode and Claude Code:
slash-command forms above.
The ladder (full mode)
Stop at the first rung that holds:
- Needs to exist? Speculative → skip, one-line note. (YAGNI)
- Already in this codebase? Helper/util/type nearby → reuse.
- Stdlib does it? Use it.
- Native platform feature?
<input type="date">over picker lib, CSS over JS, DB constraint over app code. - Installed dep solves it? Use it. Never add a new dep for what a few lines can do.
- One line? One line.
- Only then: minimum code that works.
Deactivate / resume
| Action | Say |
|---|---|
| Turn off | stop lean, normal mode, or /prompt-studio:lean off |
| Resume | /prompt-studio:lean (or with a level) |
| Check current | cat ~/.claude/.lean-active |
Configure default mode
Default is full, auto-active every session. Override:
Environment variable (highest priority):
export LEAN_DEFAULT_MODE=ultra # lite | full | ultra | off
Config file — ~/.config/lean/config.json (Windows: %APPDATA%\lean\config.json):
{ "defaultMode": "lite" }
Set "off" to disable auto-activation on session start; activate manually
with /prompt-studio:lean when wanted.
Resolution order: env var → config file → full.
MCP surface
The lean-mcp server exposes the same builder used by the FastAPI adapters
(app/services/formats.build_messages) and this plugin — one source of
truth in app/services/skills.py, no drift between transports. Wire it into
any MCP-compatible client to get Lean shaping without the plugin.
Troubleshooting
| Symptom | Fix |
|---|---|
| Mode reverts every turn | ~/.claude/.lean-active not writable — check perms. |
/lean-help prints nothing |
Skill not loaded. Reinstall (see Update). |
| Default mode ignored | Env var wins over config file — unset LEAN_DEFAULT_MODE. |
| Want Lean only in one repo | Add project-level hook, not global env var. |
Conflicts with caveman prose mode |
Fine — Lean shapes code, caveman shapes prose. Run both. |
Update
/plugin marketplace update prompt-studio
/plugin install lean@prompt-studio
Or turn on auto-update in /plugin → Marketplaces. Codex and OpenCode use
their own reinstall flow from the repo.
More
Full docs, examples, and source: https://github.com/utk2103/Prompt-Studio