prototype

A throwaway coding exercise used to answer one design question before the real implementation. It can test terminal logic such as a state machine or data model, or show several web-interface options for one route.

In plain words
What is it for?
Use it to test whether program logic, states, or an API shape feels right, or to compare possible web UI designs before building the final version.
Why use it?
Some designs are difficult to judge from written plans alone. A temporary prototype lets the team try the behavior or layout, record the conclusion, and then delete the experiment.

Skill for Claude CodeCodex

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 skills/aldianriski/lean-flow/prototype
Any agent
npx skills add aldianriski/lean-flow --skill prototype
Clone the repo
git clone --depth 1 https://github.com/aldianriski/lean-flow

Made for: Claude Code, Codex.

Per session 85 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 941 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 $0.00085 $0.00941
Opus 5 $0.00043 $0.00470
Sonnet 5 $0.00017 $0.00188
Haiku 4.5 $0.00009 $0.00094

Measured 2d ago against content hash 87e5c1295280, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

prototype 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 2d ago.

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.

skills/prototype/SKILL.md · 55 lines

How it starts

The opening of the file, as written. The whole thing — 55 lines — stays where its author put it; the contents beside it link to each section on GitHub.

prototype

A prototype is throwaway code that answers a question. The question decides the shape. It slots into the design stage — when /orchestrator's Grill can't resolve a design on paper, prototype to feel the answer, then feed it into the plan.

Pick a branch

Identify the question — from the prompt, the surrounding code, or by asking:

  • "Does this logic / state model / API feel right?" → terminal logic prototype. A tiny interactive TUI that drives a state machine by hand through cases that are hard to reason about on paper. Full process → ${CLAUDE_SKILL_DIR}/references/logic.md.
  • "What should this look like?" → web UI prototype (web projects only). Several radically different UI variations on one route, switchable from a floating bar. Full process → ${CLAUDE_SKILL_DIR}/references/ui.md.

Wrong branch = wasted prototype. If genuinely ambiguous and the user is unreachable, match the surrounding code (backend module → logic; page/component → UI) and state the assumption at the top.

Rules (both branches)

  1. Throwaway from day one, clearly marked. Locate it next to where it'll be used so context is obvious; name it so a casual reader sees it's a prototype, not production.
  2. One command to run — via the project's existing task runner. No path to remember.
  3. No persistence by default — state lives in memory. Persistence is the thing being checked, not depended on. If the question is about the DB, use a scratch store named PROTOTYPE — wipe me.
  4. Skip the polish — no tests, no error handling beyond runnable, no abstractions, no "what if we need X later". One question.
  5. Surface the state — after every action (logic) or variant switch (UI), render the full relevant state so the user sees what changed.
  6. Retire it when done, don't lose it — never leave it rotting on the working branch. Commit the spent prototype to a throwaway branch off main and leave a pointer to that branch beside the captured answer; then delete or absorb it here. The branch costs nothing, keeps the primary source retrievable when the verdict is later questioned, and avoids TD-012's shape — deleting the scaffolding also deleted the fixtures that were guarding something.

Read the full file on GitHub · 55 lines

Files

What ships with it

2 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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. 2d ago First seen · 55 lines · 85 tokens per session scan A 87e5c1295280

Subscribe to this mod's changes

prototype is a skill published in the GitHub repository aldianriski/lean-flow (4 stars, last pushed 3d ago), licensed MIT. It adds 85 tokens to every session and 941 once invoked, about $0.0004 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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