Prototype

A prototype is throwaway code that answers a question. The question decides the shape.

Pick a branch

Identify which question is being answered — from the user's prompt, the surrounding code, or by asking if the user is around:

"Does this logic / state model feel right?" → LOGIC.md. Build a tiny interactive terminal app that pushes the state machine through cases that are hard to reason about on paper.
"What should this look like?" → UI.md. Generate several radically different UI variations on a single route, switchable via a URL search param and a floating bottom bar.

The two branches produce very different artifacts — getting this wrong wastes the whole prototype. If the question is genuinely ambiguous and the user isn't reachable, default to whichever branch better matches the surrounding code (a backend module → logic; a page or component → UI) and state the assumption at the top of the prototype.

Rules that apply to both

Throwaway from day one, and clearly marked as such. Locate the prototype code close to where it will actually be used (next to the module or page it's prototyping for) so context is obvious — but name it so a casual reader can see it's a prototype, not production. For throwaway UI routes, obey whatever routing convention the project already uses; don't invent a new top-level structure.
One command to run. Whatever the project's existing task runner supports — pnpm <name>, python <path>, bun <path>, etc. The user must be able to start it without thinking.
No persistence by default. State lives in memory. Persistence is the thing the prototype is checking, not something it should depend on. If the question explicitly involves a database, hit a scratch DB or a local file with a clear "PROTOTYPE — wipe me" name.
Skip the polish. No tests, no error handling beyond what makes the prototype runnable, no abstractions. The point is to learn something fast and then delete it.
Surface the state. After every action (logic) or on every variant switch (UI), print or render the full relevant state so the user can see what changed.
Delete or absorb when done. When the prototype has answered its question, either delete it or fold the validated decision into the real code — don't leave it rotting in the repo.

When done

The answer is the only thing worth keeping from a prototype. Capture it somewhere durable (commit message, ADR, issue, or a NOTES.md next to the prototype) along with the question it was answering. If the user is around, that capture is a quick conversation; if not, leave the placeholder so they (or you, on the next pass) can fill in the verdict before deleting the prototype.

Files3

3 files · 13.1 KB

Select a file to preview

Overall Score

88/100

Grade

A

Excellent

Safety

92

Quality

87

Clarity

89

Completeness

83

Summary

A skill for building throwaway prototypes to validate design and logic questions before production commitment. It routes between two branches: a terminal-based interactive state machine explorer (LOGIC.md) for testing business logic and data models, or a multi-variant UI showcase (UI.md) for exploring design options on a single route with a floating switcher.

Static Analysis Findings

1 finding

Patterns detected by deterministic static analysis before AI scoring. Hover over any finding code for detailed information and remediation guidance.

Credential Exposure

SEC-020Direct .env File Access

Direct .env file access

UI.md.env

85% confidenceCWE-538: Sensitive Info in Externally-Accessible File

Detected Capabilities

Identify prototype questions from user intent or surrounding codeGenerate interactive terminal UIs for state machine explorationCreate multi-variant UI routes with URL-param switching and floating control barStructure pure logic modules that can be lifted into production codeDocument prototype decisions and answers for post-prototype reviewGuide throwaway code practices and anti-patterns

Trigger Keywords

Phrases that MCP clients use to match this skill to user intent.

prototype designexplore ui variantsvalidate state machinethrowaway prototypemock up apiflush out designtest edge casesdesign options

Risk Signals

INFO

SEC-020: Direct .env file access mentioned in UI.md

UI.md (implicit in environment checking pattern `process.env.NODE_ENV`)

Use Cases

Validate a state machine or data model by interactively pushing it through edge cases
Explore multiple radically different UI layouts for a page or component before committing to one
Mock up an API shape or business logic before writing production code
Sanity-check a design concept by rendering several structural variants side-by-side

Quality Notes

Excellent structural clarity: SKILL.md clearly bifurcates the two prototype shapes (logic vs. UI) with explicit decision criteria before building, reducing wasted effort.
Strong anti-patterns section in both LOGIC.md and UI.md explicitly teaching what NOT to do — e.g., 'don't blur logic and TUI together', 'don't ship the prototype to production', 'don't add tests'. This is superior to only documenting the happy path.
Well-scoped throwaway philosophy: rules explicitly state 'no persistence by default', 'skip the polish', 'delete or absorb when done' — creates a clear mental model for practitioners.
Concrete output guidance: both branches specify exactly what the user should see (formatted state, keyboard shortcuts, URL bar) and what the developer should hand over (run command, URL, or captured answer in NOTES.md).
Portable logic design: LOGIC.md strongly encourages isolating the state machine/reducer behind a pure interface so it can be lifted into production — this bridges prototype and real code cleanly.
Minor: UI.md's 'strongly prefer sub-shape A' guidance includes good reasoning ('a throwaway route on its own is a vacuum') that helps practitioners avoid invisible design problems.
Edge case coverage: addresses no existing route (sub-shape B), keyboard interaction during text input (don't intercept arrows in inputs), and reload stability (URL params for shareability).
One potential friction: LOGIC.md says 'no tests' but later says 'the TUI shell gets deleted' — implies testing happens only on the real module after the prototype ends. This is correct but could confuse practitioners unfamiliar with prototype methodology.

Model: claude-haiku-4-5-20251001Analyzed: May 7, 2026

Reviews

Add this skill to your library to leave a review.

No reviews yet

Be the first to share your experience.

prototype