---
name: "strict-api"
description: "Use when the user says 'no hallucinations', 'verify APIs' or 'don't invent functions', or code depends on a library version you have not checked. Requires proof that every method, import and variable exists in the installed version before using it."
---
# Strict API Verification
Inventing a function that doesn't exist is the opposite of efficiency. You wrote a line that looks minimal. You shipped a bug that takes an hour to debug. The true minimal path is: use only what is provably there.
## Overview
This skill is a reality-check layer applied before any code is written. It is not about being slow — it is about being correct the first time. Use it alongside `minimalist` when the user wants both less code and verified code.
## The Only Rule
Before you write any function call, import, or method access, you must be able to answer:
**"Does this exist in the version the user is running?"**
If the answer is "probably" or "I think so" — **stop**. You don't know. Say so.
## What This Blocks
**Made-up methods:**
- `fs.readFileLines()` does not exist in Node.js.
- `path.combine()` is .NET, not Node.js.
- `csv.read_csv()` is pandas, not Python's `csv` module.
Writing these is not minimal code — it is confident garbage.
**Framework confusion.** Every framework has a twin that sounds like it:
- `render_template` (Flask) vs `render()` (Django)
- `useForm()` (react-hook-form) vs nothing built into React
- `app.listen()` (Express) vs `server.listen()` (raw Node.js `http`)
**Deprecated APIs.** Writing a deprecated method is writing code that will break on the next upgrade.
## Workflow
1. **Identify every API surface** in the code you are about to write: imports, method calls, class instantiations.
2. **Verify each one** against the user's stated version. If no version is stated, ask once.
3. **Flag anything uncertain** with an inline comment rather than silently guessing.
4. **Prefer verbose-but-correct** over terse-but-wrong.
When you are not sure if a method exists, annotate it inline:
// verify fs.openAsBlob exists in your Node.js version (>= 20.0)
const blob = await fs.openAsBlob(path);
One comment costs nothing. A silent wrong call costs an hour of the user's time.
If the uncertainty is too high to write correct code without guessing, say:
"I'd need to check whether X exists in version Y before using it. What version are you on?"
## Anti-Patterns
| Anti-Pattern | What to do instead |
|---|---|
| Writing a method call you vaguely remember | Stop and verify the exact signature |
| Silently using a deprecated API | Use the current API and note the deprecation |
| Assuming API parity across frameworks | Explicitly name the framework and version |
| Guessing import paths | Check the package's actual export structure |
| Using an API from a different language's stdlib | Verify it exists in this language |
| Writing "it should work" without checking | Ask what version the user is on |
## Cross-References
- Related: `engineering/minimalist` — use together: minimalist reduces code volume; strict-api ensures what is written is correct.
- Related: `engineering/zero-hallucination-coder` — similar goal; broader hallucination prevention beyond APIs.
- Related: `engineering/karpathy-coder` — Karpathy-inspired behavioral guardrails for LLM-assisted coding.