coding

name	Coding
description	Write, run, review, and test scripts and code. Uses Bun as the execution runtime. Applies to automation scripts, data transformation, API integration, and technical validation tasks.
version	1.0.0
tools	["bash","file_read","file_write"]
context	4096

Coding Skill

Provides code writing, execution, and review capabilities using Bun as the runtime.

Operations

Script

Write a TypeScript or JavaScript script to accomplish a task.

Runtime: Bun (prefer Bun built-ins over npm packages) Style: TypeScript with strict types at module boundaries

// Always start with clear intent comment
// Script: <what this does>
// Input: <what it expects>
// Output: <what it produces>

const result = await fetch(url).then(r => r.json());
console.log(JSON.stringify(result, null, 2));

Run

Execute a script or shell command via Bash.

RUN: bun run .system/scripts/<name>.ts
RUN: bun test .system/tests/*.test.ts

Capture output: Always capture stdout/stderr for analysis.

Review

Analyze existing code for issues:

1. Correctness: Does it do what it claims?
2. Safety: Path traversal, injection, unvalidated input?
3. Error handling: Unhandled rejections, silent failures?
4. Performance: Unnecessary awaits in loops, unbounded data reads?
5. Style: Consistent with project conventions?

Update

Modify existing code based on review findings or new requirements. Always:

1. Read the current file
2. Understand the change scope
3. Apply the minimal change that achieves the goal
4. Re-read to verify no unintended changes

Test

Write or run tests to validate behavior.

Framework: Bun's built-in test runner Location: .system/tests/*.test.ts Command: bun test .system/tests/*.test.ts

import { test, expect } from "bun:test";

test("description of behavior", () => {
  expect(actual).toBe(expected);
});

Code Standards

• const over let; no var
• async/await over Promise chains
• Optional chaining (?.) and nullish coalescing (??)
• Explicit error messages at boundaries: throw new Error("X failed: " + detail)
• No hardcoded paths — use relative paths from project root
• No external npm packages unless explicitly approved

Anti-Patterns

• Do not write scripts that delete or overwrite files without reading first
• Do not run commands that affect system state outside .data/ and .system/
• Do not loop on a shell command without a clear exit condition
• Do not import packages not already in package.json
• Do not write // TODO comments in production code — finish the task or raise it explicitly