Hardening a TypeScript CLI Tool for Agent Collaboration

Problem/Feature Description

A small team is using a TypeScript CLI tool that converts CSV files to JSON. Two agents are already working on the codebase, but they keep accidentally pushing broken builds to the main branch — the unit tests pass locally because they're all mocked, but the actual CLI behavior breaks frequently. The team lead wants to add a proper enforcement layer so that broken code physically cannot be pushed, and wants real end-to-end tests that prove the CLI works correctly on actual files.

You've been asked to set up the mechanical enforcement layer and add an honest end-to-end test for the CLI. The team also wants to identify any dead code in the project. Produce the enforcement scripts and test, and write a brief setup-notes.md documenting what you set up and how to activate it.

Output Specification

Produce the following files:

1. .git-hooks/pre-push — A shell script that acts as a git pre-push hook, running lint and smoke checks. It must be executable.

2. e2e/cli.test.sh — A shell script that runs the CLI against a real input file and verifies the output is correct (e.g., using diff against an expected output file or checking for expected content). Include the fixture input file it uses.

3. e2e/fixtures/sample.csv — Sample CSV input used by the e2e test.

4. e2e/fixtures/expected.json — Expected JSON output corresponding to sample.csv.

5. setup-notes.md — Brief documentation explaining: (a) how to activate the git hook, (b) what the dead-code check command is for this TypeScript project, and (c) what the e2e test covers.

Input Files

The following files represent the current state of the project. Extract them before beginning.

=============== FILE: package.json =============== { "name": "csv-to-json-cli", "version": "2.1.0", "description": "Convert CSV files to JSON", "bin": { "csv2json": "./dist/cli.js" }, "scripts": { "build": "tsc", "lint": "eslint src/", "test": "jest" }, "dependencies": {}, "devDependencies": { "typescript": "^5.0.0", "eslint": "^8.0.0", "@typescript-eslint/parser": "^6.0.0", "jest": "^29.0.0", "ts-jest": "^29.0.0" } }

=============== FILE: src/cli.ts =============== #!/usr/bin/env node import { readFileSync, writeFileSync } from 'fs'; import { parseCsv } from './parser';

const [,, inputFile, outputFile] = process.argv;

if (!inputFile) { console.error('Usage: csv2json <input.csv> [output.json]'); process.exit(1); }

const csv = readFileSync(inputFile, 'utf-8'); const result = parseCsv(csv);

if (outputFile) { writeFileSync(outputFile, JSON.stringify(result, null, 2)); } else { console.log(JSON.stringify(result, null, 2)); }

=============== FILE: src/parser.ts =============== export function parseCsv(csv: string): Record<string, string>[] { const lines = csv.trim().split('\n'); const headers = lines[0].split(',').map(h => h.trim()); return lines.slice(1).map(line => { const values = line.split(',').map(v => v.trim()); return Object.fromEntries(headers.map((h, i) => [h, values[i] ?? ''])); }); }

export function legacyParseCsv(csv: string): string[][] { // Old implementation kept for reference but no longer used return csv.split('\n').map(line => line.split(',')); }

=============== FILE: src/parser.test.ts =============== import { parseCsv } from './parser';

jest.mock('./parser', () => ({ parseCsv: jest.fn(), legacyParseCsv: jest.fn() }));

test('parseCsv is a function', () => { expect(typeof parseCsv).toBe('function'); });

=============== FILE: tsconfig.json =============== { "compilerOptions": { "target": "ES2020", "module": "commonjs", "outDir": "./dist", "strict": true }, "include": ["src/**/*"] }