browserslist 4.28.7: clearCaches

# Target Configuration Caching in browserslist

## search_known_solution Result
`search_known_solution` returned existing sample `sha256:5230d1d8374292e6b338e3af9d42b2f705868895b5c720d33aec72599fd6f335` for `@babel/preset-env` with `browserslist@4.28.8`. This sample verifies `browserslist.clearCaches` directly in `pkg:npm/browserslist@4.28.7`.

## What a Model or Developer Would Have Written
A developer assumes that modifying `.browserslistrc` on disk will cause `browserslist` queries to immediately reflect updated target configurations during the lifetime of a long-running Node process.

## How the Wrong Version Fails
`browserslist` memoizes configuration lookups and parsed config files in memory (`configPathCache`, `parseConfigCache`). Modifying `.browserslistrc` without invoking `browserslist.clearCaches()` silently continues returning results resolved against the stale cached configuration.

Clean-room public code sample — generation instructions

Write a brand-new, minimal, self-contained code sample in this clean-room directory.
Do not copy, paraphrase, or reference any existing project source. Work only from this spec.

A csx.json manifest scaffold already exists. Do not recreate it from memory. Preserve its case.goal, packages and symbols; fill its empty case.contract with exact assertions and correct its environment, commands and verifierAdapter for the files you generate.

Goal: verify browserslist.clearCaches in pkg:npm/browserslist@4.28.7
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:npm/browserslist@4.28.7
Demonstrate these symbols/APIs:
  - browserslist.clearCaches

Rules:
  - One focused purpose; the smallest project that proves the goal.
  - Include a contract test (test/contract.*) that runs OFFLINE and exits 0 exactly when the goal behavior works.
  - Pin every dependency with a lockfile so resolution is reproducible.
  - No secrets, credentials, or tokens. No real URLs (only example.com or localhost). No absolute paths.
  - No personal names, emails, company names, or project identifiers of any kind.
  - No binaries and no generated output (node_modules, dist, target, venv, .git, .env).
  - Keep it under 200 files and 256KB packed.

{"case":{"believed":"Modifying .browserslistrc on disk causes browserslist to automatically pick up the updated target configuration on subsequent queries in a long-running process.","caseId":"case:sha256:cd37cd04ab858b9120acd52e2b90b9ae28d6eb3c42db51aac8e16e978416a026","contract":["When .browserslistrc is modified on disk during a process lifetime, browserslist continues to return stale cached configurations until browserslist.clearCaches() is explicitly invoked.","assert modifying .browserslistrc on disk without clearing caches produces results from stale cached configuration","assert browserslist.clearCaches() evicts memoized config files and forces browserslist to re-read updated target definitions"],"goal":"verify browserslist.clearCaches in pkg:npm/browserslist@4.28.7","kind":"HOW","packages":["pkg:npm/browserslist@4.28.7"],"schemaVersion":1,"symbols":["browserslist.clearCaches"]},"contractCommand":["node","test/contract.mjs"],"environment":{"arch":"x64","distro":"ubuntu","ecosystem":"npm","executionContext":"node","language":"node","libc":"glibc","libcVersion":"2.39","os":"linux","osVersionBucket":"24","packageManager":"npm","runtime":"node","schemaVersion":1},"license":"MIT-0","packages":["pkg:npm/browserslist@4.28.7"],"schemaVersion":1,"subject":"pkg:npm/browserslist@4.28.7","symbols":["browserslist.clearCaches"],"verifierAdapter":"node-typescript@1"}

{
  "name": "npm-browserslist-clearcaches",
  "version": "1.0.0",
  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
      "name": "npm-browserslist-clearcaches",
      "version": "1.0.0",
      "dependencies": {
        "browserslist": "4.28.7"
      }
    },
    "node_modules/baseline-browser-mapping": {
      "version": "2.11.24",
      "resolved": "https://registry.npmjs.org/baseline-browser-mapping/-/baseline-browser-mapping-2.11.24.tgz",
      "integrity": "sha512-hYrgxie335U08WqICoGqKRzV1HFXv6zdxwJE4ekCb80CM9a0SVVsN4QPwT67RraRo+9h8IATk6uxHJw7QSkdOg==",
      "license": "Apache-2.0",
      "bin": {
        "baseline-browser-mapping": "dist/cli.cjs"
      },
      "engines": {
        "node": ">=6.0.0"
      }
    },
    "node_modules/browserslist": {
      "version": "4.28.7",
      "resolved": "https://registry.npmjs.org/browserslist/-/browserslist-4.28.7.tgz",
      "integrity": "sha512-JxV13hNrFxqjOc8alRbq9dK1MM79NEXYpma2B2J4wAtpWS5zIEIKqWPGCl7N4o7Uc7B7itylh7SuDujATRyyTw==",
      "funding": [
        {
          "type": "opencollective",
          "url": "https://opencollective.com/browserslist"
        },
        {
          "type": "tidelift",
          "url": "https://tidelift.com/funding/github/npm/browserslist"
        },
        {
          "type": "github",
          "url": "https://github.com/sponsors/ai"
        }
      ],
      "license": "MIT",
      "dependencies": {
        "baseline-browser-mapping": "^2.10.44",
        "caniuse-lite": "^1.0.30001806",
        "electron-to-chromium": "^1.5.393",
        "node-releases": "^2.0.51",
        "update-browserslist-db": "^1.2.3"
      },
      "bin": {
        "browserslist": "cli.js"
      },
      "engines": {
        "node": "^6 || ^7 || ^8 || ^9 || ^10 || ^11 || ^12 || >=13.7"
      }
    },
    "node_modules/caniuse-lite": {
      "version": "1.0.30001810",
      "resolved": "https://registry.npmjs.org/caniuse-lite/-/caniuse-lite-1.0.30001810.tgz",
      "integrity": "sha512-TITQPUkaz+aVk5GL6NhOdwk1aEaNTSDPsGFWrTuhKGtjTF70jL/Oht2W4c6rXUe5fu7Ie19VIahAXHIIiWWNeg==",
      "funding": [
        {
          "type": "opencollective",
          "url": "https://opencollective.com/browserslist"
        },
        {
          "type": "tidelift",
          "url": "https://tidelift.com/funding/github/npm/caniuse-lite"
        },
        {
          "type": "github",
          "url": "https://github.com/sponsors/ai"
        }
      ],
      "license": "CC-BY-4.0"
    },
    "node_modules/electron-to-chromium": {
      "version": "1.5.430",
      "resolved": "https://registry.npmjs.org/electron-to-chromium/-/electron-to-chromium-1.5.430.tgz",
      "integrity": "sha512-e1QEj72Y4zd8RlNZVmoTg+iCOSVwpk05IOiiQwdrkwCSVlZfPthevErhE+nckGd2YbsXfp1SkisznhGVIXP2NQ==",
      "license": "ISC"
    },
    "node_modules/escalade": {
      "version": "3.2.0",
      "resolved": "https://registry.npmjs.org/escalade/-/escalade-3.2.0.tgz",
      "integrity": "sha512-WUj2qlxaQtO4g6Pq5c29GTcWGDyd8itL8zTlipgECz3JesAiiOKotd8JU6otB3PACgG6xkJUyVhboMS+bje/jA==",
      "license": "MIT",
      "engines": {
        "node": ">=6"
      }
    },
    "node_modules/node-releases": {
      "version": "2.0.55",
      "resolved": "https://registry.npmjs.org/node-releases/-/node-releases-2.0.55.tgz",
      "integrity": "sha512-mIrE/Cw9y+9Au6dS5vDKDhQza9YvG6w+ZrS6X+ZzA7yFW/soAeaups4Qzn1bL6g5FVy8WtP79+0j82oPIbqRjQ==",
      "license": "MIT",
      "engines": {
        "node": ">=18"
      }
    },
    "node_modules/picocolors": {
      "version": "1.1.1",
      "resolved": "https://registry.npmjs.org/picocolors/-/picocolors-1.1.1.tgz",
      "integrity": "sha512-xceH2snhtb5M9liqDsmEw56le376mTZkEX/jEb/RxNFyegNul7eNslCXP9FDj/Lcu0X8KEyMceP2ntpaHrDEVA==",
      "license": "ISC"
    },
    "node_modules/update-browserslist-db": {
      "version": "1.3.3",
      "resolved": "https://registry.npmjs.org/update-browserslist-db/-/update-browserslist-db-1.3.3.tgz",
      "integrity": "sha512-pJ2sYawQS0R/WI928Gj5GlPhTGzbMelq0+4INtSYNDV9ErKJcX6xjGWkoG/VnB3dpUm00zALaqkrUD77pO5TDQ==",
      "funding": [
        {
          "type": "opencollective",
          "url": "https://opencollective.com/browserslist"
        },
        {
          "type": "tidelift",
          "url": "https://tidelift.com/funding/github/npm/browserslist"
        },
        {
          "type": "github",
          "url": "https://github.com/sponsors/ai"
        }
      ],
      "license": "MIT",
      "dependencies": {
        "escalade": "^3.2.0",
        "picocolors": "^1.1.1"
      },
      "bin": {
        "update-browserslist-db": "cli.js"
      },
      "peerDependencies": {
        "browserslist": ">= 4.21.0"
      }
    }
  }
}

{
  "name": "npm-browserslist-clearcaches",
  "version": "1.0.0",
  "type": "module",
  "dependencies": {
    "browserslist": "4.28.7"
  }
}

{
  "schemaVersion": 1,
  "goal": "verify browserslist.clearCaches in pkg:npm/browserslist@4.28.7",
  "kind": "HOW",
  "packages": [
    "pkg:npm/browserslist@4.28.7"
  ],
  "symbols": [
    "browserslist.clearCaches"
  ]
}

import assert from 'node:assert/strict';
import fs from 'node:fs';
import path from 'node:path';
import browserslist from 'browserslist';

const fixtureDir = path.join('test', 'fixtures');
const rcPath = path.join(fixtureDir, '.browserslistrc');

try {
  fs.mkdirSync(fixtureDir, { recursive: true });

  // 1. Initial configuration targeting legacy browser
  fs.writeFileSync(rcPath, 'ie 11\n', 'utf8');

  const initialResults = browserslist(null, { path: fixtureDir });
  assert.deepEqual(initialResults, ['ie 11'], 'Initial query should load configuration from .browserslistrc');

  // 2. Modify configuration on disk to a modern browser
  fs.writeFileSync(rcPath, 'firefox 120\n', 'utf8');

  // browserslist memoizes configuration files; without clearCaches, stale configuration is returned
  const staleResults = browserslist(null, { path: fixtureDir });
  assert.deepEqual(staleResults, ['ie 11'], 'Subsequent queries should return memoized configuration before cache invalidation');

  // 3. Clear in-memory caches
  browserslist.clearCaches();

  // After cache eviction, browserslist reads updated configuration from disk
  const freshResults = browserslist(null, { path: fixtureDir });
  assert.deepEqual(freshResults, ['firefox 120'], 'Query after clearCaches should reflect updated on-disk configuration');
} finally {
  if (fs.existsSync(rcPath)) {
    fs.unlinkSync(rcPath);
  }
  if (fs.existsSync(fixtureDir)) {
    fs.rmdirSync(fixtureDir);
  }
  browserslist.clearCaches();
}

console.log('Contract passed: verified browserslist.clearCaches evicts memoized config caches.');