id: no-runner-temp-nullish
language: Tsx
severity: error
message: 'Use logical OR for RUNNER_TEMP temp roots so an empty string falls back safely.'
files:
  - '**/*.ts'
  - '**/*.tsx'
  - '**/*.mts'
  - '**/*.cts'
rule:
  any:
    - pattern: $ENV.RUNNER_TEMP ?? $$$
    - pattern: $ENV['RUNNER_TEMP'] ?? $$$
    - pattern: $ENV["RUNNER_TEMP"] ?? $$$
examples:
  - code: 'const root = process.env.RUNNER_TEMP ?? os.tmpdir()'
    isValid: false
    file: 'src/setup.mts'
  - code: 'const root = env.RUNNER_TEMP ?? env.TMPDIR'
    isValid: false
    file: 'src/env.mts'
  - code: 'const root = process.env["RUNNER_TEMP"] ?? os.tmpdir()'
    isValid: false
    file: 'src/setup.mts'
  - code: "const root = env['RUNNER_TEMP'] ?? env.TMPDIR"
    isValid: false
    file: 'src/env.mts'
  - code: 'const root = process.env.RUNNER_TEMP || os.tmpdir()'
    isValid: true
    file: 'src/setup.mts'
  - code: 'const root = env.RUNNER_TEMP || env.TMPDIR || tmpdir()'
    isValid: true
    file: 'src/env.mts'