function-length-max-50.yaml

id: function-length-max-50
name: Function length does not exceed 50 lines
description: >
  No function or method body exceeds 50 lines of code. A function longer than 50 lines
  is doing more than one thing. Single Responsibility applies at the function level:
  a 200-line function is a module masquerading as a function, with hidden dependencies
  between its parts and no clean abstraction boundary. Long functions are the primary
  cause of untestable code — they cannot be unit-tested without also testing everything
  else they do. The 50-line limit is enforced via the ESLint max-lines-per-function rule,
  which excludes comment lines and blank lines from the count. Functions that consistently
  need 60+ lines signal missing helper functions or missing abstractions.
property: Bounded
tags: [javascript, typescript, eslint]
phase: development
trigger: pr
blocking: true
check:
  type: script
  command: "npx eslint --rule '{\"max-lines-per-function\": [\"error\", {\"max\": 50, \"skipBlankLines\": true, \"skipComments\": true}]}' 'src/**/*.ts' 'src/**/*.js'"