complexity

Complexity

Thin roof: shared/rules/complexity.mdc. The lint number is law. Nesting ≤2 in ponytail is not a substitute.

Cap

Repo config wins. Else 10. Do not raise a cap that already exists. Do not switch to Sonar cognitive complexity unless this repo already uses it.

Detect (Grep, then one tool)

1. Grep complexity, C901, mccabe, gocyclo, cyclo, cognitive in eslint/ruff/clippy/biome/pyproject.toml/Makefile/CI.
2. If a cap exists, that number is law.
3. If missing and eslint, ruff, or biome is already installed: add the rule to that config. Do not add a new linter stack.
4. If no linter exists: still write as if cap 10. Cite that TOOLCHAIN has no complexity job. Do not invent eslint for a repo that has none.

TS/JS

Legacy .eslintrc*: "complexity": ["error", 10] (or the repo's number).

Flat eslint.config.*: keep the repo's existing complexity option; if absent and eslint already runs, add it next to the other rules — same number.

Run the repo lint on files you touched (pnpm exec eslint path, pnpm exec biome check path). Not a global npx stack.

Python / Go / Rust

Ruff: C901 with max-complexity = 10 (or the repo's number). Pylint R1260 only if pylint is already the house linter. gocyclo or clippy only if already in TOOLCHAIN.

Red — extract until green

Do this, in order:

1. Early return. Flatten if.
2. Replace else if chains with a map/table.
3. Pull a branch into a named function that does one job.
4. Nested ternary → if or a lookup.

Never eslint-disable complexity, # noqa: C901, --ignore C901, or clippy allow-wrap. before_shell.sh denies those bypasses.

// BAD — one function owns every branch
export function route(cmd: string, admin: boolean): string {
  if (cmd === "a") {
    if (admin) return "a-admin"
    return "a"
  } else if (cmd === "b") {
    if (admin) return "b-admin"
    return "b"
  }
  return "none"
}

// GOOD — table + early return (lint can count this)
const TABLE: Record<string, { user: string; admin: string }> = {
  a: { user: "a", admin: "a-admin" },
  b: { user: "b", admin: "b-admin" },
}
export function route(cmd: string, admin: boolean): string {
  const row = TABLE[cmd]
  if (!row) return "none"
  if (admin) return row.admin
  return row.user
}