nano-binary-search — AI Agent Rules

<!-- Canonical source: AGENTS.md — keep this file in sync -->
# nano-binary-search — AI Agent Rules

## Project identity

nano-binary-search is a single-function binary search (lower bound) for JavaScript. Zero dependencies, single file. Equivalent to C++ `std::lower_bound` / Python `bisect.bisect_left`.

## Critical rules

- **ESM-only.** The project is `"type": "module"`. Use `import`/`export` syntax.
- **Zero runtime dependencies.** Never add packages to `dependencies`.
- **Do not add comments or remove comments** unless explicitly asked.
- **Keep `index.js` and `index.d.ts` in sync.** The public API is a single function exported as both named and default export.

## Code style

- Prettier: 160 char width, single quotes, no bracket spacing, no trailing commas, arrow parens "avoid" (see `.prettierrc`).
- Imports at top of file, using `import` syntax.

## Verification commands

- `npm test` — run the full test suite
- `npm run test:bun` — run with Bun
- `npm run test:deno` — run with Deno
- `npm run ts-test` — run TS tests with Node
- `npm run ts-test:bun` — run TS tests with Bun
- `npm run ts-test:deno` — run TS tests with Deno
- `npm run ts-check` — TypeScript type checking
- `npm run lint` — Prettier format check

## File layout

- Implementation: `index.js` (single file, ~12 lines)
- TypeScript types: `index.d.ts`
- Tests: `tests/test-binary-search.js` (tape-six)
- TS typing tests: `tests/test-types.ts`
- CJS usage tests: `tests/test-cjs.cjs`
- AI/LLM reference: `llms.txt`
- Documentation: `README.md`

## Writing tests

**Before writing or updating tests**, read the tape-six skill at `node_modules/tape-six/skills/write-tests/SKILL.md` and the testing guide at `node_modules/tape-six/TESTING.md`.