# lpy agent endpoint

Base URL: the host you fetched this from (https://lpylang.dev in production)

Install the CLI from this host, then check and build locally. This page is generated in lpy.

## What lpy is
Python-shaped source. rustc borrow-checks. LLVM emits native code. crates.io for libraries.
Do not invent a second package index. Do not emit TypeScript.

## Human UI
GET /                playground + token studio
GET /api/stats       {"ok":true,"engine":"lpy","save_vs_rust":31,"save_vs_python":11}

## Agent API (CORS *)
POST /api/check      body = lpy source (text/plain) OR JSON {"source":"..."}
                     -> {"ok":bool,"output":"..."}  rustc diagnostics remapped to .lpy
POST /api/expand     body as above -> {"ok":bool,"rust":"..."}
POST /api/run        body as above -> {"ok":bool,"output":"..."}  requires def main(), 12s timeout
POST /api/tokens     body = text or JSON {"source":"..."}
                     -> {"ok":true,"o200k":N,"cl100k":N,"chars":N}
GET  /api/data       bench pairs with python/lpy/rust sources and token counts
GET  /llms.txt       this file
GET  /openapi.json   machine spec
GET  /tack.md        separate product: reasoning-token spec (not required for lpy; prompt/reply stay English)

## Rules for generated lpy
- Valid Python 3 syntax. Implicit last-expression return. Methods may omit self.
- Types: int float bool str list[T] dict[K,V] T|None
- Ok or Err: type Result[T,E] = Ok(T) | Err(E)
- Imports: from crate import name  (list crate in lpy.toml)
- from fs import read_to_string; from env import var
- Trailing ? is Rust ?
- No slices, no **kwargs, no nested def, no try/except, no import crate as module

## Local toolchain
Python 3.11+, rustc, cargo if you use crates.
From this host (no clone):
  curl -sSf $HOST/install.sh | sh -s -- --new ./myapp
  lpy doctor
  lpy check ./myapp/main.lpy
  lpy build ./myapp/main.lpy -o ./myapp/app --opt size
GET /install.sh  bootstrap script (origin baked in)
GET /lpy.tgz     source tree the script pip-installs
`lpy new` writes AGENTS.md and lpy.json (commands + forbidden syntax).

## Example
curl -sS -X POST $HOST/api/check --data-binary $'def add(a: int, b: int) -> int:\n    a + b\n'