sabline-lang

Run code an AI wrote without handing it everything you can reach.

Each function declares what it may touch. You grant the run one folder, one host or a number of calls, and the runtime refuses anything else the moment it's tried. Formerly Velaris.

npx sabline-lang script.vel

That program cannot read a file, reach the network or call Python - whatever its source says about itself - and a refusal cannot be caught and carried past. A run with no --allow gets io (5.0), so that is the default rather than something you have to remember; widen it by naming what the program needs, and --allow all grants every effect and says so on stderr.

import { audit, run } from "sabline-lang";

const report = await audit(source);
console.log(report.effects);        // ['fs', 'net']
console.log(report.proven_share);   // 66.7

const result = await run(source, { allow: ["io"] });
console.log(result.ok, result.output, result.refusedEffect);

Sabline is a language where a function's signature declares its types, the effects it may perform, whether it can fail, and promises a theorem prover checks before the program runs. This package is a thin wrapper around that compiler.

Not a security boundary - allowing ffi grants everything Python can do. It is a real guard for running a script a model wrote.

The compiler

The compiler itself is a Python package. This wrapper calls it, so install it once:

pip install sabline-lang

Two optional pieces are worth having:

pip install "sabline-lang[full]"

That adds z3-solver, which proves a function's promises before the program runs instead of leaving them to be checked as it goes, and llvmlite, which compiles pure integer and float code to native code instead of interpreting it. Neither is required. Without them Sabline runs fully interpreted and checks promises while running - it prints note: llvmlite is not installed - running fully interpreted and carries on, refusing effects outside the budget exactly the same way.

Which Python it uses

The wrapper tries py, python and python3 on Windows, python3 then python elsewhere, asks each one which Sabline it has, and uses the newest. If the newest it finds is older than this npm package it still uses it, but says so first, on stderr, naming both versions and the interpreter - so a stale install left on PATH is visible rather than mysterious. If you ask for a subcommand that version does not have, it says which command and which version introduced it instead of handing it over. pip install -U sabline-lang upgrades the compiler.

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