01 / Programming tools
Sley is a machine-native programming system for AI agents, built by Greyforge Labs. Agents change verified program structure instead of editing text, and a deterministic kernel validates every change before it commits.
Sley 2.0.7 released · Open source · Apache-2.0
Watch
Machines do not write source. They change verified program state. The introduction shows how it works.
Sley 2.x
Programs live as typed semantic state. An agent proposes a typed change against a verified root, a deterministic kernel validates it in fourteen phases, and only a valid change commits, atomically and with a receipt.
Download
Static binaries with checksums, including the sley-agent workbench. Download the archive and SHA256SUMS from the release page, verify, and run the demo.
curl -LO https://github.com/sley-lang/sley/releases/download/v2.0.7/sley-2.0.7-linux-x86_64.tar.gz
curl -LO https://github.com/sley-lang/sley/releases/download/v2.0.7/SHA256SUMS
sha256sum -c SHA256SUMS
tar xzf sley-2.0.7-linux-x86_64.tar.gz
cd sley-2.0.7-linux-x86_64
./bin/sley version
python3 demo/run_demo.py # prints "result": "PASS"Current release / 2.0.7
The graph is the program. Agents propose structural changes, a deterministic kernel validates them, and people keep authority over what runs. Sley 2.0 is a clean break by design, open source under Apache-2.0.
Read the Sley 2 docs ↗Sley 2.0.7 release ↗Why Sley 2 ↗Preserved release / 1.2.1
The complete human-readable language, open source and ready to study, use, or fork. The examples below come from this line.
Explore Sley Legacy 1.2.1 ↗The 1.x → 2.x transition (Aug 2026) ↗Sley Legacy 1.x
Everything below describes Sley Legacy 1.x, the complete human-readable language. Its final release is 1.2.1. It stays open source under Apache-2.0 for study, use, and forks.
module app.compute
task classify -> Text {
take score: Int
return if score >= 90 { "excellent" } else { "steady" }
}
task main -> Text {
bind score = 40 + 55
return call classify(score)
}The Sley 1.x line
A Sley Legacy task that classifies a score, called from another task. The tools can query the call structure before any write is authorized.
Browse the Legacy examples ↗Sley Legacy 1.x / why it exists
Text editing makes a tool guess the structure, change it, and explain itself afterward. Sley puts the structure first, so every change is known before it happens.
$ sley query --json --kind calls examples/project
"schema": "sley.query.report.v0"
"kind": "calls"
"entry_module": "app.main"
"modules": 2, "calls": 1Selected fields from a recorded Sley Legacy query.
Sley Legacy release checks, recorded on 1.2.0 on August 27, 2026, and carried into the final 1.2.1 release.
Recorded on Sley 1.2.0, August 27, 2026; carried into 1.2.1.
Sley Legacy 1.x / what the tools can inspect
Sley Legacy 1.x / what people keep