Saturn v0.3.0

Saturn runs AI agents on your own computer: the agent app, its local runtime and Saturn IDE in one download.

Preview build. The macOS app is not signed with an Apple Developer ID (Apple Silicon only), and the Windows installer is signed with Saturn's self-signed certificate, which Windows does not trust, so both systems warn the first time you open them.

Install

macOS (Apple Silicon)

1. Download Saturn-0.3.0-mac-arm64-unsigned.dmg, open it, and drag Saturn into Applications (the .zip has the same app).
2. Open Saturn. When macOS says it can't verify the developer, go to System Settings → Privacy & Security and click Open Anyway.

Windows (x64)

1. Download Saturn-0.3.0-win-x64-setup.exe and run it.
2. If SmartScreen stops it, click More info → Run anyway. Later versions update themselves.
3. Optional: confirm the installer is Saturn's. In PowerShell, (Get-AuthenticodeSignature .\Saturn-0.3.0-win-x64-setup.exe).SignerCertificate.Thumbprint should print D285DA425077C16A3D115D61F9748AFA574BC786.

Then open Settings → Models, connect a model, create an agent, and give it a task (the first launch walks you through it).

Check a download (optional): each file has a .sha256 beside it, and a signed build attestation that proves it was built from this repository's source by its public release workflow:

shasum -a 256 -c Saturn-0.3.0-mac-arm64-unsigned.dmg.sha256
gh attestation verify Saturn-0.3.0-mac-arm64-unsigned.dmg -R Saturn-Technology-Project/Saturn-App

Saturn-0.3.0-sbom.cdx.json lists every package, model and runtime this release ships (CycloneDX 1.5, with each package's SHA-512), for your scanner or your security team.

Changes

Agents work more like Claude Code and Codex

• Permission rules (allow, ask or deny a tool by pattern) from Settings, a project's .saturn/settings.json, or Always allow on an approval card; .claude/settings.json rules are read too.
• An OS sandbox around shell commands on macOS: they write only inside the workspace, and leaving it asks. (Windows has no sandbox yet.)
• Context compaction: a long chat's oldest turns fold into a running summary; /compact on demand.
• Sub-agents (delegate), background commands (dev servers, watchers), hooks, skills, slash commands and plugins.
• Pull request follow-up: failing checks go back to the agent and its fix is pushed; review comments wait for you.
• Tool calls in each provider's native format (Claude with its signed thinking, OpenAI, Gemini, DeepSeek), and heavy toolkits (GitHub, computer use, browser, automations) load only when needed: about 85% fewer input tokens per step.

Watch and review what agents do

• Agent browser: shown live in the chat's Browser tab with the agent's cursor, or in a visible Chrome or Safari window (Settings → General → Agent browser).
• Every file change is reviewable and revertible, including what shell commands change, in the foreground or the background, in git projects and in other folders (private snapshots, listed with their size in Settings → General → Storage).
• Live updates over server-sent events instead of polling.

Use it from code

• saturn command line: saturn run "…" --agent … --project …, with approvals in the terminal.
• @saturn-app/sdk: start runs, follow their steps, answer approvals from TypeScript.

Fixes

• The Browser tab loads pages again.
• Computer use returns a partial accessibility tree on very large pages instead of timing out.
• Settings → General → Computer use asks macOS for Accessibility and Screen Recording itself, so Saturn appears in System Settings.
• Usage costs bill cached prompt tokens at each provider's cache rate.

Measured

Task evals (scripts/eval, 14 tasks graded by hidden tests): Claude Sonnet 5.5 passes 14 of 14.

Full Changelog: v0.2.0...v0.3.0