Compatibility

The current public compatibility line is Manifest V1.

Surface	Public contract	Runtime
@vifu/hub	VifuHub SDK for Agent Runtime capabilities, resources, and game-owned actions	Agent Runtime browser iframe, iOS WKWebView
@vifu/vf	Setup, build, deploy, and artifact validation	Node.js CLI
@vifu/create-vifu	Starter project initializer	Node.js CLI

Version Policy

Patch and alpha releases may add VifuHub SDK helpers, diagnostics, manifest fields, and deploy validation rules, but they should not silently break valid Manifest V1 projects.

Breaking changes require a new documented compatibility line. Until then, games should use:

• manifestVersion: 1
• main.url for the browser entry file
• @vifu/hub
• VifuHub SDK APIs instead of host bridge messages

Host Requirements

• Agent Runtime browser iframe with window.postMessage.
• window.webkit.messageHandlers.vifuHost for the iOS WKWebView runtime.
• Static browser output with an HTML entry file.
• JSON-serializable context, command input, command result, observation, and signal payloads.
• Host services accessed through @vifu/hub, not direct backend calls.

What Is Not Stable Yet

These surfaces are internal during alpha:

• compiled runtime policy names
• provider manifests
• moderation and review internals
• worker/eval/security rule names
• raw host bridge messages

Use the public VifuHub SDK, CLI, and Manifest V1 docs instead of depending on internal runtime details.