# YSDK — YOS integration specification

> YSDK is how any application joins YOS: publish one manifest and become
> discoverable, harvestable, installable and seedable. It profiles W3C DID v1.1,
> UCAN v1.0.0, MCP (revision 2026-07-28) and the W3C Web Application Manifest,
> and adds exactly one artifact: ysdk.app.json.

## Core
- [Specification](https://ysdk.org/spec/): normative contract — wire formats, verification order, UI/UX contract, non-negotiables.
- [Manifest schema](https://ysdk.org/schema/ysdk.app.schema.json): JSON Schema 2020-12.
- [Our own manifest](https://ysdk.org/.well-known/ysdk.app.json): ysdk.org is itself a conforming app.

## Key facts
- Conformance is a ladder L0-L6, earned by a run, never declared.
- L0 = resolvable DID + signed manifest at /.well-known/ysdk.app.json. Reachable in a day.
- L3 requires revocation OBSERVED terminating access on a fresh connection; a passing unit test is not sufficient.
- Capabilities cross origins; private keys never do.
- YSDK narrows UCAN in one place: exp: null is forbidden, one-year ceiling.
- No component of this ecosystem has been independently audited.