Four layers of an integration contract
- API/SDK: callable surface and version.
- Data/profile: accepted inputs and bounded formats.
- Lifecycle: valid state transitions and ownership.
- Errors: stable rejection and retry semantics.
Capability negotiation instead of implicit compatibility
A host can explicitly ask whether a capability exists. Unknown or unsupported capabilities can then be represented as a defined state rather than silently falling back to something that merely looks similar.
What this page explicitly does not claim: This is an architecture principle. Publicly supported API versions and capabilities are determined only by the named release and integration scope.