§43.1 Function

IOH-01 specifies how an external system enters and leaves a bound relationship with the Kiri runtime. The handshake is HTTP, JSON, and stateless between phases except for records persisted in the interop ledger.

§43.2 Phases

ANNOUNCE → NEGOTIATE → BIND → OPERATE → DISSOLVE. Each phase has a single endpoint, a fixed request shape, and a fixed response shape. Skipping is forbidden; reordering is forbidden.

http
POST /api/public/handshake/announce
  { "schema_id": "ext:foo/v2", "namespace_uri": "https://foo.example/ns",
    "version": "2.1.0", "contact": "ops@foo.example" }
→ { "negotiation_id": "ng_…", "expires_at": "…" }

POST /api/public/handshake/negotiate
  { "negotiation_id": "ng_…" }
→ { "supported_translations": ["ext:foo/v2 → kiri:agent.v1"],
    "required_invariants": ["anti_absorption", "schema_versioned",
                            "namespace_resolvable"],
    "binding_offer_hash": "sha256:…" }

POST /api/public/handshake/bind
  { "negotiation_id": "ng_…",
    "ack_signature": "<sig over binding_offer_hash>" }
→ { "bind_token": "bnd_…", "ledger_entry": "kiri:interop/bnd_…" }

# OPERATE — all subsequent messages carry header x-kiri-bind: bnd_…

POST /api/public/handshake/dissolve
  { "bind_token": "bnd_…", "reason": "…" }
→ { "sealed_at": "…", "ledger_entry": "kiri:interop/bnd_…#sealed" }

§43.3 Required Invariants

anti_absorption: neither party may rewrite the other's canonical identifiers. schema_versioned: every bound message carries an explicit schema version. namespace_resolvable: the external namespace_uri MUST return a machine-readable schema descriptor on HTTP GET.

§43.4 Failure Behavior

Any phase that fails an invariant returns HTTP 422 with a structured reason code. The binding is NEVER created in a partial state. A dissolved bind_token is permanently sealed and cannot be re-bound — a new ANNOUNCE is required.

§43.5 Final Principle

Interoperability is a contract with five visible steps. Anything that hides a step is not interoperability — it is integration disguised as one.

“A handshake you cannot trace is a hand you should not shake.”