Module draft 

The stateless 2026-07-28 lifecycle variant (SEP-2575), behind draft-2026-07-28.

The 2026-07-28 draft removes the initialize/initialized handshake (register 1.3, 1.5a): a session is operational from its first message — there is no BeforeInitialize/Ready progression to gate on, which is the defining contrast with the 2025-11-25 machine. Each request instead carries its protocol context (protocolVersion, clientInfo, clientCapabilities) in _meta, and the one handshake-like exchange that remains is the optional server/discover probe by which a client may read the server’s protocol versions, capabilities, and identity.

This module models that lifecycle as a second state-machine variant alongside — not replacing — the stateful one (02-architecture.md §Protocol-revision strategy). It is intentionally scoped to the lifecycle — the phase model and the server/discover exchange; per-request _meta validation, the removed-method prohibitions (ping, logging/setLevel, notifications/roots/list_changed), and the UnsupportedProtocolVersionError rule are registry clauses and checks (roadmap M2.5 line 2), which land with the final spec text.

Draft-tracking: the shape here follows the SEPs catalogued in register 1.5a–1.5b and must be reconciled against the final 2026-07-28 text when it ships; the gate keeps it off the default build until then.

Structs

DiscoverExchange

The observed server/discover exchange — the optional stateless capability/identity probe — when present. A session is valid with no discovery at all.

DraftLifecycle

The stateless lifecycle, folded over a trace’s message events in order.

Enums

DraftPhase

The stateless 2026-07-28 lifecycle phase before a given event is processed.