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. That text shipped on 2026-07-28 (register 1.5h) with the inventory unchanged, so the reconciliation is now due rather than pending, and it is roadmap M2.5 line 2’s work. The feature gate keeps this off the default build until the reconciliation lands.

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.