Release v4.256.0

Added

• Semantic models written by a newer Screenplay version are now read without failing on unknown members. Unknown fields are preserved, known fields are decided by each document's major version, and malformed wire versions are refused with a clear contract error (#1067)
• CompileAdmissible exclusions distinguish root errors from dependent exclusions and identify their immediate dependencies (#1095)
• Live collection query performers expose a versioned binding contract for observable read-model updates (#1077)
• Policy predicates with implementation bodies are evaluated through the host-supplied body-execution provider, with explicit allow, deny or unsupported outcomes in authored order (part of #1099)
• Command handlers with implementation bodies run through the body-execution provider and return one payload per declared produces line. Execution faults are reported separately from unsupported bodies and commit no events (part of #1099)
• Command handlers may declare a may produce set of possible events, each optionally routed for <property> or for one of <collection> with stream and tag metadata. The set is parsed, printed and published in the language contract; binding it is still refused with PLAY0800 until the next event-model schema version (part of #1102)

Changed

• PLAY0800 refusals for command handlers now say which condition failed (conditional produces, hints, or an empty body) and how to write a handler Screenplay accepts. Reactions that read a read model and also produce directly now point to invoking a command instead (#1101)
• Handler, implementation and diagnostic records gain new init members, so their equality, hashing, ToString and serialization now include those members (part of #1102)
• The generated-values documentation now has a support matrix showing which generated-value forms each compiler, the MCP tools, Arc, Stage and Studio support (part of #614)

Fixed

• A read-model member whose type names another read model now reports a consistent error at the member in the compiler, CLI, MCP and editors, with guidance to use a supported value type (#1079)