Release v4.257.0

Added

• The event model board in VS Code and the MCP App marks a slice that uses an event or read model from a slice drawn after it, showing the PLAY0516 or PLAY0517 finding on the slice header (#413)
• Selecting a slice, feature or module on the event model board in VS Code and the MCP App highlights what it depends on and what depends on it, and draws links between the slices (#415)
• New Information diagnostic PLAY0824 for redundant braces around composite keys, with a repair and quick fix that removes them (#953)
• New Information diagnostic PLAY0825 for authorize A B without and, with a repair and quick fix that writes and (#953)
• The semantic evaluator runs result-v2 command handlers. A handler's returned items are checked against its declared possible events, destinations and payloads, then produced in order. Typed contexts describe the handler result shape. Public binding still refuses these handlers until the next event-model schema version (part of #1102)
• Proposed design record 0123 for store-backed sequences through a Chronicle allocator; sequence stays reserved (part of #619)

Changed

• SemanticCommandBodyResult and SemanticTypedContextDescriptor gain new init members, so record equality, hashing and ToString now include them (part of #1102)

Fixed

• Admissible compilation now attributes protected-read failures (PLAY0781, PLAY0784) to the reading slice when its views come from an unnamed or variant projection, and excludes that slice instead of refusing the whole model (#1094)