Diagnostic contract v1

This directory defines the stable JSON emitted on standard error when the CLI uses --diagnostic-format json or --output-format json. Validate each complete document against diagnostic.schema.json.

The code and typed context fields are the machine contract. Treat message, cause messages, and human rendering as explanatory text. Unknown context is omitted. Diagnostics never retain an input record, strategy response, or unrelated payload value.

Adding a code or optional context field is compatible within version 1. Removing a code, changing a field type, or changing a code's meaning requires a new diagnostic contract version.