ADR-010: Go model validation and schema export

Inputs and configuration are typed Go structs whose validation rules sit beside the type, checked at the boundaries: configuration load, request payload construction and external input parsing. A schema is derived from the code that owns the shape, never kept as a hand-maintained file beside it.

Every command declares in internal/cli/result the result type it fills, or states in internal/cli/outputschemas why it has none; TestEveryCommandIsModelled fails on a command that does neither. --describe gives the JSON Schema of the whole document a command writes, for a run and for a dry run (ADR-097), derived from that type when it is asked for rather than kept as a file. docs/reference/schemas exports the schemas read outside bb: the failure envelope, which every command shares (ADR-046), and the configuration schema, which editors and CI validate against. docs:verify-generated keeps each export in step with its source.

A schema file is a copy of a Go type, and a copy is where the two stop agreeing.

Not chosen

• Validation only in business logic: Error-prone and inconsistent, with weaker contract guarantees.
• Handwritten schemas detached from model types: High drift risk and duplicate maintenance burden.