[raphael]

Generated Goa validation could accept a union with an unknown branch kind or a selected object branch whose value was nil. When the branch fields had no constraints, validation could succeed even though encoding rejected the same value. Invalid typed values could therefore pass the checks callers use before conversion or encoding.

Both planned and legacy validation now call the generated union's existing Validate method before checking the selected branch's fields, including when those fields have no constraints. Optional value unions with no selection and nil optional pointers remain absent; a present pointer must contain a valid selection. Allocated empty collections still follow their declared length rules. Named and derived union roots use the methods of their underlying generated union.

Generated runtime fixtures verify invalid selections, optional absence, empty collections, named roots, and unchanged inputs. Focused validation, view, HTTP, WebSocket, and gRPC checks and affected-package lint passed. Race detection covered the outer generator fixture package; child generated-module checks ran normal tests. The full repository suite was not run. Regenerate affected code to receive the checks.