Reflection validation

Never edit generated files manually. Engine/Source/_generated/ is a legacy location and must not be used as build or validation evidence. Active outputs live under the selected build's GeneratedSource; their authoritative state is the selected output root's .he-codegen/manifest.json. Agent Game, Editor, and Tests use out/agent/game-<config>/GeneratedSource, out/agent/editor-<config>/GeneratedSource, and out/agent/tests-<config>/GeneratedSource. Multi-config Package uses out/package/build/GeneratedSource/Release. Direct Tests-consumer CMake configurations must set both HE_BUILD_TESTS=ON and HE_CODEGEN_HOST_OVERRIDE=Tests.

Use the compact interface from the repository root:

.\hectl.bat codegen status
.\hectl.bat codegen check
.\hectl.bat codegen run
.\Win-CppCodeGen.bat --no-pause

status is read-only and reports dirty reasons. check is read-only and exits nonzero when dirty. run publishes transactionally when needed. Add --json for the stable machine schema or --quiet for silent success. The batch entry remains compatible and targets build/GeneratedSource; normal Game, Editor, Tests, and Package builds use their own host/config-specific roots through the HEngineCodeGen CMake node. Full logs are under out/agent/logs.

After generation, use he-build-validate to compile the smallest affected target (HGame by default; HEngineEditor for Editor or WITH_EDITOR code). Do not reuse the VS shared cache. A final no-op check must report changed=0, deleted=0, and no generated output hash/mtime changes; inspect the manifest instead of scanning or diffing the entire generated tree.

Report codegen and build as separate commands with PASS/FAIL. If he-resource-reflection-serialization also triggers, follow its design constraints but do not repeat codegen.