What problem does it solve? Syncing a file-copy-based C++ fork with its upstream repository risks silently destroying fork-specific integration hooks, producing builds that compile cleanly but lose all custom sampler, scheduler, and guidance features. ## Core Features & Use Cases - Zone-based sync strategy: Classifies engine files into Upstream, HOT-Step, and Modified Upstream zones, with direct-copy allowed only for pristine upstream files and manual merge enforced for the three hook-carrying files. - Hook verification and failure diagnosis: Runs verify-hooks.ps1 (5 checks) before building, and maps symptoms like the linker error "unresolved external symbol hotstep_sampler_linked_" or dead solvers back to the exact clobbered include. - Six-phase sync procedure: Covers fetch/assess, selective copy, manual merge, sampler fix porting, build validation with runtime log checks, and marker/commit/tag recording without pushing release-triggering tags. - Use Case: After upstream acestep.cpp lands 60 new commits, follow the procedure to port them into the fork, verify hooks, rebuild via dev-rebuild.bat, and confirm the [DiT] Guidance log line proves the custom sampler is live. ## Quick Start Ask the assistant to check whether an upstream sync of acestep.cpp is pending and, if so, walk through the sync procedure while protecting the HOT-Step hook files.
