include/grantlee/context.h (the only grantlee header referenced by kept code) includes its sibling stubs (abstractlocalizer.h, ...); the file-level include/ prune left those siblings behind, breaking codegen_grantlee compilation (fatal error: abstractlocalizer.h). The grantlee engine stubs are a self-contained header set — keep the whole dir, same treatment as include/GeographicLib.