When designing configuration options, environment variables, and build settings, follow established patterns and ensure they serve a clear purpose. Consider cross-platform compatibility, use familiar conventions (like PATH-style lists), and align configuration choices with project requirements. Key principles: - Follow established patterns (e.g., colon/semicolon-separated lists like PATH) - Handle platform differences appropriately (`;` on Windows, `:` on Unix) - Ensure every configuration variable is actually used - avoid creating intermediate variables that serve no purpose - Align configuration granularity with project compatibility guarantees (e.g., version numbering should reflect actual compatibility boundaries) - Remove unused configuration variables rather than leaving them as dead code Example: ```cmake # Good: Uses platform-appropriate separators and follows PATH convention set(EXTENSION_DIRECTORIES "~/.duckdb/extensions" CACHE STRING "Extension directories (colon/semicolon separated)") # Good: Version reflects actual compatibility guarantees set_target_properties(duckdb PROPERTIES SOVERSION ${DUCKDB_MAJOR_VERSION}.${DUCKDB_MINOR_VERSION}) # Bad: Creates unused intermediate variable set(SUMMARIZE_FAILURES_ENV "$ENV{SUMMARIZE_FAILURES}") # Never actually used ```