[cpp-RCP-N2-05] Coverage report is polluted with STL/system headers, deflating the line-coverage denominator #68

Location: coverage-report.json — per-file entries and top-level linePct/summary.

Finding: The committed coverage report's file list includes system/toolchain headers alongside project code. Of 153 file entries, 101 are paths under /usr/include (STL and libstdc++ internals — e.g. <regex>'s never-instantiated executor/compiler machinery reported at 0% hit), totaling 5,979 of the report's 9,034 total lines — roughly two-thirds of the entire denominator. Restricting to the 52 actual project files, hit/total lines are 2,794/3,055 (about 91.5%); with the system headers folded in, the reported blended linePct drops to roughly 68.8%. A safety coverage report used as DAL/ASIL evidence should measure only the code under qualification, not third-party toolchain internals the project never controls or exercises directly.

Recommendation: Filter the coverage collection (e.g. lcov --remove/gcovr --exclude on /usr/include/* and other non-project paths) so the report reflects only first-party sources under include/, cli/, etc., and re-baseline the DAL/ASIL judgement against the filtered figure.

Verification: Independently re-read and parsed coverage-report.json from current HEAD (commit 4b9449a, 2026-07-29): confirmed 101/153 file entries have /usr/include in their path, accounting for 5,979 of 9,034 total reported lines.

Filed from the 2026-07-29 ecosystem audit register; independently re-verified against current HEAD before filing.