C++17 heuristic checker (cppperf-lint).

Slug	Default	Smell
`cx-regex-ctor-hot`	hint	`std::regex` constructed in a loop. JSONL present; not corpus-triaged
`cx-endl-hot`	hint	`endl` flush in a loop. JSONL present; not corpus-triaged
`cx-clock-hot`	hint	`clock_gettime`, `gettimeofday`, or chrono `now()` in a loop. JSONL about 147× versus one sample; stay hint

Removed (jitter 2026-10-22, no slug — see evidence/_removed/): CX001, CX003, CX004.

Line/brace heuristics — not a full AST/SSA pass.