CodeMechanic: Defect-Property-Guided Program Mitigation

On 101 real ARVO defects, CodeMechanic's first attempt generates 47.6% more plausible patches than the best baseline, with 91% fewer tokens. It uses defect properties to guide an LLM to reconstruct spatial memory safety properties from crashes, validate pointer and buffer bounds, and insert fail-stop guardrails before dangerous accesses, trading availability for safety. Manual audit shows that its patches semantically equivalent to developer fixes are 3.4–4.3 times those of the baseline.