zig-memory-safety

# Zig Memory Safety ## Operating Mode Use this skill as a defect-finding workflow, not a generic Zig tutorial. Start by proving the active toolchain and project pin: ```bash zig version test -f build.zig.zon && sed -n '1,120p' build.zig.zon ``` As of 2026-05-13, Zig `0.16.0` is the latest tagged release and `0.17.0-dev` builds are available upstream. Many production repos remain pinned to `0.15.x`; follow the repo pin unless the task is explicitly a migration. ## Memory Model - Treat every allocation as a contract with one owner, one deinit/free path, and clear transfer semantics. - Prefer passing `std.mem.Allocator` explicitly at construction boundaries. Avoid hidden globals and allocator selection inside low-level helpers. - Distinguish borrowed slices from owned buffers in names, docs, tests, and deinit behavior. - Do not return slices or pointers into stack locals, temporary parser buffers, freed environment buffers, arena memory that dies before the caller, or reallocated containers. - Use arenas only for bounded request/session lifetimes. In long-running loops, reset or deinit per iteration so arenas do not hide leaks. - Prefer slices over many-item pointers because slices carry length and normal indexing is bounds-checked in safety-enabled modes. Treat slices as borrowed pointer-plus-length views, not owners. - Treat `ArrayList.items` and similar container slices as invalidated after resize, append, deinit, or transfer. - Treat `[*]T`, C pointers, `@ptrCast`, `@a...