# RustProxy 0.24.4 specification audit

## Scope

0.24.4 is a focused Linux memory-retention maintenance release over 0.24.3. Production diagnostics showed that a large share of anonymous RSS could be backed by 2 MiB Transparent Huge Pages while the live RustProxy cache residency was much smaller. A host-wide switch from THP `always` to `madvise` removed those huge-page mappings after restart. 0.24.4 internalizes that mitigation for RustProxy only.

## Source/spec matrix

| Requirement | Source contract | Status |
|---|---|---|
| Do not require a host-wide THP policy change | `src/main.rs` calls `prctl(PR_SET_THP_DISABLE, 1, 0, 0, 0)` on Linux | implemented in source |
| Apply the policy before runtime worker heaps are created | `disable_transparent_huge_pages()` runs before `tokio::runtime::Builder::new_multi_thread()` | implemented in source |
| Keep non-Linux platforms unchanged | the THP call is guarded by `cfg(target_os = "linux")`; other platforms use a no-op helper | implemented in source |
| Avoid turning kernel capability into a startup dependency | a failed `prctl` emits a warning and startup continues | implemented in source |
| Retain the 0.24.3 glibc mitigation | managed systemd units still set `MALLOC_ARENA_MAX=2`; existing bounded `malloc_trim(0)` paths remain | retained |

## Runtime acceptance

Source inspection cannot establish steady-state RSS. On a Linux release host, return `/sys/kernel/mm/transparent_hugepage/enabled` to the host's normal policy, restart the 0.24.4 binary, and verify `/proc/<pid>/status` reports `THP_enabled: 0`. Under representative sustained traffic, `/proc/<pid>/smaps_rollup` should keep `AnonHugePages` at zero or negligible levels without changing the global THP setting. Record RSS, anonymous RSS, cache resident/transient bytes and request rate for the same 10-12 hour acceptance window used by 0.24.3.

Compiler/type/runtime acceptance remains open in this source workspace because the Rust toolchain is unavailable.