# Engine header backfills — shared notes (2026-07-19)

Per-file evidence for the `MUNGA/` back-dates. All were produced by `../backdate.py` from the
BT412 WinTesla donors (`C:\VWE\BT412\engine\MUNGA\*.h`), then compile-reviewed under BC4.52 —
**the period compiler is the reviewer**: it rejects post-1994 constructs the donors carry.
Common mechanical transforms: `#pragma once`→guard, `#include "x.h"`→guarded `<x.hpp>`,
`std::`→(none), `true/false/bool`→`True/False/Logical`, drop `<ostream>`-era includes.
VDATA.HPP has its own sidecar (VDATA.NOTES.md).

| file | donor | validation | hand fixes / open items |
|---|---|---|---|
| ROTATION.HPP | ROTATION.h (307 l) | compile-proven via BTTEAM/BTL4ARND closure; `ROTATION.TCP` survives as the period test source (cross-check pending [T3]) | ostream idiom restored per surviving VECTOR3D.HPP |
| VECTOR2D.HPP | VECTOR2D.h (285 l) | compile-proven via CONTROLS.HPP closure | ostream + `true`→`True` |
| AUDREND.HPP | AUDREND.h (250 l) | **compile-proven: BTL4ARND.CPP (original) builds clean against it** | REMOVED `virtual ReleaseSourceSet(SourceSet&)=0` — OpenAL-era addition, zero period references [T1]; ADDED guarded `<vchain.hpp>` (donor relied on lax includes); relative `..\munga_l4\l4audhdw.h` → `<l4audhdw.hpp>` |
| APP.HPP | APP.h (764 l) | **compile-proven via BTTEAM/BTCNSL closure** (round 2) | none yet — re-review when a TU exercises more of it |
| LAMP.HPP | LAMP.h (189 l) | compile-proven via the BTTOOL closure (chain resolved by GAUGREND+GAUGE) | — |
| GAUGREND.HPP | GAUGREND.h (735 l) | parses through the BTTOOL closure [T3] | `<fstream>` → `<fstream.h>` |
| GAUGE.HPP | GAUGE.h (450 l) | parses through the BTTOOL closure [T3] | — |

Class-layout caution: a back-dated header that DROPS or ADDS virtuals/members changes vtable
and object layout versus the shipped binary. `AUDREND.HPP`'s removed virtual matches 1995
truth (no period reference anywhere); any future ambiguity must be settled against the decomp
(vtable slot counts at the class's PTR_FUN table) before trusting layout-sensitive code.