# BT Port — Resource-Layout Audit (resource-layout-audit workflow, 33 agents, adversarially confirmed)

> **✅ STATUS: ALL 8 BUGS FIXED & VERIFIED** (commits 802a7a6 A, 7de66ad B, 975a397 Gyro+Searchlight).
> Each layout locked with compile-time `static_assert(offsetof/sizeof)` guards; full build green; combat +
> heat-flow un-regressed. The plan below is retained as the record of what was found and done.

**Verdict:** 24 `*__SubsystemResource` structs audited → **8 confirmed bugs** (all high-severity,
review-upheld, none refuted), 16 clean. All 8 root to **2 broken base resources** (`HeatWatcher`,
`PowerWatcher`) + **2 struct-specific field defects** (`Gyroscope`, `Searchlight`).

Same class as the heat-resource bug fixed earlier (§10d): a resource struct that doesn't mirror its
class hierarchy reads every field from the wrong offset — SILENT garbage (non-fatal). These 6 Watcher-
family subsystems (AmmoBin, Gyroscope, Searchlight, ThermalSight, Torso, HUD) currently TICK on garbage
resource data. Combat is unaffected (mech/weapons/damage/heat don't depend on them) — it bites when
WAVE 4-8 consumes gyro/torso motion, sensor/searchlight/thermalsight readouts, and ammo.

## Raw-decomp verification (done this session — the fix is bigger than "one-liner")
- `HeatWatcher::CreateStreamedSubsystem` = `FUN_004aec54` chains to `FUN_004ac9ec` (the **MechSubsystem**
  parse, fills 0x30..0xE4 — armorByFacing/videoObjectName/alarmModel/... verified) then adds only
  `DegradationTemperature@0xE8` + `FailureTemperature@0xEC`. Record ends **0xF0** (MechSubsystem + 3).
- `HeatWatcher` ctor `@4aeb40` chains to `FUN_004ac644` (MechSubsystem-level base ctor, shared with the
  HeatSink ctor) and reads only `res+0xe4/0xe8/0xec` — NO thermal-mass/heatSinkIndex reads. So HeatWatcher
  is genuinely **MechSubsystem-based**, not a full HeatableSubsystem.
- `PowerWatcher` ctor chains to `FUN_004aeb40` = **HeatWatcher's ctor** → `PowerWatcher : HeatWatcher`
  (powersub.hpp already comments "real base is HeatWatcher"). Adds `MinVoltagePercent@0xF0`, record ends **0xF4**.
- The reconstruction implemented BOTH classes as `: public HeatableSubsystem` (an approximation, with the
  real base in `// FUN_...` comments) → the resource was made HeatableSubsystem-based (0xFC) → every
  Watcher field slid +0x18 (HeatWatcher) / +0xC (PowerWatcher). Fixing the resource base alone will NOT
  compile (the ctor passes the resource to the HeatableSubsystem base ctor) → class+ctor+parser must change together.

## Fix plan (bases before children; each verified by offset logging `(char*)&res->f - (char*)res`)
1. **Root cause A — HeatWatcher → MechSubsystem** (heatfamily_reslice.hpp/.cpp):
   - class `HeatWatcher : public MechSubsystem` (was HeatableSubsystem)
   - resource `HeatWatcher__SubsystemResource : public MechSubsystem__SubsystemResource` (was HeatableSubsystem::SubsystemResource); keep `int watchedSubsystem;`(0xE4) `Scalar degradationTemperature;`(0xE8) `Scalar failureTemperature;`(0xEC) → ends **0xF0**
   - ctor chains `MechSubsystem(...)`; parser chains the MechSubsystem parse (FUN_004ac9ec)
   - de-shadow any fields HeatWatcher inherited from HeatableSubsystem it no longer has
   - **Fixes HeatWatcher + AmmoBin** (child; fields realign to 0xF0/0xF4/0xF8/0xFC/0x100, size 0x104). Target stamp: HeatWatcher **0xF0**, AmmoBin **0x104**.
2. **Root cause B — PowerWatcher → HeatWatcher** (powersub.hpp/.cpp; depends on A):
   - class `PowerWatcher : public HeatWatcher`; resource `... : public HeatWatcher::SubsystemResource`, keep `Scalar minVoltagePercent;`(0xF0) → ends **0xF4** (do NOT pad — would break the 0xF4 stamp)
   - powersub.hpp must `#include` the HeatWatcher resource (`heatfamily_reslice.hpp`)
   - ctor chains `HeatWatcher(...)`; parser chains HeatWatcher parse (FUN_004aec54, WatchedSubsystem/Degradation/Failure keys)
   - **Fixes PowerWatcher + HUD + ThermalSight + Torso** (children realign, no child edits). Target stamps: PowerWatcher **0xF4**, Torso **0x158**.
3. **Gyroscope** (gyro.hpp; after B): add `Scalar field_f4;`(0xF4, ctor `FUN_004b3778` reads it, init -1.0f — best-effort name) BEFORE `exageration`(0xF8). Then fields align through 0x21C.
4. **Searchlight** (searchlight.hpp:75 + searchlight.cpp:96; independent, after B): delete `int segmentDefault;`
   (compiles OOB at sizeof(PowerWatcher)); the binary reads `resource+0x28` = inherited `segmentIndex` →
   change searchlight.cpp:96 to `commandedOn = subsystem_resource->segmentIndex;`.

**Clean / no action (16):** Emitter, HeatableSubsystem (correctly 0xFC — do NOT touch; HeatSink/Generator/
PoweredSubsystem/Reservoir/Condenser depend on it), Condenser, Reservoir, MechSubsystem, MechTech,
MechWeapon, SubsystemMessageManager, MissileLauncher, MissileThruster, Myomers, PoweredSubsystem,
Generator, ProjectileWeapon, Seeker, Sensor.

**Rejected proposal:** aliasing HeatWatcher fields onto the 0xFC HeatableSubsystem base via accessors/union
— leaves sizeof=0xFC, contradicts the 0xF0 stamp, cascades the wrong size into PowerWatcher. Use the re-base.

**Verify after each step:** offset logging vs stamps (HeatWatcher 0xF0, PowerWatcher 0xF4, AmmoBin 0x104,
Torso 0x158, Gyroscope ends 0x21C); build green; combat/heat/torso un-regressed.
