# MECHWEAP.CPP / .HPP — reconstruction notes

`MechWeapon` (: PoweredSubsystem) is the weapon base: PPC/GaussRifle bind it via
Emitter, the SRMs via ProjectileWeapon/MissileLauncher. The resource streams
rechargeRate / weaponRange / damage / heatCostToFire (+ pip fields).

## Reconstructed

- Statics (ClassDerivations, DefaultData on Subsystem::MessageHandlers/
  AttributeIndex), ctor streaming the tuning fields, damageData prime.
- **View-fire gating (2026-07-21, the look-commit wave):** real `rearFiring` /
  `viewFireEnable` members (1995 binary @0x334/@0x3E0) + `IsRearFiring()` /
  `GetViewFireEnable()` / `SetViewFireEnable()`. The ctor resolves REAR-FIRING
  authentically (binary ctor tail @004b99a8): the mount SEGMENT site name
  (`owner->GetSegment(GetSegmentIndex())`) is tested for the 'b' (back) marker —
  only the back gun ports (`sitelbgunport`/`siterbgunport`) carry it. Spawn
  state = armed for the forward view. `Mech::CommitLookState` re-arms on every
  view change (see MECH.NOTES.md increment 7). Verified: the TEST.EGG mech's
  two rear lasers (ERMLaser_2/3) arm only in LOOK-BACK.

## Fire path (2026-07-21, Phase 5.3.8)

- **The authentic attribute table IS published** (binary @0x511890, IDs pinned):
  PercentDone 0x12 → rechargeLevel, **TriggerState 0x13 → fireImpulse** (the
  streamed per-mech fire-button mappings bind this ID — the real trigger
  wiring), DistanceToTarget 0x14, TargetWithinRange 0x15, WeaponRange 0x16 →
  effectiveRange, EstimatedReadyTime 0x1A, RearFiring 0x1B, WeaponState 0x1C →
  weaponAlarm. Pads bridge our chain gap 2..0x11 (parents publish nothing yet;
  they shrink to the authentic 0x0F..0x11 when the mechsub/heat/powersub
  attribute waves land — SENSOR.HPP pins PoweredSubsystem::NextAttributeID at
  0x0F). **Pads are LOAD-BEARING**: AttributeIndexSet::Build leaves uncovered
  gap slots as UNINITIALIZED GARBAGE (`new IndexEntry[entryCount]`, only
  inherited + listed entries written), so every ID up to the max must be
  covered or Find() on a gap ID returns a wild pointer. Pip* (0x17-0x19) are
  pads → rechargeLevel until the pip members are reconstructed.
- **Fire state machine members**: fireImpulse/previousFireImpulse (the trigger
  sample pair), rechargeLevel, rangeToTarget, effectiveRange,
  estimatedReadyTime, recoil, weaponAlarm (the state carrier: 0 Firing /
  2 Loaded / 3 Loading / 4 trigger-during-load). Spawn = charged + Loaded.
- **CheckFireEdge** (@004b9608): rising-edge on fireImpulse comparing BIT
  PATTERNS as signed ints — TriggerState carries raw ControlsButton ints
  (+(button+1) press / −(button+1) release); the release bit-pattern is a
  negative NaN as float, and an IEEE float compare would latch the detector
  shut after the first release (BT411 task #8). Int compare reproduces the
  binary's x87 semantics exactly.
- **ComputeOutputVoltage** (@004b9c9c): `rechargeLevel = (rechargeRate −
  recoil) / rechargeRate` — the recharge dial.
- **Emitter::EmitterSimulation** (PARTIAL, @004baa88) installed on every
  non-replicant energy weapon: Firing → discharge countdown →
  ResetFiringState(Loading); Loaded + trigger edge → viewFireEnable gate →
  FireWeapon; Loading → recoil decays over the authored RechargeRate seconds →
  Loaded. Deferred within it: the leading PoweredSubsystemSimulation electrical
  step, the destroyed/heat-failure/dead-mech hard gates, the TrackSeekVoltage
  generator charge integration (the partial uses the authored seconds
  directly), and the HasActiveTarget gate (targeting wave).
- **Emitter::FireWeapon** (PARTIAL, @004bace8): discharge bookkeeping (beam
  countdown re-arm, charge spent, recoil loaded). Deferred: the 0.5·V²·EC
  energy/damage/heat closed forms (need the electrical model), the heat dump
  (heat wave), the beam build + Damage submission (targeting + renderer).
- Emitter's index re-chained to MechWeapon's (ChargeLevel at the authentic
  0x1D past the table end); Emitter::DefaultData now binds
  MechWeapon::MessageHandlers.
- DEV hook `BT_FORCE_FIRE=1`: pulses the trigger whenever a weapon is Loaded →
  every armed weapon auto-fires at its authored cadence.

**VERIFIED headlessly**: forward view — PPC_1/2 + ERMLaser_1 cycle
FIRED→LOADED→FIRED at the authored 0.6 s discharge / 1 s recharge, rear lasers
silent; `BT_FORCE_LOOK=3` (look-behind) — ONLY ERMLaser_2/3 fire. The full
view-fire × fire-FSM interlock holds in both directions. Zero Fail. (SRM6s are
MissileLaunchers — the ballistic ProjectileWeaponSimulation is a later
increment.)

## Still staged

- The ballistic fire path (ProjectileWeaponSimulation @004bbd04, missile
  launch/seeker), `SendDamage` (damage/networking), `CreateStreamedSubsystem`
  (tool-side model build).
- ~~`MechWeapon::MessageHandlers` declared but not defined~~ — **FIXED
  2026-07-21**: it is now a real defined set (`(0, NULL,
  Subsystem::MessageHandlers)` — no own handlers yet, inherits the chain), and
  `MechWeapon::DefaultData` binds it. This mattered because the surviving CODE
  PPC.CPP binds the inherited name (`PPC::MessageHandlers`) into
  PPC::DefaultData, and a declared-but-undefined static links as a zero-filled
  common block — the same silent-NULL trap as the Emitter::AttributeIndex
  crash. Real weapon handlers (fire/damage messages) come with the combat wave
  (grow the table in place).