---
id: gauges-hud
title: "Cockpit Gauges / MFD HUD system"
status: established
source_sections: "docs/GAUGE_COMPOSITE.md (full map); CLAUDE.md §8"
related_topics: [reconstruction-gotchas, decomp-reference, subsystems, pod-hardware]
key_terms: [gauge, methodDescription, attribute-pointer, GaugeRenderer, MFD, PCC]
open_questions:
  - "MessageBoard LIVE 2026-07-12 (kill ticker); remaining: only strip 0 (kill) is produced -- survey the other btsmsgs.pcx strips for authentic producers"
  - "HUD attr table RESOLVED 2026-07-19 (Gitea #10 audit): re-dumped @5110b8 -- the table starts one record earlier (id 3 FlickerRate@0x1D8), every hud.hpp offset was shifted one slot; hud.hpp/CLASSMAP corrected, no behavioral impact (the reticle feeds via port globals). See GAUGE_COMPOSITE.md AUDIT finding B"
  - "SeekVoltageGraph RECONSTRUCTED 2026-07-19 (Gitea #11, was #10 finding A): full widget landed (see §SeekVoltageGraph below) -- ghosts gone steady-state (BT_PRESET_HOLD verification); remaining polish: a 1-frame transition artifact when a BT_SHOT lands on the exact page-switch frame (label BecameActive vs the graph's next rated Execute -- same lag class as the binary; self-heals next frame)"
  - "Secondary-view cycling RESOLVED 2026-07-19 (Gitea #6): the selector is the DISPLAY mode (CycleDisplayMode -> vtbl+0x4C override @4d1ae4), NOT CycleControlMode; desktop 'N' / pad RightThumb wired; pixel-verified dama->crit->heat"
  - "Upper-MFD PRESET pages RESOLVED 2026-07-19 (Gitea #9): SetPresetMode table @0051dbf0 re-decoded (little-endian -> ModeMFD bits 0-14), per-MFD pod button banks identified from the .CTL dump, desktop J/K/L cycle wired"
  - "Always-active msg-4 records IDENTIFIED 2026-07-20 (glass input audit): 0x2C = Reservoir InjectCoolant (the flush button), 0x2F/0x2E/0x2D/0x2B/0x2A/0x29 = Condenser1-6 MoveValve, 0x1A-0x1D = GeneratorA-D ToggleGeneratorOnOff (@0050fb90, unreconstructed); plus 0x13 = Mech DuckRequest (crouch), 0x28 = Mech BalanceCoolant, 0x12/0x14 = ThermalSight/Searchlight toggles -- see pod-hardware.md + docs/GLASS_COCKPIT.md 2026-07-20"
  - "MP DEATHS resolved 2026-07-12 (observed-death tally + display clamp); remaining: verify multi-death tallies stay in sync across a long session (GAUGE_COMPOSITE.md)"
---

# Cockpit Gauges / MFD HUD

The pod's cockpit instruments: the secondary MFD (radar/heat/comm), the 5 mono MFDs, and the
engineering screens. Full map + per-widget history in **`docs/GAUGE_COMPOSITE.md`**. **The gauge
system is COMPLETE** at the registration+binding level: all 50 config attribute bindings resolve
(0 NULL) and every config gauge primitive is registered + built (0 parse-skips). [T2]
**AUDIT 2026-07-19 (Gitea #10):** the full per-widget verdict table (45 rows: 34 CORRECT / 1
WRONG-filed / 6 AUTH-STATIC / 6 DEFERRED-FEED) is in `docs/GAUGE_COMPOSITE.md` §"AUDIT
2026-07-19" — the one WRONG was the missing SeekVoltageGraph reconstruction (the emitter/myomer
eng pages' POWER curve + the authentic top-box eraser; caused the stale-ammo "SYSTEM 10 PPC"
ghost). **RESOLVED (Gitea #11): full reconstruction landed — §SeekVoltageGraph below.** [T2]

## Architecture (three layers)
1. **The config** `content/GAUGE/l4gauge.cfg` — a text file the engine `GaugeInterpreter` parses
   (`BuildConfigurationFile → Initialize → GetProcedureBody → ParsePrimitive`). Each mech's gauge
   tree is built from the label `GetGameModel()+"Init"` (e.g. `bhk1Init`), which invokes shared
   blocks (`MechInit`, `Secondary1`) that `configure` the ports and call gauge primitives. [T1]
2. **Widgets** — each `keyword(...)` in the config resolves to a `MethodDescription` in
   `BTL4MethodDescription[]` (btl4grnd.cpp). An UNREGISTERED keyword is **parse-skipped** (never
   built). Base primitives (`numeric`/`digitalClock`/`rankAndScore`/`vertBar`-base/`segmentArc`)
   are ENGINE (L4GAUGE.cpp); BT-specific ones (`vertBar`/`map`/`pilotList`/`GeneratorCluster`/
   `sectorDisplay`/`prepEngr`/`messageBoard`/`vehicleSubSystems`/the ColorMapper family) are
   reconstructed + registered. [T2]
3. **Data binding** — gauges bind to game state by NAME via the engine [[attribute-pointer]]
   system: the config's `Subsystem/Attribute` (e.g. `HeatSink/CurrentTemperature`) resolves
   through `ParseAttribute → FindSubsystem (stricmp GetName()) → GetAttributePointer`. A class
   PUBLISHES an attribute via a `<Name>AttributeID` enum + `static AttributePointers[]`
   (`ATTRIBUTE_ENTRY`) + `GetAttributeIndex()` chained to its parent. ⚠ DENSE-TABLE HAZARD (see
   [[reconstruction-gotchas]] §11). [T2]

## Reconstructing a widget — the recipe
`MethodDescription Class::methodDescription = { "keyword", Class::Make, { ParameterDescription
rows } };` + a line in `BTL4MethodDescription[]` before `&BTL4ChainToPrevious`. The static
`Make(int port, Vector2DOf<int> pos, Entity*, GaugeRenderer*)` reads `methodDescription.parameterList[]`,
allocs (`operator new(binSize)` or plain `new`), placement-news the ctor. Then ctor/dtor/
TestInstance/BecameActive/Execute. **Gotchas that bite EVERY widget:**
- Container-Execute must override (§10 gotchas) — else `Gauge::Execute` aborts.
- `/FORCE` trap — a prose-only slot AVs on first call.
- Databinding trap — never raw-read owner offsets; use a bridge (`BTGetSubsystemAuxScreen`, …).
- ReconStream no-op — use `DEBUG_STREAM` for logs, not `DebugStream`.
- Lazy build — wait for the gauge window before concluding "not built" (`BT_GAUGE_SKIP_LOG`). [T2]

## The completed widgets (this project's gauge wave)
- **Attributes published:** HeatSink table (Degradation/Failure/NormalizedPressure/CoolantMassLeakRate/
  ValveSetting/…), PoweredSubsystem (InputVoltage), MechWeapon (OutputVoltage), Mech (LinearSpeed,
  radar Position/Quaternion), Sensor (RadarPercent), **AggregateHeatSink (AmbientTemperature=300 —
  the LAST NULL)**. [T2]
- **Widgets reconstructed + registered:** ColorMapper family (cmHeat/cmCrit/cmArmor/multiArmor),
  headingPointer, vertBar (VertTwoPartBar), segmentArcRatio, oneOfSeveralPixInt, map (radar),
  PlayerStatus, vehicleSubSystems (the engineering cluster panels), LeakGauge, vertNormalSlider,
  **pilotList** (Comm KILLS/DEATHS), **GeneratorCluster**, **SectorDisplay** (radar SECTOR X/Z
  read-out — live), **PrepEngrScreen** (12 engineering-screen label overlays), **MessageBoard**
  (comm ticker — deferred-empty). [T2]
- **Condenser valve gauge:** ValveSetting→coolantFlowScale reads the authentic **1/N**
  (`RecomputeCondenserValves`, FUN_0049f788, was a no-op stub). [T2]

## Dev composite (off-pod)
`BT_DEV_GAUGES` renders the 6 pod [[MFD]] surfaces in a separate 960×384 window (bit-plane masks
over one shared `SVGA16` pixelBuffer; `SVGA16::DrawDevSurface`). On the POD they come from
`SETENV.BAT`/`L4GAUGE` on the real multi-adapter hardware (`FindBestAdapterIndices`/`BuildWindows`,
intact). The `overlay` port (SectorDisplay lives there) shares the `sec` physical surface via a
different bit-plane (0x00C0). [T2]

## MP gauge-window FREEZE = dangling bindings + permanent SEH disable (Gitea #12, 2026-07-19) [T2 log-convicted]
The live-MP "dev-gauges window froze entirely mid-session" incident (issue #12) is NOT a
swap-chain/present bug: `scratchpad/incident_2157/operator_1.log` shows a burst of
`[gauge-fault] '<Widget>' Execute FAULTED -> gauge DISABLED` (PilotList, HeadingPointer,
MapDisplay, SectorDisplay, TwoPartBars, NumericDisplayScalar …) exactly while ALL THREE mechs
were being RE-CREATED at mission launch (second `[zonebuild]`/`[cyl]` set at new addresses —
the session had a pre-launch host drop/rejoin; a normal 2-player LAN launch on the same build
did not re-stream and did not freeze).  The gauge tree had been built (lazily) during the
LOBBY phase against the FIRST-stream mechs; the re-stream freed them; every gauge Execute then
AV'd on its dangling [[attribute-pointer]]s and the `BT_DEV_GAUGES` SEH guard
(`Gauge::GuardedExecute`, GAUGE.cpp:618) DISABLED each one — `Disable(True)` sets `rate=0`
PERMANENTLY, nothing re-enables or rebinds → the whole window static for the rest of the
session (= symptoms 1+3).  The AUTHENTIC engine flow handles mission transitions by
`Application::Shutdown → gaugeRenderer->Shutdown() → ShutdownImplementation → Remove(0)` (all
gauges deleted, tree lazily rebuilt next mission, APP.cpp:787/GAUGREND.cpp:3264) — the port's
in-session re-stream path bypasses it.  **FIX LANDED (2026-07-19, awaiting human MP verify):**
`BTL4GaugeRenderer::TearDownForViewpointRestream()` (btl4grnd.cpp) performs the ENTITY-BOUND
half of the engine ShutdownImplementation sequence, same order (RemoveAllAlarms → Remove(0) →
entity-grid Clear), deliberately KEEPING warehouse/graphics-ports/interpreter/controls-L4Lamps
(RemoveAllLamps mid-session would delete the CONTROLS-owned L4Lamps behind the buttonGroup's
`&lamp->automaticValue` registrations — a dangling mapping; the mech-state "lamps" like
AnimatedSubsystemLamp are Gauges and go with Remove(0)).  Called from
`BTL4Application::MakeViewpointEntity` before `ConfigureForModel("Init", entity)` whenever the
viewpoint is a RE-make (that handler empirically runs once per stream — twice in the incident
log, `[ctrlmap] installing` ×2) — the tree then rebuilds bound to the NEW mech.  Log sentinel:
`[gauge] viewpoint re-stream: tearing the gauge tree down for rebuild`.  Residual exposure:
`Remove(0)` flushes each gauge (`Update(gaugeRate_A)`, GAUGREND.cpp:3465) before deleting it, so
gauge CONNECTIONS may read the freed mech once more (plain reads; Execute stays SEH-guarded).

## The secondary screen's THREE views (Damage / Critical / Heat) — mode-gated [T0/T1/T2]
The `sec` port stacks three mode-gated mech-schematic layers at offset (50,0) over the
always-on radar/heading/speed/messageBoard (`Secondary1`): **Damage** (`ModeSecondaryDamage`,
`<mech>dama.pcc` + `colorMapArmor`/`colorMapperMultiArmor` — 4 silhouettes front/left/right/back,
pixel-plane ids 60-63, per-DAMAGE-ZONE `dz_*` tint through the adpal→adpal2 ramp), **Critical**
(`ModeSecondaryCritical`, `<mech>crit.pcc` + the cmCrit per-SUBSYSTEM list), **Heat**
(`ModeSecondaryHeat` + cmHeat). Mode bits (BTL4MODE.HPP, `nextModeBit`=0 [T0]): Mapping=0x8000,
NonMapping=0x10000, Intercom=0x20000, **SecondaryDamage=0x40000, SecondaryCritical=0x80000,
SecondaryHeat=0x100000** (bits 18-20). `ModeInitial` includes **SecondaryDamage** → the ARMOR
view is the default-on layer (our port creates `BTL4ModeManager(ModeInitial)`, btl4app.cpp:303).
The schematic shows the pilot's OWN mech only — there is no target-damage readout in the cockpit.

**The selector is the DISPLAY mode, not the control mode (Gitea #6, RESOLVED 2026-07-19) [T1→T2].**
The L4 vtable @0051e440 pins the slots: **+0x4C = @004d1ae4** — dispatched by
`CycleDisplayModeMessageHandler` (FUN_004afcac) with the new `displayMode` (0/1/2) — is the
`NotifyOfDisplayModeChange` override that clears bits 18-20 and sets the mask from the table
@0051dbe4 {0x40000,0x80000,0x100000}. (The old "SetControlMode @004d1ae4 switches the secondary
VIEW" claim was the mislabel that kept the port's copy a never-called non-virtual.) **+0x48 =
@004d1acc** — dispatched by `CycleControlModeMessageHandler` (FUN_004afbe0) — just forwards to
the base RET no-op @004b048c: a BAS/MID/ADV control-mode change NEVER touches the secondary
view (empirically confirmed: M cycles the CONTROL MODE gauge lamp, mask bits 18-20 unchanged,
schematic stays on ARMOR DAMAGE). **Authentic pod inputs** (streamed type-6 `.CTL`
EventMappings, dumped live via `BT_CTRLMAP_LOG`): secondary-panel button **0x15 → msg 0x15
CycleDisplayMode** (the manual-p13 "'Mech status Info center", bottom left of the secondary
screen: Armor/Critical/Heat Damage Schematic cycle), button **0x18 → msg 0x14 CycleControlMode**
(the manual-p6 mode button, top right), buttons 0x10/0x11 → ZoomIn/ZoomOut 0x12/0x13 (the map
zoom ± pair). The DOS keyboard fallbacks (Keypress `0x13d`/`0x13e` = extended F3/F4) never fire
under the WinTesla VK map (VK_F3=0x72 collides with 'r', VK_F4=0x73 with 's' — the 'p'/VK_F1
collision class), so the desktop was PINNED on Damage. **Port wiring (mirrors the M/ModeCycle
pattern): 'N' / pad RightThumb → action DisplayCycle → gBTDisplayCycle → `CycleDisplayModeNow()`**
(mechmppr.cpp; the same body the pod button message drives). Pixel-verified live (docked gauges +
BT_SHOT): ARMOR DAMAGE silhouette → CRITICAL DAMAGE subsystem list → HEAT DAMAGE colored list,
mask 0x450421→0x490421→0x510421. Diags: `BT_MODE_LOG`, `BT_VIEWCYCLE_TEST=<frame>`,
`BT_MODECYCLE_TEST=<frame>`.

## The upper-MFD PRESET pages — 3 MFDs × 5 pages (Gitea #9, RESOLVED 2026-07-19) [T0/T1/T2]
The three preset-able MFDs are **Mfd1 (lower left) / Mfd2 (upper center) / Mfd3 (lower right)**,
each a PAIR of bit-planes on one physical monitor: the base **Quad** plane (`Mfd1/2/3`, masks
0x0100/0x0400/0x1000, `btquad.pcx`) and the **engineering-page** plane (`Eng1/2/3`, masks
0x0200/0x0800/0x2000, `bteng.pcx`). Mode bits (BTL4MODE.HPP [T0], bits 0-14):
`ModeMFD{1,2,3}{Quad,Eng1-4}` = `1<<(group*5+item)` — **fully disjoint** from Mapping/NonMapping
(15/16), Intercom (17) and the #6 Secondary* trio (18-20); `ModeInitial` puts all three MFDs on
Quad. **What the pages show:** Quad = up to four `vehicleSubSystems` cluster mini-panels (the
quadrants, geometry table @0x51bf34); Eng item i = the FULL-SCREEN engineering detail of the
subsystem streamed onto aux screen `group*4+i` (`sub+0x1dc`; `prepEngr` screens 1-12: "SYSTEM NN"
+ per-class label cells + the cluster's eng child — GENERATOR SELECT A-D, POWER graph, COOLING
loop, DAMAGE (MJ), ammo count …). Unpopulated screens are authored-empty per mech (Blackhawk:
9 of 12 — scr 1/2/4=PPC/Streak6/ERMed, 5-8=Sensors/Myomers/ERMed/ERMed, 9/10=Streak6/PPC;
screens 3, 11, 12 empty).

**`SetPresetMode(group,item)` @004d1b24** swaps the page: table @0051dbf0 = 15 `{clear,set}`
pairs — set = the page's ModeMFD bit, clear = the group's other four (item 0) or all five
(items 1-4). ⚠ The old reconstruction had transcribed the little-endian set column as
BIG-endian dwords (0x01→0x01000000 …), so a preset press set a garbage high bit — and for
group 1 items 3-4 / group 2 items 0-2 STOMPED the live NonMapping/Intercom/Secondary* bits —
while the page bits never moved (the "presets unwired" defect). Fixed against
section_dump.txt:72901-72908; the "does group 2 duplicate #6's secondary views?" concern is
resolved: **no** — group 2 = MFD3, bits 10-14.

**Authentic dispatch (streamed type-19 "L4" .CTL, 121 records dumped via `BT_CTRLMAP_LOG`):**
every MFD has its own 8-button RIO bank whose meanings are MODE-MASK-gated — **Mfd1 =
buttons 0x08-0x0F (AuxLowerLeft), Mfd2 = 0x20-0x27 (AuxUpperCenter), Mfd3 = 0x00-0x07
(AuxLowerRight)**. On a Quad page the bank's buttons DIRECT-SELECT the populated Eng pages
(mapper EventMappings → `MechRIOMapper` messages `Aux1Eng1-4`=0x4-0x7, `Aux2Eng1-4`=0x9-0xC,
`Aux3Eng1-4`=0xE-0x11 → SetPresetMode; no button is streamed for an empty screen); on an Eng
page one button returns to Quad (`Aux1/2/3Quad` = 0x3/0x8/0xD) and the rest remap to the SHOWN
subsystem (per-subsystem msgs: 0x4-0x7 = SelectGeneratorA-D, 0x8 = ToggleGeneratorMode, 0x9 =
ConfigureMappables, 0x3/0xb = unjam/eject-class functions). The `MechRIOMapper` keyboard cases
in @004d1bf0 mirror it as three key rows: `1-4`=MFD1 Eng1-4/`5`=Quad, `a s d f`/`g`,
`z x c v`/`b` — mostly claimed by the port's WASD bindings, hence dead on desktop.
**Port wiring:** the streamed records install and fire on desktop (btinput passes the LIVE
manager mask on button press, so the NUMPAD profile's 0x20-0x27 keys page MFD2 authentically);
the default WASD profile adds **J/K/L → actions Mfd1/2/3Cycle → gBTPresetCycle → 
`CyclePresetModeNow(group)`** (btl4mppr.cpp; a port cycle-key shim — 24 mode-dependent pod
buttons don't fit a keyboard — that visits exactly the pod-reachable set: Quad + populated Eng
pages; the body is the authentic SetPresetMode).

**Dev-composite change:** `BTDrawGaugeSurfaces` (L4VB16.cpp) now draws the Eng1-3 planes into
their sibling's cell and SKIPS any mono plane whose port channel is currently `BlankColor` —
honoring the mode-driven `reconfigure` (RemapGraphicsPort) so each dev cell shows the ACTIVE
page, like the pod monitor. This SUPERSEDED the 2026-07-12 "frozen-dial" scaffold
(GAUGREND.cpp force-activated all 15 page bits under BT_DEV_GAUGES — removed; it made every eng
screen paint over the shared Eng plane, pinning it on the highest screen). Pixel-verified live
(BT_PRESET_TEST): all three MFDs page Quad → eng details → back to Quad in lockstep with the
[mode] mask log; N/M un-regressed. Diags: `BT_MODE_LOG` ([mode] preset lines),
`BT_PRESET_TEST=<frame>`, `BT_CTRLMAP_LOG`.

## pilotList (Comm KILLS/DEATHS) row semantics + the −1 [T1/T2]
One ROW PER PILOT in the mission (2-player MP = 2 rows — not duplicate displays). KILLS =
`killCount` (the victim's ScoreMessageHandler credits the shooter cross-player, works for both
rows); DEATHS = `Player::deathCount`: engine-inits to **−2** (PLAYER.cpp:759), the LOCAL
vehicle-acquire branch zeroes it (btplayer.cpp:1118), then VehicleDead(-1) ++s per death. A
REMOTE player's Player object never runs the local acquire → −2 +1 spawn increment = **−1
locked**. **RESOLVED 2026-07-12 [T2]:** deaths now tally per node from LOCALLY OBSERVED events
(the same model as the cross-pod KILLS credit) — a replicant's once-per-death transition calls
`BTPlayerCountObservedDeath` on its owning player's local copy (replicant-gated: the master's
own VehicleDead path counts its node), and `BTPilotDeaths` clamps the −2/−1 pre-acquire seed
to 0 for display. Own row counts correctly as before.

## Launcher-panel recharge dial — CORRECTION 2026-07-19: it IS live (slot 17 @004b9c9c) [T1]
The weapon panels' SegmentArc270 tick ring reads MechWeapon::rechargeLevel (+0x320).
**The old "authentically STATIC on projectile weapons" claim was WRONG** — the writer census
missed the anonymous vtable slot 17 (vtbl+0x44) body **@004b9c9c**:
`rechargeLevel = (rechargeRate@0x3DC − recoil@0x3E8) / rechargeRate` (capstone disasm, issue
#12; Ghidra never emitted it).  The recovered `ProjectileWeaponSimulation` @004bbd04 calls it
every frame in the Loading(3) and unavailable(7) alarm cases — so the launcher dial
authentically ANIMATES 0→1 through each reload.  (The census's four other writers stand: ctor
@004b99a8, stream init @004b8fec, ResetToInitialState @004b96ec, and
`Emitter::ComputeOutputVoltage` @004ba738 — slot 17 is the Emitter override of the SAME slot;
@004b9c9c is the MechWeapon/projectile base body.)  The launcher panel's other live indicators:
AMMO DIGITS (AmmoBin::ammoCount via the complete-type bridges), jam/fire lamps, eject wipe.

## ConfigMapGauge (the weapon panel's regroup lamp column) — authentically DORMANT
The per-weapon btjoy.pcc joystick image + 4 cm_* state lamps (off/other/only/both) showing,
for each mappable fire button (Pinky/ThumbLow/Trigger/ThumbHigh), whether THIS panel's weapon
is bound to it.  **The shipped binary never enables it [T1, task #6]:** no caller of SetColor
@004c6ee0 exists, so color==0 and Execute early-outs.  The state loop is reconstructed
(btl4gau2.cpp; table DAT_00518eb4 PE-recovered; sampler = LBE4ControlsManager::
buttonGroup[btn].GetMapState — NOT the ModeManager, the old guard note was wrong) behind the
PORT dev enable `BT_CONFIGMAP=1`.  The regroup MECHANISM itself (ConfigureMappables/
ChooseButton, task #6) is live regardless of the gauge.

## Authentically-static (do NOT "fix")
Degradation/Failure temps are fixed markers; AmbientTemperature 300; CoolantMassLeakRate 0 on a
pristine mech (damage-gated); cmArmor/cmCrit all-green (undamaged solo player — BT is PvP-only);
RANK 1 solo; MessageBoard empty (no status messages exist in bring-up).
**CORRECTION (task #10, 2026-07-11):** the old "Heat MFD is authentically NEAR-STATIC /
currentTemperature ~77 rounds to zero" claim was computed at the DEGENERATE bring-up heat scale.
At the authentic 1e7-unit economy (tasks #9-#10) the Heat MFD is fully dynamic: weapons run
77→2000 (the authored failure threshold), condensers/generators run 100-1400 under sustained
fire, and the bank plateaus ~600 — temperatures, heatLoad and the heat alarms all animate. [T2]

## Radar view-wedge tracks the torso twist (Gitea issue #1 — FIXED 2026-07-17) [T2]
The SECTOR radar's view cone (`MapDisplay::DrawViewWedge` @004c2484, btl4rdr.cpp) reads
`viewHorizontalRotation@0x31C`, fed by a per-frame `GaugeConnectionDirectOf<Radian>` the ctor
wires from the mech's Torso. The two helpers were NULL stubs, so the connection was never
created and the wedge sat at heading 0 (the reported "cone does not track the twist").
Reconstructed from the binary: `FindSubObject` (FUN_0041f98c) = a SUBSYSTEM-ROSTER walk
(count @+0x124 / array @+0x128) matching the streamed name (sub+0xd4) case-insensitively
(FUN_004d4b58 = tolower-strcmp) — the "Torso" sub-object IS the roster Torso subsystem;
`GetHorizontalRotation` = torso+0x1D8 = `Torso::currentTwist` (layout-locked), reached via the
existing task-#56 bridge `BTGetTorsoTwistAddr` (Radian ≡ {Scalar angle}, exact reinterpret).
VERIFIED live (MadCat, Standard mode Q/E): wedge rot tracks twist 0→−2.21 rad in lockstep, and
the SEMANTIC test passes — body turned away, torso twisted back onto the enemy → reticle goes
green AND the wedge points at the enemy's blip while the scope stays body-fixed. ⚠ Test with a
TWISTING mech: the Blackhawk's torso is FIXED (limits ±0.01°) — its wedge authentically never
moves. Diag: `BT_RADAR_LOG` ([radar] ctor probe + 1 Hz [radar-wedge] rot trace). [T2]

## Remaining = DATA FEEDS, not widgets (deferred systems)
**✅ The condenser valve CONTROL is LIVE (task #13, 2026-07-11) [T2]:** `MoveValve` (id 4, the
Condenser handler table @0x50E52C — exactly one entry) registered + guarded by the REAL
FUN_004ac9c8 = `player+0x274 == 0` (2026-07-18 correction: +0x274 = the egg EXPERIENCE level,
so this is the NOVICE lockout, not a "ROOKIE role" — see [[experience-levels]]; task #12's
`BTPlayerRoleLocksAdvanced` bridge; bring-up seeding = 2 ≈ veteran = UNLOCKED, verified live:
press → valveState 1→5 → flow redistribution 1/6 → 5/10).  Desktop: 'C' cycles the selected
condenser (BT_VALVE_SLOT).
**✅ The COOLANT FLUSH is LIVE (Gitea #7, 2026-07-19) [T2]:** `InjectCoolant` (id 4, the Reservoir
handler table @0x50e680, handler @4aee70) — HOLD flushes reservoir coolant through the loops
(InjectCoolant @4aefa4, set%-biased via each sink's flowScale); the coolant **vertBar C**
(`Reservoir/CoolantMass` = coolantLevel@0x12C, l4gauge.cfg:4526) drops live as the tank drains
(BLH: 6.0 → 0 in ~0.6 s held ≈ the manual's 3-4 punches); the bluish FLUSH.PFX condensation
cloud (psfx 19) spawns on the ReservoirState 0→1 edge.  Desktop: **'H' HELD** (action Flush).
Full chain + the two ctor decode corrections it surfaced: [[subsystems]] §coolant FLUSH.
Diags: `BT_FLUSH_LOG`, `BT_FLUSH_TEST=<frame>`.
The **MessageBoard** feed needs **StatusMessagePool** (a NULL stub) + the per-player status
queue. [T2]

## SeekVoltageGraph — the eng-page POWER graph AND the top-box eraser (Gitea #11, 2026-07-19) [T1→T2]
The emitter/PPC + myomer engineering pages' "POWER" box widget (btl4gau2.cpp/.hpp; ctor
@004c6798, BecameActive @004c6920, Execute @004c6934; a CLUSTER-CHILD — built by
EnergyWeaponCluster @004c93b0 / MyomerCluster @004c8df4, not a config keyword).  Fully
reconstructed from the capstone disasm (Ghidra dropped every x87 arg; tools/disas2.py):
- **View/geometry:** localView = the page's top data box (0x97,0x80)-(0x17d,0x13b) — exactly
  230×187, the plot scales; view coords are view-relative (GRAPH2D.h `origin =
  areaWithinPort.bottomLeft`).  Ctor sets **SetOperation(Xor)** — ticks/cursor erase by redraw.
- **The eraser role:** BecameActive poisons the cached sample (previousVoltage@0xAC = 9999);
  the next Execute's change-test (sample the response at **12000 V**) then runs the CLEAR
  @004c6be4 (SetOperation(Replace), color 0, filled 1000×1000 clipped to the box) before
  replotting — THIS is what erases the sibling pages' stale pixels on the shared Eng bit-plane
  (the #10 ghosts).  Every topBox=0 PrepEngr page owns a graph; the box erase design is coherent.
- **Plot math (recovered):** polyline v = 0..12000 step 1200 (_DAT_004c6bdc/_be0):
  x = Round(response(v)·230), y = Round(v·(1/12000)·187) — the 80-bit consts @004c6bd0/@004c6d74
  are EXACTLY 1/12000.  Ticks (@004c6c6c): per gear i in [*min..*max], the current gear draws a
  full L (axis→point→axis), others 10-px axis stubs; XOR pair moves the highlight.  Cursor
  (@004c6c30, emitter pages only): 8×8 XOR square at the LIVE voltage (the ctor's
  "OutputVoltage" attr pointer).  Destroyed subsystem (simulationState==1 via the
  BTSubsystemDestroyed bridge, powersub.cpp): centred edestryd.pcc once; revive calls own
  BecameActive (vtbl+0xC, slot 3 of PTR_0051a1fc — verified by vtable dump).
- **The sampler == subsystem vtbl+0x3C (slot 15), reached via the BTSeekVoltageSample dispatch
  bridge (emitter.cpp → myomers.cpp; databinding rule):** Emitter @004bb42c =
  `sqrt(SeekPower(v)/2.0e8)` with SeekPower @004bb3f4 = `damageFraction·v²·0.5·energyCoefficient`
  (a LINE in v — the emitter graph is authentically straight); Myomers @004b8f94 =
  `sqrt(AvailableOutput(v)·3.6/350)` (steep near-vertical curve at BLH values).
  **FUN_004dd138 = sqrt** (part_015.c:4026) — the old "fabs/fp-magnitude" reading was wrong;
  Myomers' old best-effort name "GetSpeedReading" renamed SeekVoltageResponse.
- **The attributes:** Myomers already published all 4 Seek* (@0x320-0x330).  Emitter's AUTHENTIC
  table was recovered (binary @0x511dd4, ids 0x1D-0x25) and published (emitter.cpp):
  LaserOn@0x418, LaserScale@0x42C, LaserRotation@0x41C, Current/Recommended/Min/Max
  SeekVoltageIndex@0x3F0-0x3FC, SeekVoltage@0x400, **OutputVoltage@0x414 = currentLevel (RAW
  volts — the cursor feed)**.  ⚠ The MechWeapon 0x1D "OutputVoltage" PORT ALIAS (→ rechargeLevel
  0..1) was RETIRED: the binary MechWeapon table ends at 0x1C, and `AttributeIndexSet::Find`
  walks lowest-id-first, so the alias SHADOWED the authentic Emitter row.  Emitter renames:
  @0x3F8 minSeekVoltageIndex / @0x3FC maxSeekVoltageIndex (were seekStepCounter/seekVoltageCount
  guesses; the attr table proves the identities).  PPC chains Emitter::GetAttributeIndex().
- **Verified live (BLH, autofire):** page-cycling + BT_PRESET_HOLD steady-state shots — both #10
  repro pairs ghost-free (SYSTEM 09 Streak → SYSTEM 10 PPC held clean; SYSTEM 02 → SYSTEM 04
  clean; SYSTEM 05 → 06 Myomers clean); curves draw with moving cursors (charge cycling);
  exactly ONE replot per activation ([seek] log).  Diags: `BT_SEEK_LOG` ([seek]
  BecameActive/replot), `BT_PRESET_HOLD=<n>` (freeze the #9 preset cycler after n pulses —
  steady-state pixel verification; the 120-frame cycle phase-locks with BT_SHOT's 90).

## Cockpit HUD reticle (main screen, inside view) — LIVE
`BTReticleRenderable` (0x358 bytes, ctor @004cc40c) draws over the finished 3D frame in cockpit
view only, via the recovered **dpl2d** 2D display-list API (recorders @0x487f34-0x488630; opcode
map + coordinate model in `phases/phase-02-dpl2d-reticle.md`; port: `game/reconstructed/dpl2d.cpp`).
Geometry is the ctor's hardcoded calibration (originX 0.35, originY 0.25, scaleY 0.5, right range
ladder 0..1200 m, bottom TORSO-TWIST tape (NOT a heading tape — stale wording swept task #58; see
the tape entry below), center cross + dot; tick ladders via FUN_004cd938). The
range caret binds to the live target range (`BTSetHudTargetRange`, fed by mech4's targeting step).
**Weapon pips:** the build loop (part_014.c:5386) registers EVERY subsystem
`IsDerivedFrom(0x511830 = MechWeapon)` — lasers, PPCs AND missile launchers (BLH = 7 pips) — via
`AddWeapon` @004cdac0 (verified store map in btl4vid.hpp).

**The per-frame `Execute` @004cdcf0 is RECOVERED (task #37, capstone disasm via
`tools/disas2.py` — the full annotated read: the task-37 commit + btl4vid.cpp comments) [T1],
and every instrument is now live [T2]:**
- **Right ladder** = range 0–1200 m: a YELLOW width-2 BAR from ladder-top to the caret + a
  **GREEN width-1 caret triangle** (ctor @4550-4551 sets green/1 AFTER the yellow bar call —
  transcription color bug caught by a period reference screenshot, 2026-07-09; same for the
  bottom bowtie carets @4569-4570); pegs at 1200 with no target; the DISPLAYED range slides at
  **500 m/s** toward the true pick range (HudSimulation :5652 [T1]). ⚠ A period pod screenshot
  (`C:\git\image.webp`, likely a DIFFERENT pod revision — its crosshair is ~2.5× taller with
  arrowhead arms, NOT our binary's ±0.04..0.16 program) structurally CONFIRMS our layout: yellow
  bar + green caret + colored pip dots on the right ladder, bottom tape + green bowtie, rotating
  compass circle bottom-left, and a mid-ladder range reading with no lock (the world-pick
  terrain range). Our glyph constants remain [T1] from OUR 4.10 binary. **The weapon pips sit on
  this same ladder at each weapon's authored max-range mark** — caret below a pip = that weapon
  reaches the target. BLH authored data (live dump): 3× ER-M laser red @**500 m** (two stacked
  at one column; PipExtendedRange=1), 2× missile amber (0.6,0.4,0) @**800 m**, 2× PPC blue
  @**900 m** — so the 7 pips read as 3 weapon-SYSTEM groups. (The engineering-panel "RANGE 500M"
  labels are panel text; the authoritative reach is the streamed WeaponRange.)
- **Bottom 21-tick tape = the TORSO-TWIST indicator** (NOT a heading tape): deflection line +
  carets at `∓(span/2)·(RotationOfTorsoHorizontal / HorizontalTorsoLimit)` (HUD attrs 4/5/6).
  Fixed-torso BLH: centred (authentic static).
- **Circle-with-stem = the COMPASS** (HUD attr 0xD CompassHeading, rad→deg rotation) at
  `(botX, botY−3·tickMajor−0.03)`; the **THREAT trail** (attr 0xC ThreatVector) draws inside its
  rotated frame: 0.05-unit attack-direction marks, fresh <2 s red, expiring at 6 s, 1 s blink tick.
  Port feed: the player's TakeDamage handler pushes the impact direction.
- **Pips** (composed into subB6, master-called): hidden when the weapon's DAMAGE state == 1
  (destroyed, attr 1); LIT (A) when the FIRE-CYCLE state == 2 (loaded, **attr 0x1C WeaponState**
  @0x350 == 2) else dark ring (B, charging); filtered by `weaponMode & elementMask&0xF`
  (the weapon-GROUP bits Front/Rear/Left/Right). **Range plays NO part** — Execute never reads
  the stored TargetWithinRange slots. **FIX 2026-07-18 [T2]:** the pip's "loaded" was a port
  approximation reading `rechargeLevel ≥ 1` — correct for emitters (charge-driven) but
  **statically 1.0 on projectile weapons in the PORT** (the port sim never called the slot-17
  updater @004b9c9c — see the §Launcher-panel CORRECTION), so missile/AC pips were
  **permanently lit and never blinked on fire**.
  Now reads the AUTHENTIC attr 0x1C = the weaponAlarm StateIndicator level (`WeaponStatePtr` →
  `GaugeAlarm54::LevelPtr`), compared `== stateConst2` (the const the binary itself stores in
  AddWeapon). The state cycles Loaded(2)↔Firing(0)/Loading(3)/Jammed(5) for BOTH families, so a
  missile pip now momentarily drops when fired, exactly like the emitter's. Verified live
  (Blackhawk, `BT_AUTOFIRE=1 BT_AF_MISSILE=1`): both SRM6 pips toggle 2↔0/5 on each salvo.
  (The recharge DIAL is driven by slot 17 @004b9c9c — §Launcher-panel CORRECTION.)
- **Lock ring** = subB9 (ring+cross) at frame centre, **SPINNING 4°/frame** while the Lock attr
  (0xA) is up. The Lock PRODUCER is the authentic HudSimulation rule (part_013.c:5619-5634 [T1],
  wired task #38): lock requires a target AND your own HUD's host zone damage < **0.75** (a
  shot-up targeting computer loses lock) AND the targeted zone's damage < **1.0** (whole-mech
  target checks zone 0 — so a wreck's dead zone can't re-lock). The hotbox stays visible without
  lock (box = HotBoxVector, ring = Lock — separate signals). The binary also hangs the PNAMEx.bgf
  player-name mesh on the 3D marker here (3D chain still deferred).
- **Simple-X mode** (PrimaryHudOn off, mask 0x20): the minimal reticle — a small green cross
  (±0.02..0.08 arms) riding the aim translate (ctor @4689-4705 [T1]) — swapped for the full HUD
  by Draw's state switch.
- **Target HOTBOX** (attr 0xB HotBoxVector) = a rectangle hugging the projected extents — x±4
  around the hotbox point, +1/−11.5 vertical (K=2.8145 baked projection; the port uses the live
  per-axis projection) — switching to the left/right edge ARROW past ±1.6 or behind.
- Reticle state Off/On + `PrimaryHudOn` (mask 0x20) picks full HUD vs the "simple X" list;
  the aim group SetMatrix-translates by `Reticle::reticlePosition` (screen −1..+1 [T0]) every
  frame — but **NOT by torso twist** (task #58 CORRECTION): the VIEW is torso-mounted (the eye
  hangs off jointtorso → jointeye → siteeyepoint), so the crosshair stays SCREEN-CENTERED through
  a twist — screen center IS the boresight; the twist reads on the bottom tape/compass/radar
  wedge instead. The reticlePosition writer is un-exported (one xref binary-wide: the read-side
  lookup part_014.c:5132); its coherent use is the FIXED-torso free-aim channel (mech+0x36c
  [T4]). The old "translates to the torso boresight" wording here was the falsified
  body-mounted-view model — see [[combat-damage]] Targeting for the full re-correction.
This recovery also CONFIRMS the HUD attr-table ids 4/5/6/8/0xA/0xB/0xC/0xD name↔use pairings
(hud.hpp had flagged them uncertain; the OFFSETS were re-based 2026-07-19 — the table @5110b8
starts with id 3 FlickerRate@0x1D8, so Rotation=0x1DC…CompassHeading=0x214 Scalar; hud.hpp/
CLASSMAP corrected, names/ids unchanged). Deferred: PNAME1-8.bgf 3D marker chain. (The canopy shell
is now authentic and shows by default — see [[cockpit-view]]; `BT_HIDE_COCKPIT=1` hides it.)

Player CALLSIGN labels (kill/damage feed, radar/target tags, score display) are 1bpp name
BITMAPS from the egg, not text — format, renderers, and the operator-console generator:
[[multiplayer]] §OPERATOR-SET CALLSIGNS.

## Key Relationships
- Full history: `docs/GAUGE_COMPOSITE.md`; reticle recovery: `phases/phase-02-dpl2d-reticle.md`.
- Uses: [[attribute-pointer]] + [[reconstruction-gotchas]]; reads [[subsystems]] state.
- Renders on: [[pod-hardware]] MFD surfaces.