Combat: AUTHENTIC weapon groups -- streamed per-mech button bindings + the real fire chain (task #5)

The recovered system: fire channels = LBE4ControlsManager buttonGroups
(0x40/0x45/0x46/0x47); default groups = the per-mech type-6 controls-map
resource in BTL4.RES, installed by the T0 CreateStreamedMappings the port
already called -- it needed only the TriggerState attribute (id 0x13 PINNED
to the binary value; fireImpulse@0x31C is the binary's TriggerState) and an
input feed.  Keyboard/harness now push press/release edges into the button
groups; the gBT*Trigger bypasses, per-type keyboard split and 1,0 pulse
hack are retired -- weapons sharing a button fire TOGETHER (madcat Trigger
= 4 weapons).  Myomers @4b9550/@4b95b8 misattribution corrected (they are
MechWeapon ConfigureMappables/ChooseButton).  Verified 2-node: kill through
the authentic chain (12 hits vs ~36 pre-groups).  Config-mode session
(regrouping UI) = the remaining stage, KB-scoped.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

context/open-questions.md

@@ -110,16 +110,26 @@ authentic path scoped.
 - **MechControlsMapper look/eyepoint commit** — reconstructed but its offsets collide with declared
   members; arbitrate before enabling (no port consumer yet). The fire-trigger-through-mapper is
   still the `gBTWeaponTrigger` bring-up.
-- **Weapon groups / per-button fire channels (decomp-anchored 2026-07-09)** — MechWeapon message
-  handlers id 9 **`ConfigureMappables`** (`FUN_004b9550`) and id 10 **`ChooseButton`**
-  (`FUN_004b95b8`), table @0x511860 region: ConfigureMappables binds the weapon's
-  `fireImpulse`@0x31C to mapper fire-channel #N (msg value 1-based; <1 unbinds; mapper = roster
-  slot 0, vtable +0x38 register / +0x3c unregister; weapon+0x110 = the bound-state), ChooseButton
-  re-binds (vtable +0x44) — the pod's in-cockpit weapon→button GROUPING. Weapons sharing a button
-  fire together; grouping was a PILOT choice (heat management: alpha vs split). The port's
-  SPACE=all-energy / CTRL=missiles split is a stand-in default; the authentic system needs the
-  mapper channel registration + who SENDS the default ConfigureMappables (mission/player setup —
-  not yet traced). Payoff: authentic weapon groups + a path to chain-fire.
+- **✅ Weapon groups — the AUTHENTIC defaults + fire path LIVE (task #5, 2026-07-11) [T1/T2].**
+  The system decoded end-to-end: a fire "channel" = a physical `buttonGroup` slot in the global
+  `LBE4ControlsManager` (fire buttons 0x40 Trigger / 0x45 Pinky / 0x46 ThumbLow / 0x47 ThumbHigh);
+  binding = a permanent mode-0x10000 DIRECT mapping button → the weapon's **TriggerState** attr
+  (id **0x13**, = `fireImpulse@0x31C`; the binary MechWeapon table's ONLY attribute @0x511890);
+  the weapon self-edge-detects (CheckFireEdge @4b9608).  **The default grouping is NOT messages —
+  it is the per-mech type-6 controls-map resource in BTL4.RES** ("Thrustmaster"/"L4" variants;
+  e.g. madcat: Trigger={4 weapons}, ThumbHigh={2}), installed at `MakeViewpointEntity` by the
+  ENGINE's `CreateStreamedMappings` (T0, L4CTRL.cpp) — which the port already called; it needed
+  only the TriggerState attribute published (id PINNED to 0x13 — our attr-id chain is 6 short of
+  the binary's; full binary attr-table dump in the task #5 scan) + an input feed.  Keyboard now
+  pushes press/release edges into the buttonGroups (SPACE→Trigger, '2'→ThumbLow, '3'/CTRL→
+  ThumbHigh; BT_AUTOFIRE pulses the Trigger); the gBT*Trigger bypasses + pulse hack are retired.
+  VERIFIED 2-node: full kill through the authentic chain (12 hits vs ~36 pre-groups = the
+  4-weapon trigger volley + crit cascade).  **Remaining (the config-mode session):** handlers
+  id 9/10 (@4b9550/@4b95b8 — corrected: they were mislabeled as Myomers fns), the L4 mapper
+  Enter/ExitConfiguration completion (StartMappableButtonsConfigure + mode 0x8000), the
+  ConfigMapGauge unguard — the pod's in-cockpit REGROUPING UI (pilot heat-management choice);
+  mapper vtable corrections: +0x38 Enter / +0x3c Exit / +0x44 RIO AddOrErase (Thrustmaster
+  no-ops it).
 - **Myomers authentic coupling** — the structural un-stub is INERT (mover feed + heat-gen no-op).
   Real coupling needs the advanced-damage gate (`OwnerAdvancedDamage`/`FUN_004ad7d4` → the owning
   **BTPlayer** `mech+0x190`+0x260, NOT 0xBD3 — see the mech+0x190 item above) + `MoverAttach` routing