#88 part 2: the central coolant pull-through -- HeatSink::DrawCoolant was a

return-0 stub; the Reservoir BAR now drops when a damaged mech leaks

The user watched the coolant panel's level bar during the leak bench and it
never moved -- correctly: a leaking subsystem drained only its own loop,
because the slot-14 top-up (DrawCoolant) was stubbed.  Disassembled the real
base @0x4add00: the draw RECURSES UP the sink linkage, scaling by
coolantFlowScale@0x15C per hop, terminating at the Reservoir's supply
(@0x4af3b0 -- clamp to [0, coolantLevel], drain the tank, return granted --
already faithfully ported as Reservoir::DrawCoolant).  The binary's terminal
hop is the bank's slot-14 override @0x4ae8b0 resolving its reservoir
connection @0x1D8 (the port's 'helper' member -- not vestigial after all);
the port's existing Reservoir-ctor Attach + Reservoir override terminate the
same chain equivalently (the extra bank hop scales by ctor-default 1.0).

Implemented the base recursion (null-guarded -- the binary calls through the
resolved link unguarded; authored topology always links) + a BT_COOL_LOG
[resdraw] probe at the supply.

Verified live: a destroyed myomer's damage leak pulled the central tank
6.0 -> 5.58 over ~30s ([resdraw] granted lines) -- Reservoir/CoolantMass,
the cockpit coolant bar, now visibly drops as a damaged mech bleeds
coolant, and DeathReset refills it on respawn.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_019Zh7PTkFy4KwTzVighLR9J

context/subsystems.md

@@ -180,10 +180,18 @@ disarmed, and the #64 full de-shadow sweep remains the long-term cleanup.  Verif
 rattle and weapon crits (`[critroll]`) both drive `[cool]` leak lines (draw ≈ dmg×heatLoad, level
 draining, hysteresis arming).  **Authored damage routing** (BTL4.RES): collision rattle targets
 HeatSinkBank 0.3 / Gyro 0.35 / Torso 0.25 / Myomers 0.35 — Condenser + Reservoir are authored 0
-for collisions; weapon crits select via the ZONE's crit-entry list.  Remaining fidelity item:
-`HeatSink::DrawCoolant` (vtable slot 14, the central-system top-up) is still a `return 0` TODO, so
-a leaking subsystem drains its own loop; the pull-through to the central Reservoir gauge rides the
-loop-flow machinery.
+for collisions; weapon crits select via the ZONE's crit-entry list.
+**The central pull-through is ALSO live (same day):** `HeatSink::DrawCoolant` was a `return 0`
+stub; the real base @0x4add00 (disassembled) RECURSES UP the sink linkage — `return
+resolve(linkedSinks)->DrawCoolant(requested × coolantFlowScale@0x15C)` — terminating at the
+Reservoir's supply (@0x4af3b0, already faithfully ported as `Reservoir::DrawCoolant`: clamp to
+[0, coolantLevel], drain, return granted).  Binary terminal hop = the bank's slot-14 override
+@0x4ae8b0 resolving its reservoir connection @0x1D8 (the port's `helper` member — NOT vestigial);
+the port terminates equivalently via the Reservoir-ctor Attach into the bank's `linkedSinks` +
+the Reservoir override (the extra bank hop scales by its ctor-default flowScale 1.0 — a no-op).
+Verified live (`[resdraw]`): a destroyed myomer's leak pulled the central Reservoir tank
+6.0 → 5.58 over ~30 s — **`Reservoir/CoolantMass`, the cockpit coolant BAR, now visibly drops
+as a damaged mech bleeds coolant**, and DeathReset refills it on respawn.
 
 ## The coolant FLUSH (Gitea #7, 2026-07-19) — Reservoir InjectCoolant end-to-end [T2 live-verified]
 The manual-p24 coolant button (coolant MFD top-right; punch or HOLD): message id **4 "InjectCoolant"**

game/reconstructed/heat.cpp

@@ -1001,14 +1001,30 @@ void
 }
 
 //
-// vtable slot 14 (@vtable+0x38).  Base sinks supply nothing on their own;
-// a central-cooling-system subclass overrides this.
-// TODO: verify against the real slot-14 target (not captured in decomp).
+// vtable slot 14 (@vtable+0x38) -- the base @0x4add00, disassembled + decoded
+// 2026-07-31 (the old `return 0` stub was why a leaking subsystem could never
+// pull from the central tank -- the Reservoir bar never moved on damage):
+//     linked = resolve(linkedSinks@0x164)          ; FUN_00417ab4
+//     return linked->DrawCoolant(requested * coolantFlowScale@0x15C)
+// i.e. the draw RECURSES UP the sink linkage, scaling per hop, and terminates
+// at the Reservoir's own override (@0x4af3b0: clamp to [0, coolantLevel],
+// drain the tank, return the granted amount).  In the binary the terminal hop
+// is the bank's slot-14 override @0x4ae8b0 resolving its reservoir connection
+// @0x1D8; in the port the reservoir sits in the bank's linkedSinks (the
+// Reservoir-ctor Attach) and Reservoir::DrawCoolant IS the @0x4af3b0 body, so
+// the same chain terminates identically (the extra bank hop multiplies by its
+// coolantFlowScale, ctor-default 1.0 -- a no-op).  PORT GUARD: the binary
+// calls through the resolved link UNGUARDED (authored topology always links);
+// an unlinked port sink supplies 0 instead of faulting.
 //
 Scalar
-	HeatSink::DrawCoolant(Scalar /*requested*/)
+	HeatSink::DrawCoolant(Scalar requested)
 {
-	return 0.0f;
+	HeatSink *linked = (HeatSink *)linkedSinks.Resolve();	// FUN_00417ab4(this+0x59)
+	requested *= coolantFlowScale;						// @0x15C
+	if (linked == 0)
+		return 0.0f;
+	return linked->DrawCoolant(requested);				// vtbl+0x38 (virtual)
 }
 
 

game/reconstructed/heatfamily_reslice.cpp

@@ -870,6 +870,14 @@ Scalar
 		}
 	}
 	coolantLevel -= supplied;
+	if (getenv("BT_COOL_LOG") && supplied > 0.0f)
+	{
+		static int s_n = 0;
+		if ((s_n++ % 60) == 0)
+			DEBUG_STREAM << "[resdraw] granted=" << supplied
+				<< " tank=" << coolantLevel << "/" << thermalCapacity
+				<< "\n" << std::flush;
+	}
 	return supplied;
 }