diff --git a/context/open-questions.md b/context/open-questions.md
index 40c9afa..b669baf 100644
--- a/context/open-questions.md
+++ b/context/open-questions.md
@@ -71,10 +71,17 @@ authentic path scoped.
 - Authentic per-mech TURN-RATE constant (currently a bring-up constant rate).
 - Body-callback gimp handlers (states 16-19, targets 0x70b2/0x7161 undecoded → fall back to stand);
   airborne callbacks (`FUN_004a6344`/`FUN_004a7970`).
-- Wall-block-vs-climb tuning; collision DAMAGE application (computed, not applied). **UNBLOCKED 2026-07-08:**
-  STEP 6 (cylinder hit-location) now resolves an unaimed impact point → zone, so collision damage can be
-  applied through `Mech::TakeDamageMessageHandler` (a zone==−1 hit now resolves instead of dropping). The
-  remaining piece is issuing the computed collision Damage into the TakeDamage path (currently computed only).
+- Wall-block-vs-climb tuning. **✅ Collision DAMAGE application — DONE 2026-07-08 [T2].** The two deferred
+  dispatches in `Mech::ProcessCollision` (mech4.cpp: mech-vs-mech `:15324-15358` + icon-crunch `:15369-15401`)
+  now fire: on a collision with another Mech or a CulturalIcon, an `Entity::TakeDamageMessage{zone==−1}` is
+  dispatched to the victim (via `BTDispatchCollisionDamage`, the engine ctor — same as the weapon path), and
+  STEP 6's cylinder table resolves the impact point → a zone on the receiver. Terrain (walls/hills) matches
+  neither branch → blocks without damage (faithful). Reachability is guaranteed (`Mover::ProcessCollisionList`
+  calls the **virtual** `ProcessCollision` → `Mech::ProcessCollision`); built + stable. The live dispatch
+  wasn't captured headlessly (the solo auto-walker never rammed a tree/mech), but the path is proven reachable
+  and composed of runtime-verified pieces. **Note:** validated STEP 6's height ref along the way —
+  `collisionTemplate->maxY ≈ 7.1` (a real mech height), confirming `CylinderReferenceHeight` reads a height,
+  not the heat value the `mech+0x2ec` dual-labeling (heat-gauge sink vs groundRef, mech4.cpp:2697) hinted at.
 - **✅ Cylinder hit-location (STEP 6) — DONE 2026-07-08 [T2].** Built + runtime-verified: the `dmgtable.cpp`
   classes now have real storage + a working `ResolveHit→zone`, the mech ctor loads the type-0x1d table by the
   DamageZoneStream name (`[cyl] table 'bhk1' layers=7`), and `Mech::TakeDamageMessageHandler` resolves
diff --git a/game/reconstructed/mech4.cpp b/game/reconstructed/mech4.cpp
index 6f3e9bc..1b582bc 100644
--- a/game/reconstructed/mech4.cpp
+++ b/game/reconstructed/mech4.cpp
@@ -2600,6 +2600,45 @@ void
 // baseline BT_COLLISION push-out path is byte-identical.
 //###########################################################################
 //###########################################################################
+
+//
+// Build a zone==-1 (unaimed) collision TakeDamageMessage from a resolved contact
+// and dispatch it to 'victim'.  The victim turns the WORLD impact point into a
+// damage zone -- a Mech via its cylinder table (STEP 6), an icon via its base
+// handler (crushable props have no zones -> the base handler no-ops).  Faithful
+// to the binary's mech-vs-mech / icon-crunch dispatches (:15324-15401): those
+// built a raw DamageMessage{id=0x64, inflictor=DAT_0050b9ac, zone=-1}; we use the
+// engine Entity::TakeDamageMessage ctor (as the weapon path does) with this mech
+// as the inflictor.  The impact point is the world centre of the overlap slice.
+//
+static void
+	BTDispatchCollisionDamage(
+		Mech				*inflictor,
+		Entity				*victim,
+		const Damage		*resolved,
+		BoxedSolidCollision	&collision)
+{
+	Damage dmg;
+	dmg.damageType    = Damage::CollisionDamageType;
+	dmg.damageAmount  = resolved->damageAmount;
+	dmg.surfaceNormal = resolved->surfaceNormal;
+	dmg.impactPoint   = Point3D(
+		(collision.collisionSlice.minX + collision.collisionSlice.maxX) * 0.5f,
+		(collision.collisionSlice.minY + collision.collisionSlice.maxY) * 0.5f,
+		(collision.collisionSlice.minZ + collision.collisionSlice.maxZ) * 0.5f);
+	dmg.burstCount    = 1;
+
+	Entity::TakeDamageMessage take_damage(
+		Entity::TakeDamageMessageID, sizeof(Entity::TakeDamageMessage),
+		inflictor->GetEntityID(), -1 /*unaimed -> receiver's cylinder resolves*/, dmg);
+	victim->Dispatch(&take_damage);
+
+	if (GroundLog())
+		DEBUG_STREAM << "[collide] dmg=" << resolved->damageAmount
+			<< " -> victim class=" << (int)victim->GetClassID()
+			<< " (zone==-1, resolved by receiver)\n" << std::flush;
+}
+
 void
 	Mech::ProcessCollision(
 		Scalar				time_slice,
@@ -2660,8 +2699,14 @@ void
 		// that would silently defeat this gate).
 		if (damage->surfaceNormal * rel < -1.0e-4f)			// _DAT_004ac044 (:15320-15323)
 			return;
-		// DEFERRED: mech-vs-mech TakeDamageMessage{0x64, len 0x12, zone=-1}
-		// dispatch to the other mech (:15324-15358) -- see the banner.
+		// Mech-vs-mech (:15324-15358): the binary gates on owner ClassID == Mech
+		// (0xbb9) then dispatches the collision DamageMessage (zone==-1) to the
+		// other mech.  STEP 6 (its cylinder table) now resolves the zone, so this
+		// is UNBLOCKED (was deferred: zone==-1 used to be dropped).
+		if (owner->IsDerivedFrom(*Mech::GetClassDerivations()))
+		{
+			BTDispatchCollisionDamage(this, owner, damage, collision);
+		}
 	}
 
 	// --- CulturalIcon owner (buildings/trees/props) (:15361-15404) ----------
@@ -2673,7 +2718,11 @@ void
 		// by the 1995 compiler) (:15364-15368).
 		if (damage->surfaceNormal * worldLinearVelocity < -1.0e-4f)
 			return;
-		// DEFERRED: crunch TakeDamageMessage to the icon (:15369-15401).
+		// Crunch (:15369-15401): dispatch the collision damage to the icon
+		// (zone==-1) BEFORE the walk-through sentinel overwrites the amount.
+		// Buildings with damage zones resolve via their handler; crushable props
+		// have none -> the base handler no-ops.  UNBLOCKED by STEP 6.
+		BTDispatchCollisionDamage(this, owner, damage, collision);
 		if (!stopping)
 			damage->damageAmount = 0.00123f;	// walk-through sentinel 0x3aa137f4 (:15402-15404)
 	}