diff --git a/src/ifcviewer/BufferPool.h b/src/ifcviewer/BufferPool.h
index 9f38308e72..5e9811f7a9 100644
--- a/src/ifcviewer/BufferPool.h
+++ b/src/ifcviewer/BufferPool.h
@@ -123,6 +123,13 @@ public:
                        <= max_total_capacity_bytes_);
     }
 
+    // True once the driver (not the budget) has refused growth even at the
+    // floor size. On platforms with no memory query this is the only device
+    // report there is: the owner treats the first refusal as a pressure
+    // event and carves the required-tier margin out of the cache before a
+    // required allocation has to fail for it (see ViewportCore::render).
+    bool     growth_was_refused() const { return growth_disabled_; }
+
     // Whether a growth is in flight. On web that window is real time — a
     // provisional sub-buffer validates asynchronously a frame or two later — so
     // the streaming driver has to know that free space is still on its way and
diff --git a/src/ifcviewer/ViewportCore.cpp b/src/ifcviewer/ViewportCore.cpp
index 2acc65d501..f953f566db 100644
--- a/src/ifcviewer/ViewportCore.cpp
+++ b/src/ifcviewer/ViewportCore.cpp
@@ -7732,6 +7732,24 @@ void ViewportCore::render() {
     Stopwatch frame_timer;
     frame_timer.start();
 
+    // The driver refusing pool growth is the query-less platform's device
+    // report (web has no memory query; the pool just grew until the GPU
+    // process said no). Answer it once, immediately: lower the budget so
+    // the required-tier margin comes back out of the cache NOW, instead of
+    // the next attachment resize having to fail — and paint broken frames —
+    // before pressure feedback carves the same room.
+    if (pool_.growth_was_refused() && !pool_growth_refusal_handled_) {
+        pool_growth_refusal_handled_ = true;
+        const double mb = 1.0 / (1024.0 * 1024.0);
+        Log::info() << "[wgpu] driver refused geometry-cache growth at "
+                    << double(pool_.total_capacity_bytes()) * mb
+                    << " MB -- reserving the required-tier margin out of the cache";
+        if (budget_.onPressure(pool_.total_capacity_bytes(),
+                               GpuBudget::kFixedMarginBytes, 0)) {
+            applyBudgetToPool();
+        }
+    }
+
     // Drain any HiZ async readbacks completed since last frame.
     if (hiz_enabled_) drainHizReadbacks();
 
diff --git a/src/ifcviewer/ViewportCore.h b/src/ifcviewer/ViewportCore.h
index 3890cce69c..3f1365f8e8 100644
--- a/src/ifcviewer/ViewportCore.h
+++ b/src/ifcviewer/ViewportCore.h
@@ -1155,6 +1155,9 @@ private:
     void releaseRenderAttachments();
 
     GpuBudget budget_;
+    // Latch: the pool's first driver-refused growth has been answered by
+    // carving the margin out of the cache (see render()).
+    bool      pool_growth_refusal_handled_ = false;
     // Adapter ids, read once at init, for matching the driver's memory
     // report to the card wgpu is actually using.
     std::uint32_t adapter_vendor_id_ = 0;