fix: drag speed on pan

client/ui.go

@@ -82,6 +82,10 @@ func (e *client) renderRasterImage(viewportW, viewportH int, p world.RenderParam
 		return image.NewRGBA(image.Rect(0, 0, 0, 0))
 	}
 
+	// Keep the incoming zoom snapshot so we can safely sync corrected zoom back
+	// to base params only when no newer zoom was written concurrently.
+	inputZoom := p.CameraZoom
+
 	// Record current raster pixel size (used for event coordinate conversion).
 	e.metaMu.Lock()
 	e.lastRasterPxW = viewportW
@@ -95,7 +99,17 @@ func (e *client) renderRasterImage(viewportW, viewportH int, p world.RenderParam
 	p.MarginYPx = viewportH / 4
 
 	// Correct zoom for viewport/world constraints, and clamp camera for no-wrap.
-	p.CameraZoom = e.world.CorrectCameraZoom(p.CameraZoom, viewportW, viewportH)
+	correctedZoom := e.world.CorrectCameraZoom(inputZoom, viewportW, viewportH)
+	p.CameraZoom = correctedZoom
+
+	// Sync corrected zoom to the canonical UI-facing params snapshot.
+	// Guard prevents stale render snapshots from overwriting a newer zoom value
+	// that may have been set by another UI event.
+	e.mu.Lock()
+	if e.wp.CameraZoom == inputZoom {
+		e.wp.CameraZoom = correctedZoom
+	}
+	e.mu.Unlock()
 
 	// Ensure indexing is up-to-date when viewport size or zoom changes.
 	zoomFp, err := p.CameraZoomFp()