fix: smooth settings panel transition and prevent image flicker on toggle

Animate InlineParameterPanel expand/collapse with max-height transition
instead of conditional rendering. Lock BaseNode content height during
resize operations to prevent intermediate layout states causing image
flicker.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/components/nodes/BaseNode.tsx

@@ -75,6 +75,7 @@ export function BaseNode({
   const { getNodes, setNodes } = useReactFlow();
 
   const settingsPanelRef = useRef<HTMLDivElement>(null);
+  const contentRef = useRef<HTMLDivElement>(null);
   const trackedSettingsHeightRef = useRef(0);
 
   // Adjust node height when settings collapse
@@ -82,6 +83,13 @@ export function BaseNode({
     if (!settingsExpanded && trackedSettingsHeightRef.current > 0) {
       const heightToRemove = trackedSettingsHeightRef.current;
       trackedSettingsHeightRef.current = 0;
+
+      // Lock content height to prevent image flicker during resize
+      const contentEl = contentRef.current;
+      if (contentEl) {
+        contentEl.style.height = contentEl.offsetHeight + "px";
+      }
+
       setNodes((nodes) =>
         nodes.map((node) => {
           if (node.id !== id) return node;
@@ -90,6 +98,13 @@ export function BaseNode({
           return applyNodeDimensions(node, getNodeDimension(node, "width"), newHeight);
         })
       );
+
+      // Release locked height after layout settles
+      requestAnimationFrame(() => {
+        if (contentEl) {
+          contentEl.style.height = "";
+        }
+      });
     }
     // eslint-disable-next-line react-hooks/exhaustive-deps
   }, [settingsExpanded]);
@@ -108,6 +123,13 @@ export function BaseNode({
         if (Math.abs(delta) < 2) continue; // Ignore sub-pixel changes
 
         trackedSettingsHeightRef.current = newPanelHeight;
+
+        // Lock content height to prevent image flicker during resize
+        const contentEl = contentRef.current;
+        if (contentEl) {
+          contentEl.style.height = contentEl.offsetHeight + "px";
+        }
+
         setNodes((nodes) =>
           nodes.map((node) => {
             if (node.id !== id) return node;
@@ -116,6 +138,13 @@ export function BaseNode({
             return applyNodeDimensions(node, getNodeDimension(node, "width"), newHeight);
           })
         );
+
+        // Release locked height after layout settles
+        requestAnimationFrame(() => {
+          if (contentEl) {
+            contentEl.style.height = "";
+          }
+        });
       }
     });
 
@@ -214,7 +243,7 @@ export function BaseNode({
           setHoveredNodeId(null);
         }}
       >
-        <div className={contentClassName ?? (fullBleed ? "flex-1 min-h-0 relative" : "px-3 pb-4 flex-1 min-h-0 overflow-hidden flex flex-col")}>{children}</div>
+        <div ref={contentRef} className={contentClassName ?? (fullBleed ? "flex-1 min-h-0 relative" : "px-3 pb-4 flex-1 min-h-0 overflow-hidden flex flex-col")}>{children}</div>
       </div>
       {settingsPanel && (
         <div ref={settingsPanelRef}>

src/components/nodes/InlineParameterPanel.tsx

@@ -1,6 +1,6 @@
 "use client";
 
-import React, { ReactNode } from "react";
+import React, { ReactNode, useRef, useState, useEffect } from "react";
 
 interface InlineParameterPanelProps {
   expanded: boolean;
@@ -11,7 +11,7 @@ interface InlineParameterPanelProps {
 
 /**
  * Collapsible parameter container for inline display within generation nodes.
- * Provides a chevron toggle button and instant expand/collapse.
+ * Provides a chevron toggle button and smooth animated expand/collapse.
  */
 function InlineParameterPanelInner({
   expanded,
@@ -19,6 +19,15 @@ function InlineParameterPanelInner({
   children,
   nodeId,
 }: InlineParameterPanelProps) {
+  const contentRef = useRef<HTMLDivElement>(null);
+  const [contentHeight, setContentHeight] = useState(0);
+
+  useEffect(() => {
+    if (expanded && contentRef.current) {
+      setContentHeight(contentRef.current.scrollHeight);
+    }
+  }, [expanded, children]);
+
   return (
     <>
       {/* Settings toggle button — no background when collapsed, floats below node edge */}
@@ -45,15 +54,16 @@ function InlineParameterPanelInner({
         </svg>
       </button>
 
-      {/* Content area — instant show/hide */}
-      {expanded && (
-        <div
-          id={`params-${nodeId}`}
-          className="nodrag nopan nowheel bg-[#2a2a2a] px-3 pt-2 pb-3 rounded-b-lg"
-        >
+      {/* Content area — smooth height animation */}
+      <div
+        id={`params-${nodeId}`}
+        className="nodrag nopan nowheel bg-[#2a2a2a] overflow-hidden transition-[max-height] duration-150 ease-out"
+        style={{ maxHeight: expanded ? contentHeight : 0 }}
+      >
+        <div ref={contentRef} className="px-3 pt-2 pb-3 rounded-b-lg">
           {children}
         </div>
-      )}
+      </div>
     </>
   );
 }