fix(docs): hoist FitOnResize out of FlowDiagram render

Defining FitOnResize inside the parent render gave it a new component
identity on every parent render, forcing React to unmount/remount it
and tear down the ResizeObserver each time. Hoist it to module scope
and pass useReactFlow in as a prop. Also drop the unused instanceRef.

packages/kilo-docs/components/FlowDiagram/index.tsx

@@ -3,6 +3,33 @@
 import React, { useState, useEffect, useRef } from "react"
 import { diagrams } from "./diagrams"
 
+/**
+ * Re-fits the viewport whenever the React Flow container resizes.
+ * Defined at module scope so its component identity is stable across
+ * re-renders of FlowDiagram (otherwise React would unmount/remount it
+ * on every parent render and tear down the ResizeObserver each time).
+ */
+function FitOnResize({
+  useReactFlow,
+}: {
+  useReactFlow: typeof import("@xyflow/react").useReactFlow
+}) {
+  const { fitView } = useReactFlow()
+  const containerRef = useRef<HTMLDivElement | null>(null)
+
+  useEffect(() => {
+    const el = containerRef.current?.closest(".react-flow") as HTMLElement | null
+    if (!el) return
+    const observer = new ResizeObserver(() => {
+      fitView({ padding: 0.15 })
+    })
+    observer.observe(el)
+    return () => observer.disconnect()
+  }, [fitView])
+
+  return <div ref={containerRef} style={{ display: "none" }} />
+}
+
 /**
  * FlowDiagram renders an interactive React Flow diagram.
  * Loaded lazily to avoid bundling the entire @xyflow/react library on pages that don't use it.
@@ -15,7 +42,6 @@ import { diagrams } from "./diagrams"
 export function FlowDiagram({ name, height = "400px" }: { name: string; height?: string }) {
   const [mod, setMod] = useState<typeof import("@xyflow/react") | null>(null)
   const [cssLoaded, setCssLoaded] = useState(false)
-  const instanceRef = useRef<any>(null)
 
   useEffect(() => {
     Promise.all([
@@ -69,23 +95,6 @@ export function FlowDiagram({ name, height = "400px" }: { name: string; height?:
 
   const { ReactFlow, Background, BackgroundVariant, useReactFlow, ReactFlowProvider } = mod
 
-  const FitOnResize = () => {
-    const { fitView } = useReactFlow()
-    const containerRef = useRef<HTMLDivElement | null>(null)
-
-    useEffect(() => {
-      const el = containerRef.current?.closest(".react-flow") as HTMLElement | null
-      if (!el) return
-      const observer = new ResizeObserver(() => {
-        fitView({ padding: 0.15 })
-      })
-      observer.observe(el)
-      return () => observer.disconnect()
-    }, [fitView])
-
-    return <div ref={containerRef} style={{ display: "none" }} />
-  }
-
   return (
     <figure style={{ margin: "24px 0" }}>
       <div
@@ -118,7 +127,7 @@ export function FlowDiagram({ name, height = "400px" }: { name: string; height?:
             style={{ background: "#08080c" }}
           >
             <Background variant={BackgroundVariant.Dots} color="rgba(248,160,32,0.15)" gap={20} size={1} />
-            <FitOnResize />
+            <FitOnResize useReactFlow={useReactFlow} />
           </ReactFlow>
         </ReactFlowProvider>
       </div>