refactor(core): avoid record casts for dynamic writes

- Use KiwiNodeChange index signature for raw Figma field assignment
- Type preserved raw NodeChange keys with keyof NodeChange
- Replace scene graph property write casts with a typed setter

packages/core/src/kiwi/fig/node-change/convert.ts

@@ -823,7 +823,7 @@ export const FIGMA_RAW_NODE_FIELD_KEYS = [
   'vectorData',
   'fillGeometry',
   'strokeGeometry'
-]
+] as const satisfies readonly (keyof NodeChange)[]
 
 function extractFigmaRawGeometry(
   nc: NodeChange,
@@ -831,7 +831,7 @@ function extractFigmaRawGeometry(
 ): Pick<SceneNode['source']['fig'], 'rawSize' | 'rawTransform' | 'rawNodeFields'> {
   const rawNodeFields: Record<string, unknown> = {}
   for (const key of FIGMA_RAW_NODE_FIELD_KEYS) {
-    const value = (nc as Record<string, unknown>)[key]
+    const value = nc[key]
     if (value !== undefined) rawNodeFields[key] = preserveFigmaPayloadBlobs(value, blobs)
   }
   return {

packages/core/src/kiwi/fig/node-change/export-node.ts

@@ -309,9 +309,9 @@ function applyRawFigmaNodeFields(
     blobIndexByHex: context.blobIndexByHex,
     includePaintVariables: true,
     includeVariableMaps: true
-  }) as Record<string, unknown>
-  for (const key of Object.keys(materialized)) {
-    if (RAW_FIELDS_OVERRIDE_BLOCKLIST.has(key)) continue
+  }) as Partial<KiwiNodeChange>
+  for (const key of Object.keys(materialized) as (keyof KiwiNodeChange)[]) {
+    if (RAW_FIELDS_OVERRIDE_BLOCKLIST.has(String(key))) continue
     // For paint arrays on imported nodes, the raw NC data preserves the
     // original opacity/color.a split (e.g. opacity=0 for invisible strokes).
     // The scene model may lose this distinction for instance children whose
@@ -328,7 +328,7 @@ function applyRawFigmaNodeFields(
       if (context.assetRefToVarGuid && context.assetRefToVarGuid.size > 0) {
         paints = convertColorVarAssetRefs(paints, context.assetRefToVarGuid)
       }
-      ;(nc as Record<string, unknown>)[key] = paints
+      nc[key] = paints
       continue
     }
     // Also convert colorVar.assetRef in raw effects (e.g. shadow color variables)
@@ -339,16 +339,16 @@ function applyRawFigmaNodeFields(
       context.assetRefToVarGuid.size > 0
     ) {
       const converted = convertColorVarAssetRefs(materialized[key], context.assetRefToVarGuid)
-      ;(nc as Record<string, unknown>)[key] = converted
+      nc[key] = converted
       continue
     }
     if (key === 'derivedTextData' && node.source.id) {
-      ;(nc as Record<string, unknown>)[key] = materialized[key]
+      nc[key] = materialized[key]
       continue
     }
     // Skip any key already set on nc — explicit serialization takes priority
-    if (key in (nc as Record<string, unknown>)) continue
-    ;(nc as Record<string, unknown>)[key] = materialized[key]
+    if (key in nc) continue
+    nc[key] = materialized[key]
   }
 }
 
@@ -360,7 +360,7 @@ function applyRawFigmaNodeFields(
  * reference resolvable regardless of whether key/version is present on the
  * VARIABLE NodeChange.
  */
-function convertColorVarAssetRefs(paints: unknown, assetRefToVarGuid: Map<string, GUID>): unknown {
+function convertColorVarAssetRefs<T>(paints: T, assetRefToVarGuid: Map<string, GUID>): T {
   if (!Array.isArray(paints)) return paints
   const result = paints.map((paint: Record<string, unknown>) => {
     const colorVar = paint.colorVar as Record<string, unknown> | undefined
@@ -390,7 +390,7 @@ function convertColorVarAssetRefs(paints: unknown, assetRefToVarGuid: Map<string
   })
   // Check if any paint was actually changed (skip expensive JSON comparison)
   for (let i = 0; i < paints.length; i++) {
-    if (result[i] !== paints[i]) return result
+    if (result[i] !== paints[i]) return result as T
   }
   return paints
 }

packages/core/src/scene-graph/instances.ts

@@ -1,4 +1,4 @@
-import type { SceneGraph, SceneNode, Fill, Stroke, Effect, StyleRun } from './'
+import type { SceneGraph, SceneNode } from './'
 import { copyEffects, copyFills, copyStrokes, copyStyleRuns } from './copy'
 
 const INSTANCE_SYNC_PROPS: (keyof SceneNode)[] = [
@@ -40,22 +40,30 @@ const INSTANCE_SYNC_PROPS: (keyof SceneNode)[] = [
   'borderLeftWeight'
 ]
 
+function setSceneProp<K extends keyof SceneNode>(
+  target: Partial<SceneNode>,
+  key: K,
+  value: SceneNode[K]
+): void {
+  target[key] = value
+}
+
 function copyProp(
   target: Partial<SceneNode> | SceneNode,
   source: SceneNode,
   key: keyof SceneNode
 ): void {
-  const val = source[key]
   if (key === 'fills') {
-    ;(target as Record<string, unknown>)[key] = copyFills(val as Fill[])
+    setSceneProp(target, key, copyFills(source.fills))
   } else if (key === 'strokes') {
-    ;(target as Record<string, unknown>)[key] = copyStrokes(val as Stroke[])
+    setSceneProp(target, key, copyStrokes(source.strokes))
   } else if (key === 'effects') {
-    ;(target as Record<string, unknown>)[key] = copyEffects(val as Effect[])
+    setSceneProp(target, key, copyEffects(source.effects))
   } else if (key === 'styleRuns') {
-    ;(target as Record<string, unknown>)[key] = copyStyleRuns(val as StyleRun[])
+    setSceneProp(target, key, copyStyleRuns(source.styleRuns))
   } else {
-    ;(target as Record<string, unknown>)[key] = Array.isArray(val) ? structuredClone(val) : val
+    const value = source[key]
+    setSceneProp(target, key, Array.isArray(value) ? structuredClone(value) : value)
   }
 }