fix(fig): preserve kiwi version in export worker

packages/core/src/io/formats/fig/export-worker.ts

@@ -6,10 +6,18 @@ interface CompressMessage {
   thumbnailPng: Uint8Array
   metaJson: string
   images: Array<{ name: string; data: Uint8Array }>
+  figKiwiVersion?: number
 }
 
 self.onmessage = (e: MessageEvent<CompressMessage>) => {
-  const { schemaDeflated, kiwiData, thumbnailPng, metaJson, images } = e.data
-  const result = compressFigDataSync(schemaDeflated, kiwiData, thumbnailPng, metaJson, images)
+  const { schemaDeflated, kiwiData, thumbnailPng, metaJson, images, figKiwiVersion } = e.data
+  const result = compressFigDataSync(
+    schemaDeflated,
+    kiwiData,
+    thumbnailPng,
+    metaJson,
+    images,
+    figKiwiVersion
+  )
   self.postMessage(result, { transfer: [result.buffer] })
 }

packages/core/src/io/formats/fig/export.ts

@@ -389,7 +389,8 @@ function compressViaWorker(
   kiwiData: Uint8Array,
   thumbnailPng: Uint8Array,
   metaJson: string,
-  imageEntries: Array<{ name: string; data: Uint8Array }>
+  imageEntries: Array<{ name: string; data: Uint8Array }>,
+  figKiwiVersion?: number
 ): Promise<Uint8Array> {
   return new Promise((resolve, reject) => {
     const worker = new Worker(new URL('./export-worker.ts', import.meta.url), {
@@ -409,7 +410,14 @@ function compressViaWorker(
     // internal buffer, so transferring kiwiData.buffer or schemaDeflated.buffer detaches
     // buffers that may be shared with other views, causing "already detached" errors on
     // subsequent saves. Structured clone (the default) copies the data safely.
-    worker.postMessage({ schemaDeflated, kiwiData, thumbnailPng, metaJson, images: imageEntries })
+    worker.postMessage({
+      schemaDeflated,
+      kiwiData,
+      thumbnailPng,
+      metaJson,
+      images: imageEntries,
+      figKiwiVersion
+    })
   })
 }
 
@@ -422,7 +430,14 @@ export function compressFigData(
   figKiwiVersion?: number
 ): Promise<Uint8Array> {
   if (canUseWorker()) {
-    return compressViaWorker(schemaDeflated, kiwiData, thumbnailPng, metaJson, imageEntries)
+    return compressViaWorker(
+      schemaDeflated,
+      kiwiData,
+      thumbnailPng,
+      metaJson,
+      imageEntries,
+      figKiwiVersion
+    )
   }
   return Promise.resolve(
     compressFigDataSync(

tests/engine/io/fig/export/worker.test.ts

@@ -2,6 +2,8 @@ import { describe, test, expect, beforeAll, setDefaultTimeout } from 'bun:test'
 import { readFileSync } from 'node:fs'
 import { resolve } from 'node:path'
 
+import { unzipSync } from 'fflate'
+
 import {
   parseFigFile,
   exportFigFile,
@@ -15,6 +17,42 @@ import { heavy } from '#tests/helpers/test-utils'
 setDefaultTimeout(30_000)
 
 const FIXTURES = resolve(import.meta.dir, '../../../../fixtures')
+const CUSTOM_FIG_KIWI_VERSION = 77
+
+function canvasFigVersion(figData: Uint8Array): number {
+  const zip = unzipSync(figData)
+  const canvasData = zip['canvas.fig'] ?? zip.canvas
+  expect(canvasData).toBeDefined()
+  return new DataView(canvasData.buffer, canvasData.byteOffset, canvasData.byteLength).getUint32(
+    8,
+    true
+  )
+}
+
+function compressInWorker(message: {
+  schemaDeflated: Uint8Array
+  kiwiData: Uint8Array
+  thumbnailPng: Uint8Array
+  metaJson: string
+  images: Array<{ name: string; data: Uint8Array }>
+  figKiwiVersion?: number
+}): Promise<Uint8Array> {
+  return new Promise((resolve, reject) => {
+    const worker = new Worker(
+      new URL('../../../../../packages/core/src/io/formats/fig/export-worker.ts', import.meta.url),
+      { type: 'module' }
+    )
+    worker.onmessage = (event: MessageEvent<Uint8Array>) => {
+      worker.terminate()
+      resolve(event.data)
+    }
+    worker.onerror = (event) => {
+      worker.terminate()
+      reject(new Error(event.message))
+    }
+    worker.postMessage(message, [])
+  })
+}
 
 describe('fig export compression', () => {
   test('compressFigDataSync produces valid zip', async () => {
@@ -49,6 +87,34 @@ describe('fig export compression', () => {
     expect(result[0]).toBe(0x50)
     expect(result[1]).toBe(0x4b)
   })
+
+  test('compression preserves custom fig-kiwi version in sync and worker paths', async () => {
+    const schemaDeflated = new Uint8Array([0x78, 0x01, 0x03, 0x00, 0x00, 0x00, 0x00, 0x01])
+    const kiwiData = new Uint8Array([10, 20, 30])
+    const thumbnailPng = new Uint8Array([0x89, 0x50])
+    const metaJson = JSON.stringify({ version: 1, app: 'test' })
+    const images: Array<{ name: string; data: Uint8Array }> = []
+
+    const syncResult = compressFigDataSync(
+      schemaDeflated,
+      kiwiData,
+      thumbnailPng,
+      metaJson,
+      images,
+      CUSTOM_FIG_KIWI_VERSION
+    )
+    const workerResult = await compressInWorker({
+      schemaDeflated,
+      kiwiData,
+      thumbnailPng,
+      metaJson,
+      images,
+      figKiwiVersion: CUSTOM_FIG_KIWI_VERSION
+    })
+
+    expect(canvasFigVersion(syncResult)).toBe(CUSTOM_FIG_KIWI_VERSION)
+    expect(canvasFigVersion(workerResult)).toBe(CUSTOM_FIG_KIWI_VERSION)
+  })
 })
 
 heavy('fig export roundtrip', () => {