diff --git a/src/main/kotlin/com/bolenpad/photophetch/ui/AppState.kt b/src/main/kotlin/com/bolenpad/photophetch/ui/AppState.kt
index 1ab1d3f..2233a4a 100644
--- a/src/main/kotlin/com/bolenpad/photophetch/ui/AppState.kt
+++ b/src/main/kotlin/com/bolenpad/photophetch/ui/AppState.kt
@@ -235,26 +235,16 @@ class AppState(private val configStore: ConfigStore) {
                     val cachePath = cacheDir.resolve("$hash.jpg")
                     if (tmpFile.toFile().exists() && tmpFile.toFile().length() > 0 && !cachePath.toFile().exists()) {
                         val success = if (ext in setOf("heic", "heif")) {
-                            // Extract embedded EXIF thumbnail from HEIC (fast, no full decode needed)
-                            // sips -getProperty thumbnail reads only the thumbnail track
+                            // Convert partial HEIC to JPEG via sips
+                            // sips can decode HEIC even from a partial file if the header is intact
                             val sips = ProcessBuilder(
-                                "sips", "-getProperty", "thumbnail",
+                                "sips", "--resampleWidth", "240",
+                                "--setProperty", "format", "jpeg",
                                 tmpFile.toString(), "--out", cachePath.toString()
                             ).redirectErrorStream(true).start()
-                            val output = sips.inputStream.bufferedReader().readText()
+                            sips.inputStream.readBytes()
                             sips.waitFor()
-                            val ok = cachePath.toFile().exists() && cachePath.toFile().length() > 0
-                            if (!ok) {
-                                // Thumbnail extraction failed — fall back to full resample
-                                val sips2 = ProcessBuilder(
-                                    "sips", "--resampleWidth", "240",
-                                    "--setProperty", "format", "jpeg",
-                                    tmpFile.toString(), "--out", cachePath.toString()
-                                ).redirectErrorStream(true).start()
-                                sips2.inputStream.readBytes()
-                                sips2.waitFor()
-                                cachePath.toFile().exists() && cachePath.toFile().length() > 0
-                            } else ok
+                            cachePath.toFile().exists() && cachePath.toFile().length() > 0
                         } else {
                             // JPEG/PNG: simple resample
                             val sips = ProcessBuilder(
diff --git a/src/main/resources/scripts/photophetch-ios-helper.py b/src/main/resources/scripts/photophetch-ios-helper.py
index 06ee9ba..1a13d11 100644
--- a/src/main/resources/scripts/photophetch-ios-helper.py
+++ b/src/main/resources/scripts/photophetch-ios-helper.py
@@ -176,15 +176,20 @@ async def cmd_batch_thumbs(pairs_json: str):
         for device_path, local_path in pairs:
             ext = device_path.rsplit('.', 1)[-1].lower() if '.' in device_path else ''
             is_heic = ext in ('heic', 'heif')
-            read_size = 1024 * 1024 if is_heic else 512 * 1024  # 1MB for HEIC, 512KB for others
             try:
                 os.makedirs(os.path.dirname(os.path.abspath(local_path)), exist_ok=True)
-                try:
-                    data = await afc.fread(device_path, read_size, 0)
-                    with open(local_path, 'wb') as f:
-                        f.write(data)
-                except Exception:
+                if is_heic:
+                    # HEIC: pull full file — sips needs the full image to convert to JPEG
+                    # Cached permanently so only transferred once
                     await afc.pull(device_path, local_path)
+                else:
+                    # JPEG/PNG: 512KB partial read is sufficient for sips resample
+                    try:
+                        data = await afc.fread(device_path, 512 * 1024, 0)
+                        with open(local_path, 'wb') as f:
+                            f.write(data)
+                    except Exception:
+                        await afc.pull(device_path, local_path)
                 results.append({'devicePath': device_path, 'ok': True})
             except Exception as e:
                 results.append({'devicePath': device_path, 'ok': False, 'error': str(e)})