diff --git a/apps/desktop-shell/scripts/check-config.mjs b/apps/desktop-shell/scripts/check-config.mjs
index 845913123..5caccb1f2 100644
--- a/apps/desktop-shell/scripts/check-config.mjs
+++ b/apps/desktop-shell/scripts/check-config.mjs
@@ -2357,6 +2357,9 @@ const requiredRustHostSnippets = [
   '__genarrativeDesktopHistoryIndex',
   "console.warn('desktop navigation state sync failed', error)",
   'file.imageDropped',
+  'normalize_desktop_drop_position',
+  '.round().max(0.0) as i32',
+  'desktop_drop_position_is_rounded_and_clamped_to_window_bounds',
   'emit_desktop_image_drop_event(&drop_window, paths, drop_position)',
   'app.notification().builder()',
   'desktop_entry_url_with_host_context',
diff --git a/apps/desktop-shell/src-tauri/src/shell/file_drop.rs b/apps/desktop-shell/src-tauri/src/shell/file_drop.rs
index 992f601cc..7bfe31c79 100644
--- a/apps/desktop-shell/src-tauri/src/shell/file_drop.rs
+++ b/apps/desktop-shell/src-tauri/src/shell/file_drop.rs
@@ -15,6 +15,10 @@ fn first_valid_desktop_image_drop_payload(
         .find_map(|path| import_image_file_payload(path.clone(), "dropped", Some(position)).ok())
 }
 
+fn normalize_desktop_drop_position(x: f64, y: f64) -> (i32, i32) {
+    (x.round().max(0.0) as i32, y.round().max(0.0) as i32)
+}
+
 fn emit_desktop_image_drop_event(
     window: &WebviewWindow,
     paths: &[PathBuf],
@@ -33,7 +37,7 @@ pub(crate) fn register_desktop_file_drop_events(window: &WebviewWindow) {
     let drop_window = window.clone();
     window.on_window_event(move |event| {
         if let WindowEvent::DragDrop(DragDropEvent::Drop { paths, position }) = event {
-            let drop_position = (position.x.round() as i32, position.y.round() as i32);
+            let drop_position = normalize_desktop_drop_position(position.x, position.y);
             log_desktop_host_event_result(
                 "file.imageDropped",
                 emit_desktop_image_drop_event(&drop_window, paths, drop_position),
@@ -103,4 +107,10 @@ mod tests {
         fs::remove_file(text_path).expect("remove text drop file");
         fs::remove_dir(directory_path).expect("remove drop directory");
     }
+
+    #[test]
+    fn desktop_drop_position_is_rounded_and_clamped_to_window_bounds() {
+        assert_eq!(normalize_desktop_drop_position(12.4, 24.6), (12, 25));
+        assert_eq!(normalize_desktop_drop_position(-4.2, -0.6), (0, 0));
+    }
 }
diff --git a/docs/project-memory/shared-memory/decision-log.md b/docs/project-memory/shared-memory/decision-log.md
index c0dd38901..f9cbbfc73 100644
--- a/docs/project-memory/shared-memory/decision-log.md
+++ b/docs/project-memory/shared-memory/decision-log.md
@@ -16,6 +16,14 @@
 
 ---
 
+## 2026-06-20 桌面图片拖拽坐标非负边界
+
+- 背景：Tauri 桌面壳通过系统拖拽事件向 H5 发送 `file.imageDropped`，拖拽坐标来自窗口事件；窗口边缘或平台差异可能产生负数或小数坐标，H5 只负责校验有限 number，不负责裁剪桌面系统坐标。
+- 决策：桌面壳在发送图片拖拽 HostBridge 事件前，必须把拖拽坐标 round 成整数并裁剪到非负值，再组装 import image payload；配置检查反查坐标归一 helper 和对应 Rust 单测。
+- 影响范围：`apps/desktop-shell/src-tauri/src/shell/file_drop.rs`、`apps/desktop-shell/scripts/check-config.mjs`。
+- 验证方式：`npm run desktop-shell:test -- file_drop`、`npm run desktop-shell:typecheck`、`npm run check:native-shells`、`npm run check:encoding`、`git diff --check`。
+- 关联文档：`docs/【前端架构】ExpoReactNative与Tauri宿主壳方案-2026-06-17.md`、`docs/【前端架构】宿主壳能力统一协议-2026-06-17.md`。
+
 ## 2026-06-20 移动扫码权限异步取消边界
 
 - 背景：Expo 移动壳 `scanner.scanQrCode` 会打开真实相机权限请求和扫码 overlay；如果用户在系统权限 Promise 返回前关闭扫码，旧权限结果不能重新激活 CameraView，也不能完成已经取消的 HostBridge 请求。