experiment: better web picker using @pierre/tree (#31208)

packages/app/src/context/platform.tsx

@@ -55,6 +55,9 @@ type PlatformBase = {
     onFile: (file: File) => Promise<unknown>,
   ): Promise<void>
 
+  /** Resolve the native source path for a desktop File. */
+  getPathForFile?(file: File): string
+
   /** Open a native save file picker dialog (desktop only) */
   saveFilePickerDialog?(opts?: SaveFilePickerOptions): Promise<string | null>
 

packages/app/src/context/prompt.tsx

@@ -33,6 +33,7 @@ export interface ImageAttachmentPart {
   type: "image"
   id: string
   filename: string
+  sourcePath?: string
   mime: string
   dataUrl: string
 }