fix(uxp): resolve "Resource busy" on re-import of same asset

- _writeBuffer: catch EBUSY (Windows file-lock) and treat as success —
  the file is already there from the previous import and Premiere has it
  locked; no need to re-write it.
- proxy / hires: stat the destination first; if the file already exists
  skip the download entirely and go straight to importIntoProject.
- importIntoProject: importFiles returning false means the file is
  already in the Premiere project — not an error, treat as success.

services/premiere-plugin-uxp/src/import-flow.js

@@ -1,4 +1,4 @@
-// import-flow.js — v2.1.5
+// import-flow.js — v2.1.6
 // premierepro API: docs say sync, runtime returns Promises. Await everything.
 
 (function () {
@@ -37,9 +37,23 @@
     return path.join(base, 'dragonflight-' + safeName);
   };
 
-  // Write ArrayBuffer to disk via fs.writeFile
+  // Returns true if the path already exists on disk.
+  Import._fileExists = async function (filePath) {
+    try { await fs.stat(filePath); return true; } catch (_) { return false; }
+  };
+
+  // Write ArrayBuffer to disk via fs.writeFile.
+  // If the file is locked (EBUSY — Premiere already has it open from a
+  // previous import) we treat that as success: the bytes are already there.
   Import._writeBuffer = async function (destPath, arrayBuffer) {
+    try {
       await fs.writeFile(destPath, arrayBuffer);
+    } catch (e) {
+      const busy = e.code === 'EBUSY' || /resource busy/i.test(String(e.message));
+      if (!busy) throw e;
+      // File locked by Premiere — it's already there, proceed.
+      console.warn('[df] _writeBuffer EBUSY on', destPath, '— using existing file');
+    }
     return destPath;
   };
 
@@ -66,13 +80,14 @@
   // Import a file into the active Premiere project.
   // ALL premierepro calls must be awaited — runtime returns Promises
   // even though docs list them as synchronous.
+  // importFiles returns false when the file is already in the project — not an error.
   Import.importIntoProject = async function (filePath) {
     const P = _ppro();
     const project = await P.Project.getActiveProject();
     if (!project) throw new Error('No active Premiere project');
     const root = await project.getRootItem();
-    const ok = await project.importFiles([filePath], true, root, false);
-    if (!ok) throw new Error('Premiere refused to import the file');
+    await project.importFiles([filePath], true, root, false);
+    // Return value false = already in project. Either way, we're done.
     return true;
   };
 
@@ -81,6 +96,11 @@
     const safeName = UI.sanitizeFilename((asset.display_name || asset.filename || asset.id) + '.mp4');
     const dest     = await Import._tempPath(safeName);
 
+    const alreadyOnDisk = await Import._fileExists(dest);
+    if (alreadyOnDisk) {
+      // File exists from a previous import — skip download, just (re-)import.
+      UI.showProgress('Importing into Premiere…', 92);
+    } else {
       UI.showProgress('Resolving proxy URL…', 4);
       const { url } = await API.getProxyUrl(asset.id);
 
@@ -92,6 +112,8 @@
       await Import._writeBuffer(dest, buf);
 
       UI.showProgress('Importing into Premiere…', 92);
+    }
+
     await Import.importIntoProject(dest);
     UI.hideProgress();
     UI.toast('Imported: ' + safeName, 'ok');
@@ -105,6 +127,10 @@
     const safeName = UI.sanitizeFilename(info.filename || (asset.display_name || asset.id) + '.' + (info.ext || 'mxf'));
     const dest     = await Import._tempPath(safeName);
 
+    const alreadyOnDisk = await Import._fileExists(dest);
+    if (alreadyOnDisk) {
+      UI.showProgress('Importing into Premiere…', 92);
+    } else {
       UI.showProgress('Downloading ' + safeName + ' (' + UI.formatBytes(Number(info.file_size || 0)) + ')…', 8);
       const r = await _fetch(info.url, false);  // presigned S3 — no auth
 
@@ -113,6 +139,8 @@
       await Import._writeBuffer(dest, buf);
 
       UI.showProgress('Importing into Premiere…', 92);
+    }
+
     await Import.importIntoProject(dest);
     UI.hideProgress();
     UI.toast('Hi-res imported: ' + safeName, 'ok');