fix(mod_unpack): flatten nested output directory without temporary rename steps to avoid race conditions

ts/mod_unpack/classes.tsunpacker.ts

@@ -1,3 +1,4 @@
+import * as fs from 'fs';
 import * as path from 'path';
 import { TsPublishConfig } from '../mod_config/index.js';
 import { FsHelpers } from '../mod_fs/index.js';
@@ -82,9 +83,16 @@ export class TsUnpacker {
   /**
    * Perform the unpack operation - flatten nested output directories.
    *
-   * Renames the nested directory to a temp location, removes the dest dir,
-   * then renames the temp dir back as dest. Uses only rename operations
-   * which are atomic at the kernel level.
+   * When TypeScript compiles files that import from sibling directories,
+   * it creates a nested structure like dist_ts/ts/ with siblings like
+   * dist_ts/ts_interfaces/. This method flattens by:
+   * 1. Removing sibling directories (non-source folders)
+   * 2. Moving contents of the nested source folder up to the dest dir
+   * 3. Removing the now-empty nested source folder
+   *
+   * This approach never creates temporary sibling directories and never
+   * removes the destination directory itself, avoiding filesystem race
+   * conditions observed with the previous rename-rm-rename pattern.
    *
    * Returns true if unpacking was performed, false if skipped.
    */
@@ -98,19 +106,26 @@ export class TsUnpacker {
     }
 
     const nestedPath = this.getNestedPath();
-    const tempPath = this.destDir + '.__unpack_temp__';
 
-    // Step 1: Clean up any leftover temp dir from a previous failed run
-    await FsHelpers.removeDirectory(tempPath);
+    // Step 1: Remove sibling entries (everything in dest except the source folder)
+    const destEntries = await fs.promises.readdir(this.destDir);
+    for (const entry of destEntries) {
+      if (entry !== this.sourceFolderName) {
+        await fs.promises.rm(path.join(this.destDir, entry), { recursive: true, force: true });
+      }
+    }
 
-    // Step 2: Rename nested → temp
-    await FsHelpers.move(nestedPath, tempPath);
+    // Step 2: Move all contents from nested dir up to dest dir
+    const nestedEntries = await fs.promises.readdir(nestedPath);
+    for (const entry of nestedEntries) {
+      await fs.promises.rename(
+        path.join(nestedPath, entry),
+        path.join(this.destDir, entry),
+      );
+    }
 
-    // Step 3: Remove dest dir (now contains only sibling folders)
-    await FsHelpers.removeDirectory(this.destDir);
-
-    // Step 4: Rename temp → dest
-    await FsHelpers.move(tempPath, this.destDir);
+    // Step 3: Remove the now-empty nested directory
+    await fs.promises.rmdir(nestedPath);
 
     return true;
   }