Function handleFileClick

renderer.js:13336–13456

(event, filePath)

              thumbnail = await generateThumbnail(model.filePath);
            } catch (renderError) {
              console.error(`Error generating 3D thumbnail for ${model.filePath}:`, renderError);
            }
          }

          // 3. Validate and fallback to default if necessary (STL/3MF only reach here)
          if (!thumbnail || typeof thumbnail !== 'string' || !thumbnail.startsWith('data:image') || isFailurePlaceholderThumbnail(thumbnail)) {
            thumbnail = '3d.png';
          }

          // 4. Save real renders only — never lock in failure placeholders
          if (!saved3mfEmbedsViaBatch && thumbnail !== '3d.png') {
            await window.electron.saveThumbnail(model.filePath, thumbnail);
          } else if (!saved3mfEmbedsViaBatch) {
            await window.electron.saveThumbnail(model.filePath, '3d.png');
          }
          
          // 5. Hash during bulk jobs is optional (extra I/O / memory); skip in Docker headless.
          if (!skipHash && (!model.hash || model.hash === '')) {
            try {
              await window.electron.calculateFileHash(model.filePath);
            } catch (hashError) {
              console.error(`Error calculating hash for ${model.filePath}:`, hashError);
              // Continue even if hash calculation fails
            }
          }

          thumbnail = null;
          
        } catch (error) {
          console.error(`Failed to generate thumbnail for ${model.filePath}:`, error);
          // Do not persist typed STL/3MF placeholders — that blocks retries (common on Docker timeouts).
          try {
            await window.electron.saveThumbnail(model.filePath, '3d.png');
          } catch (saveError) {
            console.error(`Failed to save default thumbnail for ${model.filePath}:`, saveError);
          }
        } finally {
          processedInBatch++;
          processedCount = processedInBatch;
          const absoluteProcessed = progressOffset + processedInBatch;
          generatedThumbnailsCount = absoluteProcessed;
          
          // Update progress
          if (hasProgressUI) {
            const progress = Math.floor((absoluteProcessed / progressTotal) * 100);
            activeProgressBar.style.width = `${progress}%`;
            activeProgressText.textContent = `Processing ${absoluteProcessed}/${progressTotal} (${progress}%)`;
          }
          if (overlay && !isCancelled) {
            overlay.update(absoluteProcessed, progressTotal);
          }
          if (!isCancelled) {
            await reportHeadlessProgress(absoluteProcessed, progressTotal);
          }

          // Between models: yield + occasional soft GC. Soft dispose only —
          // never forceContextLoss (restarts GPU process → Skia OOM log storms).
          if (maxConcurrentThumbnails === 1) {