feat(classifier): click-to-preview in Classify & Copy mode

Identifying a file is half the workflow — you preview it to see what it is,
then assign its tracking number by drag. Preview was only wired into the old
Rename grid; in Classify & Copy a source file now previews on single-click
(drag still assigns, right-click excludes). preview.previewFile() resolves a
snapshot file's handle from the workspace root (one-click read re-grant) before
opening, so it works for resumed workspaces too.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

classifier/js/preview.js

@@ -521,7 +521,28 @@
     }
 
     // Export module
+    // Preview a file on demand (Classify & Copy mode). Snapshot-loaded files
+    // have no handle yet — resolve it from the workspace root (one-click read
+    // permission re-grant) before opening the preview window.
+    async function previewFile(file) {
+        try {
+            if (!file.handle && !file.isVirtual && window.app.rootHandle) {
+                if (window.app.modules.persist && window.app.modules.persist.verifyPermission) {
+                    const ok = await window.app.modules.persist.verifyPermission(window.app.rootHandle, false);
+                    if (!ok) { if (window.zddc) window.zddc.toast('Permission to read the source directory was denied.', 'error'); return; }
+                }
+                await window.app.modules.scanner.resolveFileHandle(window.app.rootHandle, file);
+            }
+            await openPreviewWindow(file);
+        } catch (e) {
+            if (window.zddc) {
+                window.zddc.toast('Couldn’t preview ' + (file.originalFilename || 'file') + ' — ' + (e.message || e), 'error');
+            }
+        }
+    }
+
     window.app.modules.preview = {
-        init
+        init,
+        previewFile
     };
 })();

classifier/js/tree.js

@@ -270,6 +270,7 @@
         item.className = 'file-item';
         item.style.paddingLeft = `${level * 1.5}rem`;
         item.draggable = true;
+        item.title = 'Click to preview · drag onto a tracking folder or transmittal to assign';
         const key = c.srcKeyForFile(file);
         item.dataset.key = key;
         const st = c.fileState(file);
@@ -688,11 +689,15 @@
         var ft = window.app.dom.folderTree;
         if (!ft) { classifyWired = false; return; }
         ft.addEventListener('contextmenu', onContextMenu);
+        // Single-click a source file → preview it (the "look at it, then assign"
+        // half of the workflow). Drag still assigns; right-click excludes.
         ft.addEventListener('click', function (e) {
             if (!classifyOn()) return;
             var fe = e.target.closest('.file-item');
-            if (fe && fe.dataset.key && window.app.modules.targetTree) {
+            if (!fe || !fe.dataset.key) return;
-                window.app.modules.targetTree.reveal(fe.dataset.key);
+            var file = findFileByKey(fe.dataset.key);
+            if (file && window.app.modules.preview && window.app.modules.preview.previewFile) {
+                window.app.modules.preview.previewFile(file);
             }
         });
     }

tests/classify.spec.js

@@ -244,6 +244,22 @@ test('source file rows render with a state dot in classify mode', async ({ page
     await expect(page.locator('#folderTree .file-item .cl-dot--none')).toBeVisible();
 });
 
+test('classify: single-click a source file triggers preview', async ({ page }) => {
+    await page.click('#modeClassifyBtn');
+    const previewed = await page.evaluate(() => {
+        let got = null;
+        window.app.modules.preview.previewFile = (f) => { got = f.originalFilename; };  // capture, skip popup
+        window.app.folderTree = [{
+            name: 'Root', path: 'Root', expanded: true, scanState: 'done',
+            files: [{ originalFilename: 'Foundation Plan', extension: 'pdf', folderPath: 'Root' }], children: [],
+        }];
+        window.app.modules.tree.render();
+        document.querySelector('#folderTree .file-item').click();
+        return got;
+    });
+    expect(previewed).toBe('Foundation Plan');
+});
+
 test('classify: a folder with files but no subfolders is expandable (drag source)', async ({ page }) => {
     await page.click('#modeClassifyBtn');
     await page.evaluate(() => {