fix(classifier): Show toggles preserve tree state; add Reset to raw input

- Toggling Show Unassigned/Assigned/Excluded/Empty no longer force-expands the
  whole tree. Auto-expand is now reserved for the NAME search (where revealing a
  match means expanding to it); the Show toggles only hide/show, leaving your
  expand/collapse state untouched. Also preserve scrollTop across re-render so a
  toggle doesn't jump the view to the top.
- Add a "Reset" button (danger-styled, beside Export/Import) that discards every
  classification — tracking + transmittal trees, assignments, excludes, title
  overrides — and returns to just the raw scanned input. Your files are never
  touched. Destructive + irreversible, so it confirms with an "Export first"
  warning and no-ops (info toast) when there's nothing to reset.

Tests: Show toggle preserves collapse vs. name-search auto-expand (classify 42).

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

classifier/js/app.js

@@ -151,6 +151,7 @@
             exportDatasetBtn: document.getElementById('exportDatasetBtn'),
             importDatasetBtn: document.getElementById('importDatasetBtn'),
             importDatasetInput: document.getElementById('importDatasetInput'),
+            resetDatasetBtn: document.getElementById('resetDatasetBtn'),
             treeFilterInput: document.getElementById('treeFilterInput'),
             trackingFilterInput: document.getElementById('trackingFilterInput'),
             transmittalFilterInput: document.getElementById('transmittalFilterInput'),
@@ -305,6 +306,24 @@
         reader.onerror = function () { window.zddc.toast('Import failed — could not read the file.', 'error'); };
         reader.readAsText(file);
     }
+    // Reset to a clean state: keep the scanned source tree (the raw input), but
+    // discard every classification — trees, assignments, excludes, overrides.
+    // Destructive and irreversible, so warn and steer the user to Export first.
+    function resetDataset() {
+        var c = app.modules.classify;
+        var n = Object.keys(c.serialize().assignments || {}).length;
+        if (!n && !c.getTrackingTree().length && !c.getTransmittalTree().length) {
+            window.zddc.toast('Nothing to reset — already at the raw input.', 'info');
+            return;
+        }
+        if (!confirm('Reset to a clean state?\n\nThis discards ALL classifications ('
+            + n + ' assigned file' + (n === 1 ? '' : 's') + ', plus the tracking and '
+            + 'transmittal trees) and returns to just the raw scanned input. Your actual '
+            + 'files are not touched.\n\nThis cannot be undone — Export first if you might '
+            + 'need this data.')) return;
+        c.reset();
+        window.zddc.toast('Reset to the raw scanned input.', 'success');
+    }
 
     /**
      * Set up event listeners
@@ -369,6 +388,7 @@
         // Dataset export / import (round-trip the classification through a JSON file).
         if (app.dom.exportDatasetBtn) app.dom.exportDatasetBtn.addEventListener('click', exportDataset);
         if (app.dom.importDatasetBtn) app.dom.importDatasetBtn.addEventListener('click', function () { app.dom.importDatasetInput.click(); });
+        if (app.dom.resetDatasetBtn) app.dom.resetDatasetBtn.addEventListener('click', resetDataset);
         if (app.dom.importDatasetInput) app.dom.importDatasetInput.addEventListener('change', function () {
             if (this.files && this.files[0]) importDataset(this.files[0]);
             this.value = '';   // allow re-importing the same file

classifier/js/tree.js

@@ -143,6 +143,9 @@
      */
     function render() {
         const container = window.app.dom.folderTree;
+        // Preserve scroll across re-render — toggling a Show filter shouldn't
+        // jump the view back to the top.
+        const prevScroll = container.scrollTop;
         wireClassifyInteractions();
         container.innerHTML = '';
         updateFilterCounts();
@@ -164,6 +167,7 @@
         }
 
         updateSelectedCount();
+        container.scrollTop = prevScroll;
     }
 
     /**
@@ -268,7 +272,7 @@
             // expandable so its files can be revealed and dragged.
             || (classifyOn() && folder.files && folder.files.length > 0);
         if (mightHaveChildren) {
-            toggle.textContent = (folder.expanded || visible) ? '▼' : '▶';
+            toggle.textContent = (folder.expanded || filterActive()) ? '▼' : '▶';
             toggle.addEventListener('click', (e) => {
                 e.stopPropagation();
                 const recursive = e.ctrlKey || e.metaKey;
@@ -346,8 +350,9 @@
 
         div.appendChild(item);
 
-        // Children — when expanded, or auto-expanded to reveal a filter match.
-        if ((folder.expanded || visible) && folder.children && folder.children.length > 0) {
+        // Children — when expanded, or auto-expanded to reveal a NAME-search
+        // match. The Show toggles only hide/show; they never force-expand.
+        if ((folder.expanded || filterActive()) && folder.children && folder.children.length > 0) {
             const childrenDiv = document.createElement('div');
             childrenDiv.className = 'folder-children';
             folder.children.forEach(child => {
@@ -359,8 +364,8 @@
         }
 
         // Classify mode: list this folder's own files (draggable leaves) when
-        // expanded (or auto-expanded by a filter), so they can be dropped.
-        if (classifyOn() && (folder.expanded || visible) && folder.files && folder.files.length > 0) {
+        // expanded (or auto-expanded by a name search), so they can be dropped.
+        if (classifyOn() && (folder.expanded || filterActive()) && folder.files && folder.files.length > 0) {
             const filesDiv = document.createElement('div');
             filesDiv.className = 'folder-children folder-files';
             folder.files.forEach(function (file) {

classifier/template.html

@@ -165,6 +165,7 @@
                             <button id="exportDatasetBtn" class="btn btn-secondary btn-sm" title="Export the classification dataset (trees + assignments) as JSON">Export</button>
                             <button id="importDatasetBtn" class="btn btn-secondary btn-sm" title="Import a classification dataset JSON (replaces the current one)">Import</button>
                             <input type="file" id="importDatasetInput" accept="application/json,.json" hidden>
+                            <button id="resetDatasetBtn" class="btn btn-sm btn-danger" title="Discard all classifications and start over from the raw scanned input (does not touch your files)">Reset</button>
                             <button id="copyOutputBtn" class="btn btn-primary btn-sm" disabled title="Copy mapped files to an output directory (source untouched)">Copy…</button>
                         </div>
                     </div>

tests/classify.spec.js

@@ -760,3 +760,29 @@ test('Show Empty off hides folders that contain no files', async ({ page }) => {
     expect(r.before).toEqual(['Docs', 'EmptyDir']);   // both shown by default
     expect(r.after).toEqual(['Docs']);                // empty folder hidden when Show Empty off
 });
+
+test('toggling a Show filter preserves collapse state (no force-expand)', async ({ page }) => {
+    await page.click('#modeClassifyBtn');
+    const r = await page.evaluate(() => {
+        window.app.folderTree = [{
+            name: 'Project', path: 'Project', expanded: false, scanState: 'done', files: [], children: [
+                { name: 'Sub', path: 'Project/Sub', expanded: false, scanState: 'done', children: [],
+                  files: [{ originalFilename: 'a', extension: 'pdf', folderPath: 'Project/Sub' }] },
+            ],
+        }];
+        const tree = window.app.modules.tree;
+        tree.render();
+        const collapsed = Array.from(document.querySelectorAll('#folderTree .folder-item')).map((e) => e.dataset.path);
+        // A Show toggle must not expand the collapsed parent…
+        tree.setShowFilters({ unassigned: true, assigned: true, excluded: true, empty: false });
+        const afterToggle = Array.from(document.querySelectorAll('#folderTree .folder-item')).map((e) => e.dataset.path);
+        // …whereas a name search still reveals the match by auto-expanding.
+        tree.setShowFilters({ unassigned: true, assigned: true, excluded: true, empty: true });
+        tree.setNameFilter('a.pdf');
+        const afterSearch = Array.from(document.querySelectorAll('#folderTree .folder-item')).map((e) => e.dataset.path);
+        return { collapsed, afterToggle, afterSearch };
+    });
+    expect(r.collapsed).toEqual(['Project']);                 // child hidden — parent collapsed
+    expect(r.afterToggle).toEqual(['Project']);               // Show toggle leaves it collapsed
+    expect(r.afterSearch).toEqual(['Project', 'Project/Sub']); // name search auto-expands to the match
+});