feat: add side-by-side live preview to form builder

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/ui/form-builder.ts

@@ -1,5 +1,6 @@
 import { App, Modal, Notice } from 'obsidian';
 import { FormDefinition, FormField, FieldType } from '../types';
+import { renderField } from './field-renderers';
 
 const FIELD_TYPES: FieldType[] = [
   'text',
@@ -90,10 +91,15 @@ export class FormBuilderModal extends Modal {
       }
     });
 
-    // --- General settings ---
-    contentEl.createEl('h2', { text: 'Form Settings' });
+    // --- Two-column layout ---
+    const layout = contentEl.createDiv({ cls: 'ff-builder-layout' });
 
-    const generalEl = contentEl.createDiv({ cls: 'ff-builder-general' });
+    // === LEFT: Editor ===
+    const editorEl = layout.createDiv({ cls: 'ff-builder-editor' });
+
+    editorEl.createEl('h2', { text: 'Form Settings' });
+
+    const generalEl = editorEl.createDiv({ cls: 'ff-builder-general' });
 
     // Name
     this.addTextSetting(generalEl, 'Form Name', this.draft.name, (v) => {
@@ -109,7 +115,7 @@ export class FormBuilderModal extends Modal {
       (v) => {
         this.pushSnapshot();
         this.draft.mode = v as 'create' | 'update';
-        this.render(); // Re-render to show mode-specific settings
+        this.render();
       },
     );
 
@@ -151,14 +157,14 @@ export class FormBuilderModal extends Modal {
       );
     }
 
-    // --- Fields section ---
-    contentEl.createEl('h3', { text: 'Fields' });
+    // Fields section
+    editorEl.createEl('h3', { text: 'Fields' });
 
-    const fieldsContainer = contentEl.createDiv({ cls: 'ff-builder-fields' });
+    const fieldsContainer = editorEl.createDiv({ cls: 'ff-builder-fields' });
     this.renderFields(fieldsContainer);
 
     // Add field button
-    const addBtn = contentEl.createEl('button', {
+    const addBtn = editorEl.createEl('button', {
       cls: 'ff-builder-add-btn',
       text: '+ Add Field',
     });
@@ -174,7 +180,40 @@ export class FormBuilderModal extends Modal {
       this.render();
     });
 
-    // --- Footer ---
+    // === RIGHT: Preview ===
+    const previewEl = layout.createDiv({ cls: 'ff-builder-preview' });
+    previewEl.createEl('h2', { text: 'Preview' });
+
+    const previewContent = previewEl.createDiv({ cls: 'ff-builder-preview-content' });
+
+    if (this.draft.fields.length === 0) {
+      previewContent.createDiv({
+        cls: 'ff-builder-preview-empty',
+        text: 'Add fields to see a preview.',
+      });
+    } else {
+      // Form title
+      previewContent.createEl('h3', {
+        text: this.draft.name || 'Untitled Form',
+        cls: 'ff-form-title',
+      });
+
+      // Render each field
+      const previewFields = previewContent.createDiv({ cls: 'ff-fields' });
+      for (const field of this.draft.fields) {
+        renderField(this.app, previewFields, field, field.defaultValue);
+      }
+
+      // Disabled submit button
+      const previewFooter = previewContent.createDiv({ cls: 'ff-form-footer' });
+      const previewSubmit = previewFooter.createEl('button', {
+        text: this.draft.mode === 'create' ? 'Create Note' : 'Update Frontmatter',
+        cls: 'mod-cta ff-submit-btn',
+      });
+      previewSubmit.setAttribute('disabled', '');
+    }
+
+    // --- Footer (full width, below grid) ---
     const footer = contentEl.createDiv({ cls: 'ff-builder-footer' });
 
     // Left side: undo/redo