Make bin editor open to image view; corners editing on demand

- Default view: processed image (full size in dialog), or placeholder if
  not yet processed. Name and type selector always visible at top.
- "Adjust corners…" button reveals the canvas editor (lazy-loaded on
  first click, so there's no canvas allocation cost on open).
- "← Back to image" returns to the image view.
- Corners are only re-processed on Save if the canvas was opened.
- Tabs reduced to Fields | Contents (Corners is no longer a tab).
- Added preview image CSS; btn-link style for the back button.

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

public/app.mjs

@@ -2359,6 +2359,8 @@ function open_bin_editor(bin) {
 	if (!dlg) return;
 
 	bin_editor_bin_id = bin.id;
+	bin_editor_instance = null;  // canvas not loaded until needed
+
 	document.getElementById('bin-editor-name').value = bin.name;
 
 	// Populate type selector
@@ -2385,28 +2387,68 @@ function open_bin_editor(bin) {
 	type_sel.addEventListener('change', sync_dims_row);
 	sync_dims_row();
 
-	// Tabs
+	// Image preview (default view)
-	let active_tab = 'corners';
+	const view_image   = document.getElementById('bin-editor-view-image');
+	const view_corners = document.getElementById('bin-editor-view-corners');
+	const preview_img  = document.getElementById('bin-editor-preview');
+	const no_image_el  = document.getElementById('bin-editor-no-image');
+
+	function show_image_view() {
+		view_image.hidden = false;
+		view_corners.hidden = true;
+	}
+
+	function show_corners_view() {
+		view_image.hidden = true;
+		view_corners.hidden = false;
+		// Lazy-load canvas the first time
+		if (!bin_editor_instance) {
+			const canvas = document.getElementById('bin-editor-canvas');
+			bin_editor_instance = new Grid_Setup(canvas);
+			bin_editor_instance.set_rows(1);
+			bin_editor_instance.set_cols(1);
+			bin_editor_instance.load_image(`/img/${bin.source_id}`).then(() => {
+				if (bin.corners) {
+					bin_editor_instance.set_corners(bin.corners);
+				}
+			});
+		}
+	}
+
+	if (bin.image_filename) {
+		preview_img.src = `/img/${bin.image_filename}`;
+		preview_img.hidden = false;
+		no_image_el.hidden = true;
+	} else {
+		preview_img.hidden = true;
+		no_image_el.hidden = false;
+	}
+
+	document.getElementById('bin-editor-go-corners').onclick = () => {
+		dlg.showModal();  // already open; ensures layout is stable before canvas sizes
+		show_corners_view();
+	};
+	document.getElementById('bin-editor-go-back').onclick = show_image_view;
+
+	show_image_view();
+
+	// Tabs: Fields | Contents
 	const tab_panels = {
-		corners:  document.getElementById('bin-editor-tab-corners'),
 		fields:   document.getElementById('bin-editor-tab-fields'),
 		contents: document.getElementById('bin-editor-tab-contents'),
 	};
 	qs(dlg, '#bin-editor-tabs').onclick = (e) => {
 		const tab = e.target.dataset.tab;
 		if (!tab) return;
-		active_tab = tab;
 		qs(dlg, '#bin-editor-tabs').querySelectorAll('.tab-btn').forEach(btn => {
 			btn.classList.toggle('active', btn.dataset.tab === tab);
 		});
 		for (const [name, el] of Object.entries(tab_panels)) {
 			el.hidden = name !== tab;
 		}
-		const save_btn = document.getElementById('bin-editor-save');
-		save_btn.textContent = active_tab === 'corners' ? 'Save & process' : 'Save';
 	};
 
-	// Fields tab
+	// Fields
 	bin_editor_get_fields = build_field_editor(
 		document.getElementById('bin-field-rows'),
 		document.getElementById('bin-add-field-select'),
@@ -2414,22 +2456,11 @@ function open_bin_editor(bin) {
 		bin.fields ?? {}
 	).get_fields;
 
-	// Contents tab
+	// Contents
 	render_bin_contents(bin.id, document.getElementById('bin-contents-list'));
 	document.getElementById('bin-add-content').onclick = () => open_bin_content_dialog(bin.id);
 
-	// Show dialog first so the canvas has correct layout dimensions
 	dlg.showModal();
-
-	const canvas = document.getElementById('bin-editor-canvas');
-	bin_editor_instance = new Grid_Setup(canvas);
-	bin_editor_instance.set_rows(1);
-	bin_editor_instance.set_cols(1);
-	bin_editor_instance.load_image(`/img/${bin.source_id}`).then(() => {
-		if (bin.corners) {
-			bin_editor_instance.set_corners(bin.corners);
-		}
-	});
 }
 
 // ---------------------------------------------------------------------------
@@ -2678,10 +2709,9 @@ async function init() {
 		const type_id = document.getElementById('bin-editor-type').value || null;
 		const fields = bin_editor_get_fields?.() ?? {};
 		try {
-			// Always save name, type, and fields
 			const corners = bin_editor_instance?.get_corners();
 			if (corners) {
-				// Corners tab active (or image loaded) — also re-process
+				// Canvas was opened — re-process corners too
 				const phys_w = parseFloat(document.getElementById('bin-editor-width').value) || null;
 				const phys_h = parseFloat(document.getElementById('bin-editor-height').value) || null;
 				await api.update_bin(id, { name, type_id, fields });

public/style.css

@@ -1988,6 +1988,46 @@ nav {
 	margin-left: 0.25rem;
 }
 
+.bin-editor-preview-wrap {
+	width: 100%;
+	background: #0e0e0e;
+	border-radius: 4px;
+	display: flex;
+	align-items: center;
+	justify-content: center;
+	min-height: 120px;
+	margin-bottom: 0.5rem;
+	overflow: hidden;
+}
+
+.bin-editor-preview-img {
+	max-width: 100%;
+	max-height: 55vh;
+	display: block;
+	object-fit: contain;
+}
+
+.bin-editor-no-image {
+	color: var(--text-faint);
+	font-size: 0.85rem;
+	padding: 2rem;
+	text-align: center;
+}
+
+.btn-link {
+	background: none;
+	border: none;
+	color: var(--text-muted);
+	cursor: pointer;
+	font-size: 0.8rem;
+	padding: 0.25rem 0;
+	text-decoration: underline;
+}
+
+.btn-link:hover {
+	color: var(--text);
+}
+
 .bin-editor-canvas {
 	display: block;
 	border-radius: 4px;

public/templates.html

@@ -671,24 +671,29 @@
 <template id="t-dialog-bin-editor">
 	<dialog id="dialog-bin-editor" class="app-dialog app-dialog-wide">
 		<h2 class="dialog-title">Edit bin</h2>
-		<div class="tab-bar" id="bin-editor-tabs">
+
-			<button class="tab-btn active" data-tab="corners">Corners</button>
+		<div class="form-row">
-			<button class="tab-btn" data-tab="fields">Fields</button>
+			<label>Name</label>
-			<button class="tab-btn" data-tab="contents">Contents</button>
+			<input type="text" id="bin-editor-name" autocomplete="off">
+		</div>
+		<div class="form-row">
+			<label>Type</label>
+			<select id="bin-editor-type">
+				<option value="">— Custom —</option>
+			</select>
 		</div>
 
-		<!-- Corners tab -->
+		<!-- Default view: processed image -->
-		<div id="bin-editor-tab-corners">
+		<div id="bin-editor-view-image">
-			<div class="form-row">
+			<div class="bin-editor-preview-wrap">
-				<label>Name</label>
+				<img id="bin-editor-preview" class="bin-editor-preview-img" alt="" hidden>
-				<input type="text" id="bin-editor-name" autocomplete="off">
+				<div id="bin-editor-no-image" class="bin-editor-no-image">Not yet processed — click "Adjust corners" to set up</div>
-			</div>
-			<div class="form-row">
-				<label>Type</label>
-				<select id="bin-editor-type">
-					<option value="">— Custom —</option>
-				</select>
 			</div>
+			<button type="button" class="btn btn-secondary btn-sm" id="bin-editor-go-corners">Adjust corners…</button>
+		</div>
+
+		<!-- Corners canvas (revealed on demand) -->
+		<div id="bin-editor-view-corners" hidden>
 			<div class="form-row" id="bin-editor-dims-row">
 				<label>Dimensions (mm)</label>
 				<div class="bin-editor-dims">
@@ -699,11 +704,16 @@
 				</div>
 			</div>
 			<canvas id="bin-editor-canvas" class="bin-editor-canvas"></canvas>
+			<button type="button" class="btn btn-link btn-sm" id="bin-editor-go-back">← Back to image</button>
 		</div>
 
-		<!-- Fields tab -->
+		<!-- Tabs: Fields | Contents -->
-		<div id="bin-editor-tab-fields" hidden>
+		<div class="tab-bar" id="bin-editor-tabs">
-			<div class="form-section-label">Field values</div>
+			<button class="tab-btn active" data-tab="fields">Fields</button>
+			<button class="tab-btn" data-tab="contents">Contents</button>
+		</div>
+
+		<div id="bin-editor-tab-fields">
 			<div id="bin-field-rows"></div>
 			<div class="form-row add-field-row">
 				<div class="input-with-action">
@@ -715,7 +725,6 @@
 			</div>
 		</div>
 
-		<!-- Contents tab -->
 		<div id="bin-editor-tab-contents" hidden>
 			<div id="bin-contents-list"></div>
 			<div class="form-row" style="margin-top:0.5rem">
@@ -725,7 +734,7 @@
 
 		<div class="dialog-actions">
 			<button type="button" class="btn btn-secondary" id="bin-editor-cancel">Cancel</button>
-			<button type="button" class="btn btn-primary" id="bin-editor-save">Save &amp; process</button>
+			<button type="button" class="btn btn-primary" id="bin-editor-save">Save</button>
 		</div>
 	</dialog>
 </template>