diff --git a/app.py b/app.py
index 8b8a5f7..12a0172 100644
--- a/app.py
+++ b/app.py
@@ -269,6 +269,74 @@ def box_sort_key(box: Box):
     )
 
 
+def has_range_conflict(
+    *,
+    box_type: str,
+    prefix: str,
+    start_number: int,
+    slot_capacity: int,
+    exclude_box_id: int = None,
+):
+    end_number = start_number + slot_capacity - 1
+    query = Box.query.filter_by(box_type=box_type, slot_prefix=prefix)
+    if exclude_box_id is not None:
+        query = query.filter(Box.id != exclude_box_id)
+
+    for other in query.all():
+        other_start = other.start_number
+        other_end = other.start_number + other.slot_capacity - 1
+        # Two ranges overlap unless one is strictly before the other.
+        if not (end_number < other_start or start_number > other_end):
+            return True, other
+
+    return False, None
+
+
+def suggest_next_start_number(
+    *,
+    box_type: str,
+    prefix: str,
+    slot_capacity: int,
+    exclude_box_id: int = None,
+) -> int:
+    max_end = 0
+    query = Box.query.filter_by(box_type=box_type, slot_prefix=prefix)
+    if exclude_box_id is not None:
+        query = query.filter(Box.id != exclude_box_id)
+
+    for other in query.all():
+        other_end = other.start_number + other.slot_capacity - 1
+        if other_end > max_end:
+            max_end = other_end
+
+    return max_end + 1 if max_end > 0 else 1
+
+
+def build_index_anchor(box_type: str = "") -> str:
+    if box_type in BOX_TYPES:
+        return f"group-{box_type}"
+    return ""
+
+
+def bad_request(message: str, box_type: str = ""):
+    anchor = build_index_anchor(box_type)
+    if anchor:
+        back_url = f"{url_for('index')}#{anchor}"
+    else:
+        back_url = request.referrer or url_for("index")
+
+    return (
+        render_template(
+            "error.html",
+            status_code=400,
+            title="请求参数有误",
+            message=message,
+            back_url=back_url,
+        ),
+        400,
+    )
+
+
 def render_box_page(box: Box, error: str = "", notice: str = ""):
     slots = slot_data_for_box(box)
     bag_rows = bag_rows_for_box(box) if box.box_type == "bag" else []
@@ -314,17 +382,31 @@ def create_box():
     slot_prefix = request.form.get("slot_prefix", "").strip().upper()
 
     if box_type not in BOX_TYPES:
-        return "无效盒子类型", 400
+        return bad_request("无效盒子类型", box_type)
     if not base_name:
-        return "盒子名称不能为空", 400
+        return bad_request("盒子名称不能为空", box_type)
 
     try:
         start_number = _parse_non_negative_int(request.form.get("start_number", "1"), 1)
     except ValueError:
-        return "起始序号必须是大于等于 0 的整数", 400
+        return bad_request("起始序号必须是大于等于 0 的整数", box_type)
 
     meta = BOX_TYPES[box_type]
     effective_prefix = slot_prefix or meta["default_prefix"]
+    conflict, other_box = has_range_conflict(
+        box_type=box_type,
+        prefix=effective_prefix,
+        start_number=start_number,
+        slot_capacity=meta["default_capacity"],
+    )
+    if conflict:
+        return bad_request(
+            "编号范围冲突: 与现有盒子 "
+            f"[{other_box.name}]"
+            " 重叠，请更换前缀或起始序号",
+            box_type,
+        )
+
     generated_name = compose_box_name(
         base_name=base_name,
         prefix=effective_prefix,
@@ -355,14 +437,29 @@ def update_box(box_id: int):
     slot_prefix = request.form.get("slot_prefix", "").strip().upper()
 
     if not base_name:
-        return "盒子名称不能为空", 400
+        return bad_request("盒子名称不能为空", box.box_type)
 
     try:
         start_number = _parse_non_negative_int(request.form.get("start_number", "1"), 1)
     except ValueError:
-        return "起始序号必须是大于等于 0 的整数", 400
+        return bad_request("起始序号必须是大于等于 0 的整数", box.box_type)
 
     effective_prefix = slot_prefix or BOX_TYPES[box.box_type]["default_prefix"]
+    conflict, other_box = has_range_conflict(
+        box_type=box.box_type,
+        prefix=effective_prefix,
+        start_number=start_number,
+        slot_capacity=box.slot_capacity,
+        exclude_box_id=box.id,
+    )
+    if conflict:
+        return bad_request(
+            "编号范围冲突: 与现有盒子 "
+            f"[{other_box.name}]"
+            " 重叠，请更换前缀或起始序号",
+            box.box_type,
+        )
+
     generated_name = compose_box_name(
         base_name=base_name,
         prefix=effective_prefix,
@@ -387,6 +484,49 @@ def delete_box(box_id: int):
     return redirect(url_for("index"))
 
 
+@app.route("/boxes/suggest-start")
+def suggest_start():
+    box_type = request.args.get("box_type", "small_28").strip()
+    if box_type not in BOX_TYPES:
+        return {"ok": False, "message": "无效盒子类型"}, 400
+
+    slot_prefix = request.args.get("slot_prefix", "").strip().upper()
+    effective_prefix = slot_prefix or BOX_TYPES[box_type]["default_prefix"]
+
+    box_id_raw = request.args.get("box_id", "").strip()
+    exclude_box_id = None
+    slot_capacity = BOX_TYPES[box_type]["default_capacity"]
+
+    if box_id_raw:
+        try:
+            box_id = int(box_id_raw)
+        except ValueError:
+            return {"ok": False, "message": "box_id 非法"}, 400
+
+        box = Box.query.get(box_id)
+        if not box:
+            return {"ok": False, "message": "盒子不存在"}, 404
+
+        box_type = box.box_type
+        slot_capacity = box.slot_capacity
+        exclude_box_id = box.id
+
+    suggested = suggest_next_start_number(
+        box_type=box_type,
+        prefix=effective_prefix,
+        slot_capacity=slot_capacity,
+        exclude_box_id=exclude_box_id,
+    )
+    end_number = suggested + slot_capacity - 1
+
+    return {
+        "ok": True,
+        "start_number": suggested,
+        "slot_prefix": effective_prefix,
+        "preview_range": f"{effective_prefix}{suggested}-{effective_prefix}{end_number}",
+    }
+
+
 @app.route("/box/<int:box_id>")
 def view_box(box_id: int):
     box = Box.query.get_or_404(box_id)
diff --git a/static/css/style.css b/static/css/style.css
index 161d067..9bd950f 100644
--- a/static/css/style.css
+++ b/static/css/style.css
@@ -101,13 +101,18 @@ body {
 
 .new-box-form {
     display: grid;
-    grid-template-columns: 1.2fr 0.8fr 0.7fr 1fr auto;
+    grid-template-columns: 1.2fr 0.8fr 0.7fr 1fr auto auto;
     gap: 8px;
     margin-bottom: 12px;
 }
 
 .new-box-form.compact {
-    grid-template-columns: 1.1fr 0.8fr 0.7fr 1fr auto;
+    grid-template-columns: 1.1fr 0.8fr 0.7fr 1fr auto auto;
+}
+
+.new-box-form .suggest-preview {
+    grid-column: 1 / -1;
+    margin: 0;
 }
 
 .box-card,
diff --git a/templates/error.html b/templates/error.html
new file mode 100644
index 0000000..ed37c4e
--- /dev/null
+++ b/templates/error.html
@@ -0,0 +1,25 @@
+<!DOCTYPE html>
+<html lang="zh-CN">
+<head>
+    <meta charset="UTF-8">
+    <meta name="viewport" content="width=device-width, initial-scale=1.0">
+    <title>{{ status_code }} - {{ title }}</title>
+    <link rel="stylesheet" href="{{ url_for('static', filename='css/style.css') }}">
+</head>
+<body>
+    <header class="hero slim">
+        <h1>{{ status_code }} - {{ title }}</h1>
+        <a class="btn btn-light" href="{{ url_for('index') }}">回到首页</a>
+    </header>
+
+    <main class="container">
+        <section class="panel">
+            <p class="alert">{{ message }}</p>
+            <div class="actions" style="margin-top: 10px;">
+                <a class="btn" href="{{ back_url }}">返回上一页</a>
+                <button class="btn btn-light" type="button" onclick="history.back()">浏览器返回</button>
+            </div>
+        </section>
+    </main>
+</body>
+</html>
diff --git a/templates/index.html b/templates/index.html
index abfa45a..b17e683 100644
--- a/templates/index.html
+++ b/templates/index.html
@@ -16,7 +16,7 @@
 		<h2>容器列表</h2>
 
 		{% for key, meta in box_types.items() %}
-		<section class="group-panel panel">
+		<section class="group-panel panel" id="group-{{ key }}">
 			<div class="group-title-row">
 				<h3>{{ meta.label }}</h3>
 				<span class="group-desc">{{ meta.default_desc }}</span>
@@ -28,7 +28,9 @@
 				<input type="text" name="slot_prefix" placeholder="前缀(如A/B/C)">
 				<input type="number" name="start_number" min="0" value="1" placeholder="起始序号">
 				<input type="text" name="description" placeholder="备注(可选)">
+				<button class="btn btn-light suggest-start-btn" type="button" data-box-type="{{ key }}">建议起始号</button>
 				<button class="btn" type="submit">新增盒子</button>
+				<span class="hint suggest-preview"></span>
 			</form>
 
 			<section class="box-list">
@@ -67,7 +69,9 @@
 							<input type="text" name="slot_prefix" value="{{ item.box.slot_prefix }}" required>
 							<input type="number" name="start_number" min="0" value="{{ item.box.start_number }}" required>
 							<input type="text" name="description" value="{{ item.box.description or '' }}">
+							<button class="btn btn-light suggest-start-btn" type="button" data-box-id="{{ item.box.id }}" data-box-type="{{ item.box.box_type }}">建议起始号</button>
 							<button class="btn" type="submit">保存设置</button>
+							<span class="hint suggest-preview"></span>
 						</form>
 					</details>
 				</article>
@@ -78,5 +82,61 @@
 		</section>
 		{% endfor %}
 	</main>
+
+	<script>
+		(function () {
+			function updateSuggest(form, payload) {
+				var startInput = form.querySelector('input[name="start_number"]');
+				var prefixInput = form.querySelector('input[name="slot_prefix"]');
+				var preview = form.querySelector('.suggest-preview');
+
+				if (startInput) {
+					startInput.value = payload.start_number;
+				}
+				if (prefixInput && !prefixInput.value.trim()) {
+					prefixInput.value = payload.slot_prefix;
+				}
+				if (preview) {
+					preview.textContent = '建议范围: ' + payload.preview_range;
+				}
+			}
+
+			document.querySelectorAll('.suggest-start-btn').forEach(function (btn) {
+				btn.addEventListener('click', function () {
+					var form = btn.closest('form');
+					if (!form) {
+						return;
+					}
+
+					var prefixInput = form.querySelector('input[name="slot_prefix"]');
+					var boxType = btn.dataset.boxType || 'small_28';
+					var boxId = btn.dataset.boxId || '';
+					var prefix = prefixInput ? prefixInput.value.trim() : '';
+
+					var params = new URLSearchParams();
+					params.set('box_type', boxType);
+					if (prefix) {
+						params.set('slot_prefix', prefix);
+					}
+					if (boxId) {
+						params.set('box_id', boxId);
+					}
+
+					fetch('{{ url_for('suggest_start') }}?' + params.toString())
+						.then(function (resp) { return resp.json(); })
+						.then(function (data) {
+							if (!data.ok) {
+								alert(data.message || '建议起始号失败');
+								return;
+							}
+							updateSuggest(form, data);
+						})
+						.catch(function () {
+							alert('建议起始号失败，请稍后重试');
+						});
+				});
+			});
+		})();
+	</script>
 </body>
 </html>