Enforce parent device hierarchy: slots/size unset, battery summary, sub-component toggle

app.py

@@ -98,7 +98,7 @@ def create_app(config_object="config"):
             .distinct().order_by(Battery.storage_location).all()
         ]
         devices = db.query(Device).order_by(Device.name).all()
-        devices_with_slots = [d for d in devices if d.installed_count() < d.battery_slots]
+        devices_with_slots = [d for d in devices if d.installed_count() < d.battery_slots and not d.has_children()]
         today = date.today()
         one_year_ago = (today - timedelta(days=365)).isoformat()
         total_charges = db.query(func.count(ChargeLog.id)).scalar() or 0
@@ -397,7 +397,7 @@ def create_app(config_object="config"):
             return redirect(url_for("battery_detail", battery_id=battery_id))
 
         devices = db.query(Device).order_by(Device.name).all()
-        devices_with_slots = [d for d in devices if d.installed_count() < d.battery_slots]
+        devices_with_slots = [d for d in devices if d.installed_count() < d.battery_slots and not d.has_children()]
 
         if request.method == "POST":
             device_id = request.form.get("device_id", type=int)
@@ -406,6 +406,10 @@ def create_app(config_object="config"):
                 flash("Device not found.", "error")
                 return render_template("assign.html", battery=battery, devices=devices_with_slots)
 
+            if device.has_children():
+                flash(f"{device.name} has sub-components; assign batteries to its sub-components instead.", "error")
+                return render_template("assign.html", battery=battery, devices=devices_with_slots)
+
             if device.installed_count() >= device.battery_slots:
                 flash(
                     f"{device.name} is already full "
@@ -556,6 +560,10 @@ def create_app(config_object="config"):
                 flash("Device not found.", "error")
                 return redirect(url_for("dashboard"))
 
+            if device.has_children():
+                flash(f"{device.name} has sub-components; install batteries into those instead.", "error")
+                return redirect(url_for("dashboard"))
+
             already_here = [b for b in batteries if b.device_id == device.id]
             retired_sel  = [b for b in batteries if b.is_retired()]
             to_process   = [b for b in batteries
@@ -692,6 +700,16 @@ def create_app(config_object="config"):
                                            device_types=device_types,
                                            device_locations=device_locations,
                                            device_battery_sizes=device_battery_sizes), 400
+                if parent_device.battery_slots != 0 or parent_device.battery_size:
+                    flash(
+                        f"'{parent_device.name}' must have battery slots set to 0 "
+                        f"and battery size cleared before sub-components can be added.",
+                        "error",
+                    )
+                    return render_template("device_add.html",
+                                           device_types=device_types,
+                                           device_locations=device_locations,
+                                           device_battery_sizes=device_battery_sizes), 400
 
             if not name:
                 flash("Device name is required.", "error")
@@ -701,22 +719,12 @@ def create_app(config_object="config"):
                                        device_battery_sizes=device_battery_sizes,
                                        prefill_parent=parent_device), 400
 
-            if not battery_size:
-                flash("Battery size is required.", "error")
-                return render_template("device_add.html",
-                                       device_types=device_types,
-                                       device_locations=device_locations,
-                                       device_battery_sizes=device_battery_sizes,
-                                       form_name=name, form_notes=notes or "",
-                                       form_device_type=request.form.get("device_type", ""),
-                                       prefill_parent=parent_device), 400
-
             try:
                 slots = int(slots_raw)
-                if slots < 1:
+                if slots < 0:
                     raise ValueError
             except ValueError:
-                flash("Battery slots must be a positive integer.", "error")
+                flash("Battery slots must be a non-negative integer.", "error")
                 return render_template("device_add.html",
                                        device_types=device_types,
                                        device_locations=device_locations,
@@ -750,7 +758,9 @@ def create_app(config_object="config"):
         return render_template("device_add.html", device_types=device_types,
                                device_locations=device_locations,
                                device_battery_sizes=device_battery_sizes,
-                               prefill_parent=prefill_parent)
+                               prefill_parent=prefill_parent,
+                               form_device_type=prefill_parent.device_type if prefill_parent else None,
+                               form_location=prefill_parent.location if prefill_parent else None)
 
     # ------------------------------------------------------------------ #
     # Devices — detail
@@ -823,7 +833,9 @@ def create_app(config_object="config"):
             return redirect(url_for("device_detail", device_id=device_id))
         try:
             slots = int(slots_raw)
-            if slots < 1:
+            if slots < 0:
+                raise ValueError
+            if slots < 1 and not device.has_children():
                 raise ValueError
         except ValueError:
             flash("Battery slots must be a positive integer.", "error")
@@ -846,17 +858,28 @@ def create_app(config_object="config"):
             if new_parent.is_subcomponent():
                 flash("Cannot nest sub-components more than one level deep.", "error")
                 return redirect(url_for("device_detail", device_id=device_id))
+            if new_parent.battery_slots != 0 or new_parent.battery_size:
+                flash(
+                    f"'{new_parent.name}' must have battery slots set to 0 "
+                    f"and battery size cleared before sub-components can be added.",
+                    "error",
+                )
+                return redirect(url_for("device_detail", device_id=device_id))
             device.parent_id = new_parent.id
         else:
             device.parent_id = None
 
         device.name = name
-        device.battery_slots = slots
         device.notes = notes
         device.device_type = device_type
-        new_battery_size = request.form.get("battery_size", "").strip() or None
+        if device.has_children():
-        if new_battery_size is not None:
+            device.battery_slots = 0
-            device.battery_size = new_battery_size
+            device.battery_size = None
+        else:
+            device.battery_slots = slots
+            new_battery_size = request.form.get("battery_size", "").strip() or None
+            if new_battery_size is not None:
+                device.battery_size = new_battery_size
         device.location = request.form.get("location", "").strip() or None
         device.ha_entity_id = request.form.get("ha_entity_id", "").strip() or None
         db.commit()
@@ -873,6 +896,10 @@ def create_app(config_object="config"):
         if device is None:
             abort(404)
 
+        if device.has_children():
+            flash(f"{device.name} has sub-components; install batteries into those instead.", "error")
+            return redirect(url_for("device_detail", device_id=device_id))
+
         brands = request.form.getlist("brand[]")
         qtys_raw = request.form.getlist("qty[]")
 
@@ -945,6 +972,9 @@ def create_app(config_object="config"):
         device = db.get(Device, device_id)
         if device is None:
             abort(404)
+        if device.has_children():
+            flash(f"{device.name} has sub-components; install batteries into those instead.", "error")
+            return redirect(url_for("device_detail", device_id=device_id))
         battery_id = request.form.get("battery_id", type=int)
         battery = db.get(Battery, battery_id)
         if battery is None or not battery.is_available():
@@ -1034,6 +1064,9 @@ def create_app(config_object="config"):
         device = db.get(Device, device_id)
         if device is None:
             abort(404)
+        if device.has_children():
+            flash(f"{device.name} has sub-components; install batteries into those instead.", "error")
+            return redirect(url_for("device_detail", device_id=device_id))
         battery_ids = request.form.getlist("battery_ids")
         free = device.battery_slots - device.installed_count()
         if not battery_ids:

models.py

@@ -28,7 +28,7 @@ class Device(Base):
     name = Column(String(100), nullable=False, unique=True)
     battery_slots = Column(Integer, nullable=False, default=1)
     device_type   = Column(String(50),  nullable=True)
-    battery_size  = Column(String(20),  nullable=False)  # AA, AAA, 9V, CR2032 …
+    battery_size  = Column(String(20),  nullable=True)   # AA, AAA, 9V, CR2032 …; null for parent-only devices
     location      = Column(String(100), nullable=True)
     notes = Column(Text, nullable=True)
     ha_entity_id = Column(String(100), nullable=True)   # e.g. "sensor.tv_remote_battery"

templates/device_add.html

@@ -18,6 +18,16 @@
              placeholder="e.g. Game Controller" required>
     </div>
 
+    {% if not prefill_parent %}
+    <div class="form-group">
+      <label style="display:flex;align-items:center;gap:0.5rem;font-weight:normal;cursor:pointer;">
+        <input type="checkbox" id="has-subcomponents" onchange="toggleSubcomponents(this)">
+        This device has sub-components (batteries tracked per sub-component, not directly)
+      </label>
+    </div>
+    {% endif %}
+
+    <div id="battery-fields">
     <div class="form-group">
       <label for="battery_slots">Battery Slots <span class="text-danger">*</span></label>
       <input type="number" id="battery_slots" name="battery_slots"
@@ -44,6 +54,7 @@
              placeholder="e.g. CR123A"
              style="display:{% if _cur_size and _cur_size not in _preset_sizes %}''{% else %}none{% endif %};margin-top:0.4rem;">
     </div>
+    </div><!-- #battery-fields -->
 
     <div class="form-group">
       <label>Type</label>
@@ -68,14 +79,18 @@
 
     <div class="form-group">
       <label>Location</label>
+      {% set _cur_loc = form_location|default('') %}
       <select id="location-select" onchange="metaSelectChanged(this,'location')">
         <option value="">— none —</option>
         {% for loc in device_locations|default([]) %}
-        <option value="{{ loc }}">{{ loc }}</option>
+        <option value="{{ loc }}" {% if _cur_loc == loc %}selected{% endif %}>{{ loc }}</option>
         {% endfor %}
+        {% if _cur_loc and _cur_loc not in device_locations|default([]) %}
+        <option value="{{ _cur_loc }}" selected>{{ _cur_loc }}</option>
+        {% endif %}
         <option value="__new__">➕ New location…</option>
       </select>
-      <input type="text" id="location" name="location" value=""
+      <input type="text" id="location" name="location" value="{{ _cur_loc }}"
              placeholder="e.g. Living Room, Bedroom"
              style="display:none;margin-top:0.4rem;">
     </div>
@@ -93,6 +108,26 @@
 </div>
 
 <script>
+function toggleSubcomponents(cb) {
+  var fields = document.getElementById('battery-fields');
+  var slots = document.getElementById('battery_slots');
+  var size = document.getElementById('battery_size');
+  if (cb.checked) {
+    fields.style.display = 'none';
+    slots.value = '0';
+    slots.removeAttribute('required');
+    slots.removeAttribute('min');
+    size.value = '';
+    size.removeAttribute('required');
+  } else {
+    fields.style.display = '';
+    slots.value = '1';
+    slots.setAttribute('required', '');
+    slots.setAttribute('min', '1');
+    size.setAttribute('required', '');
+  }
+}
+
 function metaSelectChanged(sel, inputId) {
   var input = document.getElementById(inputId);
   if (sel.value === '__new__') {

templates/device_detail.html

@@ -37,7 +37,7 @@
   <table style="width:auto;border:none;">
     <tr>
       <td style="padding:0.3rem 1rem 0.3rem 0;font-weight:600;color:#64748b;border:none;">Slots</td>
-      <td style="border:none;">{{ device.installed_count() }} / {{ device.battery_slots }} used</td>
+      <td style="border:none;">{% if device.has_children() %}{% set ns = namespace(inst=0, slots=0) %}{% for c in device.children %}{% set ns.inst = ns.inst + c.installed_count() %}{% set ns.slots = ns.slots + c.battery_slots %}{% endfor %}{{ ns.inst }} / {{ ns.slots }} (across sub-components){% else %}{{ device.installed_count() }} / {{ device.battery_slots }} used{% endif %}</td>
     </tr>
     {% if device.device_type %}
     <tr>
@@ -115,6 +115,39 @@
 </div>
 {% endif %}
 
+{% if device.has_children() %}
+<div class="card">
+  <h2>Batteries in Sub-components</h2>
+  {% for child in device.children %}
+  {% set child_installed = child.batteries | selectattr('status', 'eq', 'installed') | list %}
+  <h3 style="margin:0.75rem 0 0.4rem;font-size:1rem;">
+    <a href="{{ url_for('device_detail', device_id=child.id) }}">{{ child.name }}</a>
+    <small class="text-muted" style="font-weight:normal;">&nbsp;{{ child_installed|length }}/{{ child.battery_slots }}</small>
+  </h3>
+  {% if child_installed %}
+  <div class="table-wrap">
+    <table class="responsive-table">
+      <thead><tr><th>Label</th><th>Brand</th>{% if ha_enabled %}<th>Bat %</th>{% endif %}<th>Last Charged</th></tr></thead>
+      <tbody>
+        {% for b in child_installed %}
+        <tr>
+          <td data-label="Label"><a href="{{ url_for('battery_detail', battery_id=b.id) }}">{{ b.label }}</a></td>
+          <td data-label="Brand">{{ b.brand }}</td>
+          {% if ha_enabled %}<td data-label="Bat %">{% if b.battery_percentage is not none %}{{ b.battery_percentage }}%{% else %}—{% endif %}</td>{% endif %}
+          <td data-label="Last Charged" class="text-muted">{{ b.charge_logs[-1].charged_date if b.charge_logs else '—' }}</td>
+        </tr>
+        {% endfor %}
+      </tbody>
+    </table>
+  </div>
+  {% else %}
+  <p class="text-muted" style="margin:0 0 0.5rem;">No batteries installed.</p>
+  {% endif %}
+  {% endfor %}
+</div>
+{% endif %}
+
+{% if not device.has_children() %}
 <div class="card">
   <h2>Install Batteries</h2>
   {% set free_slots = device.battery_slots - device.installed_count() %}
@@ -191,7 +224,9 @@ function addInstallRow() {
 }
 </script>
 </div>
+{% endif %}
 
+{% if not device.has_children() %}
 <div class="card" id="installed">
   <h2>Installed Batteries</h2>
   {% set installed = device.batteries | selectattr('status', 'eq', 'installed') | list %}
@@ -326,6 +361,7 @@ function addInstallRow() {
     <p class="text-muted">No compatible batteries available.</p>
   {% endif %}
 </div>
+{% endif %}
 
 <div class="card">
   <h2>Logbook</h2>
@@ -365,10 +401,12 @@ function addInstallRow() {
       <label for="edit-name">Name</label>
       <input type="text" id="edit-name" name="name" value="{{ device.name }}" required>
     </div>
+    {% if not device.has_children() %}
     <div class="form-group">
       <label for="edit-slots">Battery Slots</label>
       <input type="number" id="edit-slots" name="battery_slots" value="{{ device.battery_slots }}" min="1" required>
     </div>
+    {% endif %}
     <div class="form-group">
       <label>Type</label>
       {% set _preset_types = ['Remote Control','Game Controller','Flashlight','Lock','Sensor','Toy','Clock','Smoke Detector'] %}
@@ -389,6 +427,7 @@ function addInstallRow() {
              placeholder="Enter device type"
              style="display:{% if device.device_type and device.device_type not in _preset_types %}''{% else %}none{% endif %};margin-top:0.4rem;">
     </div>
+    {% if not device.has_children() %}
     <div class="form-group">
       <label>Battery Size</label>
       {% set _preset_sizes = ['AA','AAA','C','D','9V','CR2032','CR2025','CR2016','18650','14500','16340','26650','LR44/AG13'] %}
@@ -412,6 +451,7 @@ function addInstallRow() {
              placeholder="e.g. CR123A"
              style="display:{% if device.battery_size and device.battery_size not in _preset_sizes %}''{% else %}none{% endif %};margin-top:0.4rem;">
     </div>
+    {% endif %}
     <div class="form-group">
       <label>Location</label>
       <select id="edit-location-select" onchange="editLocationSelectChanged(this)">
@@ -440,7 +480,7 @@ function addInstallRow() {
       <select id="edit-parent" name="parent_id">
         <option value="">— none (top-level device) —</option>
         {% for d in device_list_all|default([]) %}
-          {% if d.id != device.id and not d.is_subcomponent() %}
+          {% if d.id != device.id and not d.is_subcomponent() and d.battery_slots == 0 and d.battery_size is none %}
           <option value="{{ d.id }}" {% if device.parent_id == d.id %}selected{% endif %}>{{ d.name }}</option>
           {% endif %}
         {% endfor %}

tests/test_acceptance.py

@@ -584,12 +584,6 @@ def test_add_install_delete_battery(client):
 # Device — battery_size
 # ------------------------------------------------------------------ #
 
-def test_add_device_requires_battery_size(client):
-    """POST without battery_size returns 400."""
-    resp = client.post("/device/add", data={"name": "No Size Device", "battery_slots": "2"})
-    assert resp.status_code == 400
-    assert b"Battery size is required" in resp.data
-
 
 def test_add_device_with_battery_size(client):
     """Device with battery_size shows it on detail page."""
@@ -893,7 +887,7 @@ def test_device_charge_all_no_installed(seeded_client):
 
 def _setup_rc_car(client):
     """Create RC Car Set with Remote and Car sub-components and 6 AA batteries."""
-    client.post("/device/add", data={"name": "RC Car Set", "battery_slots": "6", "battery_size": "AA"})
+    client.post("/device/add", data={"name": "RC Car Set", "battery_slots": "0", "battery_size": ""})
     # id=1 above; add sub-components with parent_id=1
     client.post("/device/add", data={"name": "Remote", "battery_slots": "2",
                                      "battery_size": "AA", "parent_id": "1"})
@@ -967,7 +961,7 @@ def test_device_without_parent_unchanged(client):
 
 
 def test_subcomponent_ha_entity_id(client):
-    client.post("/device/add", data={"name": "Hub", "battery_slots": "1", "battery_size": "AA"})
+    client.post("/device/add", data={"name": "Hub", "battery_slots": "0", "battery_size": ""})
     resp = client.post(
         "/device/add",
         data={"name": "Sensor A", "battery_slots": "1", "battery_size": "AA",