Redirect to device detail after create; sub-component install UI on parent detail

app.py

@@ -650,7 +650,7 @@ def create_app(config_object="config"):
 
     @app.route("/device/")
     def device_list():
-        devices = db.query(Device).order_by(Device.name).all()
+        devices = db.query(Device).filter(Device.parent_id == None).order_by(Device.name).all()
         device_types = sorted({d.device_type for d in devices if d.device_type})
         device_locations = sorted({d.location for d in devices if d.location})
         device_battery_sizes = sorted({d.battery_size for d in devices if d.battery_size})
@@ -733,8 +733,11 @@ def create_app(config_object="config"):
                                        form_device_type=request.form.get("device_type", ""),
                                        prefill_parent=parent_device), 400
 
-            if db.query(Device).filter_by(name=name).first():
+            parent_key_val = parent_device.id if parent_device else -1
-                flash(f"A device named '{name}' already exists.", "error")
+            if db.query(Device).filter(
+                Device.parent_key == parent_key_val, Device.name == name
+            ).first():
+                flash(f"A device named '{name}' already exists here.", "error")
                 return render_template("device_add.html",
                                        device_types=device_types,
                                        device_locations=device_locations,
@@ -744,23 +747,24 @@ def create_app(config_object="config"):
                                        form_device_type=request.form.get("device_type", ""),
                                        prefill_parent=parent_device), 400
 
+            is_sub = parent_device is not None
             device = Device(name=name, battery_slots=slots, notes=notes,
-                            device_type=device_type, battery_size=battery_size,
+                            device_type=None if is_sub else device_type,
-                            location=location,
+                            battery_size=battery_size,
-                            parent_id=parent_device.id if parent_device else None)
+                            location=None if is_sub else location,
+                            parent_id=parent_device.id if parent_device else None,
+                            parent_key=parent_key_val)
             db.add(device)
             db.commit()
             flash(f"Device '{name}' added.", "success")
             if parent_device:
                 return redirect(url_for("device_detail", device_id=parent_device.id))
-            return redirect(url_for("device_list"))
+            return redirect(url_for("device_detail", device_id=device.id))
 
         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
@@ -804,6 +808,19 @@ def create_app(config_object="config"):
                         changed = True
                 if changed:
                     db.commit()
+        flat_installed = []
+        children_avail = {}
+        if device.has_children():
+            for child in device.children:
+                for b in child.batteries:
+                    if b.status == "installed":
+                        flat_installed.append((b, child.name, child.id))
+                avail_q = db.query(Battery).filter_by(status="available")
+                if child.battery_size:
+                    avail_q = avail_q.filter(
+                        (Battery.size == child.battery_size) | (Battery.size == None)
+                    )
+                children_avail[child.id] = avail_q.order_by(Battery.label).all()
         return render_template("device_detail.html", device=device, brands=brands,
                                available_batteries=available_batteries,
                                device_types=device_types,
@@ -812,7 +829,9 @@ def create_app(config_object="config"):
                                device_list_all=all_devices,
                                ha_enabled=ha_client.enabled,
                                ha_live_pct=ha_live_pct,
-                               logbook_entries=device.logbook_entries)
+                               logbook_entries=device.logbook_entries,
+                               flat_installed=flat_installed,
+                               children_avail=children_avail)
 
     # ------------------------------------------------------------------ #
     # Devices — edit
@@ -840,13 +859,20 @@ def create_app(config_object="config"):
         except ValueError:
             flash("Battery slots must be a positive integer.", "error")
             return redirect(url_for("device_detail", device_id=device_id))
-        existing = db.query(Device).filter_by(name=name).first()
+        # Determine new parent key for scoped uniqueness check
-        if existing and existing.id != device_id:
+        parent_id_raw = request.form.get("parent_id", "").strip()
-            flash(f"A device named '{name}' already exists.", "error")
+        new_parent_key_val = int(parent_id_raw) if (parent_id_raw and parent_id_raw.isdigit()) else -1
+
+        existing = db.query(Device).filter(
+            Device.parent_key == new_parent_key_val,
+            Device.name == name,
+            Device.id != device_id,
+        ).first()
+        if existing:
+            flash(f"A device named '{name}' already exists here.", "error")
             return redirect(url_for("device_detail", device_id=device_id))
 
         # Validate parent_id change
-        parent_id_raw = request.form.get("parent_id", "").strip()
         if parent_id_raw and parent_id_raw.isdigit():
             new_parent = db.get(Device, int(parent_id_raw))
             if not new_parent:
@@ -866,12 +892,19 @@ def create_app(config_object="config"):
                 )
                 return redirect(url_for("device_detail", device_id=device_id))
             device.parent_id = new_parent.id
+            device.parent_key = new_parent.id
         else:
             device.parent_id = None
+            device.parent_key = -1
 
         device.name = name
         device.notes = notes
-        device.device_type = device_type
+        if device.is_subcomponent():
+            device.device_type = None
+            device.location = None
+        else:
+            device.device_type = device_type
+            device.location = request.form.get("location", "").strip() or None
         if device.has_children():
             device.battery_slots = 0
             device.battery_size = None
@@ -880,7 +913,6 @@ def create_app(config_object="config"):
             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()
         flash("Device updated.", "success")
@@ -1327,7 +1359,9 @@ def create_app(config_object="config"):
                 if not name:
                     devices_skipped += 1
                     continue
-                existing = db.query(Device).filter_by(name=name).first()
+                existing = db.query(Device).filter(
+                    Device.parent_key == -1, Device.name == name
+                ).first()
                 if existing:
                     if old_id is not None:
                         device_id_map[old_id] = existing.id
@@ -1341,6 +1375,7 @@ def create_app(config_object="config"):
                         location      = d.get("location") or None,
                         ha_entity_id  = d.get("ha_entity_id") or None,
                         notes         = d.get("notes") or None,
+                        parent_key    = -1,
                     )
                     db.add(new_dev)
                     db.flush()

models.py

@@ -1,6 +1,6 @@
 from datetime import datetime
 
-from sqlalchemy import Column, Integer, String, Text, ForeignKey, Table
+from sqlalchemy import Column, Integer, String, Text, ForeignKey, Table, UniqueConstraint
 from sqlalchemy.orm import declarative_base, relationship
 
 Base = declarative_base()
@@ -25,7 +25,7 @@ class Device(Base):
     __tablename__ = "device"
 
     id = Column(Integer, primary_key=True, autoincrement=True)
-    name = Column(String(100), nullable=False, unique=True)
+    name = Column(String(100), nullable=False)
     battery_slots = Column(Integer, nullable=False, default=1)
     device_type   = Column(String(50),  nullable=True)
     battery_size  = Column(String(20),  nullable=True)   # AA, AAA, 9V, CR2032 …; null for parent-only devices
@@ -33,6 +33,11 @@ class Device(Base):
     notes = Column(Text, nullable=True)
     ha_entity_id = Column(String(100), nullable=True)   # e.g. "sensor.tv_remote_battery"
     parent_id = Column(Integer, ForeignKey("device.id", ondelete="SET NULL"), nullable=True)
+    parent_key = Column(Integer, nullable=False, default=-1)  # -1 for top-level, parent_id for sub-components
+
+    __table_args__ = (
+        UniqueConstraint("parent_key", "name", name="uq_device_parent_key_name"),
+    )
 
     batteries = relationship("Battery", back_populates="device")
     logbook_entries = relationship(
@@ -71,6 +76,16 @@ class Device(Base):
     def is_subcomponent(self):
         return self.parent_id is not None
 
+    def effective_installed_count(self):
+        if self.has_children():
+            return sum(c.installed_count() for c in self.children)
+        return self.installed_count()
+
+    def effective_slots(self):
+        if self.has_children():
+            return sum(c.battery_slots for c in self.children)
+        return self.battery_slots
+
     def __repr__(self):
         return f"<Device {self.name}>"
 

sbin/migrate_parent_key.py

@@ -0,0 +1,139 @@
+#!/usr/bin/env python3
+"""
+sbin/migrate_parent_key.py
+==========================
+Adds parent_key column, changes uniqueness from UNIQUE(name) to
+UNIQUE(parent_key, name), and clears device_type/location for sub-components.
+
+SQLite: recreates the device table (required to change constraints).
+MariaDB: uses ALTER TABLE. Check the index name with:
+    SHOW INDEX FROM device WHERE Column_name = 'name';
+
+Usage:
+    python sbin/migrate_parent_key.py               # SQLite (batteries.db)
+    MARIADB_URL='mysql+...' python sbin/migrate_parent_key.py
+"""
+
+import os
+import shutil
+import sys
+from datetime import date
+from pathlib import Path
+
+REPO_ROOT = Path(__file__).resolve().parent.parent
+
+
+def snapshot(src: Path) -> None:
+    dst = src.parent / f"{src.name}.{date.today().isoformat()}.snapshot"
+    shutil.copy2(src, dst)
+    print(f"Snapshot: {dst.name}")
+
+
+def migrate_sqlite() -> None:
+    import sqlite3
+
+    db_path = REPO_ROOT / "batteries.db"
+    if not db_path.exists():
+        print("batteries.db not found — nothing to migrate.")
+        return
+
+    snapshot(db_path)
+    conn = sqlite3.connect(str(db_path))
+    conn.execute("PRAGMA foreign_keys = OFF")
+
+    # Check if parent_key already exists (idempotency)
+    cols = {row[1] for row in conn.execute("PRAGMA table_info(device)")}
+    if "parent_key" in cols:
+        print("parent_key already present — running data-only fixup.")
+        conn.execute("UPDATE device SET parent_key = COALESCE(parent_id, -1)")
+        conn.execute("UPDATE device SET device_type = NULL, location = NULL WHERE parent_id IS NOT NULL")
+        conn.commit()
+        conn.close()
+        print("Done.")
+        return
+
+    conn.execute("ALTER TABLE device RENAME TO device_old")
+
+    conn.execute("""
+        CREATE TABLE device (
+            id           INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT,
+            name         VARCHAR(100) NOT NULL,
+            battery_slots INTEGER NOT NULL DEFAULT 1,
+            device_type  VARCHAR(50),
+            battery_size VARCHAR(20),
+            location     VARCHAR(100),
+            notes        TEXT,
+            ha_entity_id VARCHAR(100),
+            parent_id    INTEGER REFERENCES device(id) ON DELETE SET NULL,
+            parent_key   INTEGER NOT NULL DEFAULT -1,
+            CONSTRAINT uq_device_parent_key_name UNIQUE (parent_key, name)
+        )
+    """)
+
+    conn.execute("""
+        INSERT INTO device
+            (id, name, battery_slots, device_type, battery_size, location,
+             notes, ha_entity_id, parent_id, parent_key)
+        SELECT
+            id, name, battery_slots,
+            CASE WHEN parent_id IS NOT NULL THEN NULL ELSE device_type END,
+            battery_size,
+            CASE WHEN parent_id IS NOT NULL THEN NULL ELSE location END,
+            notes, ha_entity_id, parent_id,
+            COALESCE(parent_id, -1)
+        FROM device_old
+    """)
+
+    conn.execute("DROP TABLE device_old")
+    conn.execute("PRAGMA foreign_keys = ON")
+    conn.commit()
+
+    count = conn.execute("SELECT COUNT(*) FROM device").fetchone()[0]
+    print(f"SQLite migration complete — {count} device(s) migrated.")
+    conn.close()
+
+
+def migrate_mariadb(url: str) -> None:
+    from sqlalchemy import create_engine, text
+
+    engine = create_engine(url)
+    with engine.connect() as conn:
+        # Add column (skip if already present)
+        try:
+            conn.execute(text(
+                "ALTER TABLE device ADD COLUMN parent_key INT NOT NULL DEFAULT -1"
+            ))
+        except Exception:
+            print("parent_key column already exists — skipping ADD COLUMN.")
+
+        conn.execute(text("UPDATE device SET parent_key = COALESCE(parent_id, -1)"))
+        conn.execute(text(
+            "UPDATE device SET device_type = NULL, location = NULL WHERE parent_id IS NOT NULL"
+        ))
+
+        # Drop old UNIQUE index on name — check actual name first:
+        #   SHOW INDEX FROM device WHERE Column_name = 'name';
+        # Common names: 'name' or 'ix_device_name'
+        for idx_name in ("name", "ix_device_name"):
+            try:
+                conn.execute(text(f"ALTER TABLE device DROP INDEX `{idx_name}`"))
+                print(f"Dropped index '{idx_name}'.")
+                break
+            except Exception:
+                continue
+
+        conn.execute(text(
+            "ALTER TABLE device ADD CONSTRAINT uq_device_parent_key_name "
+            "UNIQUE (parent_key, name)"
+        ))
+        conn.commit()
+
+    print("MariaDB migration complete.")
+
+
+if __name__ == "__main__":
+    mariadb_url = os.environ.get("MARIADB_URL", "").strip()
+    if mariadb_url:
+        migrate_mariadb(mariadb_url)
+    else:
+        migrate_sqlite()

templates/device_add.html

@@ -56,6 +56,7 @@
     </div>
     </div><!-- #battery-fields -->
 
+    {% if not prefill_parent %}
     <div class="form-group">
       <label>Type</label>
       {% set _preset_types = ['Remote Control','Game Controller','Flashlight','Lock','Sensor','Toy','Clock','Smoke Detector'] %}
@@ -94,6 +95,7 @@
              placeholder="e.g. Living Room, Bedroom"
              style="display:none;margin-top:0.4rem;">
     </div>
+    {% endif %}
 
     <div class="form-group">
       <label for="notes">Notes</label>

templates/device_detail.html

@@ -63,6 +63,20 @@
       <td style="border:none;">{{ device.location }}</td>
     </tr>
     {% endif %}
+    {% if device.is_subcomponent() and device.parent %}
+      {% if device.parent.device_type %}
+      <tr>
+        <td style="padding:0.3rem 1rem 0.3rem 0;font-weight:600;color:#64748b;border:none;">Type</td>
+        <td style="border:none;">{{ device.parent.device_type }} <span class="text-muted" style="font-size:0.85em;">(inherited)</span></td>
+      </tr>
+      {% endif %}
+      {% if device.parent.location %}
+      <tr>
+        <td style="padding:0.3rem 1rem 0.3rem 0;font-weight:600;color:#64748b;border:none;">Location</td>
+        <td style="border:none;">{{ device.parent.location }} <span class="text-muted" style="font-size:0.85em;">(inherited)</span></td>
+      </tr>
+      {% endif %}
+    {% endif %}
     {% if device.notes %}
     <tr>
       <td style="padding:0.3rem 1rem 0.3rem 0;font-weight:600;color:#64748b;border:none;">Notes</td>
@@ -98,13 +112,79 @@
 <div class="card">
   {% if device.children %}
   <h2>Sub-components</h2>
-  <div style="display:flex;gap:0.75rem;flex-wrap:wrap;margin-bottom:0.75rem;">
+  <div style="display:flex;flex-direction:column;gap:0.5rem;margin-bottom:0.75rem;">
     {% for child in device.children %}
-    <a href="{{ url_for('device_detail', device_id=child.id) }}"
+    {% set child_free = child.battery_slots - child.installed_count() %}
-       style="display:block;padding:0.6rem 0.9rem;border:1px solid var(--border);border-radius:6px;text-decoration:none;min-width:140px;background:var(--bg-card);">
+    {% set child_batteries = children_avail.get(child.id, []) %}
-      <strong>{{ child.name }}</strong><br>
+    <details style="border:1px solid var(--border);border-radius:6px;background:var(--bg-card);">
-      <small class="text-muted">{{ child.installed_count() }}/{{ child.battery_slots }} slots &middot; {{ child.battery_size }}{% if child.ha_entity_id %} &middot; HA{% endif %}</small>
+      <summary style="padding:0.6rem 0.9rem;cursor:pointer;list-style:none;display:flex;align-items:center;justify-content:space-between;">
-    </a>
+        <span>
+          <strong>{{ child.name }}</strong>
+          <small class="text-muted" style="margin-left:0.5rem;">{{ child.installed_count() }}/{{ child.battery_slots }} slots &middot; {{ child.battery_size }}{% if child.ha_entity_id %} &middot; HA{% endif %}</small>
+        </span>
+        <span style="display:flex;gap:0.5rem;align-items:center;">
+          {% if child_free > 0 and child_batteries %}<small class="text-muted">{{ child_batteries|length }} available</small>{% endif %}
+          <a href="{{ url_for('device_detail', device_id=child.id) }}" onclick="event.stopPropagation();" style="font-size:0.8rem;">View</a>
+        </span>
+      </summary>
+      <div style="padding:0.6rem 0.9rem;border-top:1px solid var(--border);">
+        {% if child_free <= 0 %}
+          <p class="text-muted" style="margin:0;">No free slots.</p>
+        {% elif not child_batteries %}
+          <p class="text-muted" style="margin:0;">No compatible batteries available.</p>
+        {% else %}
+          <form method="post" action="{{ url_for('device_install_batch', device_id=child.id) }}">
+            <div style="margin-bottom:0.4rem;">
+              <label style="font-size:0.85rem;cursor:pointer;">
+                <input type="checkbox" id="select-all-child-{{ child.id }}" onchange="toggleAllChild{{ child.id }}(this)"> Select all
+              </label>
+            </div>
+            <div style="max-height:180px;overflow-y:auto;border:1px solid #cbd5e1;border-radius:4px;padding:0.4rem 0.6rem;">
+              {% for b in child_batteries %}
+              <div>
+                <label style="font-size:0.9rem;cursor:pointer;">
+                  <input type="checkbox" class="child-bat-{{ child.id }}" name="battery_ids" value="{{ b.id }}">
+                  {{ b.label }} — {{ b.brand }}{% if b.battery_percentage is not none %} ({{ b.battery_percentage }}%){% endif %}
+                </label>
+              </div>
+              {% endfor %}
+            </div>
+            <button class="btn btn-sm btn-primary" type="submit" style="margin-top:0.5rem;">Install Selected</button>
+          </form>
+          <script>
+          (function() {
+            var FREE_{{ child.id }} = {{ child_free }};
+            var queue_{{ child.id }} = [];
+            document.querySelectorAll('.child-bat-{{ child.id }}').forEach(function(cb) {
+              cb.addEventListener('change', function() {
+                if (cb.checked) {
+                  queue_{{ child.id }}.push(cb);
+                  if (queue_{{ child.id }}.length > FREE_{{ child.id }}) {
+                    queue_{{ child.id }}.shift().checked = false;
+                  }
+                } else {
+                  queue_{{ child.id }} = queue_{{ child.id }}.filter(function(c) { return c !== cb; });
+                }
+                document.getElementById('select-all-child-{{ child.id }}').checked = false;
+              });
+            });
+            window['toggleAllChild{{ child.id }}'] = function(masterCb) {
+              var all = Array.from(document.querySelectorAll('.child-bat-{{ child.id }}'));
+              if (masterCb.checked) {
+                queue_{{ child.id }} = [];
+                all.forEach(function(c) { c.checked = false; });
+                all.slice(0, FREE_{{ child.id }}).forEach(function(c) { c.checked = true; queue_{{ child.id }}.push(c); });
+                if (all.length > FREE_{{ child.id }}) masterCb.checked = false;
+              } else {
+                all.forEach(function(c) { c.checked = false; });
+                queue_{{ child.id }} = [];
+              }
+            };
+          })();
+          </script>
+        {% endif %}
+      </div>
+    </details>
     {% endfor %}
   </div>
   {% else %}
@@ -116,24 +196,30 @@
 {% endif %}
 
 {% if device.has_children() %}
-<div class="card">
+<div class="card" id="installed">
-  <h2>Batteries in Sub-components</h2>
+  <h2>Installed Batteries</h2>
-  {% for child in device.children %}
+  {% if flat_installed %}
-  {% 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>
+      <thead><tr>
+        <th>Component</th><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 %}
+        {% for b, comp_name, comp_id in flat_installed %}
         <tr>
+          <td data-label="Component"><a href="{{ url_for('device_detail', device_id=comp_id) }}">{{ comp_name }}</a></td>
           <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 %}
+          {% if ha_enabled %}
+          <td data-label="Bat %">
+            {% if b.battery_percentage is not none %}
+              {% if b.battery_percentage < 20 %}<span class="badge badge-warning">⚠ {{ b.battery_percentage }}%</span>
+              {% else %}{{ b.battery_percentage }}%{% endif %}
+            {% 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 %}
@@ -141,9 +227,8 @@
     </table>
   </div>
   {% else %}
-  <p class="text-muted" style="margin:0 0 0.5rem;">No batteries installed.</p>
+  <p class="text-muted">No batteries installed across sub-components.</p>
   {% endif %}
-  {% endfor %}
 </div>
 {% endif %}
 
@@ -407,6 +492,7 @@ function addInstallRow() {
       <input type="number" id="edit-slots" name="battery_slots" value="{{ device.battery_slots }}" min="1" required>
     </div>
     {% endif %}
+    {% if not device.is_subcomponent() %}
     <div class="form-group">
       <label>Type</label>
       {% set _preset_types = ['Remote Control','Game Controller','Flashlight','Lock','Sensor','Toy','Clock','Smoke Detector'] %}
@@ -427,6 +513,7 @@ 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>
+    {% endif %}
     {% if not device.has_children() %}
     <div class="form-group">
       <label>Battery Size</label>
@@ -452,6 +539,7 @@ function addInstallRow() {
              style="display:{% if device.battery_size and device.battery_size not in _preset_sizes %}''{% else %}none{% endif %};margin-top:0.4rem;">
     </div>
     {% endif %}
+    {% if not device.is_subcomponent() %}
     <div class="form-group">
       <label>Location</label>
       <select id="edit-location-select" onchange="editLocationSelectChanged(this)">
@@ -469,6 +557,7 @@ function addInstallRow() {
              placeholder="e.g. Living Room, Bedroom"
              style="display:{% if device.location and device.location not in device_locations|default([]) %}''{% else %}none{% endif %};margin-top:0.4rem;">
     </div>
+    {% endif %}
 
     <div class="form-group">
       <label for="edit-notes">Notes</label>

templates/device_list.html

@@ -57,9 +57,10 @@
       </thead>
       <tbody>
         {% for d in devices %}
-        {% set installed = d.installed_count() %}
+        {% set installed = d.effective_installed_count() %}
-        {% if installed == 0 %}{% set fill_state = 'empty' %}
+        {% set total_slots = d.effective_slots() %}
-        {% elif installed >= d.battery_slots %}{% set fill_state = 'full' %}
+        {% if installed == 0 or total_slots == 0 %}{% set fill_state = 'empty' %}
+        {% elif installed >= total_slots %}{% set fill_state = 'full' %}
         {% else %}{% set fill_state = 'partial' %}{% endif %}
         <tr data-type="{{ d.device_type or '' }}"
             data-battery-size="{{ d.battery_size or '' }}"
@@ -68,19 +69,17 @@
             data-name="{{ d.name|lower }}">
           <td data-label="Device">
             <a href="{{ url_for('device_detail', device_id=d.id) }}"><strong>{{ d.name }}</strong></a>
-            {% if d.parent %}
+            {% if d.has_children() %}
-            <br><small class="text-muted">↳ <a href="{{ url_for('device_detail', device_id=d.parent.id) }}">{{ d.parent.name }}</a></small>
-            {% elif d.has_children() %}
             <br><small class="text-muted">{{ d.children|length }} sub-component{{ 's' if d.children|length != 1 }}</small>
             {% endif %}
           </td>
           <td data-label="Type">{{ d.device_type or '—' }}</td>
           <td data-label="Size">{{ d.battery_size or '—' }}</td>
           <td data-label="Location">{{ d.location or '—' }}</td>
-          <td data-label="Slots">{{ d.battery_slots }}</td>
+          <td data-label="Slots">{{ total_slots }}</td>
           <td data-label="Installed">
-            {{ installed }} / {{ d.battery_slots }}
+            {{ installed }} / {{ total_slots }}
-            {% if installed >= d.battery_slots %}
+            {% if total_slots > 0 and installed >= total_slots %}
               <span class="badge badge-retired">Full</span>
             {% endif %}
           </td>

tests/test_acceptance.py

@@ -975,3 +975,96 @@ def test_subcomponent_ha_entity_id(client):
     resp = client.get("/device/2")
     assert resp.status_code == 200
     assert b"Hub" in resp.data
+
+
+# ------------------------------------------------------------------ #
+# Sub-component hierarchy — parent_key, null type/location, list hiding
+# ------------------------------------------------------------------ #
+
+def _setup_parent_with_two_children(client):
+    """Hub (top-level, Sensor type, Living Room) with Sensor A and Sensor B."""
+    client.post("/device/add", data={
+        "name": "Hub", "battery_slots": "0", "battery_size": "",
+        "device_type": "Sensor", "location": "Living Room",
+    }, follow_redirects=True)
+    client.post("/device/add", data={
+        "name": "Sensor A", "battery_slots": "1", "battery_size": "AA", "parent_id": "1",
+    }, follow_redirects=True)
+    client.post("/device/add", data={
+        "name": "Sensor B", "battery_slots": "1", "battery_size": "AA", "parent_id": "1",
+    }, follow_redirects=True)
+
+
+def test_device_list_hides_subcomponents(client):
+    _setup_parent_with_two_children(client)
+    resp = client.get("/device/")
+    assert resp.status_code == 200
+    assert b"Hub" in resp.data
+    assert b"Sensor A" not in resp.data
+    assert b"Sensor B" not in resp.data
+
+
+def test_subcomponent_type_location_null(client):
+    _setup_parent_with_two_children(client)
+    # Sub-component detail shows inherited type/location from parent
+    resp = client.get("/device/2")
+    assert resp.status_code == 200
+    assert b"Sensor" in resp.data
+    assert b"Living Room" in resp.data
+    assert b"inherited" in resp.data
+    # Submitting type/location in edit for sub-component should have no effect
+    client.post("/device/2/edit", data={
+        "name": "Sensor A", "battery_slots": "1",
+        "device_type": "Remote Control", "location": "Bedroom",
+        "parent_id": "1",  # keep sub-component relationship
+    })
+    resp2 = client.get("/device/2")
+    assert b"Remote Control" not in resp2.data
+    assert b"Bedroom" not in resp2.data
+
+
+def test_subcomponent_name_unique_per_parent(client):
+    _setup_parent_with_two_children(client)
+
+    # Duplicate top-level name → 400
+    resp = client.post("/device/add", data={
+        "name": "Hub", "battery_slots": "0", "battery_size": "",
+    })
+    assert resp.status_code == 400
+    assert b"already exists" in resp.data
+
+    # Duplicate child name within same parent → 400
+    resp = client.post("/device/add", data={
+        "name": "Sensor A", "battery_slots": "1", "battery_size": "AA", "parent_id": "1",
+    })
+    assert resp.status_code == 400
+    assert b"already exists" in resp.data
+
+    # Same child name under a DIFFERENT parent → success
+    client.post("/device/add", data={
+        "name": "Hub 2", "battery_slots": "0", "battery_size": "",
+    })  # id=4
+    resp = client.post("/device/add", data={
+        "name": "Sensor A", "battery_slots": "1", "battery_size": "AA", "parent_id": "4",
+    }, follow_redirects=True)
+    assert resp.status_code == 200
+
+
+def test_parent_battery_summary_flat(client):
+    _setup_parent_with_two_children(client)
+    client.post("/battery/add", data={"brand": "Eneloop", "count": "2"})  # ids 1, 2
+    client.post("/device/2/install-one", data={"battery_id": "1"})
+    client.post("/device/3/install-one", data={"battery_id": "2"})
+
+    resp = client.get("/device/1")
+    assert resp.status_code == 200
+    # Flat table has Component column heading
+    assert b"Component" in resp.data
+    # Both batteries appear
+    assert b"Eneloop 001" in resp.data
+    assert b"Eneloop 002" in resp.data
+    # Both child names linked in the component column
+    assert b"Sensor A" in resp.data
+    assert b"Sensor B" in resp.data
+    # Only one "Installed Batteries" heading
+    assert resp.data.count(b"Installed Batteries") == 1