Initial commit: Flask battery tracker app

- Flask + SQLAlchemy (MariaDB-compatible schema) battery tracking web app
- 40 pre-seeded batteries (Eneloop, BONAI, Energizer NiMH) across 5 devices
- Business rules: block retired assignment, brand-mix warnings, capacity checks
- Mobile-friendly Jinja2 templates with inline CSS
- waitress WSGI server via systemd user service (sbin/install-service.sh)
- SQLite → MariaDB migration script (migrate_to_mariadb.py)
- 26 passing acceptance tests (pytest + Flask test client)

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

.gitignore

@@ -0,0 +1,10 @@
+.venv/
+__pycache__/
+*.pyc
+*.db
+*.db-shm
+*.db-wal
+instance/
+.pytest_cache/
+*.egg-info/
+dist/

MIGRATION.md

@@ -0,0 +1,164 @@
+# Migrating from SQLite to MariaDB
+
+This guide covers moving the Battery Tracker database from SQLite to MariaDB/MySQL
+without changing any application code — only the connection string changes.
+
+---
+
+## 1. Install PyMySQL
+
+```bash
+source .venv/bin/activate
+pip install pymysql
+pip freeze > requirements.txt
+```
+
+---
+
+## 2. Create the MariaDB database and user
+
+```sql
+CREATE DATABASE batteries CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;
+CREATE USER 'battuser'@'localhost' IDENTIFIED BY 'strongpassword';
+GRANT ALL PRIVILEGES ON batteries.* TO 'battuser'@'localhost';
+FLUSH PRIVILEGES;
+```
+
+---
+
+## 3. Update the connection string
+
+Set the `DATABASE_URL` environment variable before starting the app:
+
+```bash
+export DATABASE_URL='mysql+pymysql://battuser:strongpassword@localhost/batteries?charset=utf8mb4'
+```
+
+Or add it to a `.env` file and load it with your process manager / systemd service:
+
+```ini
+# In ~/.config/systemd/user/battery-tracker.service, add under [Service]:
+Environment=DATABASE_URL=mysql+pymysql://battuser:strongpassword@localhost/batteries?charset=utf8mb4
+```
+
+---
+
+## 4. (Optional) Use Flask-Migrate for schema management
+
+Flask-Migrate lets you apply schema changes incrementally via `flask db upgrade`
+rather than dropping and recreating tables.
+
+```bash
+pip install Flask-Migrate
+```
+
+In `app.py`, after the `db` setup, add:
+
+```python
+from flask_migrate import Migrate
+migrate = Migrate(app, db)   # pass your SQLAlchemy db object
+```
+
+Then:
+
+```bash
+flask db init       # first time only — creates migrations/ directory
+flask db migrate -m "initial schema"
+flask db upgrade
+```
+
+> **Note:** The app uses raw SQLAlchemy (not Flask-SQLAlchemy), so you will need
+> to adapt the `Migrate(app, db)` call to wrap your engine/session. Alternatively,
+> run `Base.metadata.create_all(engine)` directly for the initial schema — the app
+> already does this on startup.
+
+---
+
+## 5. Run the migration script
+
+The `migrate_to_mariadb.py` script reads every record from SQLite and inserts
+it into MariaDB using the SQLAlchemy ORM — no raw SQL, no CSV exports.
+
+```bash
+MARIADB_URL='mysql+pymysql://battuser:strongpassword@localhost/batteries?charset=utf8mb4' \
+    python migrate_to_mariadb.py
+```
+
+Or pass the URL as a positional argument:
+
+```bash
+python migrate_to_mariadb.py 'mysql+pymysql://battuser:strongpassword@localhost/batteries?charset=utf8mb4'
+```
+
+The script:
+1. Creates all tables on MariaDB if they don't exist
+2. Inserts all Device records (preserving primary keys)
+3. Inserts all Battery records (preserving primary keys and foreign keys)
+4. Resets `AUTO_INCREMENT` counters past the highest migrated ID
+5. Prints a verification table comparing row counts
+
+---
+
+## 6. Verify row counts
+
+The migration script prints a summary:
+
+```
+=== Verification ===
+Table        SQLite   MariaDB    OK?
+--------------------------------------
+device            5         5     OK
+battery          40        40     OK
+
+Migration complete. All row counts match.
+```
+
+If you see `MISMATCH`, **do not** decommission SQLite. Re-run the script after
+investigating the error output.
+
+You can also verify manually in the MariaDB shell:
+
+```sql
+SELECT COUNT(*) FROM device;
+SELECT COUNT(*) FROM battery;
+```
+
+---
+
+## 7. MariaDB configuration notes
+
+| Setting | Recommended value |
+|---|---|
+| Character set | `utf8mb4` |
+| Collation | `utf8mb4_unicode_ci` |
+| `innodb_strict_mode` | `ON` (default in MariaDB 10.2+) |
+| `sql_mode` | Include `STRICT_TRANS_TABLES` |
+
+Set these in `/etc/mysql/mariadb.conf.d/50-server.cnf` (or equivalent):
+
+```ini
+[mysqld]
+character-set-server  = utf8mb4
+collation-server      = utf8mb4_unicode_ci
+```
+
+The `?charset=utf8mb4` query parameter in the connection string ensures the
+client connection also uses utf8mb4, regardless of the server default.
+
+---
+
+## 8. Decommission SQLite
+
+Once you have confirmed the row counts match and the app is running correctly
+against MariaDB:
+
+```bash
+# Optional: keep a backup
+cp batteries.db batteries.db.bak
+
+# Remove the SQLite file
+rm batteries.db
+```
+
+The `DATABASE_URL` environment variable now fully controls which database is used —
+no code changes were required.

app.py

@@ -0,0 +1,275 @@
+from flask import Flask, render_template, redirect, url_for, request, flash, abort
+from sqlalchemy import create_engine
+from sqlalchemy.orm import scoped_session, sessionmaker
+
+from models import Base, Battery, Device
+
+
+def create_app(config_object="config"):
+    app = Flask(__name__)
+    app.config.from_object(config_object)
+
+    engine = create_engine(
+        app.config["SQLALCHEMY_DATABASE_URI"],
+        pool_pre_ping=True,
+    )
+    Base.metadata.create_all(engine)
+
+    db = scoped_session(sessionmaker(bind=engine))
+
+    @app.teardown_appcontext
+    def remove_session(exc=None):
+        db.remove()
+
+    # ------------------------------------------------------------------ #
+    # Dashboard
+    # ------------------------------------------------------------------ #
+
+    @app.route("/")
+    def dashboard():
+        batteries = db.query(Battery).order_by(Battery.label).all()
+        return render_template("dashboard.html", batteries=batteries)
+
+    # ------------------------------------------------------------------ #
+    # Battery — add
+    # ------------------------------------------------------------------ #
+
+    @app.route("/battery/add", methods=["GET", "POST"])
+    def battery_add():
+        if request.method == "POST":
+            label = request.form.get("label", "").strip()
+            brand = request.form.get("brand", "").strip()
+            status = request.form.get("status", "available").strip()
+            notes = request.form.get("notes", "").strip() or None
+
+            if not label or not brand:
+                flash("Label and brand are required.", "error")
+                return render_template("battery_add.html"), 400
+
+            if status not in ("available", "installed", "retired"):
+                status = "available"
+
+            if db.query(Battery).filter_by(label=label).first():
+                flash(f"A battery with label '{label}' already exists.", "error")
+                return render_template("battery_add.html",
+                                       form_label=label, form_brand=brand,
+                                       form_status=status, form_notes=notes or ""), 400
+
+            battery = Battery(label=label, brand=brand, status=status, notes=notes)
+            db.add(battery)
+            db.commit()
+            flash(f"Battery {label} added.", "success")
+            return redirect(url_for("dashboard"))
+
+        return render_template("battery_add.html")
+
+    # ------------------------------------------------------------------ #
+    # Battery — detail
+    # ------------------------------------------------------------------ #
+
+    @app.route("/battery/<int:battery_id>")
+    def battery_detail(battery_id):
+        battery = db.get(Battery, battery_id)
+        if battery is None:
+            abort(404)
+        return render_template("battery_detail.html", battery=battery)
+
+    # ------------------------------------------------------------------ #
+    # Battery — edit notes
+    # ------------------------------------------------------------------ #
+
+    @app.route("/battery/<int:battery_id>/edit-notes", methods=["POST"])
+    def battery_edit_notes(battery_id):
+        battery = db.get(Battery, battery_id)
+        if battery is None:
+            abort(404)
+        battery.notes = request.form.get("notes", "").strip() or None
+        db.commit()
+        flash("Notes updated.", "success")
+        return redirect(url_for("battery_detail", battery_id=battery_id))
+
+    # ------------------------------------------------------------------ #
+    # Battery — assign
+    # ------------------------------------------------------------------ #
+
+    @app.route("/battery/<int:battery_id>/assign", methods=["GET", "POST"])
+    def battery_assign(battery_id):
+        battery = db.get(Battery, battery_id)
+        if battery is None:
+            abort(404)
+
+        if battery.is_retired():
+            flash("Cannot assign a retired battery.", "error")
+            return redirect(url_for("battery_detail", battery_id=battery_id))
+
+        devices = db.query(Device).order_by(Device.name).all()
+
+        if request.method == "POST":
+            device_id = request.form.get("device_id", type=int)
+            device = db.get(Device, device_id)
+            if device is None:
+                flash("Device not found.", "error")
+                return render_template("assign.html", battery=battery, devices=devices)
+
+            if device.installed_count() >= device.battery_slots:
+                flash(
+                    f"{device.name} is already full "
+                    f"({device.battery_slots}/{device.battery_slots} slots used).",
+                    "error",
+                )
+                return render_template("assign.html", battery=battery, devices=devices)
+
+            # Warn on brand mix (non-blocking)
+            existing_brands = device.installed_brands()
+            if existing_brands and battery.brand not in existing_brands:
+                flash(
+                    f"Warning: {device.name} already has batteries from "
+                    f"{', '.join(existing_brands)}. Mixing brands is not recommended.",
+                    "warning",
+                )
+
+            # Unassign from previous device if needed
+            if battery.device_id is not None:
+                battery.device_id = None
+
+            battery.status = "installed"
+            battery.device_id = device.id
+            db.commit()
+            flash(f"{battery.label} assigned to {device.name}.", "success")
+            return redirect(url_for("dashboard"))
+
+        return render_template("assign.html", battery=battery, devices=devices)
+
+    # ------------------------------------------------------------------ #
+    # Battery — unassign
+    # ------------------------------------------------------------------ #
+
+    @app.route("/battery/<int:battery_id>/unassign", methods=["POST"])
+    def battery_unassign(battery_id):
+        battery = db.get(Battery, battery_id)
+        if battery is None:
+            abort(404)
+        battery.status = "available"
+        battery.device_id = None
+        db.commit()
+        flash(f"{battery.label} unassigned and marked available.", "success")
+        return redirect(url_for("dashboard"))
+
+    # ------------------------------------------------------------------ #
+    # Battery — retire
+    # ------------------------------------------------------------------ #
+
+    @app.route("/battery/<int:battery_id>/retire", methods=["POST"])
+    def battery_retire(battery_id):
+        battery = db.get(Battery, battery_id)
+        if battery is None:
+            abort(404)
+        if battery.is_retired():
+            flash(f"{battery.label} is already retired.", "error")
+            return redirect(url_for("battery_detail", battery_id=battery_id))
+        battery.status = "retired"
+        battery.device_id = None
+        db.commit()
+        flash(f"{battery.label} has been retired.", "success")
+        return redirect(url_for("dashboard"))
+
+    # ------------------------------------------------------------------ #
+    # Battery — delete
+    # ------------------------------------------------------------------ #
+
+    @app.route("/battery/<int:battery_id>/delete", methods=["GET", "POST"])
+    def battery_delete(battery_id):
+        battery = db.get(Battery, battery_id)
+        if battery is None:
+            abort(404)
+        if request.method == "POST":
+            label = battery.label
+            db.delete(battery)
+            db.commit()
+            flash(f"Battery {label} permanently deleted.", "success")
+            return redirect(url_for("dashboard"))
+        return render_template("battery_delete.html", battery=battery)
+
+    # ------------------------------------------------------------------ #
+    # Devices — list
+    # ------------------------------------------------------------------ #
+
+    @app.route("/device/")
+    def device_list():
+        devices = db.query(Device).order_by(Device.name).all()
+        return render_template("device_list.html", devices=devices)
+
+    # ------------------------------------------------------------------ #
+    # Devices — add
+    # ------------------------------------------------------------------ #
+
+    @app.route("/device/add", methods=["GET", "POST"])
+    def device_add():
+        if request.method == "POST":
+            name = request.form.get("name", "").strip()
+            slots_raw = request.form.get("battery_slots", "1").strip()
+            notes = request.form.get("notes", "").strip() or None
+
+            if not name:
+                flash("Device name is required.", "error")
+                return render_template("device_add.html"), 400
+
+            try:
+                slots = int(slots_raw)
+                if slots < 1:
+                    raise ValueError
+            except ValueError:
+                flash("Battery slots must be a positive integer.", "error")
+                return render_template("device_add.html",
+                                       form_name=name, form_notes=notes or ""), 400
+
+            if db.query(Device).filter_by(name=name).first():
+                flash(f"A device named '{name}' already exists.", "error")
+                return render_template("device_add.html",
+                                       form_name=name, form_slots=slots,
+                                       form_notes=notes or ""), 400
+
+            device = Device(name=name, battery_slots=slots, notes=notes)
+            db.add(device)
+            db.commit()
+            flash(f"Device '{name}' added.", "success")
+            return redirect(url_for("device_list"))
+
+        return render_template("device_add.html")
+
+    # ------------------------------------------------------------------ #
+    # Devices — detail
+    # ------------------------------------------------------------------ #
+
+    @app.route("/device/<int:device_id>")
+    def device_detail(device_id):
+        device = db.get(Device, device_id)
+        if device is None:
+            abort(404)
+        return render_template("device_detail.html", device=device)
+
+    # ------------------------------------------------------------------ #
+    # Devices — delete
+    # ------------------------------------------------------------------ #
+
+    @app.route("/device/<int:device_id>/delete", methods=["POST"])
+    def device_delete(device_id):
+        device = db.get(Device, device_id)
+        if device is None:
+            abort(404)
+        for battery in device.batteries:
+            battery.status = "available"
+            battery.device_id = None
+        name = device.name
+        db.delete(device)
+        db.commit()
+        flash(f"Device '{name}' deleted. All batteries marked available.", "success")
+        return redirect(url_for("device_list"))
+
+    return app
+
+
+app = create_app()
+
+if __name__ == "__main__":
+    app.run(debug=True)

config.py

@@ -0,0 +1,8 @@
+import os
+
+SQLALCHEMY_DATABASE_URI = os.environ.get(
+    "DATABASE_URL",
+    "sqlite:///batteries.db",
+)
+SECRET_KEY = os.environ.get("SECRET_KEY", "dev-secret-change-in-prod")
+SQLALCHEMY_TRACK_MODIFICATIONS = False

migrate_to_mariadb.py

@@ -0,0 +1,129 @@
+"""
+Migrate data from SQLite to MariaDB using SQLAlchemy ORM only — no raw SQL
+except for the AUTO_INCREMENT reset which requires a DDL statement.
+
+Usage:
+    MARIADB_URL='mysql+pymysql://user:pass@host/dbname?charset=utf8mb4' \\
+        python migrate_to_mariadb.py
+
+Or pass the URL as a CLI argument:
+    python migrate_to_mariadb.py 'mysql+pymysql://user:pass@host/dbname?charset=utf8mb4'
+"""
+
+import sys
+
+from sqlalchemy import create_engine, text
+from sqlalchemy.orm import sessionmaker
+
+import config
+from models import Base, Battery, Device
+
+
+def migrate(mariadb_url: str):
+    print("=== Battery Tracker: SQLite → MariaDB Migration ===\n")
+
+    # -- Engines --
+    sqlite_engine = create_engine(config.SQLALCHEMY_DATABASE_URI)
+    mariadb_engine = create_engine(mariadb_url, pool_pre_ping=True)
+
+    SrcSession = sessionmaker(bind=sqlite_engine)
+    DstSession = sessionmaker(bind=mariadb_engine)
+
+    src = SrcSession()
+    dst = DstSession()
+
+    try:
+        # -- Create tables on MariaDB --
+        print("Creating tables on MariaDB (if not exist)…")
+        Base.metadata.create_all(mariadb_engine)
+
+        # -- Read source data --
+        src_devices   = src.query(Device).all()
+        src_batteries = src.query(Battery).all()
+        print(f"Source: {len(src_devices)} devices, {len(src_batteries)} batteries\n")
+
+        # -- Migrate Devices first (batteries have FK → device) --
+        print("Migrating devices…")
+        for d in src_devices:
+            new_d = Device(
+                id=d.id,
+                name=d.name,
+                battery_slots=d.battery_slots,
+                notes=d.notes,
+            )
+            dst.add(new_d)
+        dst.flush()
+
+        # -- Migrate Batteries --
+        print("Migrating batteries…")
+        for b in src_batteries:
+            new_b = Battery(
+                id=b.id,
+                label=b.label,
+                brand=b.brand,
+                status=b.status,
+                device_id=b.device_id,
+                notes=b.notes,
+            )
+            dst.add(new_b)
+        dst.flush()
+
+        dst.commit()
+        print("Commit successful.\n")
+
+        # -- Reset AUTO_INCREMENT so new rows don't collide --
+        # This DDL is required; there is no ORM-level equivalent.
+        with mariadb_engine.connect() as conn:
+            max_device_id   = max((d.id for d in src_devices),   default=0)
+            max_battery_id  = max((b.id for b in src_batteries),  default=0)
+            conn.execute(text("ALTER TABLE device SET AUTO_INCREMENT = :v"),
+                         {"v": max_device_id + 1})
+            conn.execute(text("ALTER TABLE battery SET AUTO_INCREMENT = :v"),
+                         {"v": max_battery_id + 1})
+            conn.commit()
+        print("AUTO_INCREMENT counters reset.\n")
+
+        # -- Verify counts --
+        dst_device_count   = dst.query(Device).count()
+        dst_battery_count  = dst.query(Battery).count()
+        src_device_count   = len(src_devices)
+        src_battery_count  = len(src_batteries)
+
+        print("=== Verification ===")
+        print(f"{'Table':<12} {'SQLite':>8} {'MariaDB':>9} {'OK?':>5}")
+        print("-" * 38)
+
+        device_ok  = src_device_count  == dst_device_count
+        battery_ok = src_battery_count == dst_battery_count
+
+        print(f"{'device':<12} {src_device_count:>8} {dst_device_count:>9} {'OK' if device_ok else 'MISMATCH':>5}")
+        print(f"{'battery':<12} {src_battery_count:>8} {dst_battery_count:>9} {'OK' if battery_ok else 'MISMATCH':>5}")
+
+        if not (device_ok and battery_ok):
+            print("\nERROR: Row count mismatch. Do not decommission SQLite.")
+            sys.exit(1)
+
+        print("\nMigration complete. All row counts match.")
+
+    except Exception as exc:
+        dst.rollback()
+        print(f"\nERROR: {exc}")
+        raise
+    finally:
+        src.close()
+        dst.close()
+
+
+if __name__ == "__main__":
+    if len(sys.argv) > 1:
+        url = sys.argv[1]
+    else:
+        import os
+        url = os.environ.get("MARIADB_URL")
+
+    if not url:
+        print("ERROR: Provide MariaDB URL via MARIADB_URL env var or as a CLI argument.")
+        print("  Example: python migrate_to_mariadb.py 'mysql+pymysql://user:pass@host/db?charset=utf8mb4'")
+        sys.exit(1)
+
+    migrate(url)

models.py

@@ -0,0 +1,52 @@
+from sqlalchemy import Column, Integer, String, Text, ForeignKey
+from sqlalchemy.orm import declarative_base, relationship
+
+Base = declarative_base()
+
+
+class Device(Base):
+    __tablename__ = "device"
+
+    id = Column(Integer, primary_key=True, autoincrement=True)
+    name = Column(String(100), nullable=False, unique=True)
+    battery_slots = Column(Integer, nullable=False, default=1)
+    notes = Column(Text, nullable=True)
+
+    batteries = relationship("Battery", back_populates="device")
+
+    def installed_count(self):
+        return sum(1 for b in self.batteries if b.status == "installed")
+
+    def installed_brands(self):
+        return set(b.brand for b in self.batteries if b.status == "installed")
+
+    def has_mixed_brands(self):
+        return len(self.installed_brands()) > 1
+
+    def __repr__(self):
+        return f"<Device {self.name}>"
+
+
+class Battery(Base):
+    __tablename__ = "battery"
+
+    id = Column(Integer, primary_key=True, autoincrement=True)
+    label = Column(String(50), nullable=False, unique=True)
+    brand = Column(String(100), nullable=False)
+    status = Column(String(20), nullable=False, default="available")
+    device_id = Column(Integer, ForeignKey("device.id", ondelete="SET NULL"), nullable=True)
+    notes = Column(Text, nullable=True)
+
+    device = relationship("Device", back_populates="batteries")
+
+    def is_available(self):
+        return self.status == "available"
+
+    def is_retired(self):
+        return self.status == "retired"
+
+    def is_installed(self):
+        return self.status == "installed"
+
+    def __repr__(self):
+        return f"<Battery {self.label}>"

requirements.txt

@@ -0,0 +1,5 @@
+Flask>=3.0,<4.0
+SQLAlchemy>=2.0,<3.0
+PyMySQL>=1.1,<2.0
+waitress>=3.0,<4.0
+pytest>=8.0,<9.0

sbin/README.md

@@ -0,0 +1,43 @@
+# sbin — Support Scripts
+
+## install-service.sh
+
+Generates a systemd **user-level** service file and enables it. No root required.
+
+**Prerequisites:** The app's `.venv` must exist and have Flask installed.
+
+```bash
+bash sbin/install-service.sh
+```
+
+You will be prompted for a host (default `127.0.0.1`) and port (default `5000`).
+The script writes `~/.config/systemd/user/battery-tracker.service` and enables it.
+
+**Start the service:**
+```bash
+systemctl --user start battery-tracker
+systemctl --user status battery-tracker
+```
+
+**View live logs:**
+```bash
+journalctl --user -u battery-tracker -f
+```
+
+**Make it start on login** (requires lingering to be enabled for your user):
+```bash
+loginctl enable-linger "$USER"
+```
+
+**Uninstall:**
+```bash
+systemctl --user disable --now battery-tracker
+rm ~/.config/systemd/user/battery-tracker.service
+systemctl --user daemon-reload
+```
+
+**Re-run to update** (e.g. if you moved the app directory):
+```bash
+bash sbin/install-service.sh
+systemctl --user restart battery-tracker
+```

sbin/install-service.sh

@@ -0,0 +1,79 @@
+#!/usr/bin/env bash
+# install-service.sh
+# Generates and installs a systemd user-level service for the Battery Tracker app.
+# No root required — uses ~/.config/systemd/user/.
+#
+# Usage:  bash sbin/install-service.sh
+
+set -euo pipefail
+
+# Resolve the app root directory from the script's own location
+APP_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
+VENV_WAITRESS="$APP_DIR/.venv/bin/waitress-serve"
+SERVICE_DIR="$HOME/.config/systemd/user"
+SERVICE_FILE="$SERVICE_DIR/battery-tracker.service"
+
+echo "=== Battery Tracker — systemd user service installer ==="
+echo "App directory: $APP_DIR"
+echo
+
+# Sanity checks
+if [[ ! -f "$VENV_WAITRESS" ]]; then
+  echo "ERROR: waitress-serve not found at $VENV_WAITRESS"
+  echo "Run:  python3 -m venv .venv && .venv/bin/pip install -r requirements.txt"
+  exit 1
+fi
+
+if [[ ! -f "$APP_DIR/app.py" ]]; then
+  echo "ERROR: app.py not found in $APP_DIR"
+  exit 1
+fi
+
+# Prompt for port and host
+read -rp "Listen host [default: 127.0.0.1]: " HOST
+HOST="${HOST:-127.0.0.1}"
+
+read -rp "Listen port [default: 5000]: " PORT
+PORT="${PORT:-5000}"
+
+echo
+echo "Generating service file → $SERVICE_FILE"
+
+mkdir -p "$SERVICE_DIR"
+
+cat > "$SERVICE_FILE" <<EOF
+[Unit]
+Description=Battery Tracker Flask App
+After=network.target
+
+[Service]
+Type=simple
+WorkingDirectory=$APP_DIR
+ExecStart=$VENV_WAITRESS --host=$HOST --port=$PORT app:app
+Environment=PYTHONPATH=$APP_DIR
+Restart=on-failure
+RestartSec=5
+
+[Install]
+WantedBy=default.target
+EOF
+
+echo "Service file written."
+echo
+
+# Reload and enable
+systemctl --user daemon-reload
+systemctl --user enable battery-tracker
+
+echo
+echo "=== Done ==="
+echo
+echo "Start the service:   systemctl --user start battery-tracker"
+echo "Check status:        systemctl --user status battery-tracker"
+echo "View logs:           journalctl --user -u battery-tracker -f"
+echo "Stop the service:    systemctl --user stop battery-tracker"
+echo
+echo "To uninstall:"
+echo "  systemctl --user disable --now battery-tracker"
+echo "  rm $SERVICE_FILE"
+echo "  systemctl --user daemon-reload"

seed.py

@@ -0,0 +1,57 @@
+"""
+Seed the database with initial batteries and devices.
+Safe to run multiple times — exits early if data already exists.
+"""
+
+from sqlalchemy import create_engine
+from sqlalchemy.orm import sessionmaker
+
+import config
+from models import Base, Battery, Device
+
+
+def seed():
+    engine = create_engine(config.SQLALCHEMY_DATABASE_URI, pool_pre_ping=True)
+    Base.metadata.create_all(engine)
+    Session = sessionmaker(bind=engine)
+    db = Session()
+
+    if db.query(Battery).count() > 0:
+        print("Database already seeded — skipping.")
+        db.close()
+        return
+
+    # --- Devices ---
+    device_specs = [
+        ("RC Car",      4),
+        ("TV Remote",   2),
+        ("Flashlight",  3),
+        ("Kids Toy 1",  3),
+        ("Kids Toy 2",  2),
+    ]
+    devices = []
+    for name, slots in device_specs:
+        d = Device(name=name, battery_slots=slots)
+        db.add(d)
+        devices.append(d)
+
+    # --- Batteries ---
+    battery_specs = [
+        ("ENL", "Panasonic Eneloop", 16),
+        ("BON", "BONAI",             16),
+        ("ENR", "Energizer NiMH",     8),
+    ]
+    for prefix, brand, count in battery_specs:
+        for i in range(1, count + 1):
+            label = f"{prefix}-{i:02d}"
+            db.add(Battery(label=label, brand=brand, status="available"))
+
+    db.commit()
+    db.close()
+
+    total = sum(c for _, _, c in battery_specs)
+    print(f"Seeded {len(device_specs)} devices and {total} batteries.")
+
+
+if __name__ == "__main__":
+    seed()

templates/assign.html

@@ -0,0 +1,48 @@
+{% extends "base.html" %}
+{% block title %}Assign {{ battery.label }} — Battery Tracker{% endblock %}
+
+{% block content %}
+<h1>Assign {{ battery.label }}</h1>
+<p class="text-muted" style="margin-bottom:1rem;">Brand: {{ battery.brand }}</p>
+
+<div class="card">
+  {% if devices %}
+    <form method="post" action="{{ url_for('battery_assign', battery_id=battery.id) }}">
+      <div class="form-group">
+        <label>Select Device</label>
+        {% for device in devices %}
+          {% set full = device.installed_count() >= device.battery_slots %}
+          {% set mix  = device.installed_brands() and battery.brand not in device.installed_brands() %}
+          <div style="margin-bottom:0.75rem;padding:0.6rem 0.75rem;border:1px solid #e2e8f0;border-radius:4px;
+                      {% if full %}opacity:0.5;{% endif %}background:#fff;">
+            <label style="display:flex;align-items:center;gap:0.6rem;font-weight:normal;cursor:{% if full %}not-allowed{% else %}pointer{% endif %};">
+              <input type="radio" name="device_id" value="{{ device.id }}"
+                     {% if full %}disabled{% endif %}
+                     style="cursor:{% if full %}not-allowed{% else %}pointer{% endif %};">
+              <span>
+                <strong>{{ device.name }}</strong>
+                <span class="text-muted">({{ device.installed_count() }}/{{ device.battery_slots }} slots used)</span>
+                {% if full %}
+                  <span class="badge badge-retired">Full</span>
+                {% endif %}
+              </span>
+            </label>
+            {% if mix and not full %}
+              <p class="text-warning" style="margin-top:0.3rem;margin-left:1.6rem;">
+                ⚠ Already has {{ device.installed_brands()|join(', ') }} — mixing brands not recommended.
+              </p>
+            {% endif %}
+          </div>
+        {% endfor %}
+      </div>
+
+      <div class="form-actions">
+        <button class="btn btn-primary" type="submit">Assign Battery</button>
+        <a class="btn btn-secondary" href="{{ url_for('battery_detail', battery_id=battery.id) }}">Cancel</a>
+      </div>
+    </form>
+  {% else %}
+    <p class="text-muted">No devices exist yet. <a href="{{ url_for('device_add') }}">Add a device first.</a></p>
+  {% endif %}
+</div>
+{% endblock %}

templates/base.html

@@ -0,0 +1,110 @@
+<!DOCTYPE html>
+<html lang="en">
+<head>
+  <meta charset="UTF-8">
+  <meta name="viewport" content="width=device-width, initial-scale=1">
+  <title>{% block title %}Battery Tracker{% endblock %}</title>
+  <style>
+    *, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
+    body { font-family: system-ui, sans-serif; font-size: 15px; background: #f5f5f5; color: #222; }
+    a { color: #2563eb; text-decoration: none; }
+    a:hover { text-decoration: underline; }
+
+    /* Nav */
+    nav {
+      background: #1e40af;
+      color: #fff;
+      display: flex;
+      flex-wrap: wrap;
+      gap: 0.5rem;
+      align-items: center;
+      padding: 0.75rem 1rem;
+    }
+    nav .brand { font-weight: 700; font-size: 1.1rem; margin-right: auto; color: #fff; }
+    nav a { color: #bfdbfe; font-size: 0.9rem; padding: 0.25rem 0.5rem; border-radius: 4px; }
+    nav a:hover { background: #1d4ed8; color: #fff; text-decoration: none; }
+
+    /* Layout */
+    .container { max-width: 960px; margin: 1.5rem auto; padding: 0 1rem; }
+
+    /* Flash messages */
+    .flash { padding: 0.6rem 1rem; border-radius: 4px; margin-bottom: 1rem; font-size: 0.9rem; }
+    .flash.success { background: #dcfce7; color: #166534; border: 1px solid #86efac; }
+    .flash.error   { background: #fee2e2; color: #991b1b; border: 1px solid #fca5a5; }
+    .flash.warning { background: #fef9c3; color: #854d0e; border: 1px solid #fde047; }
+
+    /* Cards / boxes */
+    .card { background: #fff; border-radius: 6px; box-shadow: 0 1px 3px rgba(0,0,0,.1); padding: 1.25rem; margin-bottom: 1rem; }
+
+    /* Tables */
+    .table-wrap { overflow-x: auto; }
+    table { width: 100%; border-collapse: collapse; }
+    th { text-align: left; padding: 0.5rem 0.75rem; background: #f1f5f9; font-size: 0.8rem; text-transform: uppercase; letter-spacing: .05em; color: #64748b; border-bottom: 2px solid #e2e8f0; }
+    td { padding: 0.5rem 0.75rem; border-bottom: 1px solid #e2e8f0; vertical-align: middle; }
+    tr:last-child td { border-bottom: none; }
+    tr:hover td { background: #f8fafc; }
+
+    /* Status badges */
+    .badge { display: inline-block; padding: 0.2em 0.55em; border-radius: 999px; font-size: 0.75rem; font-weight: 600; }
+    .badge-available { background: #dcfce7; color: #166534; }
+    .badge-installed { background: #dbeafe; color: #1e40af; }
+    .badge-retired   { background: #f1f5f9; color: #64748b; }
+    .badge-warning   { background: #fef9c3; color: #854d0e; }
+
+    /* Buttons */
+    .btn { display: inline-block; padding: 0.4rem 0.9rem; border-radius: 4px; border: none; cursor: pointer; font-size: 0.875rem; font-family: inherit; text-decoration: none; }
+    .btn:hover { text-decoration: none; }
+    .btn-primary  { background: #2563eb; color: #fff; }
+    .btn-primary:hover  { background: #1d4ed8; }
+    .btn-danger   { background: #dc2626; color: #fff; }
+    .btn-danger:hover   { background: #b91c1c; }
+    .btn-warning  { background: #d97706; color: #fff; }
+    .btn-warning:hover  { background: #b45309; }
+    .btn-secondary { background: #e2e8f0; color: #334155; }
+    .btn-secondary:hover { background: #cbd5e1; }
+    .btn-sm { padding: 0.25rem 0.6rem; font-size: 0.8rem; }
+
+    /* Forms */
+    .form-group { margin-bottom: 1rem; }
+    label { display: block; font-size: 0.875rem; font-weight: 600; margin-bottom: 0.3rem; color: #374151; }
+    input[type=text], input[type=number], select, textarea {
+      width: 100%; padding: 0.45rem 0.65rem; border: 1px solid #d1d5db;
+      border-radius: 4px; font-size: 0.9rem; font-family: inherit;
+    }
+    input:focus, select:focus, textarea:focus { outline: 2px solid #3b82f6; border-color: #3b82f6; }
+    textarea { min-height: 80px; resize: vertical; }
+    .form-actions { display: flex; gap: 0.75rem; align-items: center; flex-wrap: wrap; margin-top: 1.25rem; }
+
+    /* Headings */
+    h1 { font-size: 1.5rem; margin-bottom: 1rem; color: #1e293b; }
+    h2 { font-size: 1.15rem; margin-bottom: 0.75rem; color: #334155; }
+
+    /* Inline form (for POST buttons in tables) */
+    form.inline { display: inline; }
+
+    /* Warning text */
+    .text-warning { color: #b45309; font-size: 0.8rem; }
+    .text-danger  { color: #dc2626; }
+    .text-muted   { color: #6b7280; font-size: 0.85rem; }
+  </style>
+</head>
+<body>
+  <nav>
+    <span class="brand">Battery Tracker</span>
+    <a href="{{ url_for('dashboard') }}">Dashboard</a>
+    <a href="{{ url_for('device_list') }}">Devices</a>
+    <a href="{{ url_for('battery_add') }}">+ Battery</a>
+    <a href="{{ url_for('device_add') }}">+ Device</a>
+  </nav>
+
+  <div class="container">
+    {% with messages = get_flashed_messages(with_categories=true) %}
+      {% for category, message in messages %}
+        <div class="flash {{ category }}">{{ message }}</div>
+      {% endfor %}
+    {% endwith %}
+
+    {% block content %}{% endblock %}
+  </div>
+</body>
+</html>

templates/battery_add.html

@@ -0,0 +1,41 @@
+{% extends "base.html" %}
+{% block title %}Add Battery — Battery Tracker{% endblock %}
+
+{% block content %}
+<h1>Add Battery</h1>
+
+<div class="card">
+  <form method="post" action="{{ url_for('battery_add') }}">
+    <div class="form-group">
+      <label for="label">Label <span class="text-danger">*</span></label>
+      <input type="text" id="label" name="label" value="{{ form_label|default('') }}"
+             placeholder="e.g. ENL-17" required>
+    </div>
+
+    <div class="form-group">
+      <label for="brand">Brand <span class="text-danger">*</span></label>
+      <input type="text" id="brand" name="brand" value="{{ form_brand|default('') }}"
+             placeholder="e.g. Panasonic Eneloop" required>
+    </div>
+
+    <div class="form-group">
+      <label for="status">Initial Status</label>
+      <select id="status" name="status">
+        <option value="available" {% if form_status|default('available') == 'available' %}selected{% endif %}>Available</option>
+        <option value="installed" {% if form_status|default('') == 'installed' %}selected{% endif %}>Installed</option>
+        <option value="retired"   {% if form_status|default('') == 'retired' %}selected{% endif %}>Retired</option>
+      </select>
+    </div>
+
+    <div class="form-group">
+      <label for="notes">Notes</label>
+      <textarea id="notes" name="notes" placeholder="Optional notes…">{{ form_notes|default('') }}</textarea>
+    </div>
+
+    <div class="form-actions">
+      <button class="btn btn-primary" type="submit">Add Battery</button>
+      <a class="btn btn-secondary" href="{{ url_for('dashboard') }}">Cancel</a>
+    </div>
+  </form>
+</div>
+{% endblock %}

templates/battery_delete.html

@@ -0,0 +1,29 @@
+{% extends "base.html" %}
+{% block title %}Delete {{ battery.label }} — Battery Tracker{% endblock %}
+
+{% block content %}
+<h1>Delete Battery</h1>
+
+<div class="card">
+  <p style="margin-bottom:1rem;">
+    You are about to <strong>permanently delete</strong> battery
+    <strong>{{ battery.label }}</strong> ({{ battery.brand }}).
+    This action cannot be undone.
+  </p>
+
+  {% if battery.is_installed() %}
+    <p class="text-warning" style="margin-bottom:1rem;">
+      ⚠ This battery is currently installed in
+      <strong>{{ battery.device.name }}</strong>.
+      Deleting it will free that slot.
+    </p>
+  {% endif %}
+
+  <div class="form-actions">
+    <form method="post" action="{{ url_for('battery_delete', battery_id=battery.id) }}">
+      <button class="btn btn-danger" type="submit">Confirm Delete</button>
+    </form>
+    <a class="btn btn-secondary" href="{{ url_for('battery_detail', battery_id=battery.id) }}">Cancel</a>
+  </div>
+</div>
+{% endblock %}

templates/battery_detail.html

@@ -0,0 +1,70 @@
+{% extends "base.html" %}
+{% block title %}{{ battery.label }} — Battery Tracker{% endblock %}
+
+{% block content %}
+<h1>{{ battery.label }}</h1>
+
+<div class="card">
+  <table style="width:auto;border:none;">
+    <tr>
+      <td style="padding:0.3rem 1rem 0.3rem 0;font-weight:600;color:#64748b;border:none;">Label</td>
+      <td style="border:none;">{{ battery.label }}</td>
+    </tr>
+    <tr>
+      <td style="padding:0.3rem 1rem 0.3rem 0;font-weight:600;color:#64748b;border:none;">Brand</td>
+      <td style="border:none;">{{ battery.brand }}</td>
+    </tr>
+    <tr>
+      <td style="padding:0.3rem 1rem 0.3rem 0;font-weight:600;color:#64748b;border:none;">Status</td>
+      <td style="border:none;"><span class="badge badge-{{ battery.status }}">{{ battery.status|capitalize }}</span></td>
+    </tr>
+    <tr>
+      <td style="padding:0.3rem 1rem 0.3rem 0;font-weight:600;color:#64748b;border:none;">Device</td>
+      <td style="border:none;">
+        {% if battery.device %}
+          <a href="{{ url_for('device_detail', device_id=battery.device.id) }}">{{ battery.device.name }}</a>
+        {% else %}
+          <span class="text-muted">None</span>
+        {% endif %}
+      </td>
+    </tr>
+  </table>
+</div>
+
+<!-- Notes -->
+<div class="card">
+  <h2>Notes</h2>
+  <form method="post" action="{{ url_for('battery_edit_notes', battery_id=battery.id) }}">
+    <div class="form-group">
+      <textarea name="notes" placeholder="No notes yet…">{{ battery.notes or '' }}</textarea>
+    </div>
+    <button class="btn btn-primary" type="submit">Save Notes</button>
+  </form>
+</div>
+
+<!-- Actions -->
+<div class="card">
+  <h2>Actions</h2>
+  <div class="form-actions">
+    {% if battery.is_available() %}
+      <a class="btn btn-primary" href="{{ url_for('battery_assign', battery_id=battery.id) }}">Assign to Device</a>
+    {% endif %}
+
+    {% if battery.is_installed() %}
+      <form method="post" action="{{ url_for('battery_unassign', battery_id=battery.id) }}">
+        <button class="btn btn-warning" type="submit">Unassign</button>
+      </form>
+    {% endif %}
+
+    {% if not battery.is_retired() %}
+      <form method="post" action="{{ url_for('battery_retire', battery_id=battery.id) }}">
+        <button class="btn btn-secondary" type="submit">Retire Battery</button>
+      </form>
+    {% endif %}
+
+    <a class="btn btn-danger" href="{{ url_for('battery_delete', battery_id=battery.id) }}">Delete Battery</a>
+  </div>
+</div>
+
+<a class="text-muted" href="{{ url_for('dashboard') }}">&larr; Back to Dashboard</a>
+{% endblock %}

templates/dashboard.html

@@ -0,0 +1,88 @@
+{% extends "base.html" %}
+{% block title %}Dashboard — Battery Tracker{% endblock %}
+
+{% block content %}
+<h1>Battery Dashboard</h1>
+
+{% set total = batteries|length %}
+{% set available = batteries|selectattr('status','eq','available')|list|length %}
+{% set installed = batteries|selectattr('status','eq','installed')|list|length %}
+{% set retired  = batteries|selectattr('status','eq','retired')|list|length %}
+
+<div style="display:flex;gap:1rem;flex-wrap:wrap;margin-bottom:1.25rem;">
+  <div class="card" style="flex:1;min-width:120px;text-align:center;">
+    <div style="font-size:1.8rem;font-weight:700;">{{ total }}</div>
+    <div class="text-muted">Total</div>
+  </div>
+  <div class="card" style="flex:1;min-width:120px;text-align:center;">
+    <div style="font-size:1.8rem;font-weight:700;color:#166534;">{{ available }}</div>
+    <div class="text-muted">Available</div>
+  </div>
+  <div class="card" style="flex:1;min-width:120px;text-align:center;">
+    <div style="font-size:1.8rem;font-weight:700;color:#1e40af;">{{ installed }}</div>
+    <div class="text-muted">Installed</div>
+  </div>
+  <div class="card" style="flex:1;min-width:120px;text-align:center;">
+    <div style="font-size:1.8rem;font-weight:700;color:#64748b;">{{ retired }}</div>
+    <div class="text-muted">Retired</div>
+  </div>
+</div>
+
+<div class="card">
+  <div class="table-wrap">
+    <table>
+      <thead>
+        <tr>
+          <th>Label</th>
+          <th>Brand</th>
+          <th>Status</th>
+          <th>Assigned To</th>
+          <th>Actions</th>
+        </tr>
+      </thead>
+      <tbody>
+        {% for b in batteries %}
+        <tr>
+          <td><a href="{{ url_for('battery_detail', battery_id=b.id) }}"><strong>{{ b.label }}</strong></a></td>
+          <td>{{ b.brand }}</td>
+          <td>
+            <span class="badge badge-{{ b.status }}">{{ b.status|capitalize }}</span>
+          </td>
+          <td>
+            {% if b.device %}
+              <a href="{{ url_for('device_detail', device_id=b.device.id) }}">{{ b.device.name }}</a>
+              {% if b.device.has_mixed_brands() %}
+                <span class="badge badge-warning" title="Mixed brands in this device">⚠ mixed</span>
+              {% endif %}
+            {% else %}
+              <span class="text-muted">—</span>
+            {% endif %}
+          </td>
+          <td style="white-space:nowrap;">
+            <a class="btn btn-sm btn-secondary" href="{{ url_for('battery_detail', battery_id=b.id) }}">View</a>
+
+            {% if b.is_available() %}
+              <a class="btn btn-sm btn-primary" href="{{ url_for('battery_assign', battery_id=b.id) }}">Assign</a>
+            {% endif %}
+
+            {% if b.is_installed() %}
+              <form class="inline" method="post" action="{{ url_for('battery_unassign', battery_id=b.id) }}">
+                <button class="btn btn-sm btn-warning" type="submit">Unassign</button>
+              </form>
+            {% endif %}
+
+            {% if not b.is_retired() %}
+              <form class="inline" method="post" action="{{ url_for('battery_retire', battery_id=b.id) }}">
+                <button class="btn btn-sm btn-secondary" type="submit">Retire</button>
+              </form>
+            {% endif %}
+          </td>
+        </tr>
+        {% else %}
+        <tr><td colspan="5" class="text-muted" style="text-align:center;padding:1rem;">No batteries found. <a href="{{ url_for('battery_add') }}">Add one.</a></td></tr>
+        {% endfor %}
+      </tbody>
+    </table>
+  </div>
+</div>
+{% endblock %}

templates/device_add.html

@@ -0,0 +1,32 @@
+{% extends "base.html" %}
+{% block title %}Add Device — Battery Tracker{% endblock %}
+
+{% block content %}
+<h1>Add Device</h1>
+
+<div class="card">
+  <form method="post" action="{{ url_for('device_add') }}">
+    <div class="form-group">
+      <label for="name">Device Name <span class="text-danger">*</span></label>
+      <input type="text" id="name" name="name" value="{{ form_name|default('') }}"
+             placeholder="e.g. Game Controller" required>
+    </div>
+
+    <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"
+             value="{{ form_slots|default(1) }}" min="1" required>
+    </div>
+
+    <div class="form-group">
+      <label for="notes">Notes</label>
+      <textarea id="notes" name="notes" placeholder="Optional notes…">{{ form_notes|default('') }}</textarea>
+    </div>
+
+    <div class="form-actions">
+      <button class="btn btn-primary" type="submit">Add Device</button>
+      <a class="btn btn-secondary" href="{{ url_for('device_list') }}">Cancel</a>
+    </div>
+  </form>
+</div>
+{% endblock %}

templates/device_detail.html

@@ -0,0 +1,69 @@
+{% extends "base.html" %}
+{% block title %}{{ device.name }} — Battery Tracker{% endblock %}
+
+{% block content %}
+<h1>{{ device.name }}</h1>
+
+<div class="card">
+  <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>
+    </tr>
+    {% if device.has_mixed_brands() %}
+    <tr>
+      <td style="padding:0.3rem 1rem 0.3rem 0;font-weight:600;color:#64748b;border:none;">Warning</td>
+      <td style="border:none;"><span class="badge badge-warning">⚠ Mixed brands installed</span></td>
+    </tr>
+    {% endif %}
+    {% if device.notes %}
+    <tr>
+      <td style="padding:0.3rem 1rem 0.3rem 0;font-weight:600;color:#64748b;border:none;">Notes</td>
+      <td style="border:none;">{{ device.notes }}</td>
+    </tr>
+    {% endif %}
+  </table>
+</div>
+
+<div class="card">
+  <h2>Installed Batteries</h2>
+  {% set installed = device.batteries | selectattr('status', 'eq', 'installed') | list %}
+  {% if installed %}
+    <div class="table-wrap">
+      <table>
+        <thead>
+          <tr><th>Label</th><th>Brand</th><th>Notes</th><th>Actions</th></tr>
+        </thead>
+        <tbody>
+          {% for b in installed %}
+          <tr>
+            <td><a href="{{ url_for('battery_detail', battery_id=b.id) }}">{{ b.label }}</a></td>
+            <td>{{ b.brand }}</td>
+            <td class="text-muted">{{ b.notes or '—' }}</td>
+            <td>
+              <form class="inline" method="post" action="{{ url_for('battery_unassign', battery_id=b.id) }}">
+                <button class="btn btn-sm btn-warning" type="submit">Unassign</button>
+              </form>
+            </td>
+          </tr>
+          {% endfor %}
+        </tbody>
+      </table>
+    </div>
+  {% else %}
+    <p class="text-muted">No batteries installed.</p>
+  {% endif %}
+</div>
+
+<div class="card">
+  <h2>Delete Device</h2>
+  <p style="margin-bottom:1rem;" class="text-muted">
+    Deleting this device will unassign all installed batteries and mark them available.
+  </p>
+  <form method="post" action="{{ url_for('device_delete', device_id=device.id) }}">
+    <button class="btn btn-danger" type="submit">Delete {{ device.name }}</button>
+  </form>
+</div>
+
+<a class="text-muted" href="{{ url_for('device_list') }}">&larr; Back to Devices</a>
+{% endblock %}

templates/device_list.html

@@ -0,0 +1,58 @@
+{% extends "base.html" %}
+{% block title %}Devices — Battery Tracker{% endblock %}
+
+{% block content %}
+<h1>Devices</h1>
+
+<div class="card">
+  <div class="table-wrap">
+    <table>
+      <thead>
+        <tr>
+          <th>Name</th>
+          <th>Slots</th>
+          <th>Installed</th>
+          <th>Brands</th>
+          <th>Actions</th>
+        </tr>
+      </thead>
+      <tbody>
+        {% for d in devices %}
+        <tr>
+          <td><a href="{{ url_for('device_detail', device_id=d.id) }}"><strong>{{ d.name }}</strong></a></td>
+          <td>{{ d.battery_slots }}</td>
+          <td>
+            {{ d.installed_count() }} / {{ d.battery_slots }}
+            {% if d.installed_count() >= d.battery_slots %}
+              <span class="badge badge-retired">Full</span>
+            {% endif %}
+          </td>
+          <td>
+            {% set brands = d.installed_brands() %}
+            {% if brands %}
+              {{ brands|join(', ') }}
+              {% if d.has_mixed_brands() %}
+                <span class="badge badge-warning">⚠ mixed</span>
+              {% endif %}
+            {% else %}
+              <span class="text-muted">—</span>
+            {% endif %}
+          </td>
+          <td style="white-space:nowrap;">
+            <a class="btn btn-sm btn-secondary" href="{{ url_for('device_detail', device_id=d.id) }}">View</a>
+            <form class="inline" method="post" action="{{ url_for('device_delete', device_id=d.id) }}"
+                  onsubmit="return confirm('Delete {{ d.name }}? All installed batteries will be unassigned.');">
+              <button class="btn btn-sm btn-danger" type="submit">Delete</button>
+            </form>
+          </td>
+        </tr>
+        {% else %}
+        <tr><td colspan="5" class="text-muted" style="text-align:center;padding:1rem;">No devices yet. <a href="{{ url_for('device_add') }}">Add one.</a></td></tr>
+        {% endfor %}
+      </tbody>
+    </table>
+  </div>
+</div>
+
+<a class="btn btn-primary" href="{{ url_for('device_add') }}">+ Add Device</a>
+{% endblock %}

tests/conftest.py

@@ -0,0 +1,41 @@
+import os
+import tempfile
+
+import pytest
+
+
+@pytest.fixture()
+def app():
+    """Create app with a temporary file-based SQLite DB, removed after the test."""
+    db_fd, db_path = tempfile.mkstemp(suffix=".db")
+    os.close(db_fd)
+
+    class TestConfig:
+        SQLALCHEMY_DATABASE_URI = f"sqlite:///{db_path}"
+        SECRET_KEY = "test-secret"
+        SQLALCHEMY_TRACK_MODIFICATIONS = False
+        TESTING = True
+
+    from app import create_app
+    flask_app = create_app(TestConfig)
+
+    yield flask_app
+
+    os.unlink(db_path)
+
+
+@pytest.fixture()
+def client(app):
+    return app.test_client()
+
+
+@pytest.fixture()
+def seeded_client(app):
+    """Test client pre-loaded with 2 devices and 3 batteries (2 available, 1 retired)."""
+    with app.test_client() as c:
+        c.post("/device/add", data={"name": "Device A", "battery_slots": "2"})
+        c.post("/device/add", data={"name": "Device B", "battery_slots": "1"})
+        c.post("/battery/add", data={"label": "TST-01", "brand": "BrandX", "status": "available"})
+        c.post("/battery/add", data={"label": "TST-02", "brand": "BrandY", "status": "available"})
+        c.post("/battery/add", data={"label": "TST-03", "brand": "BrandX", "status": "retired"})
+        yield c

tests/test_acceptance.py

@@ -0,0 +1,281 @@
+"""
+Acceptance tests for Battery Tracker.
+
+Each test gets a fresh in-memory SQLite database via the fixtures in conftest.py.
+The `seeded_client` fixture pre-populates:
+  Devices:   Device A (2 slots), Device B (1 slot)
+  Batteries: TST-01 (BrandX, available), TST-02 (BrandY, available), TST-03 (BrandX, retired)
+"""
+
+import pytest
+
+
+# ------------------------------------------------------------------ #
+# Helpers
+# ------------------------------------------------------------------ #
+
+def get_location(resp):
+    """Return the redirect Location header (without host)."""
+    loc = resp.headers.get("Location", "")
+    # Strip scheme+host if present
+    if loc.startswith("http"):
+        from urllib.parse import urlparse
+        loc = urlparse(loc).path
+    return loc
+
+
+def follow(client, resp):
+    """Follow a single redirect."""
+    return client.get(get_location(resp))
+
+
+# ------------------------------------------------------------------ #
+# Dashboard
+# ------------------------------------------------------------------ #
+
+def test_dashboard_loads(seeded_client):
+    resp = seeded_client.get("/")
+    assert resp.status_code == 200
+    assert b"TST-01" in resp.data
+    assert b"TST-02" in resp.data
+    assert b"TST-03" in resp.data
+
+
+# ------------------------------------------------------------------ #
+# Battery — add
+# ------------------------------------------------------------------ #
+
+def test_add_battery(client):
+    resp = client.post("/battery/add",
+                       data={"label": "NEW-01", "brand": "TestBrand", "status": "available"},
+                       follow_redirects=True)
+    assert resp.status_code == 200
+    assert b"NEW-01" in resp.data
+
+
+def test_add_battery_duplicate_label(seeded_client):
+    resp = seeded_client.post("/battery/add",
+                              data={"label": "TST-01", "brand": "OtherBrand", "status": "available"})
+    assert resp.status_code == 400
+    assert b"already exists" in resp.data
+
+
+def test_add_battery_missing_fields(client):
+    resp = client.post("/battery/add", data={"label": "", "brand": ""})
+    assert resp.status_code == 400
+    assert b"required" in resp.data
+
+
+# ------------------------------------------------------------------ #
+# Battery — detail
+# ------------------------------------------------------------------ #
+
+def test_battery_detail(seeded_client):
+    resp = seeded_client.get("/battery/1")
+    assert resp.status_code == 200
+    assert b"TST-01" in resp.data
+    assert b"BrandX" in resp.data
+
+
+def test_battery_detail_not_found(client):
+    resp = client.get("/battery/9999")
+    assert resp.status_code == 404
+
+
+# ------------------------------------------------------------------ #
+# Battery — edit notes
+# ------------------------------------------------------------------ #
+
+def test_edit_notes(seeded_client):
+    seeded_client.post("/battery/1/edit-notes", data={"notes": "test note here"})
+    resp = seeded_client.get("/battery/1")
+    assert b"test note here" in resp.data
+
+
+# ------------------------------------------------------------------ #
+# Battery — assign
+# ------------------------------------------------------------------ #
+
+def test_assign_battery(seeded_client):
+    # TST-01 is battery id=1, Device A is device id=1
+    resp = seeded_client.post("/battery/1/assign",
+                              data={"device_id": "1"},
+                              follow_redirects=True)
+    assert resp.status_code == 200
+    assert b"Device A" in resp.data
+
+
+def test_assign_retired_battery_blocked(seeded_client):
+    # TST-03 is retired (id=3)
+    resp = seeded_client.post("/battery/3/assign",
+                              data={"device_id": "1"},
+                              follow_redirects=True)
+    assert resp.status_code == 200
+    assert b"retired" in resp.data.lower()
+
+
+def test_assign_over_capacity_blocked(seeded_client):
+    # Fill Device B (1 slot) with TST-01
+    seeded_client.post("/battery/1/assign", data={"device_id": "2"})
+    # Try to assign TST-02 to the same full device
+    resp = seeded_client.post("/battery/2/assign",
+                              data={"device_id": "2"},
+                              follow_redirects=True)
+    assert resp.status_code == 200
+    assert b"full" in resp.data.lower()
+
+
+def test_brand_mix_warning(seeded_client):
+    # Assign TST-01 (BrandX) to Device A
+    seeded_client.post("/battery/1/assign", data={"device_id": "1"})
+    # Assign TST-02 (BrandY) to same Device A → brand mix warning, but succeeds
+    resp = seeded_client.post("/battery/2/assign",
+                              data={"device_id": "1"},
+                              follow_redirects=True)
+    assert resp.status_code == 200
+    # Warning flash should mention mixing
+    assert b"mixing" in resp.data.lower() or b"mix" in resp.data.lower() or b"brand" in resp.data.lower()
+
+
+# ------------------------------------------------------------------ #
+# Battery — unassign
+# ------------------------------------------------------------------ #
+
+def test_unassign_battery(seeded_client):
+    seeded_client.post("/battery/1/assign", data={"device_id": "1"})
+    resp = seeded_client.post("/battery/1/unassign", follow_redirects=True)
+    assert resp.status_code == 200
+    # Battery should show as available on dashboard
+    resp2 = seeded_client.get("/battery/1")
+    assert b"available" in resp2.data.lower()
+
+
+# ------------------------------------------------------------------ #
+# Battery — retire
+# ------------------------------------------------------------------ #
+
+def test_retire_battery(seeded_client):
+    resp = seeded_client.post("/battery/1/retire", follow_redirects=True)
+    assert resp.status_code == 200
+    resp2 = seeded_client.get("/battery/1")
+    assert b"retired" in resp2.data.lower()
+
+
+def test_retire_clears_device(seeded_client):
+    seeded_client.post("/battery/1/assign", data={"device_id": "1"})
+    seeded_client.post("/battery/1/retire")
+    resp = seeded_client.get("/battery/1")
+    assert b"None" in resp.data or b"retired" in resp.data.lower()
+
+
+def test_retire_already_retired(seeded_client):
+    # TST-03 is already retired (id=3)
+    resp = seeded_client.post("/battery/3/retire", follow_redirects=True)
+    assert resp.status_code == 200
+    assert b"already retired" in resp.data.lower()
+
+
+# ------------------------------------------------------------------ #
+# Battery — delete
+# ------------------------------------------------------------------ #
+
+def test_delete_battery_confirmation_page(seeded_client):
+    resp = seeded_client.get("/battery/1/delete")
+    assert resp.status_code == 200
+    assert b"Confirm Delete" in resp.data
+    assert b"TST-01" in resp.data
+
+
+def test_delete_battery(seeded_client):
+    seeded_client.post("/battery/1/delete")
+    resp = seeded_client.get("/battery/1")
+    assert resp.status_code == 404
+
+
+# ------------------------------------------------------------------ #
+# Device — list
+# ------------------------------------------------------------------ #
+
+def test_device_list(seeded_client):
+    resp = seeded_client.get("/device/")
+    assert resp.status_code == 200
+    assert b"Device A" in resp.data
+    assert b"Device B" in resp.data
+
+
+# ------------------------------------------------------------------ #
+# Device — add
+# ------------------------------------------------------------------ #
+
+def test_add_device(client):
+    resp = client.post("/device/add",
+                       data={"name": "My Gadget", "battery_slots": "3"},
+                       follow_redirects=True)
+    assert resp.status_code == 200
+    assert b"My Gadget" in resp.data
+
+
+def test_add_device_duplicate_name(seeded_client):
+    resp = seeded_client.post("/device/add",
+                              data={"name": "Device A", "battery_slots": "2"})
+    assert resp.status_code == 400
+    assert b"already exists" in resp.data
+
+
+def test_add_device_missing_name(client):
+    resp = client.post("/device/add", data={"name": "", "battery_slots": "1"})
+    assert resp.status_code == 400
+
+
+# ------------------------------------------------------------------ #
+# Device — detail
+# ------------------------------------------------------------------ #
+
+def test_device_detail(seeded_client):
+    resp = seeded_client.get("/device/1")
+    assert resp.status_code == 200
+    assert b"Device A" in resp.data
+    assert b"2" in resp.data  # battery_slots
+
+
+def test_device_detail_not_found(client):
+    resp = client.get("/device/9999")
+    assert resp.status_code == 404
+
+
+# ------------------------------------------------------------------ #
+# Device — delete
+# ------------------------------------------------------------------ #
+
+def test_delete_device_frees_batteries(seeded_client):
+    # Assign TST-01 to Device A
+    seeded_client.post("/battery/1/assign", data={"device_id": "1"})
+    # Delete Device A
+    resp = seeded_client.post("/device/1/delete", follow_redirects=True)
+    assert resp.status_code == 200
+    # TST-01 should now be available
+    resp2 = seeded_client.get("/battery/1")
+    assert b"available" in resp2.data.lower()
+
+
+def test_delete_device_removed(seeded_client):
+    seeded_client.post("/device/1/delete")
+    resp = seeded_client.get("/device/1")
+    assert resp.status_code == 404
+
+
+# ------------------------------------------------------------------ #
+# Full round-trip
+# ------------------------------------------------------------------ #
+
+def test_add_assign_delete_battery(client):
+    # Add a device
+    client.post("/device/add", data={"name": "Gadget", "battery_slots": "1"})
+    # Add a battery
+    client.post("/battery/add", data={"label": "RT-01", "brand": "AcmeBrand", "status": "available"})
+    # Assign it
+    resp = client.post("/battery/1/assign", data={"device_id": "1"}, follow_redirects=True)
+    assert b"Gadget" in resp.data
+    # Delete it
+    client.post("/battery/1/delete")
+    assert client.get("/battery/1").status_code == 404