Add logbook entries, data export page, and JSON import

models.py

@@ -1,10 +1,25 @@
 from datetime import datetime
 
-from sqlalchemy import Column, Integer, String, Text, ForeignKey
+from sqlalchemy import Column, Integer, String, Text, ForeignKey, Table
 from sqlalchemy.orm import declarative_base, relationship
 
 Base = declarative_base()
 
+# Association tables for logbook (defined before ORM classes so they can be
+# referenced as `secondary` in relationship()). String-based FKs are resolved
+# lazily when create_all() binds the metadata.
+battery_logbook_table = Table(
+    "battery_logbook", Base.metadata,
+    Column("battery_id", Integer, ForeignKey("battery.id", ondelete="CASCADE"), primary_key=True),
+    Column("logbook_id", Integer, ForeignKey("logbook.id", ondelete="CASCADE"), primary_key=True),
+)
+
+device_logbook_table = Table(
+    "device_logbook", Base.metadata,
+    Column("device_id", Integer, ForeignKey("device.id", ondelete="CASCADE"), primary_key=True),
+    Column("logbook_id", Integer, ForeignKey("logbook.id", ondelete="CASCADE"), primary_key=True),
+)
+
 
 class Device(Base):
     __tablename__ = "device"
@@ -19,6 +34,12 @@ class Device(Base):
     ha_entity_id = Column(String(100), nullable=True)   # e.g. "sensor.tv_remote_battery"
 
     batteries = relationship("Battery", back_populates="device")
+    logbook_entries = relationship(
+        "Logbook", secondary=device_logbook_table,
+        order_by="Logbook.recorded_at.desc()",
+        cascade="all, delete-orphan",
+        single_parent=True,
+    )
 
     def installed_count(self):
         return sum(1 for b in self.batteries if b.status == "installed")
@@ -70,6 +91,12 @@ class Battery(Base):
         order_by="BatteryPctLog.recorded_at.desc()",
         cascade="all, delete-orphan",
     )
+    logbook_entries = relationship(
+        "Logbook", secondary=battery_logbook_table,
+        order_by="Logbook.recorded_at.desc()",
+        cascade="all, delete-orphan",
+        single_parent=True,
+    )
 
     def is_available(self):
         return self.status == "available"
@@ -127,3 +154,18 @@ class BatteryPctLog(Base):
 
     def __repr__(self):
         return f"<BatteryPctLog {self.battery_id} {self.recorded_at} {self.percentage}%>"
+
+
+class Logbook(Base):
+    __tablename__ = "logbook"
+
+    id          = Column(Integer, primary_key=True, autoincrement=True)
+    body        = Column(Text, nullable=False)
+    recorded_at = Column(String(19), nullable=False)  # "YYYY-MM-DD HH:MM:SS"
+    # Note: SQLite has no native DATETIME type (stores dates as text).
+    # On MariaDB this would be a native DATETIME column — swap String(19) for
+    # DateTime when migrating, since SQLAlchemy's DateTime maps to DATETIME there.
+    # String(19) is used here to match every other timestamp column in the codebase.
+
+    def __repr__(self):
+        return f"<Logbook {self.recorded_at}>"