M5-T02: add modbus_device and modbus_reading tables and models

alembic_app/env.py

@@ -11,6 +11,7 @@ from app.models.auth_throttle import LoginThrottle  # noqa: F401
 from app.models.public_ip import PublicIPHistory, PublicIPState  # noqa: F401
 from app.models.location import Location  # noqa: F401
 from app.models.poo import PooRecord  # noqa: F401
+from app.models.modbus import ModbusDevice, ModbusReading  # noqa: F401
 
 config = context.config
 

alembic_app/versions/20260622_09_modbus_tables.py

@@ -0,0 +1,81 @@
+"""add modbus_device and modbus_reading tables
+
+Revision ID: 20260622_09_modbus_tables
+Revises: 20260621_08_totp
+Create Date: 2026-06-22 00:00:00.000000
+"""
+
+from typing import Sequence, Union
+
+import sqlalchemy as sa
+from alembic import op
+
+
+revision: str = "20260622_09_modbus_tables"
+down_revision: Union[str, None] = "20260621_08_totp"
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+    # modbus_device — deployment/configurable metadata for each polled device.
+    op.create_table(
+        "modbus_device",
+        sa.Column("id", sa.Integer(), autoincrement=True, nullable=False),
+        sa.Column("uuid", sa.String(length=36), nullable=False),
+        sa.Column("friendly_name", sa.String(length=255), nullable=False),
+        sa.Column("transport", sa.String(length=16), nullable=False),
+        sa.Column("host", sa.String(length=255), nullable=False),
+        sa.Column("port", sa.Integer(), nullable=False),
+        sa.Column("unit_id", sa.Integer(), nullable=False),
+        sa.Column("profile", sa.String(length=64), nullable=False),
+        sa.Column("poll_interval_s", sa.Integer(), nullable=False),
+        sa.Column("enabled", sa.Boolean(), nullable=False),
+        sa.Column("last_poll_at", sa.DateTime(timezone=True), nullable=True),
+        sa.Column("last_poll_ok", sa.Boolean(), nullable=True),
+        sa.Column("created_at", sa.DateTime(timezone=True), nullable=False),
+        sa.Column("updated_at", sa.DateTime(timezone=True), nullable=False),
+        sa.PrimaryKeyConstraint("id"),
+        sa.UniqueConstraint("uuid", name="uq_modbus_device_uuid"),
+    )
+
+    # modbus_reading — generic telemetry, one row per device per poll cycle.
+    op.create_table(
+        "modbus_reading",
+        sa.Column("id", sa.Integer(), autoincrement=True, nullable=False),
+        sa.Column("device_id", sa.Integer(), nullable=False),
+        sa.Column("recorded_at", sa.DateTime(timezone=True), nullable=False),
+        sa.Column("payload", sa.JSON(), nullable=False),
+        sa.ForeignKeyConstraint(
+            ["device_id"],
+            ["modbus_device.id"],
+            ondelete="RESTRICT",
+        ),
+        sa.PrimaryKeyConstraint("id"),
+    )
+
+    # Individual index on recorded_at (from the ORM-level index=True).
+    op.create_index(
+        "ix_modbus_reading_recorded_at",
+        "modbus_reading",
+        ["recorded_at"],
+        unique=False,
+    )
+
+    # Composite index for efficient time-range queries per device.
+    op.create_index(
+        "ix_modbus_reading_device_recorded",
+        "modbus_reading",
+        ["device_id", "recorded_at"],
+        unique=False,
+    )
+
+
+def downgrade() -> None:
+    # Drop the reading table first (it has a FK referencing modbus_device).
+    op.drop_index("ix_modbus_reading_device_recorded", table_name="modbus_reading")
+    op.drop_index("ix_modbus_reading_recorded_at", table_name="modbus_reading")
+    op.drop_table("modbus_reading")
+
+    # Drop the device table.
+    op.drop_table("modbus_device")

app/models/modbus.py

@@ -0,0 +1,114 @@
+"""SQLAlchemy models for Modbus device management and telemetry.
+
+Two tables:
+  - modbus_device: deployment/configurable metadata for each polled device.
+  - modbus_reading: generic telemetry rows (one per device per poll cycle).
+"""
+
+from __future__ import annotations
+
+import uuid as _uuid
+from datetime import datetime
+
+from sqlalchemy import Boolean, DateTime, ForeignKey, Index, Integer, String
+from sqlalchemy.orm import Mapped, mapped_column, relationship
+from sqlalchemy.types import JSON
+
+from app.db import Base
+
+
+def _uuid4_str() -> str:
+    return str(_uuid.uuid4())
+
+
+class ModbusDevice(Base):
+    """Deployment-layer record for a Modbus slave device reachable via a TCP gateway.
+
+    Protocol knowledge (register map, decoding rules) lives in the YAML profile
+    referenced by ``profile``.  Per-device variables (network address, slave ID,
+    display name, poll rate) live here.
+    """
+
+    __tablename__ = "modbus_device"
+
+    id: Mapped[int] = mapped_column(Integer, primary_key=True, autoincrement=True)
+
+    # Stable internal identity — used as the API path key and HA Discovery unique_id anchor.
+    uuid: Mapped[str] = mapped_column(
+        String(36), unique=True, nullable=False, default=_uuid4_str
+    )
+
+    # Human-readable label (may be changed; changing it triggers re-publish of HA Discovery).
+    friendly_name: Mapped[str] = mapped_column(String(255), nullable=False)
+
+    # Transport protocol — only "tcp" is supported for now.
+    transport: Mapped[str] = mapped_column(String(16), nullable=False, default="tcp")
+
+    # TCP gateway address.
+    host: Mapped[str] = mapped_column(String(255), nullable=False)
+    port: Mapped[int] = mapped_column(Integer, nullable=False, default=502)
+
+    # Modbus slave address (set on the device panel; different meters on the same gateway
+    # must have distinct unit_ids).
+    unit_id: Mapped[int] = mapped_column(Integer, nullable=False, default=1)
+
+    # Which YAML profile to use for register mapping and decoding (e.g. "sdm120").
+    profile: Mapped[str] = mapped_column(String(64), nullable=False)
+
+    # Polling interval in seconds.
+    poll_interval_s: Mapped[int] = mapped_column(Integer, nullable=False, default=5)
+
+    # Whether this device is included in the periodic poll sweep.
+    enabled: Mapped[bool] = mapped_column(Boolean, nullable=False, default=True)
+
+    # Poll-status fields (updated by the poll service after each attempt).
+    last_poll_at: Mapped[datetime | None] = mapped_column(
+        DateTime(timezone=True), nullable=True
+    )
+    last_poll_ok: Mapped[bool | None] = mapped_column(Boolean, nullable=True)
+
+    # Audit timestamps.
+    created_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True), nullable=False
+    )
+    updated_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True), nullable=False
+    )
+
+    # Relationship to readings (back-reference; not loaded eagerly).
+    readings: Mapped[list["ModbusReading"]] = relationship(
+        back_populates="device", cascade="save-update, merge"
+    )
+
+
+class ModbusReading(Base):
+    """Generic telemetry row: one device, one poll instant, all decoded metrics as JSON.
+
+    ``payload`` contains the full dict of engineering values produced by the YAML profile
+    decoder, e.g. ``{"voltage": 230.2, "current": 1.3, ...}``.  The profile is the key
+    to interpreting which keys exist and what units they carry.
+    """
+
+    __tablename__ = "modbus_reading"
+
+    id: Mapped[int] = mapped_column(Integer, primary_key=True, autoincrement=True)
+
+    # FK to the device that produced this reading.
+    # ON DELETE RESTRICT: prevents accidental deletion of a device that has historical data.
+    device_id: Mapped[int] = mapped_column(
+        ForeignKey("modbus_device.id", ondelete="RESTRICT"), nullable=False
+    )
+
+    # The UTC timestamp of when the sample was taken — real indexed column, NOT embedded in payload.
+    recorded_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True), nullable=False, index=True
+    )
+
+    # Profile-decoded engineering values as a JSON object.
+    payload: Mapped[dict] = mapped_column(JSON, nullable=False)
+
+    device: Mapped["ModbusDevice"] = relationship(back_populates="readings")
+
+
+# Composite index for efficient time-range queries scoped to a single device.
+Index("ix_modbus_reading_device_recorded", ModbusReading.device_id, ModbusReading.recorded_at)

docs/design/m5-iot-energy.md

@@ -290,7 +290,7 @@ Phase C（MQTT / Discovery，依赖 B 的设备数据与 provider 接口）
 - **Reviewer checklist**: 仅改 ConfigPage（+其测试），未碰 config 后端或主 layout；保存逻辑无回归；页面内**无第二个 app 级 sidebar**（accordion 是内容、非 chrome）。
 
 ### M5-T02 — `modbus_device` + `modbus_reading` 表与模型 `[schema]`
-- **Status**: `todo` · **Depends**: none
+- **Status**: `done` · **Depends**: none
 - **Context**: 单库 app 链新增两张**通用**表，建出 §3.2 结构（设备 = 部署层，读数 = JSON payload 通用遥测层）。本任务只建 schema + 模型，不写采集/接口。
 - **Files**: `create app/models/modbus.py`（`ModbusDevice`、`ModbusReading`，继承 `app.db.Base`）；`create alembic_app/versions/<date>_07_modbus_tables.py`；`modify alembic_app/env.py`（import 新模型）；`modify scripts/app_db_adopt.py`（`APP_BASELINE_REVISION` → 新 head）；`create tests/test_modbus_models.py`
 - **Steps**:

scripts/app_db_adopt.py

@@ -15,7 +15,7 @@ if str(PROJECT_ROOT) not in sys.path:
 
 from app.config import get_settings
 
-APP_BASELINE_REVISION = "20260621_08_totp"
+APP_BASELINE_REVISION = "20260622_09_modbus_tables"
 
 
 class AppDatabaseAdoptionError(RuntimeError):

tests/test_modbus_models.py

@@ -0,0 +1,396 @@
+"""Tests for M5-T02: modbus_device + modbus_reading tables and ORM models.
+
+Covers:
+  1. Migration shape: upgrade to head creates both tables with correct columns,
+     constraints, and indexes; downgrade -1 cleanly removes them.
+  2. ORM metadata: Base.metadata.tables contains both tables; FK is RESTRICT;
+     uuid column is unique and auto-generated.
+  3. Baseline constant: APP_BASELINE_REVISION matches the actual Alembic head.
+  4. Basic ORM round-trip: insert + retrieve, uuid auto-population, nullable fields.
+"""
+
+from __future__ import annotations
+
+from datetime import datetime, timezone
+from pathlib import Path
+
+import pytest
+from alembic import command
+from alembic.config import Config
+from sqlalchemy import create_engine, inspect, text
+from sqlalchemy.orm import Session
+
+from app.db import Base
+from app.models.modbus import ModbusDevice, ModbusReading
+from scripts.app_db_adopt import APP_BASELINE_REVISION
+
+
+# ---------------------------------------------------------------------------
+# Helpers
+# ---------------------------------------------------------------------------
+
+
+def _make_app_alembic_config(database_url: str) -> Config:
+    cfg = Config("alembic_app.ini")
+    cfg.set_main_option("sqlalchemy.url", database_url)
+    return cfg
+
+
+# ---------------------------------------------------------------------------
+# Fixtures
+# ---------------------------------------------------------------------------
+
+
+@pytest.fixture()
+def modbus_db(tmp_path: Path):
+    """Temporary SQLite DB upgraded to the current Alembic head."""
+    db_path = tmp_path / "modbus_test.db"
+    db_url = f"sqlite:///{db_path}"
+    alembic_cfg = _make_app_alembic_config(db_url)
+    command.upgrade(alembic_cfg, "head")
+    engine = create_engine(db_url, connect_args={"check_same_thread": False})
+    yield engine
+    engine.dispose()
+
+
+# ---------------------------------------------------------------------------
+# 1. Migration shape tests
+# ---------------------------------------------------------------------------
+
+
+def test_modbus_tables_exist_after_upgrade(modbus_db):
+    """Both modbus_device and modbus_reading tables must exist after upgrade to head."""
+    inspector = inspect(modbus_db)
+    table_names = inspector.get_table_names()
+    assert "modbus_device" in table_names, "modbus_device table missing after upgrade"
+    assert "modbus_reading" in table_names, "modbus_reading table missing after upgrade"
+
+
+def test_modbus_device_columns(modbus_db):
+    """modbus_device must have all required columns with correct nullability."""
+    inspector = inspect(modbus_db)
+    columns = {col["name"]: col for col in inspector.get_columns("modbus_device")}
+
+    expected_non_nullable = {
+        "id", "uuid", "friendly_name", "transport", "host", "port",
+        "unit_id", "profile", "poll_interval_s", "enabled",
+        "created_at", "updated_at",
+    }
+    expected_nullable = {"last_poll_at", "last_poll_ok"}
+
+    for col_name in expected_non_nullable:
+        assert col_name in columns, f"Missing column: {col_name}"
+        assert not columns[col_name]["nullable"], f"Column {col_name} should be NOT NULL"
+
+    for col_name in expected_nullable:
+        assert col_name in columns, f"Missing column: {col_name}"
+        assert columns[col_name]["nullable"], f"Column {col_name} should be nullable"
+
+
+def test_modbus_reading_columns(modbus_db):
+    """modbus_reading must have id, device_id, recorded_at, payload with correct nullability."""
+    inspector = inspect(modbus_db)
+    columns = {col["name"]: col for col in inspector.get_columns("modbus_reading")}
+
+    expected_non_nullable = {"id", "device_id", "recorded_at", "payload"}
+    for col_name in expected_non_nullable:
+        assert col_name in columns, f"Missing column: {col_name}"
+        assert not columns[col_name]["nullable"], f"Column {col_name} should be NOT NULL"
+
+
+def test_modbus_device_uuid_is_unique(modbus_db):
+    """modbus_device.uuid must have a unique constraint."""
+    inspector = inspect(modbus_db)
+    unique_constraints = inspector.get_unique_constraints("modbus_device")
+    unique_cols = [
+        col
+        for uc in unique_constraints
+        for col in uc["column_names"]
+    ]
+    assert "uuid" in unique_cols, "uuid column must have a unique constraint"
+
+
+def test_modbus_reading_fk_to_device(modbus_db):
+    """modbus_reading.device_id must have a FK referencing modbus_device.id."""
+    inspector = inspect(modbus_db)
+    fks = inspector.get_foreign_keys("modbus_reading")
+    assert len(fks) == 1, f"Expected 1 FK on modbus_reading, got {len(fks)}"
+    fk = fks[0]
+    assert fk["referred_table"] == "modbus_device"
+    assert "device_id" in fk["constrained_columns"]
+    assert "id" in fk["referred_columns"]
+
+
+def test_modbus_reading_composite_index_exists(modbus_db):
+    """Composite index (device_id, recorded_at) must exist on modbus_reading."""
+    inspector = inspect(modbus_db)
+    indexes = {idx["name"]: idx for idx in inspector.get_indexes("modbus_reading")}
+    assert "ix_modbus_reading_device_recorded" in indexes, (
+        "Composite index ix_modbus_reading_device_recorded missing"
+    )
+    composite_idx = indexes["ix_modbus_reading_device_recorded"]
+    assert "device_id" in composite_idx["column_names"]
+    assert "recorded_at" in composite_idx["column_names"]
+
+
+def test_modbus_reading_recorded_at_index_exists(modbus_db):
+    """Individual index on recorded_at must exist on modbus_reading."""
+    inspector = inspect(modbus_db)
+    indexes = {idx["name"]: idx for idx in inspector.get_indexes("modbus_reading")}
+    # The ORM-level index=True creates ix_modbus_reading_recorded_at
+    assert "ix_modbus_reading_recorded_at" in indexes, (
+        "Index ix_modbus_reading_recorded_at missing from modbus_reading"
+    )
+
+
+def test_downgrade_removes_modbus_tables(tmp_path: Path):
+    """downgrade -1 from head must drop both modbus tables cleanly."""
+    db_path = tmp_path / "downgrade_modbus_test.db"
+    db_url = f"sqlite:///{db_path}"
+    alembic_cfg = _make_app_alembic_config(db_url)
+
+    command.upgrade(alembic_cfg, "head")
+
+    engine = create_engine(db_url, connect_args={"check_same_thread": False})
+    inspector = inspect(engine)
+    assert "modbus_device" in inspector.get_table_names()
+    assert "modbus_reading" in inspector.get_table_names()
+    engine.dispose()
+
+    # Downgrade one step removes the modbus migration.
+    command.downgrade(alembic_cfg, "-1")
+
+    engine = create_engine(db_url, connect_args={"check_same_thread": False})
+    inspector = inspect(engine)
+    table_names = inspector.get_table_names()
+    assert "modbus_device" not in table_names, "modbus_device should be gone after downgrade"
+    assert "modbus_reading" not in table_names, "modbus_reading should be gone after downgrade"
+    engine.dispose()
+
+
+# ---------------------------------------------------------------------------
+# 2. ORM metadata checks (Base.metadata)
+# ---------------------------------------------------------------------------
+
+
+def test_base_metadata_contains_modbus_tables():
+    """Base.metadata.tables must include both new modbus tables."""
+    assert "modbus_device" in Base.metadata.tables, "modbus_device not in Base.metadata"
+    assert "modbus_reading" in Base.metadata.tables, "modbus_reading not in Base.metadata"
+
+
+def test_modbus_reading_fk_ondelete_restrict():
+    """The FK from modbus_reading.device_id to modbus_device.id must be ON DELETE RESTRICT."""
+    reading_table = Base.metadata.tables["modbus_reading"]
+    fk_columns = {
+        col.name: col
+        for col in reading_table.columns
+    }
+    device_id_col = fk_columns["device_id"]
+    assert device_id_col.foreign_keys, "device_id must have a foreign key"
+    fk = next(iter(device_id_col.foreign_keys))
+    assert fk.ondelete == "RESTRICT", (
+        f"FK ondelete must be RESTRICT, got: {fk.ondelete!r}"
+    )
+
+
+def test_modbus_device_uuid_unique_constraint_in_metadata():
+    """ModbusDevice.uuid column must be declared unique in ORM metadata."""
+    device_table = Base.metadata.tables["modbus_device"]
+    uuid_col = device_table.columns["uuid"]
+    assert uuid_col.unique, "ModbusDevice.uuid must be declared unique"
+
+
+# ---------------------------------------------------------------------------
+# 3. Baseline constant
+# ---------------------------------------------------------------------------
+
+
+def test_app_baseline_revision_matches_head(tmp_path: Path):
+    """APP_BASELINE_REVISION must equal the Alembic head revision."""
+    from alembic.script import ScriptDirectory
+
+    db_url = f"sqlite:///{tmp_path / 'rev_check.db'}"
+    alembic_cfg = _make_app_alembic_config(db_url)
+    script = ScriptDirectory.from_config(alembic_cfg)
+    heads = script.get_heads()
+    assert len(heads) == 1, f"Expected exactly 1 Alembic head, got {heads}"
+    head = heads[0]
+    assert APP_BASELINE_REVISION == head, (
+        f"APP_BASELINE_REVISION={APP_BASELINE_REVISION!r} does not match "
+        f"Alembic head={head!r}"
+    )
+
+
+# ---------------------------------------------------------------------------
+# 4. ORM round-trip tests
+# ---------------------------------------------------------------------------
+
+
+def test_modbus_device_uuid_auto_generated(modbus_db):
+    """uuid must be auto-populated when not explicitly provided."""
+    now = datetime.now(tz=timezone.utc)
+    with Session(modbus_db) as session:
+        device = ModbusDevice(
+            friendly_name="Test Meter",
+            host="192.168.1.100",
+            profile="sdm120",
+            created_at=now,
+            updated_at=now,
+        )
+        session.add(device)
+        session.commit()
+        device_id = device.id
+
+    with Session(modbus_db) as session:
+        fetched = session.get(ModbusDevice, device_id)
+        assert fetched is not None
+        assert fetched.uuid is not None, "uuid should be auto-populated"
+        assert len(fetched.uuid) == 36, "uuid should be a standard UUID4 string (36 chars)"
+        # Verify it's a valid UUID4 format
+        import uuid as _uuid_mod
+        parsed = _uuid_mod.UUID(fetched.uuid)
+        assert parsed.version == 4, "uuid should be version 4"
+
+
+def test_modbus_device_defaults(modbus_db):
+    """Default values for port, unit_id, poll_interval_s, enabled, transport must apply."""
+    now = datetime.now(tz=timezone.utc)
+    with Session(modbus_db) as session:
+        device = ModbusDevice(
+            friendly_name="Default Test",
+            host="10.0.0.1",
+            profile="sdm120",
+            created_at=now,
+            updated_at=now,
+        )
+        session.add(device)
+        session.commit()
+        device_id = device.id
+
+    with Session(modbus_db) as session:
+        fetched = session.get(ModbusDevice, device_id)
+        assert fetched is not None
+        assert fetched.port == 502
+        assert fetched.unit_id == 1
+        assert fetched.poll_interval_s == 5
+        assert fetched.enabled is True
+        assert fetched.transport == "tcp"
+        assert fetched.last_poll_at is None
+        assert fetched.last_poll_ok is None
+
+
+def test_modbus_device_two_unique_uuids(modbus_db):
+    """Two independently created devices must have different auto-generated UUIDs."""
+    now = datetime.now(tz=timezone.utc)
+    with Session(modbus_db) as session:
+        d1 = ModbusDevice(
+            friendly_name="Device 1", host="10.0.0.1", profile="sdm120",
+            created_at=now, updated_at=now,
+        )
+        d2 = ModbusDevice(
+            friendly_name="Device 2", host="10.0.0.2", profile="sdm120",
+            created_at=now, updated_at=now,
+        )
+        session.add_all([d1, d2])
+        session.commit()
+        assert d1.uuid != d2.uuid, "Two devices must receive distinct UUIDs"
+
+
+def test_modbus_reading_insert_and_retrieve(modbus_db):
+    """A ModbusReading can be inserted with a JSON payload and retrieved correctly."""
+    now = datetime.now(tz=timezone.utc)
+    sample_payload = {
+        "voltage": 230.2,
+        "current": 1.3,
+        "active_power": 295.0,
+        "power_factor": 0.98,
+        "frequency": 50.0,
+        "import_energy": 123.4,
+        "export_energy": 0.0,
+        "total_energy": 123.4,
+    }
+
+    with Session(modbus_db) as session:
+        device = ModbusDevice(
+            friendly_name="SDM120 AC",
+            host="192.168.1.100",
+            profile="sdm120",
+            created_at=now,
+            updated_at=now,
+        )
+        session.add(device)
+        session.flush()
+
+        reading = ModbusReading(
+            device_id=device.id,
+            recorded_at=now,
+            payload=sample_payload,
+        )
+        session.add(reading)
+        session.commit()
+        reading_id = reading.id
+
+    with Session(modbus_db) as session:
+        fetched = session.get(ModbusReading, reading_id)
+        assert fetched is not None
+        assert fetched.recorded_at is not None
+        assert fetched.payload == sample_payload
+        assert fetched.payload["voltage"] == 230.2
+        assert fetched.payload["frequency"] == 50.0
+
+
+def test_modbus_reading_restrict_prevents_device_deletion(tmp_path: Path):
+    """Deleting a device with readings must fail due to ON DELETE RESTRICT.
+
+    SQLite only enforces FK constraints when ``PRAGMA foreign_keys = ON`` is set
+    on the connection, so we build a dedicated engine that enables this pragma.
+    """
+    import sqlalchemy.exc
+    from sqlalchemy import event as sa_event
+
+    db_path = tmp_path / "restrict_test.db"
+    db_url = f"sqlite:///{db_path}"
+    alembic_cfg = _make_app_alembic_config(db_url)
+    command.upgrade(alembic_cfg, "head")
+
+    engine = create_engine(db_url, connect_args={"check_same_thread": False})
+
+    # Enable FK enforcement for every connection on this engine.
+    @sa_event.listens_for(engine, "connect")
+    def _enable_fk(dbapi_conn, _rec):
+        cursor = dbapi_conn.cursor()
+        cursor.execute("PRAGMA foreign_keys = ON")
+        cursor.close()
+
+    now = datetime.now(tz=timezone.utc)
+    with Session(engine) as session:
+        device = ModbusDevice(
+            friendly_name="Restricted Device",
+            host="10.0.0.1",
+            profile="sdm120",
+            created_at=now,
+            updated_at=now,
+        )
+        session.add(device)
+        session.flush()
+
+        reading = ModbusReading(
+            device_id=device.id,
+            recorded_at=now,
+            payload={"voltage": 230.0},
+        )
+        session.add(reading)
+        session.commit()
+        device_id = device.id
+
+    # Attempting to delete the device should raise an IntegrityError.
+    with pytest.raises(sqlalchemy.exc.IntegrityError):
+        with Session(engine) as session:
+            session.execute(
+                text("DELETE FROM modbus_device WHERE id = :did"),
+                {"did": device_id},
+            )
+            session.commit()
+
+    engine.dispose()

tests/test_totp_models.py

@@ -262,8 +262,10 @@ def test_downgrade_removes_totp_columns_and_table(tmp_path: Path):
     assert "totp_enabled" in auth_user_cols
     engine.dispose()
 
-    # Downgrade one step (removes TOTP migration).
-    command.downgrade(alembic_cfg, "-1")
+    # Downgrade to the revision before TOTP (removes TOTP migration).
+    # We use an explicit target rather than "-1" so the test stays correct even
+    # as new revisions are added on top of the TOTP revision.
+    command.downgrade(alembic_cfg, "20260621_07_auth_login_throttle")
 
     engine = create_engine(db_url, connect_args={"check_same_thread": False})
     inspector = inspect(engine)