diff --git a/alembic_app/env.py b/alembic_app/env.py
index 56c4383..efa98a9 100644
--- a/alembic_app/env.py
+++ b/alembic_app/env.py
@@ -12,6 +12,7 @@ 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
+from app.models.expose import ExposedEntityToggle  # noqa: F401
 
 config = context.config
 
diff --git a/alembic_app/versions/20260622_10_exposed_entities.py b/alembic_app/versions/20260622_10_exposed_entities.py
new file mode 100644
index 0000000..83148ea
--- /dev/null
+++ b/alembic_app/versions/20260622_10_exposed_entities.py
@@ -0,0 +1,44 @@
+"""add exposed_entity_toggle table
+
+Revision ID: 20260622_10_exposed_entities
+Revises: 20260622_09_modbus_tables
+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_10_exposed_entities"
+down_revision: Union[str, None] = "20260622_09_modbus_tables"
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+    # exposed_entity_toggle — per-entity on/off switch for MQTT / HA Discovery.
+    op.create_table(
+        "exposed_entity_toggle",
+        sa.Column("id", sa.Integer(), autoincrement=True, nullable=False),
+        sa.Column("key", sa.String(length=255), nullable=False),
+        sa.Column("enabled", sa.Boolean(), nullable=False),
+        sa.Column("updated_at", sa.DateTime(timezone=True), nullable=False),
+        sa.PrimaryKeyConstraint("id"),
+        sa.UniqueConstraint("key", name="uq_exposed_entity_toggle_key"),
+    )
+
+    # Index on key for fast single-key lookups (toggle by key).
+    op.create_index(
+        "ix_exposed_entity_toggle_key",
+        "exposed_entity_toggle",
+        ["key"],
+        unique=True,
+    )
+
+
+def downgrade() -> None:
+    # Drop index then table — only removes what this revision created.
+    op.drop_index("ix_exposed_entity_toggle_key", table_name="exposed_entity_toggle")
+    op.drop_table("exposed_entity_toggle")
diff --git a/app/integrations/expose.py b/app/integrations/expose.py
new file mode 100644
index 0000000..3eef5fc
--- /dev/null
+++ b/app/integrations/expose.py
@@ -0,0 +1,325 @@
+"""Expose framework: ExposableEntity, provider protocol, and build_catalog.
+
+This module defines:
+
+- ``ExposableEntity`` — a dataclass describing one publishable MQTT/HA entity.
+- Provider protocol — a simple callable ``(session) -> list[ExposableEntity]``.
+- A provider registry and registration helper.
+- ``build_catalog(session)`` — merges all registered providers' entities with
+  per-key toggle state from the ``exposed_entity_toggle`` table.
+
+Design notes
+------------
+- **No over-engineering**: providers are plain callables, not abstract base
+  classes.  This project is personal / single-user; keep it flat.
+- **Key stability**: entity keys MUST be derived from device uuid + metric key
+  (e.g. ``"modbus.<uuid>.voltage"``), never from auto-increment IDs.  Stable
+  keys mean the toggle table survives device removal/re-addition without drift.
+- **Metadata from profile**: the modbus provider reads ``device_class``,
+  ``unit``, and ``component`` directly from the YAML profile's ``metrics[]``
+  rather than maintaining a separate mapping.
+- **value_getter**: a callable ``() -> object | None`` or ``None`` if not yet
+  implemented (T11 will wire real getters).  Presence of the field lets T11
+  call it without changing the dataclass interface.
+"""
+
+from __future__ import annotations
+
+import logging
+from dataclasses import dataclass, field
+from typing import Any, Callable, Optional, Protocol
+
+from sqlalchemy.orm import Session
+
+logger = logging.getLogger(__name__)
+
+
+# ---------------------------------------------------------------------------
+# ExposableEntity
+# ---------------------------------------------------------------------------
+
+
+@dataclass
+class DeviceInfo:
+    """Grouping metadata that maps an entity to a logical HA device.
+
+    ``identifiers`` corresponds to ``device.identifiers`` in HA Discovery
+    config — a stable tuple used to group entities under one device card.
+    ``name`` is the human-readable device name (friendly_name).
+    """
+
+    identifiers: tuple[str, ...]
+    """Stable identifiers for HA device grouping (e.g. ``("modbus", "<uuid>")``).
+
+    These must not change over the device lifetime; they anchor the HA device
+    card even when friendly_name changes.
+    """
+
+    name: str
+    """Human-readable device name (may change; triggers HA discovery re-publish)."""
+
+
+@dataclass
+class ExposableEntity:
+    """One publishable entity in the MQTT / HA Discovery expose framework.
+
+    Fields
+    ------
+    key
+        Stable unique identifier for this entity.  Used as the toggle table
+        key and as part of the HA Discovery ``unique_id`` derivation.
+        Convention: ``"<provider>.<device_uuid>.<metric_key>"``,
+        e.g. ``"modbus.abc123.voltage"`` or ``"modbus.abc123.online"``.
+
+    component
+        HA MQTT component type: ``"sensor"``, ``"binary_sensor"``, ``"switch"``, etc.
+
+    device
+        Grouping info (DeviceInfo) that determines which HA device card this
+        entity belongs to.
+
+    device_class
+        HA ``device_class`` string (e.g. ``"voltage"``, ``"power"``, ``"None"``).
+        Empty string or ``None`` means no device_class (e.g. for the online sensor).
+
+    unit
+        Physical unit string (e.g. ``"V"``, ``"A"``, ``"kWh"``).
+        Empty string for dimensionless.
+
+    name
+        Human-readable entity label (friendly display name, may include device
+        context, e.g. ``"SDM120 Voltage"``).
+
+    value_getter
+        Optional callable ``() -> object | None`` that returns the current
+        entity value.  ``None`` means "not yet wired" (T11 will populate this).
+        T11 calls this to obtain the current state before publishing.
+
+    state_class
+        HA ``state_class`` string (e.g. ``"measurement"``, ``"total_increasing"``).
+        ``None`` means not set.
+    """
+
+    key: str
+    component: str
+    device: DeviceInfo
+    device_class: Optional[str]
+    unit: str
+    name: str
+    value_getter: Optional[Callable[[], Any]] = field(default=None, repr=False)
+    state_class: Optional[str] = None
+
+
+# ---------------------------------------------------------------------------
+# Provider protocol
+# ---------------------------------------------------------------------------
+
+
+class EntityProvider(Protocol):
+    """Protocol for entity provider callables.
+
+    A provider is any callable that accepts a ``Session`` and returns a list
+    of ``ExposableEntity`` objects.  Using a Protocol (not ABC) keeps the
+    implementation lightweight — any matching callable qualifies.
+    """
+
+    def __call__(self, session: Session) -> list[ExposableEntity]: ...
+
+
+# ---------------------------------------------------------------------------
+# Provider registry
+# ---------------------------------------------------------------------------
+
+_REGISTRY: list[EntityProvider] = []
+
+
+def register_provider(provider: EntityProvider) -> EntityProvider:
+    """Register an entity provider.
+
+    Can be used as a decorator::
+
+        @register_provider
+        def my_provider(session: Session) -> list[ExposableEntity]:
+            ...
+
+    Or called directly::
+
+        register_provider(my_provider)
+
+    Returns the provider unchanged (for decorator compatibility).
+    """
+    _REGISTRY.append(provider)
+    return provider
+
+
+def get_providers() -> list[EntityProvider]:
+    """Return a snapshot of the currently registered providers."""
+    return list(_REGISTRY)
+
+
+# ---------------------------------------------------------------------------
+# Catalog builder
+# ---------------------------------------------------------------------------
+
+
+@dataclass
+class CatalogEntry:
+    """An entity from the catalog, enriched with its current toggle state."""
+
+    entity: ExposableEntity
+    enabled: bool
+    """True if this entity is currently enabled in the toggle table."""
+
+
+def build_catalog(session: Session) -> list[CatalogEntry]:
+    """Enumerate all entities from registered providers and attach toggle state.
+
+    For each entity key, the toggle state is looked up in ``exposed_entity_toggle``.
+    Entities with no toggle row default to ``enabled=False``.
+
+    Parameters
+    ----------
+    session:
+        Active SQLAlchemy session for DB access.
+
+    Returns
+    -------
+    list[CatalogEntry]
+        All entities from all registered providers, each paired with its
+        current ``enabled`` state.
+    """
+    from app.models.expose import ExposedEntityToggle  # local import to avoid circular
+
+    # Collect all entities from all providers.
+    all_entities: list[ExposableEntity] = []
+    for provider in _REGISTRY:
+        try:
+            entities = provider(session)
+            all_entities.extend(entities)
+        except Exception:
+            logger.exception("Provider %r raised an error; skipping its entities", provider)
+
+    if not all_entities:
+        return []
+
+    # Load all toggle rows in one query for efficiency.
+    keys = [e.key for e in all_entities]
+    toggle_rows = session.query(ExposedEntityToggle).filter(
+        ExposedEntityToggle.key.in_(keys)
+    ).all()
+    toggle_map: dict[str, bool] = {row.key: row.enabled for row in toggle_rows}
+
+    return [
+        CatalogEntry(entity=entity, enabled=toggle_map.get(entity.key, False))
+        for entity in all_entities
+    ]
+
+
+# ---------------------------------------------------------------------------
+# Modbus provider
+# ---------------------------------------------------------------------------
+
+
+def _modbus_provider(session: Session) -> list[ExposableEntity]:
+    """Enumerate ExposableEntity objects for all enabled Modbus devices.
+
+    For each enabled ``ModbusDevice``:
+    - Loads its YAML profile.
+    - Produces one ``sensor`` entity per metric in ``profile.metrics``
+      (device_class / unit / component taken from the metric spec).
+    - Produces one ``binary_sensor`` entity named "online" (derived from
+      ``device.last_poll_ok``).
+
+    Entity keys follow the pattern ``"modbus.<uuid>.<metric_key>"``, which is
+    stable across device renames and DB rebuilds.
+    """
+    from app.models.modbus import ModbusDevice  # local import
+    from app.integrations.modbus.profiles import (
+        load_profile,
+        ProfileNotFoundError,
+        ProfileValidationError,
+    )
+
+    devices: list[ModbusDevice] = session.query(ModbusDevice).filter(
+        ModbusDevice.enabled.is_(True)
+    ).all()
+
+    entities: list[ExposableEntity] = []
+
+    for device in devices:
+        device_info = DeviceInfo(
+            identifiers=("modbus", device.uuid),
+            name=device.friendly_name,
+        )
+
+        # Load the profile to get metric metadata.
+        try:
+            profile = load_profile(device.profile)
+        except (ProfileNotFoundError, ProfileValidationError) as exc:
+            logger.warning(
+                "Skipping device %r (uuid=%s): cannot load profile %r: %s",
+                device.friendly_name,
+                device.uuid,
+                device.profile,
+                exc,
+            )
+            continue
+
+        # One sensor entity per profile metric.
+        for metric in profile.metrics:
+            entity_key = f"modbus.{device.uuid}.{metric.key}"
+
+            # Capture metric and device for the value_getter closure.
+            _device_uuid = device.uuid
+            _metric_key = metric.key
+
+            def _make_value_getter(dev_uuid: str, m_key: str) -> Callable[[], Any]:
+                """Return a getter stub for this metric; T11 will wire real retrieval."""
+                def _getter() -> Any:
+                    # Stub — T11 will call build_catalog with a live session
+                    # and replace this with a real value-fetch callable.
+                    return None
+
+                return _getter
+
+            entities.append(
+                ExposableEntity(
+                    key=entity_key,
+                    component=metric.ha_component,
+                    device=device_info,
+                    device_class=metric.device_class or None,
+                    unit=metric.unit,
+                    name=f"{device.friendly_name} {metric.key.replace('_', ' ').title()}",
+                    value_getter=_make_value_getter(_device_uuid, _metric_key),
+                    state_class=metric.state_class,
+                )
+            )
+
+        # One binary_sensor entity for device "online" status.
+        online_key = f"modbus.{device.uuid}.online"
+        _dev_uuid_online = device.uuid
+
+        def _make_online_getter(dev_uuid: str) -> Callable[[], Any]:
+            def _getter() -> Any:
+                # T11 will wire this to last_poll_ok.
+                return None
+            return _getter
+
+        entities.append(
+            ExposableEntity(
+                key=online_key,
+                component="binary_sensor",
+                device=device_info,
+                device_class="connectivity",
+                unit="",
+                name=f"{device.friendly_name} Online",
+                value_getter=_make_online_getter(_dev_uuid_online),
+                state_class=None,
+            )
+        )
+
+    return entities
+
+
+# Register the modbus provider at module load time.
+register_provider(_modbus_provider)
diff --git a/app/models/expose.py b/app/models/expose.py
new file mode 100644
index 0000000..f907a17
--- /dev/null
+++ b/app/models/expose.py
@@ -0,0 +1,49 @@
+"""SQLAlchemy model for the exposed-entity toggle table.
+
+``ExposedEntityToggle`` stores the per-entity enable/disable state for the
+MQTT / HA Discovery expose framework.  The *catalog* of what *can* be
+exposed is computed dynamically by provider functions (see
+``app/integrations/expose.py``); this table only records which entries the
+user has explicitly enabled.
+
+Key design decisions
+--------------------
+- ``key`` is a stable string identifier derived from device uuid + metric key
+  (e.g. ``"modbus.<uuid>.voltage"``), so it does not drift if rows are
+  deleted and re-inserted.
+- Default state for an entity not yet in this table is **disabled** (false).
+  ``build_catalog`` in expose.py treats a missing row as ``enabled=False``.
+- Only one row per entity key (``key`` is UNIQUE).
+"""
+
+from __future__ import annotations
+
+from datetime import datetime
+
+from sqlalchemy import Boolean, DateTime, Integer, String
+from sqlalchemy.orm import Mapped, mapped_column
+
+from app.db import Base
+
+
+class ExposedEntityToggle(Base):
+    """Per-entity on/off switch for MQTT / HA Discovery publishing.
+
+    Rows are created on demand (first toggle); entities with no row are
+    treated as disabled.
+    """
+
+    __tablename__ = "exposed_entity_toggle"
+
+    id: Mapped[int] = mapped_column(Integer, primary_key=True, autoincrement=True)
+
+    # Stable entity key, e.g. "modbus.<uuid>.voltage" or "modbus.<uuid>.online".
+    key: Mapped[str] = mapped_column(String(255), unique=True, nullable=False)
+
+    # Whether this entity should be published via MQTT / HA Discovery.
+    enabled: Mapped[bool] = mapped_column(Boolean, nullable=False, default=False)
+
+    # Last time this row was created or modified.
+    updated_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True), nullable=False
+    )
diff --git a/docs/design/m5-iot-energy.md b/docs/design/m5-iot-energy.md
index 547830c..90f1443 100644
--- a/docs/design/m5-iot-energy.md
+++ b/docs/design/m5-iot-energy.md
@@ -399,7 +399,7 @@ Phase C（MQTT / Discovery，依赖 B 的设备数据与 provider 接口）
 - **Reviewer checklist**: secret 不回显/不入 OpenAPI 示例；`_settings_payload` 未漏字段（否则运行期 override 丢失）。
 
 ### M5-T09 — `exposed_entities` 表 + ExposableEntity/provider 框架 `[schema]`
-- **Status**: `todo` · **Depends**: M5-T02
+- **Status**: `done` · **Depends**: M5-T02
 - **Context**: 建"可暴露实体目录"的抽象与开关存储；modbus provider 把设备映射成 device/entities，**实体元数据从 profile 派生**。
 - **Files**: `create app/integrations/expose.py`（`ExposableEntity`、provider 协议、注册表、modbus provider）；`create app/models/expose.py`（`ExposedEntityToggle`：`key` unique + `enabled` + `updated_at`）；`create alembic_app/versions/<date>_08_exposed_entities.py`；`modify alembic_app/env.py`、`scripts/app_db_adopt.py`；`create tests/test_expose_catalog.py`
 - **Steps**:
diff --git a/scripts/app_db_adopt.py b/scripts/app_db_adopt.py
index 1ca952f..1155e29 100644
--- a/scripts/app_db_adopt.py
+++ b/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 = "20260622_09_modbus_tables"
+APP_BASELINE_REVISION = "20260622_10_exposed_entities"
 
 
 class AppDatabaseAdoptionError(RuntimeError):
diff --git a/tests/test_expose_catalog.py b/tests/test_expose_catalog.py
new file mode 100644
index 0000000..c257713
--- /dev/null
+++ b/tests/test_expose_catalog.py
@@ -0,0 +1,681 @@
+"""Tests for M5-T09: exposed_entities table + ExposableEntity/provider framework.
+
+Covers:
+  1. ExposableEntity dataclass: fields, key stability.
+  2. Provider registry: register_provider, get_providers.
+  3. build_catalog: entity enumeration, device grouping, metadata from profile,
+     toggle defaults (enabled=False), binary_sensor presence.
+  4. Migration shape: upgrade creates the table + unique index; downgrade drops it.
+  5. ORM round-trip: toggle insert/read/update; default enabled=False.
+  6. APP_BASELINE_REVISION matches the new Alembic head.
+"""
+
+from __future__ import annotations
+
+from datetime import datetime, timezone
+from pathlib import Path
+from typing import TYPE_CHECKING
+import pytest
+from alembic import command
+from alembic.config import Config
+from sqlalchemy import create_engine, inspect
+from sqlalchemy.orm import Session
+
+if TYPE_CHECKING:
+    pass
+
+
+# ---------------------------------------------------------------------------
+# 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
+
+
+def _make_modbus_device(session: Session, *, friendly_name: str, uuid: str) -> object:
+    """Insert a ModbusDevice row into a test DB session and return it."""
+    from datetime import datetime, timezone
+
+    from app.models.modbus import ModbusDevice
+
+    now = datetime.now(tz=timezone.utc)
+    device = ModbusDevice(
+        uuid=uuid,
+        friendly_name=friendly_name,
+        host="192.168.1.1",
+        port=502,
+        unit_id=1,
+        profile="sdm120",
+        poll_interval_s=5,
+        enabled=True,
+        created_at=now,
+        updated_at=now,
+    )
+    session.add(device)
+    session.flush()
+    return device
+
+
+# ---------------------------------------------------------------------------
+# Fixtures
+# ---------------------------------------------------------------------------
+
+
+@pytest.fixture()
+def expose_db(tmp_path: Path):
+    """Temporary SQLite DB upgraded to the current Alembic head (includes new toggle table)."""
+    db_path = tmp_path / "expose_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. ExposableEntity / DeviceInfo dataclass tests
+# ---------------------------------------------------------------------------
+
+
+def test_exposable_entity_fields():
+    """ExposableEntity must have all required fields with correct defaults."""
+    from app.integrations.expose import DeviceInfo, ExposableEntity
+
+    device = DeviceInfo(identifiers=("modbus", "abc-uuid"), name="Test Device")
+    entity = ExposableEntity(
+        key="modbus.abc-uuid.voltage",
+        component="sensor",
+        device=device,
+        device_class="voltage",
+        unit="V",
+        name="Test Device Voltage",
+    )
+
+    assert entity.key == "modbus.abc-uuid.voltage"
+    assert entity.component == "sensor"
+    assert entity.device.identifiers == ("modbus", "abc-uuid")
+    assert entity.device.name == "Test Device"
+    assert entity.device_class == "voltage"
+    assert entity.unit == "V"
+    assert entity.name == "Test Device Voltage"
+    assert entity.value_getter is None  # default
+    assert entity.state_class is None  # default
+
+
+def test_exposable_entity_with_value_getter():
+    """ExposableEntity.value_getter stores and calls the provided callable."""
+    from app.integrations.expose import DeviceInfo, ExposableEntity
+
+    device = DeviceInfo(identifiers=("modbus", "dev1"), name="D1")
+    getter = lambda: 230.5  # noqa: E731
+    entity = ExposableEntity(
+        key="modbus.dev1.voltage",
+        component="sensor",
+        device=device,
+        device_class="voltage",
+        unit="V",
+        name="D1 Voltage",
+        value_getter=getter,
+    )
+    assert entity.value_getter is not None
+    assert entity.value_getter() == 230.5
+
+
+def test_entity_key_stability_uses_uuid_not_id():
+    """Keys must be derived from uuid (stable), never from auto-increment DB ids."""
+    from app.integrations.expose import DeviceInfo, ExposableEntity
+
+    uuid_val = "550e8400-e29b-41d4-a716-446655440000"
+    key = f"modbus.{uuid_val}.voltage"
+    device = DeviceInfo(identifiers=("modbus", uuid_val), name="Stable Device")
+    entity = ExposableEntity(
+        key=key,
+        component="sensor",
+        device=device,
+        device_class="voltage",
+        unit="V",
+        name="Stable Device Voltage",
+    )
+    # Key is uuid-based: it must not contain any integer-only segment that
+    # looks like an auto-increment id (i.e., it contains the full uuid string).
+    assert uuid_val in entity.key
+    assert "modbus" in entity.key
+    assert "voltage" in entity.key
+
+
+# ---------------------------------------------------------------------------
+# 2. Provider registry tests
+# ---------------------------------------------------------------------------
+
+
+def test_register_provider_as_decorator():
+    """register_provider used as a decorator must add the callable to the registry."""
+    from app.integrations.expose import get_providers, register_provider
+
+    before = len(get_providers())
+
+    @register_provider
+    def _dummy_provider(session):
+        return []
+
+    after_providers = get_providers()
+    assert len(after_providers) == before + 1
+    assert _dummy_provider in after_providers
+
+    # Clean up: remove the dummy from the module-level registry.
+    from app.integrations import expose as _expose_mod
+    _expose_mod._REGISTRY.remove(_dummy_provider)
+
+
+def test_register_provider_direct_call():
+    """register_provider called directly must also register the callable."""
+    from app.integrations.expose import get_providers, register_provider
+    from app.integrations import expose as _expose_mod
+
+    def _another_dummy(session):
+        return []
+
+    before = len(get_providers())
+    returned = register_provider(_another_dummy)
+    assert returned is _another_dummy  # returns the provider unchanged
+    assert len(get_providers()) == before + 1
+
+    # Clean up.
+    _expose_mod._REGISTRY.remove(_another_dummy)
+
+
+# ---------------------------------------------------------------------------
+# 3. build_catalog tests
+# ---------------------------------------------------------------------------
+
+
+def test_build_catalog_empty_with_no_devices(expose_db):
+    """build_catalog with no enabled devices must return an empty list."""
+    from app.integrations.expose import build_catalog
+
+    with Session(expose_db) as session:
+        catalog = build_catalog(session)
+
+    # The modbus provider will find no enabled devices; other providers may
+    # add entries only if registered.  Since we only register the modbus
+    # provider at module load, the result should be empty.
+    assert catalog == []
+
+
+def test_build_catalog_produces_entities_for_enabled_device(expose_db):
+    """build_catalog must yield entities (including binary_sensor) for each enabled device."""
+    from app.integrations.expose import build_catalog, CatalogEntry
+
+    # Insert a test device.
+    test_uuid = "aaaaaaaa-0000-0000-0000-000000000001"
+    with Session(expose_db) as session:
+        _make_modbus_device(session, friendly_name="SDM120 Test", uuid=test_uuid)
+        session.commit()
+
+    with Session(expose_db) as session:
+        catalog = build_catalog(session)
+
+    assert len(catalog) > 0, "Expected at least one entity for the enabled device"
+
+    keys = [entry.entity.key for entry in catalog]
+
+    # Must contain a 'modbus.<uuid>.online' binary_sensor.
+    online_key = f"modbus.{test_uuid}.online"
+    assert online_key in keys, f"Expected online entity key {online_key!r} in catalog"
+
+    # Must contain at least one sensor entity (voltage is always in sdm120 profile).
+    voltage_key = f"modbus.{test_uuid}.voltage"
+    assert voltage_key in keys, f"Expected voltage entity key {voltage_key!r} in catalog"
+
+    # Verify CatalogEntry type.
+    assert all(isinstance(e, CatalogEntry) for e in catalog)
+
+
+def test_build_catalog_default_enabled_false(expose_db):
+    """Entities with no toggle row must default to enabled=False."""
+    from app.integrations.expose import build_catalog
+
+    test_uuid = "aaaaaaaa-0000-0000-0000-000000000002"
+    with Session(expose_db) as session:
+        _make_modbus_device(session, friendly_name="SDM120 B", uuid=test_uuid)
+        session.commit()
+
+    with Session(expose_db) as session:
+        catalog = build_catalog(session)
+
+    # No toggle rows inserted → all must be disabled.
+    assert all(not entry.enabled for entry in catalog), (
+        "All catalog entries must default to enabled=False when no toggle row exists"
+    )
+
+
+def test_build_catalog_respects_toggle_enabled(expose_db):
+    """An entity with a toggle row enabled=True must appear as enabled in the catalog."""
+    from datetime import datetime, timezone
+
+    from app.integrations.expose import build_catalog
+    from app.models.expose import ExposedEntityToggle
+
+    test_uuid = "aaaaaaaa-0000-0000-0000-000000000003"
+    voltage_key = f"modbus.{test_uuid}.voltage"
+
+    with Session(expose_db) as session:
+        _make_modbus_device(session, friendly_name="SDM120 C", uuid=test_uuid)
+        # Enable the voltage entity explicitly.
+        toggle = ExposedEntityToggle(
+            key=voltage_key,
+            enabled=True,
+            updated_at=datetime.now(tz=timezone.utc),
+        )
+        session.add(toggle)
+        session.commit()
+
+    with Session(expose_db) as session:
+        catalog = build_catalog(session)
+
+    enabled_keys = {entry.entity.key for entry in catalog if entry.enabled}
+    assert voltage_key in enabled_keys, (
+        f"Expected {voltage_key!r} to be enabled after toggling"
+    )
+
+    # Other entities (no toggle row) must still default to disabled.
+    online_key = f"modbus.{test_uuid}.online"
+    disabled_keys = {entry.entity.key for entry in catalog if not entry.enabled}
+    assert online_key in disabled_keys, f"Expected {online_key!r} to remain disabled"
+
+
+def test_build_catalog_device_grouping(expose_db):
+    """All entities for a device must share the same DeviceInfo (device grouping)."""
+    from app.integrations.expose import build_catalog
+
+    test_uuid = "aaaaaaaa-0000-0000-0000-000000000004"
+    with Session(expose_db) as session:
+        _make_modbus_device(session, friendly_name="SDM120 D", uuid=test_uuid)
+        session.commit()
+
+    with Session(expose_db) as session:
+        catalog = build_catalog(session)
+
+    device_entities = [e for e in catalog if test_uuid in e.entity.key]
+    assert len(device_entities) > 0
+
+    # All entities for this device must use the same device identifiers tuple.
+    identifiers_set = {e.entity.device.identifiers for e in device_entities}
+    assert len(identifiers_set) == 1, (
+        "All entities for one device must share the same DeviceInfo identifiers"
+    )
+    assert identifiers_set.pop() == ("modbus", test_uuid)
+
+
+def test_build_catalog_metric_metadata_from_profile(expose_db):
+    """Entity device_class and unit must match the sdm120 profile's metrics."""
+    from app.integrations.expose import build_catalog
+    from app.integrations.modbus.profiles import load_profile
+
+    test_uuid = "aaaaaaaa-0000-0000-0000-000000000005"
+    with Session(expose_db) as session:
+        _make_modbus_device(session, friendly_name="SDM120 E", uuid=test_uuid)
+        session.commit()
+
+    profile = load_profile("sdm120")
+    metric_map = {m.key: m for m in profile.metrics}
+
+    with Session(expose_db) as session:
+        catalog = build_catalog(session)
+
+    sensor_entities = [
+        e for e in catalog
+        if e.entity.component == "sensor" and test_uuid in e.entity.key
+    ]
+
+    for entry in sensor_entities:
+        # Extract metric key from entity key: "modbus.<uuid>.<metric_key>"
+        _, _, metric_key = entry.entity.key.split(".", 2)
+        if metric_key in metric_map:
+            metric_spec = metric_map[metric_key]
+            assert entry.entity.device_class == (metric_spec.device_class or None), (
+                f"device_class mismatch for {metric_key!r}: "
+                f"expected {metric_spec.device_class!r}, "
+                f"got {entry.entity.device_class!r}"
+            )
+            assert entry.entity.unit == metric_spec.unit, (
+                f"unit mismatch for {metric_key!r}: "
+                f"expected {metric_spec.unit!r}, got {entry.entity.unit!r}"
+            )
+            assert entry.entity.component == metric_spec.ha_component, (
+                f"component mismatch for {metric_key!r}: "
+                f"expected {metric_spec.ha_component!r}, "
+                f"got {entry.entity.component!r}"
+            )
+
+
+def test_build_catalog_online_binary_sensor_present(expose_db):
+    """Each enabled device must produce exactly one binary_sensor 'online' entity."""
+    from app.integrations.expose import build_catalog
+
+    uuid1 = "aaaaaaaa-0000-0000-0000-000000000006"
+    uuid2 = "aaaaaaaa-0000-0000-0000-000000000007"
+
+    with Session(expose_db) as session:
+        _make_modbus_device(session, friendly_name="Device F1", uuid=uuid1)
+        _make_modbus_device(session, friendly_name="Device F2", uuid=uuid2)
+        session.commit()
+
+    with Session(expose_db) as session:
+        catalog = build_catalog(session)
+
+    binary_sensors = [e for e in catalog if e.entity.component == "binary_sensor"]
+    binary_sensor_keys = {e.entity.key for e in binary_sensors}
+
+    assert f"modbus.{uuid1}.online" in binary_sensor_keys
+    assert f"modbus.{uuid2}.online" in binary_sensor_keys
+    # No sensor must masquerade as binary_sensor and vice versa.
+    assert all("online" in e.entity.key for e in binary_sensors), (
+        "All binary_sensor entities should be 'online' entities"
+    )
+
+
+def test_build_catalog_has_non_sensor_component(expose_db):
+    """The catalog must contain at least one entity with component != 'sensor'."""
+    from app.integrations.expose import build_catalog
+
+    test_uuid = "aaaaaaaa-0000-0000-0000-000000000008"
+    with Session(expose_db) as session:
+        _make_modbus_device(session, friendly_name="SDM120 G", uuid=test_uuid)
+        session.commit()
+
+    with Session(expose_db) as session:
+        catalog = build_catalog(session)
+
+    non_sensor = [e for e in catalog if e.entity.component != "sensor"]
+    assert len(non_sensor) >= 1, (
+        "Expected at least one non-sensor component (binary_sensor 'online')"
+    )
+
+
+def test_build_catalog_only_includes_enabled_devices(expose_db):
+    """Disabled devices must not contribute entities to the catalog."""
+    from app.models.modbus import ModbusDevice
+
+    now = datetime.now(tz=timezone.utc)
+    enabled_uuid = "aaaaaaaa-0000-0000-0000-000000000009"
+    disabled_uuid = "aaaaaaaa-0000-0000-0000-00000000000a"
+
+    with Session(expose_db) as session:
+        enabled_device = ModbusDevice(
+            uuid=enabled_uuid,
+            friendly_name="Enabled Device",
+            host="10.0.0.1",
+            port=502,
+            unit_id=1,
+            profile="sdm120",
+            poll_interval_s=5,
+            enabled=True,
+            created_at=now,
+            updated_at=now,
+        )
+        disabled_device = ModbusDevice(
+            uuid=disabled_uuid,
+            friendly_name="Disabled Device",
+            host="10.0.0.2",
+            port=502,
+            unit_id=2,
+            profile="sdm120",
+            poll_interval_s=5,
+            enabled=False,
+            created_at=now,
+            updated_at=now,
+        )
+        session.add_all([enabled_device, disabled_device])
+        session.commit()
+
+    from app.integrations.expose import build_catalog
+
+    with Session(expose_db) as session:
+        catalog = build_catalog(session)
+
+    all_keys = {e.entity.key for e in catalog}
+    assert any(enabled_uuid in k for k in all_keys), "Enabled device must be in catalog"
+    assert not any(disabled_uuid in k for k in all_keys), (
+        "Disabled device must NOT be in catalog"
+    )
+
+
+def test_build_catalog_key_uses_uuid_not_db_id(expose_db):
+    """Entity keys must contain the device uuid, not the integer DB primary key."""
+    from app.integrations.expose import build_catalog
+
+    test_uuid = "bbbbbbbb-1111-0000-0000-000000000001"
+    with Session(expose_db) as session:
+        device = _make_modbus_device(session, friendly_name="UUID Key Test", uuid=test_uuid)
+        session.commit()
+        db_id = device.id  # type: ignore[union-attr]
+
+    with Session(expose_db) as session:
+        catalog = build_catalog(session)
+
+    entity_keys = [e.entity.key for e in catalog if test_uuid in e.entity.key]
+    assert len(entity_keys) > 0, "Expected entities for the test device"
+
+    # Keys must contain the uuid string and not be keyed by integer id only.
+    for key in entity_keys:
+        assert test_uuid in key, f"Key {key!r} must contain the uuid {test_uuid!r}"
+        # Ensure the integer DB id does not appear where the uuid should be.
+        parts = key.split(".")
+        assert str(db_id) not in parts[1:2], (
+            f"Key {key!r} must not use the integer DB id {db_id} in the uuid slot"
+        )
+
+
+# ---------------------------------------------------------------------------
+# 4. Migration shape tests
+# ---------------------------------------------------------------------------
+
+
+def test_exposed_entity_toggle_table_exists_after_upgrade(expose_db):
+    """exposed_entity_toggle table must exist after upgrade to head."""
+    inspector = inspect(expose_db)
+    assert "exposed_entity_toggle" in inspector.get_table_names(), (
+        "exposed_entity_toggle table missing after upgrade to head"
+    )
+
+
+def test_exposed_entity_toggle_columns(expose_db):
+    """exposed_entity_toggle must have id, key, enabled, updated_at columns."""
+    inspector = inspect(expose_db)
+    columns = {col["name"]: col for col in inspector.get_columns("exposed_entity_toggle")}
+
+    assert "id" in columns
+    assert "key" in columns
+    assert "enabled" in columns
+    assert "updated_at" in columns
+
+    # id must be non-nullable.
+    assert not columns["id"]["nullable"]
+    # key must be non-nullable.
+    assert not columns["key"]["nullable"]
+    # enabled must be non-nullable.
+    assert not columns["enabled"]["nullable"]
+
+
+def test_exposed_entity_toggle_key_unique_constraint(expose_db):
+    """exposed_entity_toggle.key must have a unique constraint."""
+    inspector = inspect(expose_db)
+    unique_constraints = inspector.get_unique_constraints("exposed_entity_toggle")
+    unique_cols = [col for uc in unique_constraints for col in uc["column_names"]]
+    assert "key" in unique_cols, "key column must have a unique constraint"
+
+
+def test_exposed_entity_toggle_key_unique_index(expose_db):
+    """exposed_entity_toggle must have a unique index on key."""
+    inspector = inspect(expose_db)
+    indexes = {idx["name"]: idx for idx in inspector.get_indexes("exposed_entity_toggle")}
+    assert "ix_exposed_entity_toggle_key" in indexes, (
+        "Index ix_exposed_entity_toggle_key missing"
+    )
+    assert indexes["ix_exposed_entity_toggle_key"]["unique"]
+
+
+def test_downgrade_removes_toggle_table(tmp_path: Path):
+    """downgrade -1 from head must drop the exposed_entity_toggle table cleanly."""
+    db_path = tmp_path / "downgrade_expose_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 "exposed_entity_toggle" in inspector.get_table_names()
+    engine.dispose()
+
+    # Downgrade one step removes the exposed_entity_toggle revision.
+    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 "exposed_entity_toggle" not in table_names, (
+        "exposed_entity_toggle should be gone after downgrade -1"
+    )
+    # Previous tables must still exist.
+    assert "modbus_device" in table_names
+    assert "modbus_reading" in table_names
+    engine.dispose()
+
+
+# ---------------------------------------------------------------------------
+# 5. ORM round-trip tests
+# ---------------------------------------------------------------------------
+
+
+def test_expose_toggle_in_base_metadata():
+    """Base.metadata.tables must include exposed_entity_toggle."""
+    from app.db import Base
+
+    # Importing the model registers it with Base.metadata.
+    from app.models.expose import ExposedEntityToggle  # noqa: F401
+
+    assert "exposed_entity_toggle" in Base.metadata.tables, (
+        "exposed_entity_toggle not in Base.metadata after model import"
+    )
+
+
+def test_expose_toggle_insert_and_read(expose_db):
+    """ExposedEntityToggle can be inserted and retrieved correctly."""
+    from app.models.expose import ExposedEntityToggle
+
+    now = datetime.now(tz=timezone.utc)
+    key = "modbus.test-uuid.voltage"
+
+    with Session(expose_db) as session:
+        toggle = ExposedEntityToggle(key=key, enabled=True, updated_at=now)
+        session.add(toggle)
+        session.commit()
+        toggle_id = toggle.id
+
+    with Session(expose_db) as session:
+        fetched = session.get(ExposedEntityToggle, toggle_id)
+        assert fetched is not None
+        assert fetched.key == key
+        assert fetched.enabled is True
+
+
+def test_expose_toggle_default_enabled_is_false(expose_db):
+    """ExposedEntityToggle.enabled must default to False after INSERT (column default).
+
+    SQLAlchemy applies ``default=False`` at INSERT time, not at Python object
+    construction time.  We verify the column default by inserting a row without
+    providing ``enabled`` and reading it back.
+    """
+    from app.models.expose import ExposedEntityToggle
+
+    now = datetime.now(tz=timezone.utc)
+
+    with Session(expose_db) as session:
+        toggle = ExposedEntityToggle(key="default.enabled.test", updated_at=now)
+        session.add(toggle)
+        session.commit()
+        toggle_id = toggle.id
+
+    with Session(expose_db) as session:
+        fetched = session.get(ExposedEntityToggle, toggle_id)
+        assert fetched is not None
+        assert fetched.enabled is False, (
+            "ExposedEntityToggle.enabled must default to False (not True, not None)"
+        )
+
+
+def test_expose_toggle_key_uniqueness_enforced(expose_db):
+    """Inserting two rows with the same key must raise an IntegrityError."""
+    import sqlalchemy.exc
+
+    from app.models.expose import ExposedEntityToggle
+
+    now = datetime.now(tz=timezone.utc)
+    key = "modbus.dup-uuid.power"
+
+    with Session(expose_db) as session:
+        session.add(ExposedEntityToggle(key=key, enabled=False, updated_at=now))
+        session.commit()
+
+    with pytest.raises(sqlalchemy.exc.IntegrityError):
+        with Session(expose_db) as session:
+            session.add(ExposedEntityToggle(key=key, enabled=True, updated_at=now))
+            session.commit()
+
+
+def test_expose_toggle_update(expose_db):
+    """Updating an existing toggle row must persist the new enabled value."""
+    from app.models.expose import ExposedEntityToggle
+
+    now = datetime.now(tz=timezone.utc)
+    key = "modbus.update-uuid.current"
+
+    with Session(expose_db) as session:
+        toggle = ExposedEntityToggle(key=key, enabled=False, updated_at=now)
+        session.add(toggle)
+        session.commit()
+        toggle_id = toggle.id
+
+    with Session(expose_db) as session:
+        toggle = session.get(ExposedEntityToggle, toggle_id)
+        toggle.enabled = True
+        toggle.updated_at = datetime.now(tz=timezone.utc)
+        session.commit()
+
+    with Session(expose_db) as session:
+        fetched = session.get(ExposedEntityToggle, toggle_id)
+        assert fetched.enabled is True
+
+
+# ---------------------------------------------------------------------------
+# 6. APP_BASELINE_REVISION
+# ---------------------------------------------------------------------------
+
+
+def test_app_baseline_revision_matches_new_head(tmp_path: Path):
+    """APP_BASELINE_REVISION must equal the Alembic head after the new migration."""
+    from alembic.script import ScriptDirectory
+
+    from scripts.app_db_adopt import APP_BASELINE_REVISION
+
+    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}"
+    )
+    # Confirm the new revision is the head.
+    assert head == "20260622_10_exposed_entities", (
+        f"Expected new head to be '20260622_10_exposed_entities', got {head!r}"
+    )
diff --git a/tests/test_modbus_models.py b/tests/test_modbus_models.py
index 0231df9..9674dfd 100644
--- a/tests/test_modbus_models.py
+++ b/tests/test_modbus_models.py
@@ -144,7 +144,13 @@ def test_modbus_reading_recorded_at_index_exists(modbus_db):
 
 
 def test_downgrade_removes_modbus_tables(tmp_path: Path):
-    """downgrade -1 from head must drop both modbus tables cleanly."""
+    """Downgrading past the modbus migration must drop both modbus tables cleanly.
+
+    We downgrade to the explicit revision ``20260621_08_totp`` (the down_revision
+    of the modbus tables migration), so the test stays correct as new revisions
+    are added on top.  Using an explicit target rather than ``-2`` avoids drift
+    with chain growth (same fix pattern as T02 applied to the TOTP downgrade test).
+    """
     db_path = tmp_path / "downgrade_modbus_test.db"
     db_url = f"sqlite:///{db_path}"
     alembic_cfg = _make_app_alembic_config(db_url)
@@ -157,8 +163,11 @@ def test_downgrade_removes_modbus_tables(tmp_path: Path):
     assert "modbus_reading" in inspector.get_table_names()
     engine.dispose()
 
-    # Downgrade one step removes the modbus migration.
-    command.downgrade(alembic_cfg, "-1")
+    # Downgrade to the explicit down_revision of the modbus tables migration
+    # ("20260621_08_totp"), consistent with how T02 fixed the TOTP downgrade test.
+    # Using an explicit target instead of "-2" ensures the test stays correct even
+    # as new revisions are added on top of this one (no drift with chain growth).
+    command.downgrade(alembic_cfg, "20260621_08_totp")
 
     engine = create_engine(db_url, connect_args={"check_same_thread": False})
     inspector = inspect(engine)