feat(13-02): add wireless_links table migration, ORM model, register both models

- Migration 033 creates wireless_links with state machine, missed_polls, RLS
- WirelessLink model with LinkState enum (discovered/active/degraded/down/stale)
- Register DeviceInterface, WirelessLink, LinkState in models __init__

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

backend/app/models/__init__.py

@@ -18,6 +18,8 @@ from app.models.audit_log import AuditLog
 from app.models.maintenance_window import MaintenanceWindow
 from app.models.api_key import ApiKey
 from app.models.config_backup import RouterConfigSnapshot, RouterConfigDiff, RouterConfigChange
+from app.models.device_interface import DeviceInterface
+from app.models.wireless_link import WirelessLink, LinkState
 
 __all__ = [
     "Tenant",
@@ -45,4 +47,7 @@ __all__ = [
     "RouterConfigSnapshot",
     "RouterConfigDiff",
     "RouterConfigChange",
+    "DeviceInterface",
+    "WirelessLink",
+    "LinkState",
 ]

backend/app/models/wireless_link.py

@@ -0,0 +1,85 @@
+"""WirelessLink model -- AP-to-CPE link state tracking for link discovery."""
+
+import uuid
+from datetime import datetime
+from enum import Enum
+
+from sqlalchemy import DateTime, ForeignKey, Integer, String, UniqueConstraint, func
+from sqlalchemy.dialects.postgresql import UUID
+from sqlalchemy.orm import Mapped, mapped_column, relationship
+
+from app.models.base import Base
+
+
+class LinkState(str, Enum):
+    """Link health state machine values."""
+
+    DISCOVERED = "discovered"
+    ACTIVE = "active"
+    DEGRADED = "degraded"
+    DOWN = "down"
+    STALE = "stale"
+
+
+class WirelessLink(Base):
+    __tablename__ = "wireless_links"
+    __table_args__ = (
+        UniqueConstraint("ap_device_id", "cpe_device_id", name="uq_wireless_links_ap_cpe"),
+    )
+
+    id: Mapped[uuid.UUID] = mapped_column(
+        UUID(as_uuid=True),
+        primary_key=True,
+        default=uuid.uuid4,
+        server_default=func.gen_random_uuid(),
+    )
+    ap_device_id: Mapped[uuid.UUID] = mapped_column(
+        UUID(as_uuid=True),
+        ForeignKey("devices.id", ondelete="CASCADE"),
+        nullable=False,
+    )
+    cpe_device_id: Mapped[uuid.UUID] = mapped_column(
+        UUID(as_uuid=True),
+        ForeignKey("devices.id", ondelete="CASCADE"),
+        nullable=False,
+    )
+    tenant_id: Mapped[uuid.UUID] = mapped_column(
+        UUID(as_uuid=True),
+        ForeignKey("tenants.id", ondelete="CASCADE"),
+        nullable=False,
+    )
+    interface: Mapped[str | None] = mapped_column(String(255), nullable=True)
+    client_mac: Mapped[str] = mapped_column(String(17), nullable=False)
+    signal_strength: Mapped[int | None] = mapped_column(Integer, nullable=True)
+    tx_ccq: Mapped[int | None] = mapped_column(Integer, nullable=True)
+    tx_rate: Mapped[str | None] = mapped_column(String(50), nullable=True)
+    rx_rate: Mapped[str | None] = mapped_column(String(50), nullable=True)
+    state: Mapped[str] = mapped_column(
+        String(20),
+        nullable=False,
+        default=LinkState.DISCOVERED.value,
+    )
+    missed_polls: Mapped[int] = mapped_column(Integer, nullable=False, default=0)
+    discovered_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True), server_default=func.now(), nullable=False
+    )
+    last_seen: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True), server_default=func.now(), nullable=False
+    )
+    updated_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True), server_default=func.now(), nullable=False
+    )
+
+    # Relationships
+    ap_device: Mapped["Device"] = relationship(  # type: ignore[name-defined]
+        "Device", foreign_keys=[ap_device_id]
+    )
+    cpe_device: Mapped["Device"] = relationship(  # type: ignore[name-defined]
+        "Device", foreign_keys=[cpe_device_id]
+    )
+
+    def __repr__(self) -> str:
+        return (
+            f"<WirelessLink id={self.id} ap={self.ap_device_id} "
+            f"cpe={self.cpe_device_id} state={self.state!r}>"
+        )