feat(15-01): add site alert rules/events migration, models, schemas, and config

- Create Alembic migration 035 with site_alert_rules and site_alert_events tables, RLS policies, and GRANT
- Add SiteAlertRule/SiteAlertEvent ORM models with enums for rule_type, severity, state
- Add Pydantic schemas for rule/event CRUD and signal history points
- Add SIGNAL_DEGRADATION_THRESHOLD_DB, ALERT_EVALUATION_INTERVAL_SECONDS, TREND_DETECTION_INTERVAL_SECONDS to Settings

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

backend/app/models/__init__.py

@@ -21,6 +21,7 @@ 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
+from app.models.site_alert import SiteAlertRule, SiteAlertEvent
 
 __all__ = [
     "Tenant",
@@ -52,4 +53,6 @@ __all__ = [
     "DeviceInterface",
     "WirelessLink",
     "LinkState",
+    "SiteAlertRule",
+    "SiteAlertEvent",
 ]

backend/app/models/site_alert.py

@@ -0,0 +1,168 @@
+"""Site alert system ORM models: site/sector-scoped alert rules and events.
+
+Separate from the device-level alert system in alert.py. These models support
+site-wide and sector-scoped alerting for Phase 15 (signal trending, site alerting).
+"""
+
+import uuid
+from datetime import datetime
+from enum import Enum
+
+from sqlalchemy import Boolean, DateTime, ForeignKey, Integer, Numeric, String, Text, func
+from sqlalchemy.dialects.postgresql import UUID
+from sqlalchemy.orm import Mapped, mapped_column, relationship
+
+from app.models.base import Base
+
+
+class SiteAlertRuleType(str, Enum):
+    """Types of site/sector alert rules."""
+
+    DEVICE_OFFLINE_PERCENT = "device_offline_percent"
+    DEVICE_OFFLINE_COUNT = "device_offline_count"
+    SECTOR_SIGNAL_AVG = "sector_signal_avg"
+    SECTOR_CLIENT_DROP = "sector_client_drop"
+    SIGNAL_DEGRADATION = "signal_degradation"
+
+
+class AlertSeverity(str, Enum):
+    """Alert severity levels."""
+
+    WARNING = "warning"
+    CRITICAL = "critical"
+
+
+class AlertState(str, Enum):
+    """Alert event states."""
+
+    ACTIVE = "active"
+    RESOLVED = "resolved"
+
+
+class SiteAlertRule(Base):
+    """Configurable site/sector-scoped alert threshold rule.
+
+    Rules are always scoped to a site, and optionally to a specific sector.
+    When conditions are met, site_alert_events are created by the evaluation task.
+    """
+
+    __tablename__ = "site_alert_rules"
+
+    id: Mapped[uuid.UUID] = mapped_column(
+        UUID(as_uuid=True),
+        primary_key=True,
+        default=uuid.uuid4,
+        server_default=func.gen_random_uuid(),
+    )
+    tenant_id: Mapped[uuid.UUID] = mapped_column(
+        UUID(as_uuid=True),
+        ForeignKey("tenants.id", ondelete="CASCADE"),
+        nullable=False,
+    )
+    site_id: Mapped[uuid.UUID] = mapped_column(
+        UUID(as_uuid=True),
+        ForeignKey("sites.id", ondelete="CASCADE"),
+        nullable=False,
+    )
+    sector_id: Mapped[uuid.UUID | None] = mapped_column(
+        UUID(as_uuid=True),
+        ForeignKey("sectors.id", ondelete="SET NULL"),
+        nullable=True,
+    )
+    rule_type: Mapped[str] = mapped_column(String(50), nullable=False)
+    name: Mapped[str] = mapped_column(String(255), nullable=False)
+    description: Mapped[str | None] = mapped_column(Text, nullable=True)
+    threshold_value: Mapped[float] = mapped_column(Numeric, nullable=False)
+    threshold_unit: Mapped[str] = mapped_column(String(20), nullable=False)
+    enabled: Mapped[bool] = mapped_column(
+        Boolean, nullable=False, default=True, server_default="true"
+    )
+    created_at: 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(), onupdate=func.now(), nullable=False
+    )
+
+    # Relationships
+    site: Mapped["Site"] = relationship("Site")  # type: ignore[name-defined]
+    sector: Mapped["Sector | None"] = relationship("Sector")  # type: ignore[name-defined]
+
+    def __repr__(self) -> str:
+        return f"<SiteAlertRule id={self.id} name={self.name!r} type={self.rule_type}>"
+
+
+class SiteAlertEvent(Base):
+    """Record of a site/sector alert firing or being resolved.
+
+    Created by the scheduled alert evaluation task (Plan 02).
+    Resolved manually by operators via the API.
+    """
+
+    __tablename__ = "site_alert_events"
+
+    id: Mapped[uuid.UUID] = mapped_column(
+        UUID(as_uuid=True),
+        primary_key=True,
+        default=uuid.uuid4,
+        server_default=func.gen_random_uuid(),
+    )
+    tenant_id: Mapped[uuid.UUID] = mapped_column(
+        UUID(as_uuid=True),
+        ForeignKey("tenants.id", ondelete="CASCADE"),
+        nullable=False,
+    )
+    site_id: Mapped[uuid.UUID] = mapped_column(
+        UUID(as_uuid=True),
+        ForeignKey("sites.id", ondelete="CASCADE"),
+        nullable=False,
+    )
+    sector_id: Mapped[uuid.UUID | None] = mapped_column(
+        UUID(as_uuid=True),
+        ForeignKey("sectors.id", ondelete="SET NULL"),
+        nullable=True,
+    )
+    rule_id: Mapped[uuid.UUID | None] = mapped_column(
+        UUID(as_uuid=True),
+        ForeignKey("site_alert_rules.id", ondelete="SET NULL"),
+        nullable=True,
+    )
+    device_id: Mapped[uuid.UUID | None] = mapped_column(
+        UUID(as_uuid=True),
+        ForeignKey("devices.id", ondelete="SET NULL"),
+        nullable=True,
+    )
+    link_id: Mapped[uuid.UUID | None] = mapped_column(
+        UUID(as_uuid=True),
+        ForeignKey("wireless_links.id", ondelete="SET NULL"),
+        nullable=True,
+    )
+    severity: Mapped[str] = mapped_column(
+        String(20), nullable=False, default="warning", server_default="warning"
+    )
+    message: Mapped[str] = mapped_column(Text, nullable=False)
+    state: Mapped[str] = mapped_column(
+        String(20), nullable=False, default="active", server_default="active"
+    )
+    consecutive_hits: Mapped[int] = mapped_column(
+        Integer, nullable=False, default=1, server_default="1"
+    )
+    triggered_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True), server_default=func.now(), nullable=False
+    )
+    resolved_at: Mapped[datetime | None] = mapped_column(
+        DateTime(timezone=True), nullable=True
+    )
+    resolved_by: Mapped[uuid.UUID | None] = mapped_column(
+        UUID(as_uuid=True),
+        ForeignKey("users.id", ondelete="SET NULL"),
+        nullable=True,
+    )
+
+    # Relationships
+    site: Mapped["Site"] = relationship("Site")  # type: ignore[name-defined]
+    sector: Mapped["Sector | None"] = relationship("Sector")  # type: ignore[name-defined]
+    rule: Mapped["SiteAlertRule | None"] = relationship("SiteAlertRule")
+
+    def __repr__(self) -> str:
+        return f"<SiteAlertEvent id={self.id} state={self.state} severity={self.severity}>"