Initial commit: CI Agent competitive-intelligence monitoring app

FastAPI + Celery + Next.js + Postgres/Redis app with company monitoring,
source collection, LLM-based change analysis, enrichment, and account
security (Turnstile, escalating lockout, email verification).

apps/api/app/models/detected_change.py

@@ -0,0 +1,44 @@
+from __future__ import annotations
+
+import uuid
+from typing import Any
+
+from sqlalchemy import JSON, Enum, Float, ForeignKey, String
+from sqlalchemy.orm import Mapped, mapped_column
+
+from app.db.base import Base, TimestampMixin, UUIDPrimaryKeyMixin
+from app.models.enums import ChangeStatus, ChangeType, SeverityLevel
+
+
+class DetectedChange(Base, UUIDPrimaryKeyMixin, TimestampMixin):
+    __tablename__ = "detected_changes"
+
+    company_id: Mapped[uuid.UUID] = mapped_column(
+        ForeignKey("companies.id", ondelete="CASCADE"), index=True
+    )
+    source_id: Mapped[uuid.UUID] = mapped_column(
+        ForeignKey("sources.id", ondelete="CASCADE"), index=True
+    )
+    monitoring_run_id: Mapped[uuid.UUID] = mapped_column(
+        ForeignKey("monitoring_runs.id", ondelete="CASCADE"), index=True
+    )
+    previous_snapshot_id: Mapped[uuid.UUID | None] = mapped_column(
+        ForeignKey("snapshots.id", ondelete="SET NULL"), nullable=True
+    )
+    current_snapshot_id: Mapped[uuid.UUID] = mapped_column(
+        ForeignKey("snapshots.id", ondelete="CASCADE")
+    )
+    change_type: Mapped[ChangeType] = mapped_column(Enum(ChangeType, native_enum=False, length=30))
+    raw_diff: Mapped[dict[str, Any]] = mapped_column(JSON, default=dict)
+    significance_score: Mapped[float] = mapped_column(Float)
+    confidence_score: Mapped[float] = mapped_column(Float)
+    severity: Mapped[SeverityLevel] = mapped_column(
+        Enum(SeverityLevel, native_enum=False, length=20)
+    )
+    status: Mapped[ChangeStatus] = mapped_column(
+        Enum(ChangeStatus, native_enum=False, length=20), default=ChangeStatus.NEW
+    )
+    # Short human-readable label, e.g. "3 new job postings detected" -
+    # populated deterministically here; Phase 7's LLM may later add a
+    # richer "why it matters" narrative on top without replacing this.
+    summary: Mapped[str] = mapped_column(String(500))