feat(auth): add oauth_identities table for Google/Microsoft sign-in

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

backend/app/models/__init__.py

@@ -62,6 +62,7 @@ from .session_fact import SessionFact
 from .session_suggested_fix import SessionSuggestedFix
 from .draft_template import DraftTemplate
 from .account_settings import AccountSettings
+from .oauth_identity import OAuthIdentity  # noqa: F401
 
 __all__ = [
     "User",
@@ -138,4 +139,5 @@ __all__ = [
     "SessionSuggestedFix",
     "DraftTemplate",
     "AccountSettings",
+    "OAuthIdentity",
 ]

backend/app/models/oauth_identity.py

@@ -0,0 +1,36 @@
+import uuid
+from datetime import datetime, timezone
+from typing import TYPE_CHECKING
+from sqlalchemy import String, DateTime, ForeignKey, UniqueConstraint, Index
+from sqlalchemy.orm import Mapped, mapped_column, relationship
+from sqlalchemy.dialects.postgresql import UUID
+from app.core.database import Base
+
+if TYPE_CHECKING:
+    from app.models.user import User
+
+
+class OAuthIdentity(Base):
+    __tablename__ = "oauth_identities"
+    __table_args__ = (
+        UniqueConstraint("provider", "provider_subject", name="uq_oauth_identities_provider_subject"),
+        Index("ix_oauth_identities_user_id", "user_id"),
+    )
+
+    id: Mapped[uuid.UUID] = mapped_column(UUID(as_uuid=True), primary_key=True, default=uuid.uuid4)
+    user_id: Mapped[uuid.UUID] = mapped_column(
+        UUID(as_uuid=True), ForeignKey("users.id", ondelete="CASCADE"), nullable=False
+    )
+    provider: Mapped[str] = mapped_column(String(20), nullable=False)
+    provider_subject: Mapped[str] = mapped_column(String(255), nullable=False)
+    provider_email_at_link: Mapped[str] = mapped_column(String(255), nullable=False)
+    created_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True), default=lambda: datetime.now(timezone.utc)
+    )
+    updated_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True),
+        default=lambda: datetime.now(timezone.utc),
+        onupdate=lambda: datetime.now(timezone.utc),
+    )
+
+    user: Mapped["User"] = relationship("User", backref="oauth_identities")