feat(db): add conversation models

src/arbiter/db/migrations/versions/002_conversations.py

@@ -0,0 +1,96 @@
+"""Add conversations tables for follow-up Q&A.
+
+Revision ID: 002
+Revises: 001
+Create Date: 2024-01-20
+
+"""
+
+from collections.abc import Sequence
+
+import sqlalchemy as sa
+from alembic import op
+from sqlalchemy.dialects import postgresql
+
+revision: str = "002"
+down_revision: str | None = "001"
+branch_labels: str | Sequence[str] | None = None
+depends_on: str | Sequence[str] | None = None
+
+
+def upgrade() -> None:
+    # Create conversations table
+    op.create_table(
+        "conversations",
+        sa.Column("id", postgresql.UUID(as_uuid=False), primary_key=True),
+        sa.Column(
+            "review_id",
+            postgresql.UUID(as_uuid=False),
+            sa.ForeignKey("reviews.id", ondelete="CASCADE"),
+            nullable=False,
+        ),
+        sa.Column("platform", sa.String(50), nullable=False),
+        sa.Column("repository", sa.String(255), nullable=False),
+        sa.Column("pr_number", sa.Integer(), nullable=False),
+        sa.Column(
+            "started_at",
+            sa.DateTime(timezone=True),
+            server_default=sa.text("now()"),
+            nullable=False,
+        ),
+        sa.Column(
+            "last_activity",
+            sa.DateTime(timezone=True),
+            server_default=sa.text("now()"),
+            nullable=False,
+        ),
+        sa.Column("total_tokens", sa.Integer(), default=0),
+        sa.Column("total_cost_usd", sa.Float(), default=0.0),
+    )
+
+    # Create indexes for conversations
+    op.create_index("ix_conversations_review_id", "conversations", ["review_id"])
+    op.create_index("ix_conversations_repository_pr", "conversations", ["repository", "pr_number"])
+
+    # Create conversation_messages table
+    op.create_table(
+        "conversation_messages",
+        sa.Column("id", postgresql.UUID(as_uuid=False), primary_key=True),
+        sa.Column(
+            "conversation_id",
+            postgresql.UUID(as_uuid=False),
+            sa.ForeignKey("conversations.id", ondelete="CASCADE"),
+            nullable=False,
+        ),
+        sa.Column("role", sa.String(20), nullable=False),
+        sa.Column("platform_comment_id", sa.String(100), nullable=True),
+        sa.Column("author", sa.String(255), nullable=True),
+        sa.Column("content", sa.Text(), nullable=False),
+        sa.Column("responding_agents", postgresql.JSON(), nullable=True),
+        sa.Column("referenced_finding_ids", postgresql.JSON(), nullable=True),
+        sa.Column("tokens_used", sa.Integer(), default=0),
+        sa.Column("cost_usd", sa.Float(), default=0.0),
+        sa.Column(
+            "created_at",
+            sa.DateTime(timezone=True),
+            server_default=sa.text("now()"),
+            nullable=False,
+        ),
+        sa.Column("sequence", sa.Integer(), nullable=False),
+    )
+
+    # Create indexes for conversation_messages
+    op.create_index(
+        "ix_conversation_messages_conversation_id", "conversation_messages", ["conversation_id"]
+    )
+    op.create_index(
+        "ix_conversation_messages_sequence",
+        "conversation_messages",
+        ["conversation_id", "sequence"],
+    )
+
+
+def downgrade() -> None:
+    # Drop tables in reverse order
+    op.drop_table("conversation_messages")
+    op.drop_table("conversations")

src/arbiter/db/models.py

@@ -97,6 +97,9 @@ class ReviewModel(Base):
         "DeliberationStepModel", back_populates="review", cascade="all, delete-orphan"
     )
     policy: Mapped["PolicyModel | None"] = relationship("PolicyModel", back_populates="reviews")
+    conversations: Mapped[list["ConversationModel"]] = relationship(
+        "ConversationModel", back_populates="review", cascade="all, delete-orphan"
+    )
 
     __table_args__ = (
         Index("ix_reviews_repository_pr", "repository", "pr_number"),
@@ -236,3 +239,81 @@ class PolicyModel(Base):
 
     # Relationship
     reviews: Mapped[list["ReviewModel"]] = relationship("ReviewModel", back_populates="policy")
+
+
+class ConversationModel(Base):
+    """Database model for follow-up conversations linked to reviews."""
+
+    __tablename__ = "conversations"
+
+    id: Mapped[str] = mapped_column(
+        UUID(as_uuid=False), primary_key=True, default=lambda: str(uuid4())
+    )
+    review_id: Mapped[str] = mapped_column(
+        UUID(as_uuid=False), ForeignKey("reviews.id"), nullable=False, index=True
+    )
+
+    # PR context
+    platform: Mapped[str] = mapped_column(String(50), nullable=False)  # github/gitlab
+    repository: Mapped[str] = mapped_column(String(255), nullable=False)
+    pr_number: Mapped[int] = mapped_column(Integer, nullable=False)
+
+    # Timestamps
+    started_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True), server_default=func.now(), nullable=False
+    )
+    last_activity: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True), server_default=func.now(), nullable=False
+    )
+
+    # Cost tracking
+    total_tokens: Mapped[int] = mapped_column(Integer, default=0)
+    total_cost_usd: Mapped[float] = mapped_column(Float, default=0.0)
+
+    # Relationships
+    review: Mapped["ReviewModel"] = relationship("ReviewModel", back_populates="conversations")
+    messages: Mapped[list["ConversationMessageModel"]] = relationship(
+        "ConversationMessageModel", back_populates="conversation", cascade="all, delete-orphan"
+    )
+
+    __table_args__ = (Index("ix_conversations_repository_pr", "repository", "pr_number"),)
+
+
+class ConversationMessageModel(Base):
+    """Database model for individual messages in a conversation."""
+
+    __tablename__ = "conversation_messages"
+
+    id: Mapped[str] = mapped_column(
+        UUID(as_uuid=False), primary_key=True, default=lambda: str(uuid4())
+    )
+    conversation_id: Mapped[str] = mapped_column(
+        UUID(as_uuid=False), ForeignKey("conversations.id"), nullable=False, index=True
+    )
+
+    # Message data
+    role: Mapped[str] = mapped_column(String(20), nullable=False)  # "user" or "assistant"
+    platform_comment_id: Mapped[str | None] = mapped_column(String(100), nullable=True)
+    author: Mapped[str | None] = mapped_column(String(255), nullable=True)
+    content: Mapped[str] = mapped_column(Text, nullable=False)
+
+    # Agent routing info (for assistant messages)
+    responding_agents: Mapped[list[str] | None] = mapped_column(JSON, nullable=True)
+    referenced_finding_ids: Mapped[list[str] | None] = mapped_column(JSON, nullable=True)
+
+    # Cost tracking
+    tokens_used: Mapped[int] = mapped_column(Integer, default=0)
+    cost_usd: Mapped[float] = mapped_column(Float, default=0.0)
+
+    # Timestamps and ordering
+    created_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True), server_default=func.now(), nullable=False
+    )
+    sequence: Mapped[int] = mapped_column(Integer, nullable=False)
+
+    # Relationship
+    conversation: Mapped["ConversationModel"] = relationship(
+        "ConversationModel", back_populates="messages"
+    )
+
+    __table_args__ = (Index("ix_conversation_messages_sequence", "conversation_id", "sequence"),)