feat(agent): persist pending tool call in session snapshot

backend/src/models/agent_chat_session.py

@@ -14,7 +14,7 @@ from sqlalchemy import (
     func,
     text,
 )
-from sqlalchemy.dialects.postgresql import UUID
+from sqlalchemy.dialects.postgresql import JSONB, UUID
 from sqlalchemy.orm import Mapped, mapped_column
 
 from core.db.base import Base, SoftDeleteMixin, TimestampMixin
@@ -75,3 +75,7 @@ class AgentChatSession(TimestampMixin, SoftDeleteMixin, Base):
     total_cost: Mapped[Decimal] = mapped_column(
         Numeric(12, 6), nullable=False, server_default=text("0")
     )
+    state_snapshot: Mapped[dict | None] = mapped_column(
+        JSONB,
+        nullable=True,
+    )

backend/src/v1/agent/service.py

@@ -284,3 +284,54 @@ class AgentChatService(BaseService):
             "content": message,
             "usage": {"input_tokens": 0, "output_tokens": 0, "cost": "0"},
         }
+
+    async def get_state_snapshot(self, session_id: UUID) -> dict | None:
+        stmt = select(AgentChatSession).where(AgentChatSession.id == session_id)
+        session = await self._session.scalar(stmt)
+        if session is None:
+            return None
+        return session.state_snapshot
+
+    async def set_pending_tool_call(
+        self,
+        *,
+        session_id: UUID,
+        interrupt_id: str,
+        tool_name: str,
+        tool_args: dict,
+        expires_at: datetime,
+    ) -> None:
+        stmt = select(AgentChatSession).where(AgentChatSession.id == session_id)
+        session = await self._session.scalar(stmt)
+        if session is None:
+            raise ValueError(f"Session {session_id} not found")
+        snapshot = session.state_snapshot or {}
+        snapshot["pending_tool_call"] = {
+            "interrupt_id": interrupt_id,
+            "tool_name": tool_name,
+            "tool_args": tool_args,
+            "status": "PENDING_APPROVAL",
+            "expires_at": expires_at.isoformat(),
+            "decision": None,
+            "result": None,
+        }
+        session.state_snapshot = snapshot
+
+    async def update_pending_tool_call_status(
+        self,
+        *,
+        session_id: UUID,
+        interrupt_id: str,
+        status: str,
+    ) -> None:
+        stmt = select(AgentChatSession).where(AgentChatSession.id == session_id)
+        session = await self._session.scalar(stmt)
+        if session is None:
+            raise ValueError(f"Session {session_id} not found")
+        snapshot = session.state_snapshot
+        if snapshot is None or "pending_tool_call" not in snapshot:
+            raise ValueError("No pending tool call found")
+        if snapshot["pending_tool_call"]["interrupt_id"] != interrupt_id:
+            raise ValueError("Interrupt ID mismatch")
+        snapshot["pending_tool_call"]["status"] = status
+        session.state_snapshot = snapshot