feat: add scratchpad field to session model and schemas

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

backend/app/models/session.py

@@ -1,7 +1,8 @@
 import uuid
 from datetime import datetime, timezone
 from typing import Optional, Any
-from sqlalchemy import String, DateTime, ForeignKey, Boolean
+from sqlalchemy import String, DateTime, ForeignKey, Boolean, Text
+import sqlalchemy as sa
 from sqlalchemy.orm import Mapped, mapped_column, relationship
 from sqlalchemy.dialects.postgresql import UUID, JSONB
 from app.core.database import Base
@@ -44,6 +45,9 @@ class Session(Base):
     ticket_number: Mapped[Optional[str]] = mapped_column(String(100), nullable=True)
     client_name: Mapped[Optional[str]] = mapped_column(String(255), nullable=True)
     exported: Mapped[bool] = mapped_column(Boolean, default=False)
+    scratchpad: Mapped[Optional[str]] = mapped_column(
+        Text, nullable=True, server_default=sa.text("''")
+    )
 
     # Relationships
     tree: Mapped["Tree"] = relationship("Tree", back_populates="sessions")

backend/app/schemas/session.py

@@ -1,7 +1,7 @@
 from datetime import datetime
 from typing import Optional, Any
 from uuid import UUID
-from pydantic import BaseModel, Field
+from pydantic import BaseModel, Field, validator
 
 
 class DecisionRecord(BaseModel):
@@ -27,6 +27,7 @@ class SessionUpdate(BaseModel):
     custom_steps: Optional[list[dict[str, Any]]] = None
     ticket_number: Optional[str] = Field(None, max_length=100)
     client_name: Optional[str] = Field(None, max_length=255)
+    scratchpad: Optional[str] = None
 
 
 class SessionResponse(BaseModel):
@@ -42,6 +43,11 @@ class SessionResponse(BaseModel):
     ticket_number: Optional[str] = None
     client_name: Optional[str] = None
     exported: bool
+    scratchpad: str = ""
+
+    @validator('scratchpad', pre=True, always=True)
+    def normalize_scratchpad(cls, v):
+        return v or ""
 
     class Config:
         from_attributes = True
@@ -51,3 +57,7 @@ class SessionExport(BaseModel):
     format: str = Field(default="markdown", pattern="^(text|markdown|html)$")
     include_timestamps: bool = True
     include_tree_info: bool = True
+
+
+class ScratchpadUpdate(BaseModel):
+    scratchpad: str

backend/tests/test_sessions.py

@@ -315,3 +315,51 @@ class TestSessions:
         data = response.json()
         assert len(data) >= 1
         assert all(s["completed_at"] is None for s in data)
+
+    @pytest.mark.asyncio
+    async def test_create_session_has_scratchpad(
+        self, client: AsyncClient, auth_headers: dict, test_tree: dict
+    ):
+        """Test that new sessions include scratchpad field."""
+        session_data = {
+            "tree_id": test_tree["id"],
+        }
+
+        response = await client.post(
+            "/api/v1/sessions",
+            json=session_data,
+            headers=auth_headers
+        )
+
+        assert response.status_code == 201
+        data = response.json()
+        assert "scratchpad" in data
+        assert data["scratchpad"] == ""
+
+    @pytest.mark.asyncio
+    async def test_update_scratchpad_via_put(
+        self, client: AsyncClient, auth_headers: dict, test_tree: dict
+    ):
+        """Test updating scratchpad through the existing PUT endpoint."""
+        # Create session
+        create_response = await client.post(
+            "/api/v1/sessions",
+            json={"tree_id": test_tree["id"]},
+            headers=auth_headers
+        )
+        session_id = create_response.json()["id"]
+
+        # Update scratchpad via PUT
+        update_data = {
+            "scratchpad": "- Server IP: 192.168.1.50\n- Error: 0x80070005"
+        }
+
+        response = await client.put(
+            f"/api/v1/sessions/{session_id}",
+            json=update_data,
+            headers=auth_headers
+        )
+
+        assert response.status_code == 200
+        data = response.json()
+        assert data["scratchpad"] == update_data["scratchpad"]