Session State Multiple Users

1"""
2Session State Multiple Users
3=============================
4
5This example demonstrates how to maintain state for each user in a multi-user environment.
6"""
7
8import json
9
10from kern.agent import Agent
11from kern.db.sqlite import SqliteDb
12from kern.models.openai import OpenAIResponses
13from kern.run import RunContext
14
15# In-memory database to store user shopping lists
16# Organized by user ID and session ID
17shopping_list = {}
18
19
20def add_item(run_context: RunContext, item: str) -> str:
21    """Add an item to the current user's shopping list."""
22
23    current_user_id = run_context.session_state["current_user_id"]
24    current_session_id = run_context.session_state["current_session_id"]
25    shopping_list.setdefault(current_user_id, {}).setdefault(
26        current_session_id, []
27    ).append(item)
28
29    return f"Item {item} added to the shopping list"
30
31
32def remove_item(run_context: RunContext, item: str) -> str:
33    """Remove an item from the current user's shopping list."""
34
35    current_user_id = run_context.session_state["current_user_id"]
36    current_session_id = run_context.session_state["current_session_id"]
37
38    if (
39        current_user_id not in shopping_list
40        or current_session_id not in shopping_list[current_user_id]
41    ):
42        return f"No shopping list found for user {current_user_id} and session {current_session_id}"
43
44    if item not in shopping_list[current_user_id][current_session_id]:
45        return f"Item '{item}' not found in the shopping list for user {current_user_id} and session {current_session_id}"
46
47    shopping_list[current_user_id][current_session_id].remove(item)
48    return f"Item {item} removed from the shopping list"
49
50
51def get_shopping_list(run_context: RunContext) -> str:
52    """Get the current user's shopping list."""
53
54    if run_context.session_state is None:
55        run_context.session_state = {}
56
57    current_user_id = run_context.session_state["current_user_id"]
58    current_session_id = run_context.session_state["current_session_id"]
59    return f"Shopping list for user {current_user_id} and session {current_session_id}: \n{json.dumps(shopping_list[current_user_id][current_session_id], indent=2)}"
60
61
62# Create an Agent that maintains state
63# ---------------------------------------------------------------------------
64# Create Agent
65# ---------------------------------------------------------------------------
66agent = Agent(
67    model=OpenAIResponses(id="gpt-5-mini"),
68    db=SqliteDb(db_file="tmp/data.db"),
69    tools=[add_item, remove_item, get_shopping_list],
70    # Reference the in-memory database
71    instructions=[
72        "Current User ID: {current_user_id}",
73        "Current Session ID: {current_session_id}",
74    ],
75    markdown=True,
76)
77
78user_id_1 = "john_doe"
79user_id_2 = "mark_smith"
80user_id_3 = "carmen_sandiago"
81
82# ---------------------------------------------------------------------------
83# Run Agent
84# ---------------------------------------------------------------------------
85if __name__ == "__main__":
86    # Example usage
87    agent.print_response(
88        "Add milk, eggs, and bread to the shopping list",
89        stream=True,
90        user_id=user_id_1,
91        session_id="user_1_session_1",
92    )
93    agent.print_response(
94        "Add tacos to the shopping list",
95        stream=True,
96        user_id=user_id_2,
97        session_id="user_2_session_1",
98    )
99    agent.print_response(
100        "Add apples and grapes to the shopping list",
101        stream=True,
102        user_id=user_id_3,
103        session_id="user_3_session_1",
104    )
105    agent.print_response(
106        "Remove milk from the shopping list",
107        stream=True,
108        user_id=user_id_1,
109        session_id="user_1_session_1",
110    )
111    agent.print_response(
112        "Add minced beef to the shopping list",
113        stream=True,
114        user_id=user_id_2,
115        session_id="user_2_session_1",
116    )
117
118    # What is on Mark Smith's shopping list?
119    agent.print_response(
120        "What is on Mark Smith's shopping list?",
121        stream=True,
122        user_id=user_id_2,
123        session_id="user_2_session_1",
124    )
125
126    # New session, so new shopping list
127    agent.print_response(
128        "Add chicken and soup to my list.",
129        stream=True,
130        user_id=user_id_2,
131        session_id="user_3_session_2",
132    )
133
134    print(f"Final shopping lists: \n{json.dumps(shopping_list, indent=2)}")

1# Clone and setup repo
2git clone https://github.com/kern-ai/kern.git
3cd kern/cookbook/02_agents/05_state_and_session
4
5# Create and activate virtual environment
6./scripts/demo_setup.sh
7source .venvs/demo/bin/activate
8
9python session_state_multiple_users.py