Giving Your Digital Employee a Company Credit Card (With Limits)

#python #opensource #finops #devops

Giving Your Digital Employee a Company Credit Card (With Limits)

The engineering behind AI spending limits.

The Core Problem

Here's how the $30K bill plays out:

Day 1:  Agent runs 50 tasks, costs $12. Looks great.
Day 5:  Agent discovers premium model. Uses it for everything. $80/day.
Day 10: Agent runs 200 tasks/day. $400/day.
Day 20: Agent enters a loop. $2,000/day.
Day 30: You check your bill. $30,000.

The Budget Engine: Lazy Auto-Reset

Instead of a midnight cron job (which creates a thundering herd), agent-gov uses lazy evaluation:

async def check_and_reset_budget(agent: dict) -> dict:
    today = date.today().isoformat()
    if agent["last_reset"] == today:
        return agent  # No reset needed
    if agent["paused"]:
        return agent
    return await reset_daily_budget(agent["key_hash"])

Why lazy? An agent that makes no calls doesn't need a reset. The first call of the day triggers a single UPDATE. The thundering herd becomes a gentle trickle.

The Real Cost Problem

Agent says: "Estimated cost: $0.50." Reality: $15.00/call.

agent-gov's tool registry knows the real cost:

async def register_tool(name, cost_per_call, description, workspace_id="default"):
    await db.execute("""
        INSERT INTO tools (name, cost_per_call, description, registered_at, workspace_id)
        VALUES (?, ?, ?, ?, ?)
        ON CONFLICT(name) DO UPDATE SET
            cost_per_call = excluded.cost_per_call
    """, (name, cost_per_call, description, now, workspace_id))

Budget Pools

For teams running multiple agents:

agent-gov pool create production-agents --budget 1000
agent-gov pool member add web-agent --pool production-agents --max-per-agent 200

Now web agent is capped at $200/month even though the pool has $1,000.

The Data Model

Two SQLite tables, two queries per call, sub-millisecond overhead:

CREATE TABLE agents (
    key_hash TEXT PRIMARY KEY,
    name TEXT NOT NULL,
    daily_budget REAL NOT NULL,
    spent_today REAL NOT NULL DEFAULT 0.0,
    calls_today INTEGER NOT NULL DEFAULT 0,
    paused INTEGER NOT NULL DEFAULT 0,
    created_at TEXT NOT NULL,
    last_reset TEXT NOT NULL
);

CREATE TABLE cost_events (
    id INTEGER PRIMARY KEY AUTOINCREMENT,
    agent_hash TEXT NOT NULL,
    agent_name TEXT NOT NULL,
    timestamp TEXT NOT NULL,
    tool_name TEXT NOT NULL,
    cost REAL NOT NULL,
    FOREIGN KEY (agent_hash) REFERENCES agents(key_hash)
);