Scenario: Silent Tier Escalation
A provider changes its default model, or your agent starts selecting a pricier tier. No code changed; the bill doubles. Nobody notices until the invoice.
What happens without a firewall
The per-token rate rises silently. Volume stays the same; cost doubles.
The bill shows the damage; the code shows nothing.
What happens with sipi.bot
The per-agent daily ceiling caps total spend regardless of tier.
When spend approaches the ceiling, further calls are BLOCKED or FLAGGED — the escalation becomes visible, not silent.
The rule set
Per-agent daily ceiling + category rule for inference.
The decision
{
"decision": "FLAGGED",
"reason": "Daily inference ceiling at 90%",
"rule_id": "rul_daily_04",
"transaction_id": "txn_31c9d8"
}Tier drift surfaces instead of compounding.
FAQ
Can the firewall detect tier changes?
It doesn't need to — the dollar ceiling catches the effect regardless of cause.
What should I do on a flag?
Review the model selection, pin the tier, and re-baseline the ceiling.
Related
Stop the next $12,400 night.
One API call (or MCP tool) in front of every agent transaction — APPROVED, BLOCKED, or FLAGGED, deterministic, ~5 ms, fully logged.
See plans — from $99/mo Try a live check