Demo: deterministic budget / resource-limit enforcement

EVE enforces deterministic budget/resource limits: a permitted call executes until the configured limit is reached, then further calls are blocked. This demo sets a call budget of 3, runs 5 attempts, and shows the tool executing exactly 3 times.

Synthetic recording tool. No production credentials.

Readiness

• Deterministic budget/resource controls: PILOT_READY (part of the pilot-validated agent governance surface).
• Python only (embedded(service) mode).

Setup

# demo_budget_enforcement.py — synthetic fixtures only
from core.eve_sdk import EVE

IDENT = {"tenant_id": "acme", "principal_id": "agent-1", "session_id": "sess-1"}
searches = []  # recording target

def web_search(**kwargs):
    searches.append(kwargs)
    return {"results": []}

# Budget: at most 3 governed calls of this tool per session.
eve = EVE(policy="lending_v1", mode="embedded",
          budgets={"web_search": {"max_calls": 3}})

Code

verdicts = []
for i in range(5):
    r = eve.govern_tool_call(
        tool="web_search",
        arguments={"q": f"query-{i}"},
        context=IDENT,
    )
    verdicts.append(r.action)
    if r.allowed:
        web_search(q=f"query-{i}")

print("verdicts:", verdicts)
print("executions:", len(searches))
assert len(searches) == 3, "tool must execute exactly up to the budget"
assert verdicts[:3] == ["ALLOW", "ALLOW", "ALLOW"]
assert all(v == "BLOCK" for v in verdicts[3:]), "over-budget calls must be blocked"

Expected decision

Expected evidence

Over-budget decisions carry a budget finding:

{"action": "BLOCK",
 "budget_finding": {"limit": 3, "consumed": 3, "exceeded": true},
 "reason_codes": ["...budget_exceeded..."],
 "certificate": {"signature": "ed25519-...", "canon": "jcs-1"}}

Verification command

from core.eve_sdk import verify_evidence
last = eve.govern_tool_call(tool="web_search", arguments={"q": "extra"}, context=IDENT)
assert not last.allowed
assert verify_evidence("decision", last.certificate, expected_tenant="acme")["valid"]
print("verify: True")

Zero-side-effect assertion

len(searches) == 3 after 5 attempts: the tool ran exactly to the configured budget and never once beyond it. Over-budget attempts left the recording list unchanged.

Cleanup

searches.clear()

No external state created.

Limitations

• Budget counters are deterministic; durable cross-instance budgets require a shared store. In the pilot, budget state is in-process.
• PILOT_READY, not production. Enforcement depends on your code honoring the verdict (or a gateway/sidecar).