FERZ is not SIEM

SIEM is post-hoc; FERZ is ex-ante. A SIEM platform ingests events emitted by source systems after those systems have acted: log lines, API call records, authentication events, system telemetry. The SIEM aggregates these events across the enterprise, applies correlation rules, and surfaces patterns for human investigators. By the time the SIEM sees an action, the action has already executed and produced whatever consequence it produced. FERZ evaluates proposed actions before they execute. The architectural layer is fundamentally different: observability after the fact versus authorization before the fact.

The authority source is correlation, not authorization. A SIEM rule asks whether this pattern of events across event streams matches an alerting condition. The output is a confidence-weighted alert: this pattern looks unusual, this pattern matches a known indicator of compromise, this pattern correlates across systems in a way that warrants human attention. FERZ asks whether a specific proposed action is permitted by policy. The output is a verdict reconstructable from policy, action specification, and governed state. Correlation outputs and authorization verdicts are not points on a spectrum; they answer different questions about different objects.

The evidence artifacts reflect this. A SIEM artifact describes what was observed and what should be investigated: an alert with severity, correlation source, time window, and recommended response. The reader is a human investigator deciding what to look into. A FERZ verdict describes what was permitted: policy version, canonicalized action specification, governed state, evaluator version, and the resulting decision. The reader is a third party reconstructing the decision against the same policy and state. Alerts and authorization verdicts serve different audiences and answer different questions; a more sophisticated correlation engine produces better alerts, not authorization properties.

The structural claim follows. SIEM and FERZ are layered, not substitutable. A mature AI deployment has both: FERZ at the action proposal boundary authorizing individual proposed actions; SIEM ingesting the resulting verdicts, overrides, and operational events alongside the rest of the enterprise security event stream for correlation and incident response. SIEM ingesting FERZ events does not produce AI-action authorization; producing authorization is FERZ's job, and the SIEM treats those authorization events as one signal source among many. The architectural class remains post-hoc event aggregation regardless of which events are being ingested. Calling a SIEM module "AI governance" in the authorization sense is a category error that the impossibility result establishes formally.