docs: README positioning note — management-plane simulator, state materialized not computed (v0.20.1)

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

CHANGELOG.md

@@ -6,6 +6,13 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html)
 (pre-1.0: minor bumps may include breaking changes to the sim's behavior).
 
+## [0.20.1] - 2026-07-07
+
+### Docs
+- README: added a "What it simulates (and what it doesn't)" positioning note —
+  aci-sim is a management-plane simulator; protocol operational state is
+  materialized from configuration, not computed by running protocols.
+
 ## [0.20.0] - 2026-07-07
 
 ### Changed

README.md

@@ -21,6 +21,17 @@ entire fabric — nodes, tenants, VRFs/BDs/EPGs, contracts, L3Outs, faults,
 endpoints, and the whole NDO schema tree — is generated deterministically
 from a single `topology.yaml`.
 
+> **What it simulates (and what it doesn't):** aci-sim simulates the
+> **management plane** — the REST API and the operational state a converged
+> fabric would report. It does **not** run routing protocols: OSPF/BGP/LLDP
+> state (`operSt=full`, `established`, adjacencies, /31 link addressing) is
+> **materialized from configuration, not computed** — push the config and the
+> matching operational MOs appear, exactly as your automation would read them
+> off a healthy fabric. That's why the cisco.aci/cisco.mso collections and
+> API clients work unmodified, and why the whole thing runs on a Raspberry
+> Pi 4 — and also why it can't test convergence, failover timing, or actual
+> traffic forwarding.
+
 ![aci-sim topology](docs/images/topology.png)
 
 *A 2-site, 15-node fabric rendered by `aci-sim graph` — spines (blue),

pyproject.toml

@@ -1,6 +1,6 @@
 [project]
 name = "aci-sim"
-version = "0.20.0"
+version = "0.20.1"
 description = "Faithful REST simulator of a 2-site Cisco ACI fabric (per-site APIC + ND/NDO)"
 readme = "README.md"
 license = "PolyForm-Noncommercial-1.0.0"