Complete networking integration gate (#58)

docs/network-manager.md

@@ -113,6 +113,26 @@ canceled login leaves no simulator installed. Passwords, login tokens, MFA
 hashes, session identifiers, seed capabilities, and estate access tokens are
 excluded from `Debug` output and diagnostic messages.
 
+## Statistics and milestone gate
+
+`SimulatorSimStats` is the native thread-safe counterpart of the reference
+`Simulator.SimStats`. Atomic counters track received/sent packets and bytes,
+resends, drops, pings, pongs, lag, and bandwidth samples. Server `SimStats`
+blocks update the 25 defined simulator measurements with the reference ID and
+rounding rules; unknown IDs are ignored. Debug snapshots contain aggregate
+counters only—never packet bytes, endpoints, capability URLs, or credentials.
+
+The offline fake-grid gate composes the completed layers rather than replacing
+their focused tests. It authenticates through injected LLSD HTTP, establishes a
+real loopback UDP circuit, discovers seed capabilities, consumes an
+`EventQueueGet` message that enables a second region, downloads a capability
+asset, promotes that region, and completes the logout handshake. It then proves
+CAPS polling was canceled, download and network workers were joined, sockets
+were closed, state was cleared, and diagnostic formatting contains none of the
+fixture tokens. `tools/check_milestone_08.py` also audits owned source files for
+failure-only bodies and verifies the explicit queue, payload, event, retry, and
+concurrency policy markers remain present.
+
 The deterministic tests use loopback fake simulators and require no live grid:
 
 ```sh