diff --git a/tests/common/relay.rs b/tests/common/relay.rs
index 6d97e81..540e97d 100644
--- a/tests/common/relay.rs
+++ b/tests/common/relay.rs
@@ -401,12 +401,11 @@ impl TestRelay {
     /// URL in the announcement so the relay under test targets the proxied
     /// connection. Under the permissive test policy the source itself also
     /// treats that URL as an event-directed sync target — it is a distinct
-    /// host:port that happens to front the source — and opens its own REQ
-    /// traffic through the proxy, contending with the relay under test for a
-    /// budget the scenario means to measure alone. The production policy
-    /// rejects non-global event-directed targets, so the source stays
-    /// scenery. Its own hosting, admission, and serving behavior is
-    /// unchanged.
+    /// host:port that happens to front the source — and opens its own sync
+    /// traffic through the proxy, contaminating measurements the scenario
+    /// means to attribute to the relay under test alone. The production
+    /// policy rejects non-global event-directed targets, so the source stays
+    /// scenery. Its own hosting, admission, and serving behavior is unchanged.
     pub async fn start_archive_source_behind_proxy() -> Self {
         Self::start_internal(
             port::reserve_port(),
diff --git a/tests/sync/neg_concurrency.rs b/tests/sync/neg_concurrency.rs
index c91ab15..e565dc5 100644
--- a/tests/sync/neg_concurrency.rs
+++ b/tests/sync/neg_concurrency.rs
@@ -97,7 +97,10 @@ async fn startup_historic_sync_stays_within_relay_neg_concurrency_limit() {
     //    announcement's relays tag lists the proxy (so the syncing relay
     //    targets the proxied connection), not the source itself, so the
     //    source runs in archive-all mode to accept it.
-    let source = TestRelay::start_with_archive_config(true, false).await;
+    // The source applies the production outbound target policy so it does
+    // not itself sync through the proxy: the proxy's NEG measurements belong
+    // to the syncing relay under test.
+    let source = TestRelay::start_archive_source_behind_proxy().await;
     let proxy = NegLimitingProxy::start(source.url(), PROXY_NEG_LIMIT).await;
 
     // 3. One hosted repository: announcement + state event + git data. The