test(v3): account for cold raw proof and instrument retry source opens

src/api/router/snapshot_session_tests.rs

@@ -861,9 +861,15 @@ async fn mst2_durable_http_frame_and_raw_delivery_recheck_after_release() {
             "revocation must suppress the next raw block or END frame"
         );
         assert!(stream.next().await.is_none());
+        // Cold raw first earns an immutable receipt, then opens the separate
+        // authenticated delivery stream. Revocation still suppresses its tail.
         fixture.counts.assert(
-            if raw { 1 } else { 0 },
-            if raw { fixture.raw.len() } else { 0 },
+            if raw { 2 } else { 0 },
+            if raw {
+                fixture.raw.len() + first.len()
+            } else {
+                0
+            },
         );
     }
 }

src/ceres/snapshot/chunks_stream_tests.rs

@@ -104,7 +104,10 @@ async fn exact_source_builder_admits_all_install_workspace_before_open_and_cance
     let projection = build_source_with_resources(
         digest,
         size,
-        || async { Ok(stream(vec![Ok(raw.clone())])) },
+        || async {
+            opens.fetch_add(1, Ordering::SeqCst);
+            Ok(stream(vec![Ok(raw.clone())]))
+        },
         &budget,
         &builders,
     )