diff --git a/quest/m0/test-flakes-2/README.md b/quest/m0/test-flakes-2/README.md
index b60c298e85..a293a8c68e 100644
--- a/quest/m0/test-flakes-2/README.md
+++ b/quest/m0/test-flakes-2/README.md
@@ -249,9 +249,14 @@ cancelled one missed an appended group during
 [moq-dev/moq#8363](https://github.com/moq-dev/moq/pull/8363)'s loaded
 `just check`. It is quarantined with `t.Skip` until its child fixes it.
 
+Added 2026-11-09 (maintainer, /quest-complete): interop's `finish` cases with
+a cpp or rust publisher, which failed under a loaded host and passed on rerun.
+They are quarantined until their child fixes them.
+
 Public API: none. Wire: none.
 
 ## Required
 
 - [js/net's lite-07 datagram queue test holds up under load](/quest/m0/test-flakes-2/datagram-queues.md) - the test waits for the first track's queue instead of asserting at once, and its `test.skip` is removed
+- [Interop's cpp and rust finish cases hold up under load](/quest/m0/test-flakes-2/interop-finish.md) - the publishers' finish cells pass under load, and their quarantine is removed
 - [The Go wrapper's cancelled-RecvGroup test holds up under load](/quest/m0/test-flakes-2/go-recv-cancel.md) - a `RecvGroup` after a cancelled one is woken by the next group, and its `t.Skip` is removed
diff --git a/quest/m0/test-flakes-2/interop-finish.md b/quest/m0/test-flakes-2/interop-finish.md
new file mode 100644
index 0000000000..fda97fc79a
--- /dev/null
+++ b/quest/m0/test-flakes-2/interop-finish.md
@@ -0,0 +1,29 @@
+# [S] Interop's cpp and rust finish cases hold up under load
+
+## Goal
+
+`just test interop --finish --all` passes its `finish cpp -> *` and
+`finish rust -> *` cells on a loaded host, and their quarantine in
+`test/interop/interop.sh`'s `run_finishes` is removed.
+
+## Plan
+
+Planned 2026-11-09 (maintainer, /quest-complete), under the repository's
+flaky-test rule. Two agents' local `just test interop --all` runs, both under a
+host load average above 30, failed once each and passed on rerun. No logs were
+kept.
+
+- All nine `finish cpp -> *` cells failed together, while iterating
+  [moq-dev/moq#8358](https://github.com/moq-dev/moq/pull/8358).
+- The `finish rust -> *` cells failed, while iterating
+  [moq-dev/moq#8220](https://github.com/moq-dev/moq/pull/8220): the Rust
+  publisher never printed `finish acknowledged`, though every reader ended
+  clean.
+
+Reproduce it first, under load as the epic describes, with the interop logs
+kept. Suspected, not confirmed: the publisher's wait for the finish
+acknowledgement (the FIFO the runner writes after every reader ends). That
+cpp's cells all failed together also points at its publisher rather than any
+reader. Fix the cause, never with a longer limit, then remove the quarantine.
+
+Public API: none. Wire: none.
diff --git a/test/interop/interop.sh b/test/interop/interop.sh
index 81dd928a6e..ad911f4db7 100755
--- a/test/interop/interop.sh
+++ b/test/interop/interop.sh
@@ -1812,6 +1812,15 @@ run_finishes() {
     fi
     for pub in "${PUB_LIST[@]}"; do
         name="finish-$pub"
+        # Quarantined: quest/m0/test-flakes-2/interop-finish.md. The cpp and rust publishers'
+        # finish cases failed under a loaded host and passed on rerun.
+        if [[ "$pub" == cpp || "$pub" == rust ]]; then
+            for sub in "${SUB_LIST[@]}"; do
+                echo "  SKIP  finish $pub -> $sub (quarantined)"
+                record skip case=finish publisher="$pub" subscriber="$sub" detail="quarantined: quest/m0/test-flakes-2/interop-finish.md"
+            done
+            continue
+        fi
         # The fixture and its .health sibling share a parent, so one prefix grant covers both:
         # moq-transport's AUTH extension carries prefixes alone.
         broadcast="$name-$$-$RANDOM/fixture.hang"