diff --git a/fleetd/src/main/java/dev/ltms/fleet/member/CompositePeerLauncher.java b/fleetd/src/main/java/dev/ltms/fleet/member/CompositePeerLauncher.java
index 1469b30..465a6fe 100644
--- a/fleetd/src/main/java/dev/ltms/fleet/member/CompositePeerLauncher.java
+++ b/fleetd/src/main/java/dev/ltms/fleet/member/CompositePeerLauncher.java
@@ -44,9 +44,9 @@ import java.util.stream.Collectors;
  *       the single adapter that declares it. Profiles partition cleanly across adapters: the
  *       constructor rejects a name claimed by two.</li>
  *   <li><strong>By pane id</strong> — {@link #stop} routes to the adapter that spawned that pane
- *       (recorded at spawn time). A pane the composite never spawned (only real for a caller that
- *       hand-rolls an id) falls back to the first delegate; teardown is pane-id addressed and
- *       tab cleanup is single-occupant guarded, so it is safe either way.</li>
+ *       (recorded at spawn time). A pane the composite never spawned can use the single delegate
+ *       in a one-daemon fleet. With more than one delegate, its owner is unknown, so stop refuses
+ *       the ambiguous id rather than closing a pane on an arbitrary herdr daemon.</li>
  *   <li><strong>Fleet-wide</strong> — {@link #reapOrphanWorkers} and {@link #capabilities} fan out
  *       and combine. {@link #list} is deduplicated by pane id because every herdr-backed delegate
  *       shares one herdr connection and so reports the same global agent set.</li>
@@ -437,7 +437,11 @@ public final class CompositePeerLauncher implements PeerLauncher {
     public void stop(String id) {
         HerdrPeerLauncher d = spawnedBy.remove(id);
         if (d == null) {
-            log.debug("stop({}) — no recorded owner, routing to the first adapter (pane-addressed)", id);
+            if (delegates.size() != 1) {
+                throw new IllegalArgumentException("ambiguous paneId '" + id
+                        + "': no owning herdr daemon was recorded");
+            }
+            log.debug("stop({}) — no recorded owner in a single-daemon fleet", id);
             d = delegates.getFirst();
         }
         d.stop(id);
diff --git a/fleetd/src/test/java/dev/ltms/fleet/member/CompositePeerLauncherTest.java b/fleetd/src/test/java/dev/ltms/fleet/member/CompositePeerLauncherTest.java
index 48ed960..060fc28 100644
--- a/fleetd/src/test/java/dev/ltms/fleet/member/CompositePeerLauncherTest.java
+++ b/fleetd/src/test/java/dev/ltms/fleet/member/CompositePeerLauncherTest.java
@@ -248,6 +248,54 @@ class CompositePeerLauncherTest {
                 "stop routes to the spawning adapter and closes exactly that worker's pane");
     }
 
+    @Test
+    void stopKeepsSameHerdrPaneIdSeparateByOwningAdapter() {
+        // Separate herdr daemons can both issue w9:pRoot_1. The opaque handles identify their
+        // spawning adapters, so each stop reaches only its recorded owner.
+        FakeHerdr first = new FakeHerdr();
+        FakeHerdr second = new FakeHerdr();
+        PeerLauncher composite = new CompositePeerLauncher(
+                List.of(claudeAdapter(first), opencodeAdapter(second)), "claude");
+
+        PeerHandle claude = composite.spawn(new SpawnRequest("claude", null, null));
+        PeerHandle opencode = composite.spawn(new SpawnRequest("gemini", null, null));
+
+        assertNotEquals(claude.id(), opencode.id(), "each public paneId keeps its adapter owner");
+        composite.stop(claude.id());
+        assertTrue(first.calls.stream().anyMatch(c -> c.method().equals("pane.close")
+                        && "w9:pRoot_1".equals(((Map<?, ?>) c.params()).get("pane_id"))),
+                "the first daemon closes its own pane");
+        assertFalse(second.called("pane.close"), "the matching pane on the second daemon stays live");
+
+        composite.stop(opencode.id());
+        assertTrue(second.calls.stream().anyMatch(c -> c.method().equals("pane.close")
+                        && "w9:pRoot_1".equals(((Map<?, ?>) c.params()).get("pane_id"))),
+                "the second daemon then closes its own pane");
+    }
+
+    @Test
+    void stopAllowsALegacyBarePaneIdWithOneDaemon() {
+        FakeHerdr herdr = new FakeHerdr();
+        PeerLauncher composite = new CompositePeerLauncher(List.of(claudeAdapter(herdr)), "claude");
+
+        composite.stop("w9:pRoot_1");
+
+        assertTrue(herdr.calls.stream().anyMatch(c -> c.method().equals("pane.close")
+                        && "w9:pRoot_1".equals(((Map<?, ?>) c.params()).get("pane_id"))),
+                "one daemon keeps the legacy bare-pane routing behaviour");
+    }
+
+    @Test
+    void stopRejectsAnUnownedPaneIdWhenMultipleDaemonsCouldOwnIt() {
+        PeerLauncher composite = new CompositePeerLauncher(
+                List.of(claudeAdapter(new FakeHerdr()), opencodeAdapter(new FakeHerdr())), "claude");
+
+        IllegalArgumentException error = assertThrows(IllegalArgumentException.class,
+                () -> composite.stop("w1:p1"));
+
+        assertEquals("ambiguous paneId 'w1:p1': no owning herdr daemon was recorded", error.getMessage());
+    }
+
     @Test
     void opencodeContextResetIsANoOpAndWarnsOnlyOnce() {
         FakeHerdr herdr = new FakeHerdr();