Fix five Wave-1 pure-layer FX/park review findings: resume-point stall, stale doc comments, implicit mode read, keying reset

tests/test_applied_state.cpp

@@ -102,10 +102,15 @@ static void testEditsTheApplyDidNotDriveAreNotDifferences() {
     ViewModeModel vm = parkedPair();
     const AppliedState before = appliedState(vm);
 
-    vm.membership().tag("{OTHER}", kDesignModeId);
+    // {T1} is already parked (tagged Design, active mode Arrange); retagging it
+    // INTO the active mode changes what the next apply must drive (release it)
+    // while its park record — and so the fingerprint — is untouched. Pinning
+    // this on a GUID actually in the parked set is the point: an unrelated GUID
+    // would pass even if membership were folded into the fingerprint by mistake.
+    vm.membership().tag("{T1}", kArrangeModeId);
     CHECK(appliedState(vm) == before);
 
-    vm.membership().setShowBoth("{OTHER}", true);
+    vm.membership().setShowBoth("{T1}", true);
     CHECK(appliedState(vm) == before);
 
     vm.lanes().setManaged("{T1}", "reasampler:design", kDesignModeId);