diff --git a/packages/mosaic/framework/tools/fleet/start-agent-session.sh b/packages/mosaic/framework/tools/fleet/start-agent-session.sh
index 0fced5c1..d2e44eda 100755
--- a/packages/mosaic/framework/tools/fleet/start-agent-session.sh
+++ b/packages/mosaic/framework/tools/fleet/start-agent-session.sh
@@ -272,8 +272,9 @@ _build_runtime_bin_prefix() {
   # records it in ~/.profile. The fleet unit runs `env -i ... bash --noprofile --norc`
   # by design, so ~/.profile is never read and the directory has to be named here.
   # The npm probe below cannot cover this: it reports a package prefix
-  # (~/.npm-global), never a Node runtime directory. It is first so the bootstrapped
-  # runtime wins on a host that has both — that is the one the installer verified.
+  # (~/.npm-global), never a Node runtime directory. It sits ahead of the npm probe so
+  # the bootstrapped runtime wins on a host that has both — that is the one the installer
+  # verified — while an explicit MOSAIC_RUNTIME_BIN still outranks it.
   # Runtime binaries are `#!/usr/bin/env node`, so without this the pane resolves the
   # binary and then dies on `env: 'node': No such file or directory`.
   candidates+=("$PANE_HOME/.mosaic/node/current/bin")