diff --git a/config/backends.conf b/config/backends.conf
index 3202332e7d..05c2a673b8 100644
--- a/config/backends.conf
+++ b/config/backends.conf
@@ -551,6 +551,9 @@ codex_default_sandbox_mode() {
 # Bob renamed its key in 2.x. Fill either missing alias so both versions
 # work, preserving explicit values when contributors supply both names.
 # Call in the parent shell so the relay and CLI inherit the exports.
+# Unlike hub agents, which pin provider "harness" in Bob settings to override
+# stale settings, contributors rely on Bob 2.x's default provider in a fresh
+# container. Existing Bob settings can therefore select a different provider.
 backend_bob_prepare_env() {
   export BOB_API_KEY="${BOB_API_KEY:-${BOBSHELL_API_KEY:-}}"
   export BOBSHELL_API_KEY="${BOBSHELL_API_KEY:-${BOB_API_KEY:-}}"