diff --git a/.codex/config.toml b/.codex/config.toml
index 2b0f1f39..410fb6ac 100644
--- a/.codex/config.toml
+++ b/.codex/config.toml
@@ -27,7 +27,10 @@ notify = [
   "-sound", "default",
 ]
 
-# Prefer AGENTS.md and project-local .codex/AGENTS.md for instructions.
+# Persistent instructions are appended to every prompt (additive, unlike
+# model_instructions_file which replaces AGENTS.md).
+persistent_instructions = "Follow project AGENTS.md guidelines. Use available MCP servers when they can help."
+
 # model_instructions_file replaces built-in instructions instead of AGENTS.md,
 # so leave it unset unless you intentionally want a single override file.
 # model_instructions_file = "/absolute/path/to/instructions.md"
diff --git a/scripts/codex/check-codex-global-state.sh b/scripts/codex/check-codex-global-state.sh
index f0c2242c..147e9fb3 100755
--- a/scripts/codex/check-codex-global-state.sh
+++ b/scripts/codex/check-codex-global-state.sh
@@ -89,7 +89,13 @@ fi
 if [[ -f "$CONFIG_FILE" ]]; then
   check_config_pattern '^multi_agent\s*=\s*true' "multi_agent is enabled"
   check_config_absent '^\s*collab\s*=' "deprecated collab flag is absent"
-  check_config_pattern '^persistent_instructions\s*=' "persistent_instructions is configured"
+  # persistent_instructions is recommended but optional; warn instead of fail
+  # so users who rely on AGENTS.md alone are not blocked (#967).
+  if rg -n '^[[:space:]]*persistent_instructions\s*=' "$CONFIG_FILE" >/dev/null 2>&1; then
+    ok "persistent_instructions is configured"
+  else
+    warn "persistent_instructions is not set (recommended but optional)"
+  fi
   check_config_pattern '^\[profiles\.strict\]' "profiles.strict exists"
   check_config_pattern '^\[profiles\.yolo\]' "profiles.yolo exists"