diff --git a/scripts/check-installed-state.sh b/scripts/check-installed-state.sh
index 99407d99..8bde0581 100755
--- a/scripts/check-installed-state.sh
+++ b/scripts/check-installed-state.sh
@@ -3,6 +3,7 @@ set -Eeuo pipefail
 
 state_file=${CI_FLEET_INSTALL_STATE_FILE:-/var/lib/ci-fleet/install-state.json}
 installer=${CI_FLEET_INSTALLER:-/opt/ci-fleet/manager/current/scripts/install-worker-controller.sh}
+remote_reconciler=${CI_FLEET_REMOTE_RECONCILER:-/opt/ci-fleet/manager/current/scripts/remote-reconcile.sh}
 
 [[ -f "$state_file" ]] || { echo "ERROR: installed desired-state record is missing: $state_file" >&2; exit 2; }
 expected_owner=0
@@ -34,6 +35,11 @@ controller=${values[0]}
 config_repository=${values[1]}
 config_ref=${values[2]}
 
+if [[ "$config_repository" =~ ^[A-Za-z0-9_.-]+/[A-Za-z0-9_.-]+$ ]]; then
+  [[ -x "$remote_reconciler" ]] || { echo "ERROR: remote reconciler is unavailable: $remote_reconciler" >&2; exit 2; }
+  CI_FLEET_REMOTE_STATE_FILE="$state_file" exec "$remote_reconciler" --check-only --desired-ref "$config_ref"
+fi
+
 exec "$installer" --check \
   --config-repo "$config_repository" \
   --ref "$config_ref" \
diff --git a/scripts/remote-reconcile.sh b/scripts/remote-reconcile.sh
index 2d331cbc..e615d185 100755
--- a/scripts/remote-reconcile.sh
+++ b/scripts/remote-reconcile.sh
@@ -6,7 +6,7 @@
 # validates the configuration, checks for drift, and reconciles if needed.
 #
 # Usage:
-#   remote-reconcile.sh [--check-only] [--no-op]
+#   remote-reconcile.sh [--check-only] [--desired-ref SHA] [--no-op]
 set -Eeuo pipefail
 
 script_dir=$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)
@@ -26,17 +26,19 @@ trap cleanup_temp EXIT
 
 mode=reconcile  # reconcile or check-only
 no_op=false
+desired_ref=
 max_attempts=${CI_FLEET_RECONCILE_MAX_ATTEMPTS:-3}
 
 usage() {
   cat >&2 <<'EOF'
 usage:
-  remote-reconcile.sh [--check-only] [--no-op]
+  remote-reconcile.sh [--check-only] [--desired-ref SHA] [--no-op]
 
   Fetches the desired-state repository at the current default-branch HEAD,
   validates it, and reconciles the controller if a newer commit is available.
 
   --check-only  Validate and report without reconciling.
+  --desired-ref Check this exact commit instead of remote HEAD (check-only only).
   --no-op       Log what would be done without side effects.
 EOF
 }
@@ -44,12 +46,15 @@ EOF
 while (($#)); do
   case "$1" in
     --check-only) mode=check-only ;;
+    --desired-ref) shift; (($#)) || { echo 'ERROR: --desired-ref requires a commit' >&2; exit 2; }; desired_ref=$1 ;;
     --no-op) no_op=true ;;
     -h|--help) usage; exit 0 ;;
     *) echo "ERROR: unknown argument: $1" >&2; usage; exit 2 ;;
   esac
   shift
 done
+[[ -z "$desired_ref" || "$mode" == check-only ]] || { echo 'ERROR: --desired-ref requires --check-only' >&2; exit 2; }
+[[ -z "$desired_ref" || "$desired_ref" =~ ^[0-9a-f]{40}$ ]] || { echo 'ERROR: --desired-ref must be a full lowercase commit SHA' >&2; exit 2; }
 
 note() { printf 'RECONCILE %s\n' "$*"; }
 die() {
@@ -135,16 +140,16 @@ generate_token() {
 # --- Remote fetch ---
 
 fetch_remote_config() {
-  local repo=$1 token=$2
+  local repo=$1 token=$2 ref=${3:-HEAD}
   local fetch_dir=$temp_dir/config-repo
   mkdir -p "$fetch_dir"
   git init -q "$fetch_dir"
   # Use auth_url with embedded token for authenticated fetch
   local auth_url="https://x-access-token:${token}@github.com/${repo}.git"
-  GIT_TERMINAL_PROMPT=0 git -C "$fetch_dir" fetch -q --filter=blob:none --depth=1 origin HEAD 2>"$temp_dir/fetch_err" || {
+  GIT_TERMINAL_PROMPT=0 git -C "$fetch_dir" fetch -q --filter=blob:none --depth=1 origin "$ref" 2>"$temp_dir/fetch_err" || {
     local err
     # Retry with auth_url if plain fetch failed (private repo needs auth)
-    GIT_TERMINAL_PROMPT=0 git -C "$fetch_dir" fetch -q --filter=blob:none --depth=1 "$auth_url" HEAD 2>"$temp_dir/fetch_err" || {
+    GIT_TERMINAL_PROMPT=0 git -C "$fetch_dir" fetch -q --filter=blob:none --depth=1 "$auth_url" "$ref" 2>"$temp_dir/fetch_err" || {
       local err
       err=$(<"$temp_dir/fetch_err")
       [[ -n "$err" ]] || err="fetch failed"
@@ -349,7 +354,7 @@ while ((attempt < max_attempts)); do
 
   # Fetch remote config
   note "FETCHING_CONFIG repo=${installed_config_repo}"
-  desired_commit=$(fetch_remote_config "$installed_config_repo" "$token") || {
+  desired_commit=$(fetch_remote_config "$installed_config_repo" "$token" "${desired_ref:-HEAD}") || {
     note "FETCH_FAILED attempt=${attempt}"
     ((attempt < max_attempts)) && { sleep 5; continue; }
     die "fetch exhausted after ${max_attempts} attempts"
diff --git a/scripts/test-install-worker-controller.sh b/scripts/test-install-worker-controller.sh
index e9a87061..4e34c07f 100755
--- a/scripts/test-install-worker-controller.sh
+++ b/scripts/test-install-worker-controller.sh
@@ -316,6 +316,24 @@ expect_failure 'install state must be owned by root with mode 0600' env CI_FLEET
 unset FAKE_WRONG_INSTALL_STATE_OWNER
 expect_success env CI_FLEET_INSTALL_STATE_FILE="$install_state" CI_FLEET_INSTALLER="$installer" "$repo_root/scripts/check-installed-state.sh" >/dev/null
 
+remote_reconciler=$tmp/fake-remote-reconciler
+remote_reconciler_log=$tmp/fake-remote-reconciler.log
+# shellcheck disable=SC2016
+printf '#!/usr/bin/env bash\nprintf "%%s\\n%%s\\n" "$*" "$CI_FLEET_REMOTE_STATE_FILE" >"$REMOTE_RECONCILER_LOG"\n' >"$remote_reconciler"
+chmod 0755 "$remote_reconciler"
+python3 - "$install_state" <<'PY'
+import json, sys
+path = sys.argv[1]
+state = json.load(open(path))
+state["config_repository"] = "example/private-config"
+with open(path, "w") as output:
+    json.dump(state, output)
+PY
+expect_success env CI_FLEET_INSTALL_STATE_FILE="$install_state" CI_FLEET_INSTALLER="$installer" CI_FLEET_REMOTE_RECONCILER="$remote_reconciler" REMOTE_RECONCILER_LOG="$remote_reconciler_log" "$repo_root/scripts/check-installed-state.sh"
+mapfile -t remote_call <"$remote_reconciler_log"
+[[ ${remote_call[0]} == "--check-only --desired-ref $ref_one" && ${remote_call[1]} == "$install_state" ]] || fail 'remote drift check did not delegate the exact installed state to authenticated reconciliation'
+expect_success "$installer" --install "${base_args[@]}" --ref "$ref_one" >/dev/null
+
 export FAKE_DISABLED_TIMER=ci-fleet-cleanup.timer
 expect_failure 'DRIFT maintenance_timers' "$installer" --check "${base_args[@]}" --ref "$ref_one"
 unset FAKE_DISABLED_TIMER
diff --git a/scripts/test_remote_reconcile.py b/scripts/test_remote_reconcile.py
index 3cffde10..2c4851c3 100644
--- a/scripts/test_remote_reconcile.py
+++ b/scripts/test_remote_reconcile.py
@@ -197,6 +197,20 @@ def test_help_exits_0(self):
         self.assertEqual(result.returncode, 0)
         self.assertIn("usage", result.stdout + result.stderr)
 
+    def test_desired_ref_is_full_sha_and_check_only(self):
+        invalid = subprocess.run(
+            [str(RECONCILE_SCRIPT), "--check-only", "--desired-ref", "main"],
+            capture_output=True, text=True, env=self.env,
+        )
+        mutating = subprocess.run(
+            [str(RECONCILE_SCRIPT), "--desired-ref", "a" * 40],
+            capture_output=True, text=True, env=self.env,
+        )
+        self.assertEqual(invalid.returncode, 2)
+        self.assertIn("full lowercase commit SHA", invalid.stderr)
+        self.assertEqual(mutating.returncode, 2)
+        self.assertIn("requires --check-only", mutating.stderr)
+
     def test_reconcile_state_saved_on_failure(self):
         """State file is saved even when reconciliation fails."""
         result = subprocess.run(