diff --git a/.github/workflows/agent-authorship-label.yml b/.github/workflows/agent-authorship-label.yml
index d9c6112..844ce66 100644
--- a/.github/workflows/agent-authorship-label.yml
+++ b/.github/workflows/agent-authorship-label.yml
@@ -16,10 +16,10 @@ on:
         type: boolean
         default: false
       runner_label:
-        description: "Runner label used for the label job"
+        description: "Runner label used for the label job (owned private-CI ARC only)"
         required: false
         type: string
-        default: ubuntu-latest
+        default: evalops-private-ci
       helper_ref:
         description: "evalops/.github ref used to checkout helper scripts"
         required: false
diff --git a/.github/workflows/codex-rails-check.yml b/.github/workflows/codex-rails-check.yml
index 089ae87..e062cbd 100644
--- a/.github/workflows/codex-rails-check.yml
+++ b/.github/workflows/codex-rails-check.yml
@@ -27,17 +27,17 @@ on:
         type: boolean
         default: false
       runner_label:
-        description: "Runner label used for the validation job"
+        description: "Runner label used for the validation job (owned private-CI ARC only)"
         required: false
         type: string
-        default: ubuntu-latest
+        default: evalops-private-ci
 
 permissions:
   contents: read
 
 jobs:
   validate:
-    runs-on: ${{ inputs.runner_label || 'ubuntu-latest' }}
+    runs-on: ${{ inputs.runner_label || 'evalops-private-ci' }}
     timeout-minutes: 10
     steps:
       - uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5
diff --git a/.github/workflows/review-thread-guard.yml b/.github/workflows/review-thread-guard.yml
index fcef288..ddd8156 100644
--- a/.github/workflows/review-thread-guard.yml
+++ b/.github/workflows/review-thread-guard.yml
@@ -20,10 +20,10 @@ on:
         default: "high"
         type: string
       runner_label:
-        description: "Runner label used for the validation job"
+        description: "Runner label used for the validation job (owned private-CI ARC only)"
         required: false
         type: string
-        default: ubuntu-latest
+        default: evalops-private-ci
       guard_ref:
         description: "evalops/.github ref to checkout for guard scripts"
         required: false
@@ -68,7 +68,7 @@ permissions:
 
 jobs:
   unresolved-review-threads:
-    runs-on: ${{ inputs.runner_label || 'ubuntu-latest' }}
+    runs-on: ${{ inputs.runner_label || 'evalops-private-ci' }}
     timeout-minutes: 5
     steps:
       - uses: actions/checkout@v5