diff --git a/.github/workflows/ci-check-testbox.yml b/.github/workflows/ci-check-testbox.yml
index b9f51849..0f101c7a 100644
--- a/.github/workflows/ci-check-testbox.yml
+++ b/.github/workflows/ci-check-testbox.yml
@@ -11,6 +11,10 @@ on:
 permissions:
   contents: read
 
+concurrency:
+  group: clawhub-testbox-${{ github.ref }}
+  cancel-in-progress: true
+
 env:
   BUN_VERSION: "1.3.10"
   FORCE_JAVASCRIPT_ACTIONS_TO_NODE24: "true"
diff --git a/.github/workflows/security-scan-codex.yml b/.github/workflows/security-scan-codex.yml
index b8361015..1193f334 100644
--- a/.github/workflows/security-scan-codex.yml
+++ b/.github/workflows/security-scan-codex.yml
@@ -37,6 +37,7 @@ jobs:
     environment: Production
     strategy:
       fail-fast: false
+      max-parallel: 2
       matrix:
         shard: [0, 1, 2, 3]
     env:
diff --git a/.github/workflows/skill-card-worker.yml b/.github/workflows/skill-card-worker.yml
index 72806534..94163999 100644
--- a/.github/workflows/skill-card-worker.yml
+++ b/.github/workflows/skill-card-worker.yml
@@ -34,6 +34,7 @@ jobs:
     environment: Production
     strategy:
       fail-fast: false
+      max-parallel: 2
       matrix:
         shard: [0, 1, 2, 3]
     env: