diff --git a/.github/workflows/container-policy.yml b/.github/workflows/container-policy.yml
index 28207e3..582dba9 100644
--- a/.github/workflows/container-policy.yml
+++ b/.github/workflows/container-policy.yml
@@ -1,6 +1,15 @@
 # SPDX-License-Identifier: AGPL-3.0-or-later
 name: Container Policy
-on: [push, pull_request]
+on:
+  push:
+    branches: [main, master]
+  pull_request:
+
+# Estate guardrail: scope push to default branches (PR fires once, not
+# push+PR) and cancel superseded runs. Safe — read-only PR check.
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
 
 permissions: read-all
 
diff --git a/.github/workflows/guix-nix-policy.yml b/.github/workflows/guix-nix-policy.yml
index 3a27f56..3f7b334 100644
--- a/.github/workflows/guix-nix-policy.yml
+++ b/.github/workflows/guix-nix-policy.yml
@@ -1,6 +1,15 @@
 # SPDX-License-Identifier: AGPL-3.0-or-later
 name: Guix/Nix Package Policy
-on: [push, pull_request]
+on:
+  push:
+    branches: [main, master]
+  pull_request:
+
+# Estate guardrail: scope push to default branches (PR fires once, not
+# push+PR) and cancel superseded runs. Safe — read-only PR check.
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
 
 permissions: read-all
 
diff --git a/.github/workflows/quality.yml b/.github/workflows/quality.yml
index 68972c5..4898668 100644
--- a/.github/workflows/quality.yml
+++ b/.github/workflows/quality.yml
@@ -1,6 +1,15 @@
 # SPDX-License-Identifier: AGPL-3.0-or-later
 name: Code Quality
-on: [push, pull_request]
+on:
+  push:
+    branches: [main, master]
+  pull_request:
+
+# Estate guardrail: scope push to default branches (PR fires once, not
+# push+PR) and cancel superseded runs. Safe — read-only PR check.
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
 
 permissions: read-all
 
diff --git a/.github/workflows/security-policy.yml b/.github/workflows/security-policy.yml
index be11d4b..2e0044b 100644
--- a/.github/workflows/security-policy.yml
+++ b/.github/workflows/security-policy.yml
@@ -1,6 +1,15 @@
 # SPDX-License-Identifier: AGPL-3.0-or-later
 name: Security Policy
-on: [push, pull_request]
+on:
+  push:
+    branches: [main, master]
+  pull_request:
+
+# Estate guardrail: scope push to default branches (PR fires once, not
+# push+PR) and cancel superseded runs. Safe — read-only PR check.
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
 
 permissions: read-all