diff --git a/actions/setup-cli/install.sh b/actions/setup-cli/install.sh
index 1c6a0c2a9b2..d5488a9a7e2 100755
--- a/actions/setup-cli/install.sh
+++ b/actions/setup-cli/install.sh
@@ -1,6 +1,7 @@
 #!/bin/bash
 set +o histexpand
 
+# Kept in sync with ../../install-gh-aw.sh — edit that file, then copy here.
 
 # Script to download and install gh-aw binary for the current OS and architecture
 # Supports: Linux, macOS (Darwin), FreeBSD, Windows (Git Bash/MSYS/Cygwin)
@@ -54,6 +55,17 @@ YELLOW='\033[1;33m'
 BLUE='\033[0;34m'
 NC='\033[0m' # No Color
 
+# Disable colors when output is captured or color is explicitly disabled.
+# NO_COLOR is the no-color.org standard; NO_COLORS covers tools that use the non-standard variant.
+# Per the spec, NO_COLOR disables colors even when set to an empty string, so we test with +set.
+if [ -n "${CI:-}" ] || [ "${NO_COLOR+set}" = "set" ] || [ "${NO_COLORS+set}" = "set" ] || [ ! -t 1 ] || [ "${TERM:-}" = "dumb" ]; then
+    RED=""
+    GREEN=""
+    YELLOW=""
+    BLUE=""
+    NC=""
+fi
+
 # Function to print colored output
 print_info() {
     echo -e "${BLUE}[INFO]${NC} $1"
diff --git a/actions/setup-cli/install_test.sh b/actions/setup-cli/install_test.sh
index d758fc66b4d..de208ce04d2 100755
--- a/actions/setup-cli/install_test.sh
+++ b/actions/setup-cli/install_test.sh
@@ -125,6 +125,19 @@ test_version_mismatch_detection() {
   fi
 }
 
+# Test 8: Verify no-color gate for CI environments
+test_no_color_gate() {
+  echo ""
+  echo "Test 8: Verify no-color gate"
+
+  if grep -q 'NO_COLOR+set' "$SCRIPT_PATH" && \
+     grep -q 'RED=""' "$SCRIPT_PATH"; then
+    print_result "No-color gate present and spec-compliant" "PASS"
+  else
+    print_result "No-color gate missing or not spec-compliant" "FAIL"
+  fi
+}
+
 # Run all tests
 echo "========================================="
 echo "Testing setup-cli action install.sh"
@@ -137,6 +150,7 @@ test_gh_install
 test_version_pinning
 test_checksum_validation
 test_version_mismatch_detection
+test_no_color_gate
 
 # Summary
 echo ""
diff --git a/install-gh-aw.sh b/install-gh-aw.sh
index 1c6a0c2a9b2..c7a5ed2ffed 100755
--- a/install-gh-aw.sh
+++ b/install-gh-aw.sh
@@ -1,6 +1,7 @@
 #!/bin/bash
 set +o histexpand
 
+# Kept in sync with actions/setup-cli/install.sh — edit this file, then copy to that path.
 
 # Script to download and install gh-aw binary for the current OS and architecture
 # Supports: Linux, macOS (Darwin), FreeBSD, Windows (Git Bash/MSYS/Cygwin)
@@ -54,6 +55,17 @@ YELLOW='\033[1;33m'
 BLUE='\033[0;34m'
 NC='\033[0m' # No Color
 
+# Disable colors when output is captured or color is explicitly disabled.
+# NO_COLOR is the no-color.org standard; NO_COLORS covers tools that use the non-standard variant.
+# Per the spec, NO_COLOR disables colors even when set to an empty string, so we test with +set.
+if [ -n "${CI:-}" ] || [ "${NO_COLOR+set}" = "set" ] || [ "${NO_COLORS+set}" = "set" ] || [ ! -t 1 ] || [ "${TERM:-}" = "dumb" ]; then
+    RED=""
+    GREEN=""
+    YELLOW=""
+    BLUE=""
+    NC=""
+fi
+
 # Function to print colored output
 print_info() {
     echo -e "${BLUE}[INFO]${NC} $1"
diff --git a/scripts/test-install-script.sh b/scripts/test-install-script.sh
index 2998084ed2d..3db7346d869 100755
--- a/scripts/test-install-script.sh
+++ b/scripts/test-install-script.sh
@@ -331,5 +331,16 @@ else
     exit 1
 fi
 
+# Test 12: Verify no-color gate for CI environments
+echo ""
+echo "Test 12: Verify no-color gate"
+if grep -q 'NO_COLOR+set' "$PROJECT_ROOT/install-gh-aw.sh" && \
+   grep -q 'RED=""' "$PROJECT_ROOT/install-gh-aw.sh"; then
+    echo "  ✓ PASS: No-color gate present and spec-compliant"
+else
+    echo "  ✗ FAIL: No-color gate missing or not spec-compliant"
+    exit 1
+fi
+
 echo ""
 echo "=== All tests passed ==="