diff --git a/local/recipes/system/redbear-hwutils/source/src/bin/redbear-usb-check.rs b/local/recipes/system/redbear-hwutils/source/src/bin/redbear-usb-check.rs
index 355c4504..dd7ca27f 100644
--- a/local/recipes/system/redbear-hwutils/source/src/bin/redbear-usb-check.rs
+++ b/local/recipes/system/redbear-hwutils/source/src/bin/redbear-usb-check.rs
@@ -40,7 +40,6 @@ impl Report {
     fn new(json_mode: bool) -> Self { Report { checks: Vec::new(), json_mode } }
     fn add(&mut self, check: Check) { self.checks.push(check); }
     fn any_failed(&self) -> bool { self.checks.iter().any(|c| c.result == CheckResult::Fail) }
-
     fn print(&self) {
         if self.json_mode { self.print_json(); } else { self.print_human(); }
     }
diff --git a/local/scripts/test-posix-runtime.sh b/local/scripts/test-posix-runtime.sh
new file mode 100644
index 00000000..1d617a51
--- /dev/null
+++ b/local/scripts/test-posix-runtime.sh
@@ -0,0 +1,102 @@
+#!/usr/bin/env bash
+# POSIX/relibc completeness runtime validation harness.
+# Runs relibc-phase1-tests C programs and validates POSIX compliance.
+# Follows Phase 1-5 pattern: guest + QEMU, exit-code-based.
+
+set -euo pipefail
+PROG="$(basename "$0")"
+
+usage() {
+    cat <<'EOF'
+Usage: test-posix-runtime.sh [--guest|--qemu CONFIG]
+Modes:
+  --guest          Run inside already-booted Red Bear OS
+  --qemu CONFIG    Launch QEMU with CONFIG and run checks
+Exit: 0 if all pass, 1 otherwise.
+EOF
+    exit 1
+}
+
+MODE=""; CONFIG=""
+while [[ $# -gt 0 ]]; do
+    case "$1" in
+        --guest) MODE="guest"; shift ;;
+        --qemu) MODE="qemu"; CONFIG="$2"; shift 2 ;;
+        -h|--help) usage ;;
+        *) echo "$PROG: unknown: $1"; usage ;;
+    esac
+done
+[[ -z "$MODE" ]] && usage
+
+EXPECTED_TESTS=(
+    test_signalfd_wayland
+    test_timerfd_qt6
+    test_eventfd_qt6
+    test_shm_open_qt6
+    test_sem_open_qt6
+    test_waitid_qt6
+)
+
+run_guest_checks() {
+    local failures=0
+    local posix_dir="/home/user/relibc-phase1-tests"
+
+    echo "=== POSIX/relibc Completeness Validation ==="; echo
+
+    if [[ ! -d "$posix_dir" ]]; then
+        echo "  FAIL  POSIX test directory not found at $posix_dir"
+        failures=$((failures + 1))
+    else
+        for test_name in "${EXPECTED_TESTS[@]}"; do
+            local test_bin="$posix_dir/$test_name"
+            if [[ ! -x "$test_bin" ]]; then
+                echo "  FAIL  $test_name: binary missing or not executable"
+                failures=$((failures + 1))
+                continue
+            fi
+            echo "  Running $test_name..."
+            if "$test_bin" >/dev/null 2>&1; then
+                echo "  PASS  $test_name"
+            else
+                echo "  FAIL  $test_name (exit code non-zero)"
+                failures=$((failures + 1))
+            fi
+        done
+    fi
+
+    echo
+    echo "=== POSIX Summary ==="
+    if [[ $failures -eq 0 ]]; then
+        echo "ALL POSIX TESTS PASSED"
+    else
+        echo "FAILURES: $failures"
+        exit 1
+    fi
+    exit 0
+}
+
+run_qemu_checks() {
+    local arch="${ARCH:-x86_64}"
+    local image="build/${arch}/${CONFIG}/harddrive.img"
+    local firmware="${FIRMWARE_PATH:-/usr/share/ovmf/x64/OVMF.fd}"
+    if [[ ! -f "$image" ]]; then echo "$PROG: image not found: $image"; exit 1; fi
+    if [[ ! -f "$firmware" ]]; then echo "$PROG: firmware not found: $firmware"; exit 1; fi
+    expect <<EXPECT_SCRIPT
+log_user 1; set timeout 300
+spawn qemu-system-x86_64 -name {Red Bear OS} -device qemu-xhci -smp 4 -m 2048 -bios $firmware -chardev stdio,id=debug,signal=off,mux=on -serial chardev:debug -mon chardev:debug -machine q35 -device virtio-net,netdev=net0 -netdev user,id=net0 -nographic -vga none -drive file=$image,format=raw,if=none,id=drv0 -device nvme,drive=drv0,serial=NVME_SERIAL -enable-kvm -cpu host
+expect "login:"; send "root\r"
+expect "assword:"; send "password\r"
+expect "Type 'help' for available commands."
+send "echo __READY__\r"; expect "__READY__"
+send "cd /home/user/relibc-phase1-tests && POSIX_FAIL=0; for t in test_signalfd_wayland test_timerfd_qt6 test_eventfd_qt6 test_shm_open_qt6 test_sem_open_qt6 test_waitid_qt6; do echo \"POSIX:\\\$t\"; if ./\\\$t >/dev/null 2>&1; then echo \"\\\${t}:PASS\"; else echo \"\\\${t}:FAIL\"; POSIX_FAIL=1; fi; done; echo __POSIX_DONE__\\\$POSIX_FAIL__\r"
+expect { "__POSIX_DONE__0__" { } "__POSIX_DONE__1__" { puts "FAIL: POSIX tests"; exit 1 } timeout { puts "FAIL: timeout"; exit 1 } eof { puts "FAIL: eof"; exit 1 } }
+puts "ALL POSIX TESTS PASSED"
+EXPECT_SCRIPT
+    exit $?
+}
+
+case "$MODE" in
+    guest) run_guest_checks ;;
+    qemu) export FIRMWARE_PATH="${FIRMWARE_PATH:-/usr/share/ovmf/x64/OVMF.fd}"; run_qemu_checks ;;
+    *) usage ;;
+esac