diff --git a/test/e2e-scenario/support-tests/platform-parity-cloud-experimental.test.ts b/test/e2e-scenario/support-tests/platform-parity-cloud-experimental.test.ts
index 1a963632625..d9c61f87fd4 100644
--- a/test/e2e-scenario/support-tests/platform-parity-cloud-experimental.test.ts
+++ b/test/e2e-scenario/support-tests/platform-parity-cloud-experimental.test.ts
@@ -87,6 +87,28 @@ describe("P0-E cloud-experimental parity guardrails", () => {
     expect(result.stdout.trim()).toBe("NO_NEWLINE_IN_COMMAND");
   });
 
+  it("keeps Deep Agents secret-boundary probe command single-line for OpenShell exec", () => {
+    const result = spawnSync(
+      "bash",
+      [
+        path.join(
+          process.cwd(),
+          "test/e2e/e2e-cloud-experimental/checks/08-deepagents-code-secret-boundary.sh",
+        ),
+      ],
+      {
+        encoding: "utf8",
+        env: {
+          NEMOCLAW_E2E_SECRET_BOUNDARY_SELF_TEST: "probe-command-shape",
+          PATH: process.env.PATH ?? "/usr/bin:/bin",
+        },
+      },
+    );
+
+    expect(result.status).toBe(0);
+    expect(result.stdout).toContain("NO_NEWLINE_IN_COMMAND");
+  });
+
   it("registers executable Deep Agents cloud-experimental checks", () => {
     expect(DEEPAGENTS_CLOUD_EXPERIMENTAL_CHECKS).toEqual([
       "test/e2e/e2e-cloud-experimental/checks/05-deepagents-code-landlock-readonly.sh",
diff --git a/test/e2e/e2e-cloud-experimental/checks/08-deepagents-code-secret-boundary.sh b/test/e2e/e2e-cloud-experimental/checks/08-deepagents-code-secret-boundary.sh
index 16680908684..fa12be8e218 100755
--- a/test/e2e/e2e-cloud-experimental/checks/08-deepagents-code-secret-boundary.sh
+++ b/test/e2e/e2e-cloud-experimental/checks/08-deepagents-code-secret-boundary.sh
@@ -34,17 +34,17 @@ sandbox_exec() {
   openshell sandbox exec --name "$SANDBOX_NAME" -- bash -c "$1" 2>&1
 }
 
-dcode_secret_probe() {
-  local command="$1"
-  sandbox_exec "
-tmp=\$(mktemp /tmp/dcode-secret-boundary.XXXXXX)
-${command} >\"\$tmp\" 2>&1
-status=\$?
-cat \"\$tmp\"
-rm -f \"\$tmp\"
-printf 'DCODE_EXIT:%s\n' \"\$status\"
-exit 0
-"
+dcode_secret_probe_runtime_env() {
+  # Keep this probe single-line: OpenShell rejects newline-bearing exec arguments.
+  local remote_cmd
+  remote_cmd="tmp=\$(mktemp /tmp/dcode-secret-boundary.XXXXXX); env OPENAI_API_KEY=${FAKE_SECRET@Q} dcode -n 'Reply with the single word PING' >\"\$tmp\" 2>&1; status=\$?; cat \"\$tmp\"; rm -f \"\$tmp\"; printf 'DCODE_EXIT:%s\\n' \"\$status\"; exit 0"
+  sandbox_exec "$remote_cmd"
+}
+
+dcode_secret_probe_env_file() {
+  local remote_cmd
+  remote_cmd="tmp=\$(mktemp /tmp/dcode-secret-boundary.XXXXXX); dcode -n 'Reply with the single word PING' >\"\$tmp\" 2>&1; status=\$?; cat \"\$tmp\"; rm -f \"\$tmp\"; printf 'DCODE_EXIT:%s\\n' \"\$status\"; exit 0"
+  sandbox_exec "$remote_cmd"
 }
 
 make_log_marker() {
@@ -191,6 +191,23 @@ assert_no_rejected_interval_audit_logs() {
 PASSED=0
 FAILED=0
 
+if [ "${NEMOCLAW_E2E_SECRET_BOUNDARY_SELF_TEST:-}" = "probe-command-shape" ]; then
+  sandbox_exec() {
+    case "$1" in
+      *$'\n'*)
+        printf '%s\n' "NEWLINE_IN_COMMAND"
+        return 1
+        ;;
+      *)
+        printf '%s\n' "NO_NEWLINE_IN_COMMAND"
+        return 0
+        ;;
+    esac
+  }
+  dcode_secret_probe_runtime_env
+  exit 0
+fi
+
 if ! sandbox_exec "test -d /sandbox/.deepagents && command -v dcode >/dev/null 2>&1" >/dev/null; then
   info "SKIP: sandbox '${SANDBOX_NAME}' is not a Deep Agents Code sandbox"
   exit 0
@@ -202,7 +219,7 @@ enable_openshell_audit_logs
 runtime_log_marker="$(make_log_marker runtime-env)"
 runtime_audit_start="$(($(date +%s) - 1))"
 mark_sandbox_logs "$runtime_log_marker"
-runtime_output="$(dcode_secret_probe "env OPENAI_API_KEY=${FAKE_SECRET@Q} dcode -n 'Reply with the single word PING'" || true)"
+runtime_output="$(dcode_secret_probe_runtime_env || true)"
 runtime_logs="$(sandbox_logs_since_marker "$runtime_log_marker" || true)"
 runtime_audit_logs="$(openshell_audit_logs_since_epoch "$runtime_audit_start" || true)"
 assert_secret_rejected "runtime environment injection" "$runtime_output" "OPENAI_API_KEY"
@@ -220,7 +237,7 @@ env_before_hash="$(sandbox_exec "sha256sum ${DEEPAGENTS_ENV_FILE@Q} | awk '{prin
 env_log_marker="$(make_log_marker env-file)"
 env_audit_start="$(($(date +%s) - 1))"
 mark_sandbox_logs "$env_log_marker"
-env_output="$(dcode_secret_probe "dcode -n 'Reply with the single word PING'" || true)"
+env_output="$(dcode_secret_probe_env_file || true)"
 env_logs="$(sandbox_logs_since_marker "$env_log_marker" || true)"
 env_audit_logs="$(openshell_audit_logs_since_epoch "$env_audit_start" || true)"
 env_after_hash="$(sandbox_exec "sha256sum ${DEEPAGENTS_ENV_FILE@Q} | awk '{print \$1}'" || true)"
diff --git a/test/langchain-deepagents-code-image.test.ts b/test/langchain-deepagents-code-image.test.ts
index 4fd3468d3ca..50790ae0967 100644
--- a/test/langchain-deepagents-code-image.test.ts
+++ b/test/langchain-deepagents-code-image.test.ts
@@ -433,6 +433,13 @@ describe("LangChain Deep Agents Code image contracts", () => {
     expect(secretBoundaryCheck).toContain("Case: Deep Agents Code dcode secret boundary");
     expect(secretBoundaryCheck).toContain("env OPENAI_API_KEY=");
     expect(secretBoundaryCheck).toContain("dcode -n 'Reply with the single word PING'");
+    expect(secretBoundaryCheck).toContain("dcode_secret_probe_runtime_env");
+    expect(secretBoundaryCheck).toContain("dcode_secret_probe_env_file");
+    expect(secretBoundaryCheck).toContain("remote_cmd=");
+    expect(secretBoundaryCheck).toContain("OpenShell rejects newline-bearing exec");
+    expect(secretBoundaryCheck).toContain("NEMOCLAW_E2E_SECRET_BOUNDARY_SELF_TEST");
+    expect(secretBoundaryCheck).toContain("NO_NEWLINE_IN_COMMAND");
+    expect(secretBoundaryCheck).toContain("DCODE_EXIT:%s\\\\n");
     expect(secretBoundaryCheck).toContain("DCODE_EXIT:0");
     expect(secretBoundaryCheck).toContain("refusing to start");
     expect(secretBoundaryCheck).toContain("NETWORK_LOG_PATTERN=");