diff --git a/docs/get-started/quickstart.mdx b/docs/get-started/quickstart.mdx
index 5c35825c1e5..1d57cd00a67 100644
--- a/docs/get-started/quickstart.mdx
+++ b/docs/get-started/quickstart.mdx
@@ -192,7 +192,7 @@ Use these details when your first-run path needs more control.
     Express install switches onboarding to non-interactive mode, allows `sudo` password prompts for required host changes, and selects the managed local inference path for that platform.
     DGX Spark uses managed vLLM with `qwen3.6-35b-a3b-nvfp4` by default, and DGX Station uses `deepseek-v4-flash` by default.
     Unless `NEMOCLAW_POLICY_TIER` is set, express install applies policy in `suggested` mode with the `balanced` tier, including the base sandbox policy and supported package, model, web-search, and local-inference presets.
-    DGX Spark uses `my-spark-assistant` as the sandbox name unless `NEMOCLAW_SANDBOX_NAME` is set.
+    Express install uses `my-assistant` as the sandbox name across all platforms unless `NEMOCLAW_SANDBOX_NAME` is set.
     Windows WSL selects the Windows-host Ollama setup path.
     Set `NEMOCLAW_NO_EXPRESS=1` to skip the express prompt, or set `NEMOCLAW_PROVIDER` before launching the installer to choose a provider yourself.
 
diff --git a/scripts/install.sh b/scripts/install.sh
index fceb01142cc..0bc02fef3aa 100755
--- a/scripts/install.sh
+++ b/scripts/install.sh
@@ -2675,7 +2675,7 @@ describe_express_install() {
         inference_summary="managed local vLLM using the DGX Spark profile default model"
       fi
       inference_disclosure="Managed vLLM pulls the configured vLLM image/model and runs a local vLLM inference container."
-      sandbox_summary="${NEMOCLAW_SANDBOX_NAME:-my-spark-assistant}"
+      sandbox_summary="${NEMOCLAW_SANDBOX_NAME:-my-assistant}"
       ;;
     "DGX Station")
       inference_summary="managed local vLLM"
@@ -2774,7 +2774,7 @@ maybe_offer_express_install() {
       export NEMOCLAW_POLICY_MODE=suggested
       case "$platform" in
         "DGX Spark")
-          export NEMOCLAW_SANDBOX_NAME="${NEMOCLAW_SANDBOX_NAME:-my-spark-assistant}"
+          export NEMOCLAW_SANDBOX_NAME="${NEMOCLAW_SANDBOX_NAME:-my-assistant}"
           export NEMOCLAW_PROVIDER=install-vllm
           if [ -n "${NEMOCLAW_VLLM_MODEL:-}" ]; then
             export NEMOCLAW_VLLM_MODEL
diff --git a/test/install-express-prompt.test.ts b/test/install-express-prompt.test.ts
index 1606ddc5507..f916e84c9d3 100644
--- a/test/install-express-prompt.test.ts
+++ b/test/install-express-prompt.test.ts
@@ -119,12 +119,12 @@ sys.exit(exit_code)
     expect(output).toMatch(
       /Managed vLLM pulls the configured vLLM image\/model and runs a local vLLM inference container/,
     );
-    expect(output).toMatch(/Sandbox name: my-spark-assistant/);
+    expect(output).toMatch(/Sandbox name: my-assistant/);
     expect(output).toMatch(/Sandbox policy: suggested mode, tier 'balanced'/);
     expect(output).toMatch(/Run express install/);
     expect(output).toMatch(/Using express install for DGX Spark/);
     expect(output).toMatch(
-      /RESULT NON_INTERACTIVE=1 SUDO_MODE=prompt PROVIDER=install-vllm MODEL= VLLM_MODEL= POLICY=suggested YES=1 SANDBOX=my-spark-assistant/,
+      /RESULT NON_INTERACTIVE=1 SUDO_MODE=prompt PROVIDER=install-vllm MODEL= VLLM_MODEL= POLICY=suggested YES=1 SANDBOX=my-assistant/,
     );
   });
 
@@ -142,7 +142,20 @@ sys.exit(exit_code)
       /Managed vLLM pulls the configured vLLM image\/model and runs a local vLLM inference container/,
     );
     expect(output).toMatch(
-      /RESULT NON_INTERACTIVE=1 SUDO_MODE=prompt PROVIDER=install-vllm MODEL= VLLM_MODEL=custom-qwen3\.6 POLICY=suggested YES=1 SANDBOX=my-spark-assistant/,
+      /RESULT NON_INTERACTIVE=1 SUDO_MODE=prompt PROVIDER=install-vllm MODEL= VLLM_MODEL=custom-qwen3\.6 POLICY=suggested YES=1 SANDBOX=my-assistant/,
+    );
+  });
+
+  it("preserves an explicit NEMOCLAW_SANDBOX_NAME over the DGX Spark default (#6525)", () => {
+    const result = runExpressPromptWithTty("y\n", "pipe", "DGX Spark", {
+      NEMOCLAW_SANDBOX_NAME: "custom-spark",
+    });
+    const output = `${result.stdout}${result.stderr}`;
+    expect(result.status, output).toBe(0);
+    expect(output).toMatch(/Detected DGX Spark/);
+    expect(output).toMatch(/Sandbox name: custom-spark/);
+    expect(output).toMatch(
+      /RESULT NON_INTERACTIVE=1 SUDO_MODE=prompt PROVIDER=install-vllm MODEL= VLLM_MODEL= POLICY=suggested YES=1 SANDBOX=custom-spark/,
     );
   });