diff --git a/test/e2e-scenario/live/agent-turn-latency-helpers.ts b/test/e2e-scenario/live/agent-turn-latency-helpers.ts
index 9fde9c79fc5..07e340613bc 100644
--- a/test/e2e-scenario/live/agent-turn-latency-helpers.ts
+++ b/test/e2e-scenario/live/agent-turn-latency-helpers.ts
@@ -12,6 +12,7 @@ import {
 } from "../fixtures/clients/sandbox.ts";
 import { expect } from "../fixtures/e2e-test.ts";
 import type { ShellProbeResult } from "../fixtures/shell-probe.ts";
+import { installShOnboardArgs } from "./install-sh-onboard.ts";
 import { isTransientProviderValidationFailure } from "./network-policy-transient-provider.ts";
 
 export const REPO_ROOT = path.resolve(import.meta.dirname, "../../..");
@@ -220,17 +221,13 @@ export async function installSandbox(
 ): Promise<ShellProbeResult> {
   let install: ShellProbeResult | undefined;
   for (let attempt = 1; attempt <= INSTALL_ATTEMPTS; attempt += 1) {
-    install = await host.command(
-      "bash",
-      ["install.sh", "--non-interactive", "--yes-i-accept-third-party-software"],
-      {
-        artifactName: `${agent}-install-attempt-${attempt}`,
-        cwd: REPO_ROOT,
-        env: env(sandboxName, agent, apiKey),
-        redactionValues: [apiKey],
-        timeoutMs: 30 * 60_000,
-      },
-    );
+    install = await host.command("bash", installShOnboardArgs(), {
+      artifactName: `${agent}-install-attempt-${attempt}`,
+      cwd: REPO_ROOT,
+      env: env(sandboxName, agent, apiKey),
+      redactionValues: [apiKey],
+      timeoutMs: 30 * 60_000,
+    });
     const retry =
       install.exitCode !== 0 &&
       isTransientProviderValidationFailure(install) &&
diff --git a/test/e2e-scenario/live/cron-preflight-inference-local.test.ts b/test/e2e-scenario/live/cron-preflight-inference-local.test.ts
index a31658092b3..73ccb2ef1d3 100644
--- a/test/e2e-scenario/live/cron-preflight-inference-local.test.ts
+++ b/test/e2e-scenario/live/cron-preflight-inference-local.test.ts
@@ -19,6 +19,7 @@ import { type SandboxClient, validateSandboxName } from "../fixtures/clients/san
 import { expect, test } from "../fixtures/e2e-test.ts";
 import { shouldRunLiveE2EScenarios } from "../fixtures/live-project-gate.ts";
 import type { ShellProbeResult } from "../fixtures/shell-probe.ts";
+import { installShOnboardArgs } from "./install-sh-onboard.ts";
 import { isTransientProviderValidationFailure } from "./network-policy-transient-provider.ts";
 
 const REPO_ROOT = path.resolve(import.meta.dirname, "../../..");
@@ -265,20 +266,16 @@ test.skipIf(!shouldRunLiveE2EScenarios())(
 
     let install: ShellProbeResult | undefined;
     for (let attempt = 1; attempt <= INSTALL_ATTEMPTS; attempt += 1) {
-      install = await host.command(
-        "bash",
-        ["install.sh", "--non-interactive", "--yes-i-accept-third-party-software"],
-        {
-          artifactName:
-            attempt === 1
-              ? "phase-1-install-cron-preflight"
-              : `phase-1-install-cron-preflight-attempt-${attempt}`,
-          cwd: REPO_ROOT,
-          env: commandEnv(apiKey),
-          redactionValues: [apiKey],
-          timeoutMs: 20 * 60_000,
-        },
-      );
+      install = await host.command("bash", installShOnboardArgs(), {
+        artifactName:
+          attempt === 1
+            ? "phase-1-install-cron-preflight"
+            : `phase-1-install-cron-preflight-attempt-${attempt}`,
+        cwd: REPO_ROOT,
+        env: commandEnv(apiKey),
+        redactionValues: [apiKey],
+        timeoutMs: 20 * 60_000,
+      });
       if (install.exitCode === 0) break;
       if (isTransientProviderValidationFailure(install) && attempt < INSTALL_ATTEMPTS) {
         await new Promise((resolve) => setTimeout(resolve, 10_000 * attempt));
diff --git a/test/e2e-scenario/live/install-sh-onboard.ts b/test/e2e-scenario/live/install-sh-onboard.ts
new file mode 100644
index 00000000000..beca9c5e41b
--- /dev/null
+++ b/test/e2e-scenario/live/install-sh-onboard.ts
@@ -0,0 +1,14 @@
+// SPDX-FileCopyrightText: Copyright (c) 2026 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
+// SPDX-License-Identifier: Apache-2.0
+
+/**
+ * Canonical install.sh arguments for live Vitest scenarios that auto-onboard.
+ *
+ * Live scenario retries must not inherit a failed persisted onboarding session
+ * from an earlier failed attempt. `--fresh` makes install.sh bypass the failed
+ * session classifier and lets the CLI clear stale session state before creating
+ * the new session.
+ */
+export function installShOnboardArgs(): string[] {
+  return ["install.sh", "--non-interactive", "--yes-i-accept-third-party-software", "--fresh"];
+}
diff --git a/test/e2e-scenario/support-tests/install-sh-onboard.test.ts b/test/e2e-scenario/support-tests/install-sh-onboard.test.ts
new file mode 100644
index 00000000000..3631881279b
--- /dev/null
+++ b/test/e2e-scenario/support-tests/install-sh-onboard.test.ts
@@ -0,0 +1,35 @@
+// SPDX-FileCopyrightText: Copyright (c) 2026 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
+// SPDX-License-Identifier: Apache-2.0
+
+import fs from "node:fs";
+import path from "node:path";
+
+import { describe, expect, it } from "vitest";
+
+import { installShOnboardArgs } from "../live/install-sh-onboard.ts";
+
+const RETRY_SENSITIVE_LIVE_TESTS = [
+  "test/e2e-scenario/live/agent-turn-latency-helpers.ts",
+  "test/e2e-scenario/live/cron-preflight-inference-local.test.ts",
+];
+
+describe("live install.sh onboarding arguments", () => {
+  it("force a fresh onboarding session so retries discard failed session state", () => {
+    expect(installShOnboardArgs()).toEqual([
+      "install.sh",
+      "--non-interactive",
+      "--yes-i-accept-third-party-software",
+      "--fresh",
+    ]);
+  });
+
+  it("routes retry-sensitive live install.sh callers through the fresh-session helper", () => {
+    for (const relativePath of RETRY_SENSITIVE_LIVE_TESTS) {
+      const source = fs.readFileSync(path.join(process.cwd(), relativePath), "utf8");
+      expect(source, relativePath).toContain("installShOnboardArgs()");
+      expect(source, relativePath).not.toContain(
+        '["install.sh", "--non-interactive", "--yes-i-accept-third-party-software"]',
+      );
+    }
+  });
+});