diff --git a/docs/security/credential-storage.mdx b/docs/security/credential-storage.mdx
index 036a1507ba8..9970c998f60 100644
--- a/docs/security/credential-storage.mdx
+++ b/docs/security/credential-storage.mdx
@@ -59,6 +59,8 @@ This means you can:
 
 When the host environment is empty, day-two operations such as `$$nemoclaw <name> rebuild` and remote-provider updates can reuse the credential already registered with the OpenShell gateway.
 Export the credential only when you want to create, replace, or rotate the stored provider value.
+For rebuilds that use a non-local upstream provider, the matching OpenShell provider entry must still exist.
+If the sandbox registry points at a provider that is missing from OpenShell, `$$nemoclaw <name> rebuild` stops before backup or delete even when the matching credential environment variable is exported; rerun `$$nemoclaw onboard` or re-register the provider first.
 
 ## Deploy Reads from Environment Only
 
diff --git a/src/lib/actions/sandbox/rebuild-provider-preflight.ts b/src/lib/actions/sandbox/rebuild-provider-preflight.ts
new file mode 100644
index 00000000000..81408aefbe0
--- /dev/null
+++ b/src/lib/actions/sandbox/rebuild-provider-preflight.ts
@@ -0,0 +1,59 @@
+// SPDX-FileCopyrightText: Copyright (c) 2026 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
+// SPDX-License-Identifier: Apache-2.0
+
+import { runOpenshell } from "../../adapters/openshell/runtime";
+import { RD as _RD, R } from "../../cli/terminal-style";
+import { isLocalInferenceProvider } from "./rebuild-resume-config";
+
+const hermesProviderAuth = require("../../hermes-provider-auth") as {
+  HERMES_PROVIDER_NAME: string;
+};
+const { providerExistsInGateway } = require("../../onboard/providers") as {
+  providerExistsInGateway: (name: string, runOpenshellFn: typeof runOpenshell) => boolean;
+};
+
+function printMissingRebuildGatewayProvider(provider: string, credentialEnv: string | null): void {
+  console.error("");
+  console.error(
+    `  ${_RD}Rebuild preflight failed:${R} provider '${provider}' is not registered in OpenShell.`,
+  );
+  console.error("  The sandbox registry still points at this upstream provider,");
+  console.error("  so rebuild will not recreate it before destroying the sandbox.");
+  if (credentialEnv) {
+    console.error(`  Rebuild cannot rely on ${credentialEnv} while that provider is missing.`);
+  }
+  console.error("");
+  console.error("  Re-register the provider in OpenShell or rerun onboard, then retry rebuild.");
+  console.error("  Sandbox is untouched — no data was lost.");
+}
+
+export function shouldVerifyRebuildGatewayProvider(
+  provider: string | null | undefined,
+): provider is string {
+  return Boolean(
+    provider &&
+      !isLocalInferenceProvider(provider) &&
+      provider !== hermesProviderAuth.HERMES_PROVIDER_NAME,
+  );
+}
+
+export function checkRebuildGatewayProviderOrBail(
+  provider: string | null | undefined,
+  credentialEnv: string | null,
+  log: (msg: string) => void,
+  bail: (msg: string, code?: number) => never,
+): boolean {
+  if (!shouldVerifyRebuildGatewayProvider(provider)) return true;
+
+  const providerRegisteredInGateway = providerExistsInGateway(provider, runOpenshell);
+  log(
+    `Preflight gateway provider check: provider '${provider}' is ${
+      providerRegisteredInGateway ? "registered" : "missing"
+    } in OpenShell`,
+  );
+  if (providerRegisteredInGateway) return true;
+
+  printMissingRebuildGatewayProvider(provider, credentialEnv);
+  bail(`Missing gateway provider: ${provider}`);
+  return false;
+}
diff --git a/src/lib/actions/sandbox/rebuild.ts b/src/lib/actions/sandbox/rebuild.ts
index 403717b6c95..b4f1f23c4f6 100644
--- a/src/lib/actions/sandbox/rebuild.ts
+++ b/src/lib/actions/sandbox/rebuild.ts
@@ -22,9 +22,6 @@ const hermesProviderAuth = require("../../hermes-provider-auth") as {
     baseUrl?: string,
   ) => void;
 };
-const { providerExistsInGateway } = require("../../onboard/providers") as {
-  providerExistsInGateway: (name: string, runOpenshellFn: typeof runOpenshell) => boolean;
-};
 
 import {
   detectOpenShellStateRpcPreflightIssue,
@@ -80,6 +77,10 @@ import {
   resolveRebuildLiveState,
 } from "./rebuild-flow-helpers";
 import { buildRebuildRecreateOnboardOpts } from "./rebuild-gpu-opt-out";
+import {
+  checkRebuildGatewayProviderOrBail,
+  shouldVerifyRebuildGatewayProvider,
+} from "./rebuild-provider-preflight";
 import {
   getRebuildCredentialEnvFromRegistry,
   isLocalInferenceProvider,
@@ -434,6 +435,7 @@ function preflightRebuildCredentials(
   }
 
   const rebuildProvider = sb.provider;
+
   // Compatibility boundary for GH #2519: pre-fix local-provider sessions could
   // persist credentialEnv="OPENAI_API_KEY" even though current local-provider
   // write paths persist null. Only a session for this sandbox plus a local
@@ -469,6 +471,9 @@ function preflightRebuildCredentials(
   }
 
   if (!rebuildCredentialEnv) {
+    if (!checkRebuildGatewayProviderOrBail(rebuildProvider, rebuildCredentialEnv, log, bail)) {
+      return false;
+    }
     log(
       "Preflight credential check: no credentialEnv in session (local inference or missing session)",
     );
@@ -479,13 +484,16 @@ function preflightRebuildCredentials(
   log(
     `Preflight credential check: ${rebuildCredentialEnv} → ${credentialValue ? "present" : "MISSING"}`,
   );
-  if (credentialValue) return true;
-  if (rebuildProvider && providerExistsInGateway(rebuildProvider, runOpenshell)) {
+  if (!checkRebuildGatewayProviderOrBail(rebuildProvider, rebuildCredentialEnv, log, bail)) {
+    return false;
+  }
+  if (!credentialValue && shouldVerifyRebuildGatewayProvider(rebuildProvider)) {
     log(
       `Preflight credential check: provider '${rebuildProvider}' registered in gateway — skipping env check for ${rebuildCredentialEnv}`,
     );
     return true;
   }
+  if (credentialValue) return true;
 
   console.error("");
   console.error(`  ${_RD}Rebuild preflight failed:${R} provider credential not found.`);
diff --git a/test/rebuild-credential-preflight.test.ts b/test/rebuild-credential-preflight.test.ts
index 66664dfd2dc..18a0c768413 100644
--- a/test/rebuild-credential-preflight.test.ts
+++ b/test/rebuild-credential-preflight.test.ts
@@ -478,9 +478,12 @@ describe("Issue #2273: atomic rebuild", () => {
       const result = runRebuild(f);
       const output = (result.stderr || "") + (result.stdout || "");
 
-      // Should mention preflight failure
+      // Should prefer the missing-provider abort over the generic missing-env fallback.
       expect(output).toContain("preflight failed");
+      expect(output).toContain("provider 'nvidia-prod' is not registered in OpenShell");
       expect(output).toContain("NVIDIA_INFERENCE_API_KEY");
+      expect(output).not.toContain("provider credential not found");
+      expect(output).not.toContain("export NVIDIA_INFERENCE_API_KEY=<your-key>");
       // Should say sandbox is untouched
       expect(output).toContain("untouched");
       // Sandbox should still be in the registry (not destroyed)
@@ -508,6 +511,32 @@ describe("Issue #2273: atomic rebuild", () => {
       expect(output).toContain("Backing up sandbox state");
     });
 
+    it("aborts before backup when the gateway provider is missing even with host credential", {
+      timeout: 60_000,
+    }, () => {
+      const f = createFixture({
+        credentialEnv: "NVIDIA_INFERENCE_API_KEY",
+        provider: "nvidia-prod",
+        providerRegistered: false,
+      });
+
+      const result = runRebuild(f, {
+        NVIDIA_INFERENCE_API_KEY: "nvapi-test-key-for-rebuild",
+      });
+      const output = (result.stderr || "") + (result.stdout || "");
+
+      expect(result.status).not.toBe(0);
+      expect(output).toContain("preflight failed");
+      expect(output).toContain("provider 'nvidia-prod' is not registered in OpenShell");
+      expect(output).toContain("NVIDIA_INFERENCE_API_KEY");
+      expect(output).toContain("Sandbox is untouched");
+      expect(output).not.toContain("Backing up sandbox state");
+      expect(output).not.toContain("Old sandbox deleted");
+      expect(output).not.toContain("Creating new sandbox with current image");
+      expect(output).not.toContain("missing from gateway; recreating it");
+      expect(registryHasSandbox(f)).toBe(true);
+    });
+
     it("copies Hermes messaging channels from the registry into the rebuild resume session", {
       timeout: 60_000,
     }, () => {
@@ -631,7 +660,8 @@ describe("Issue #2273: atomic rebuild", () => {
 
       expect(result.status).not.toBe(0);
       expect(output).toContain("preflight failed");
-      expect(output).toContain("requires OPENAI_API_KEY");
+      expect(output).toContain("provider 'openai-api' is not registered in OpenShell");
+      expect(output).toContain("OPENAI_API_KEY");
       expect(output).not.toContain("Backing up sandbox state");
       expect(output).not.toContain("Old sandbox deleted");
       expect(registryHasSandbox(f)).toBe(true);
@@ -656,7 +686,8 @@ describe("Issue #2273: atomic rebuild", () => {
 
       expect(result.status).not.toBe(0);
       expect(output).toContain("preflight failed");
-      expect(output).toContain("requires OPENAI_API_KEY");
+      expect(output).toContain("provider 'openai-api' is not registered in OpenShell");
+      expect(output).toContain("OPENAI_API_KEY");
       expect(output).not.toContain("Backing up sandbox state");
       expect(output).not.toContain("Old sandbox deleted");
       expect(registryHasSandbox(f)).toBe(true);
@@ -682,7 +713,8 @@ describe("Issue #2273: atomic rebuild", () => {
 
       expect(result.status).not.toBe(0);
       expect(output).toContain("preflight failed");
-      expect(output).toContain("requires OPENAI_API_KEY");
+      expect(output).toContain("provider 'openai-api' is not registered in OpenShell");
+      expect(output).toContain("OPENAI_API_KEY");
       expect(output).not.toContain("GH #2519");
       expect(output).not.toContain("Backing up sandbox state");
       expect(output).not.toContain("Old sandbox deleted");
@@ -786,7 +818,9 @@ describe("Issue #2273: atomic rebuild", () => {
 
       expect(result.status).not.toBe(0);
       expect(output).toContain("preflight failed");
+      expect(output).toContain("provider 'nvidia-prod' is not registered in OpenShell");
       expect(output).toContain("NVIDIA_INFERENCE_API_KEY");
+      expect(output).not.toContain("provider credential not found");
       expect(output).toContain("untouched");
       expect(registryHasSandbox(f)).toBe(true);
     });