diff --git a/packages/plugins/openapi/src/react/AddOpenApiSource.tsx b/packages/plugins/openapi/src/react/AddOpenApiSource.tsx
index 4eb425572..09e45c242 100644
--- a/packages/plugins/openapi/src/react/AddOpenApiSource.tsx
+++ b/packages/plugins/openapi/src/react/AddOpenApiSource.tsx
@@ -78,6 +78,10 @@ import {
   googleStandardUserOAuthPresets,
   openApiPresets,
 } from "../sdk/presets";
+import {
+  secretCredentialBindingsSubmitError,
+  type PendingSecretCredentialBinding,
+} from "../sdk/secret-binding-validation";
 import { GOOGLE_BUNDLE_PRESET_ID } from "../sdk/google-presets";
 import type { SpecPreview, HeaderPreset, OAuth2Preset } from "../sdk/preview";
 import {
@@ -719,17 +723,10 @@ export default function AddOpenApiSource(props: {
   const resolvedBaseUrl = baseUrl.trim();
   const sourceScope = ScopeId.make(scopeId);
 
-  type PendingSecretBinding = {
-    readonly slot: string;
-    readonly secretId: string;
-    readonly scope: ScopeId;
-    readonly secretScope: ScopeId;
-  };
-
   const configuredHeaders: Record<string, { kind: "secret"; prefix?: string }> = {};
-  const headerBindings: PendingSecretBinding[] = [];
+  const headerBindings: PendingSecretCredentialBinding[] = [];
   const configuredQueryParams: Record<string, string | { kind: "secret"; prefix?: string }> = {};
-  const queryParamBindings: PendingSecretBinding[] = [];
+  const queryParamBindings: PendingSecretCredentialBinding[] = [];
   for (const ch of customHeaders) {
     if (!ch.name.trim()) continue;
     const slot = headerBindingSlot(ch.name.trim());
@@ -768,7 +765,7 @@ export default function AddOpenApiSource(props: {
     string,
     string | { kind: "secret"; prefix?: string }
   > = {};
-  const specFetchBindings: PendingSecretBinding[] = [];
+  const specFetchBindings: PendingSecretCredentialBinding[] = [];
   for (const header of specFetchCredentials.headers) {
     const name = header.name.trim();
     if (!name || !header.secretId) continue;
@@ -1641,6 +1638,41 @@ export default function AddOpenApiSource(props: {
       return;
     }
 
+    const pendingSecretBindings: PendingSecretCredentialBinding[] = [
+      ...headerBindings,
+      ...queryParamBindings,
+      ...specFetchBindings,
+      ...(configuredOAuth2 && oauth2ClientIdSecretId
+        ? [
+            {
+              slot: configuredOAuth2.clientIdSlot,
+              secretId: oauth2ClientIdSecretId,
+              scope: clientIdBindingScope,
+              secretScope: clientIdBindingScope,
+            },
+          ]
+        : []),
+      ...(configuredOAuth2?.clientSecretSlot && oauth2ClientSecretSecretId
+        ? [
+            {
+              slot: configuredOAuth2.clientSecretSlot,
+              secretId: oauth2ClientSecretSecretId,
+              scope: clientSecretBindingScope,
+              secretScope: clientSecretBindingScope,
+            },
+          ]
+        : []),
+    ];
+    const missingSecretMessage = secretCredentialBindingsSubmitError(
+      pendingSecretBindings,
+      secretList,
+    );
+    if (missingSecretMessage) {
+      setAddError(missingSecretMessage);
+      setAdding(false);
+      return;
+    }
+
     const namespace = resolvedSourceId;
     const specForAdd =
       googleServicePickerEnabled && selectedGooglePresets.length > 0
diff --git a/packages/plugins/openapi/src/sdk/secret-binding-validation.test.ts b/packages/plugins/openapi/src/sdk/secret-binding-validation.test.ts
new file mode 100644
index 000000000..7ec87223b
--- /dev/null
+++ b/packages/plugins/openapi/src/sdk/secret-binding-validation.test.ts
@@ -0,0 +1,47 @@
+import { describe, expect, it } from "@effect/vitest";
+
+import { ScopeId } from "@executor-js/sdk/shared";
+
+import {
+  findMissingSecretCredentialBindings,
+  secretCredentialBindingsSubmitError,
+  type PendingSecretCredentialBinding,
+} from "./secret-binding-validation";
+
+const binding = (secretId: string, secretScope: string): PendingSecretCredentialBinding => ({
+  slot: "header:authorization",
+  secretId,
+  scope: ScopeId.make(secretScope),
+  secretScope: ScopeId.make(secretScope),
+});
+
+describe("OpenAPI secret binding validation", () => {
+  it("keeps bindings whose secret exists in the selected credential scope", () => {
+    const missing = findMissingSecretCredentialBindings(
+      [binding("cloudflare-api-authorization", "mulroy-cloud")],
+      [{ id: "cloudflare-api-authorization", scopeId: "mulroy-cloud" }],
+    );
+
+    expect(missing).toEqual([]);
+  });
+
+  it("returns a submit-blocking error when a selected secret no longer exists", () => {
+    const message = secretCredentialBindingsSubmitError(
+      [binding("cloudflare-dmmulroy-api-authorization", "mulroy-cloud")],
+      [{ id: "cloudflare-api-authorization-dmmulroy", scopeId: "mulroy-cloud" }],
+    );
+
+    expect(message).toContain("cloudflare-dmmulroy-api-authorization");
+    expect(message).toContain("before adding the source");
+  });
+
+  it("requires the secret to exist in the same credential scope", () => {
+    const staleOrgBinding = binding("api-token", "mulroy-cloud");
+    const missing = findMissingSecretCredentialBindings(
+      [staleOrgBinding],
+      [{ id: "api-token", scopeId: "user-dmmulroy" }],
+    );
+
+    expect(missing).toEqual([staleOrgBinding]);
+  });
+});
diff --git a/packages/plugins/openapi/src/sdk/secret-binding-validation.ts b/packages/plugins/openapi/src/sdk/secret-binding-validation.ts
new file mode 100644
index 000000000..e69c4ac0a
--- /dev/null
+++ b/packages/plugins/openapi/src/sdk/secret-binding-validation.ts
@@ -0,0 +1,42 @@
+import type { ScopeId } from "@executor-js/sdk/shared";
+
+export interface PendingSecretCredentialBinding {
+  readonly slot: string;
+  readonly secretId: string;
+  readonly scope: ScopeId;
+  readonly secretScope: ScopeId;
+}
+
+export interface AvailableSecretRef {
+  readonly id: string;
+  readonly scopeId: string | ScopeId;
+}
+
+const secretKey = (scopeId: string | ScopeId, secretId: string): string =>
+  `${String(scopeId)}\u0000${secretId}`;
+
+export const findMissingSecretCredentialBindings = (
+  bindings: readonly PendingSecretCredentialBinding[],
+  secrets: readonly AvailableSecretRef[],
+): readonly PendingSecretCredentialBinding[] => {
+  const available = new Set(secrets.map((secret) => secretKey(secret.scopeId, secret.id)));
+  return bindings.filter(
+    (binding) => !available.has(secretKey(binding.secretScope, binding.secretId)),
+  );
+};
+
+export const missingSecretCredentialBindingsMessage = (
+  missing: readonly PendingSecretCredentialBinding[],
+): string | null => {
+  if (missing.length === 0) return null;
+  if (missing.length === 1) {
+    return `Secret "${missing[0]!.secretId}" no longer exists in the selected credential scope. Choose an existing secret or create a new one before adding the source.`;
+  }
+  return `${missing.length} selected secrets no longer exist in their selected credential scopes. Choose existing secrets or create new ones before adding the source.`;
+};
+
+export const secretCredentialBindingsSubmitError = (
+  bindings: readonly PendingSecretCredentialBinding[],
+  secrets: readonly AvailableSecretRef[],
+): string | null =>
+  missingSecretCredentialBindingsMessage(findMissingSecretCredentialBindings(bindings, secrets));