diff --git a/src/ZB.MOM.WW.ScadaBridge.InboundAPI/EndpointExtensions.cs b/src/ZB.MOM.WW.ScadaBridge.InboundAPI/EndpointExtensions.cs
index d1049cb0..5c70ed53 100644
--- a/src/ZB.MOM.WW.ScadaBridge.InboundAPI/EndpointExtensions.cs
+++ b/src/ZB.MOM.WW.ScadaBridge.InboundAPI/EndpointExtensions.cs
@@ -82,7 +82,7 @@ public static class EndpointExtensions
 
         // Auth re-arch (A+B) + X-API-Key restore: the inbound credential is accepted
         // from EITHER the Authorization header ("Bearer sbk_<keyId>_<secret>") OR the
-        // legacy "X-API-Key: sbk_<keyId>_<secret>" header (raw token). Both are passed
+        // alternate "X-API-Key: sbk_<keyId>_<secret>" header (raw token). Both are passed
         // to the SAME shared ZB.MOM.WW.Auth.ApiKeys verifier — the parser strips an
         // optional "Bearer " prefix and otherwise accepts a bare token, so the
         // peppered-HMAC constant-time secret compare is identical for both transports.
diff --git a/tests/ZB.MOM.WW.ScadaBridge.InboundAPI.Tests/EndpointExtensionsTests.cs b/tests/ZB.MOM.WW.ScadaBridge.InboundAPI.Tests/EndpointExtensionsTests.cs
index 5fd18d9a..4a9f792c 100644
--- a/tests/ZB.MOM.WW.ScadaBridge.InboundAPI.Tests/EndpointExtensionsTests.cs
+++ b/tests/ZB.MOM.WW.ScadaBridge.InboundAPI.Tests/EndpointExtensionsTests.cs
@@ -116,7 +116,7 @@ public sealed class EndpointExtensionsTests : IDisposable
     [Fact]
     public async Task HappyPath_ValidXApiKeyInScope_Returns200WithScriptResultJson()
     {
-        // X-API-Key restore: the SAME seeded key, presented in the legacy
+        // X-API-Key restore: the SAME seeded key, presented in the alternate
         // "X-API-Key: sbk_<keyId>_<secret>" header (raw token, no "Bearer " prefix),
         // must authenticate through the SAME shared verifier and reach the script —
         // proving the broadened credential extraction feeds X-API-Key to VerifyAsync.
@@ -213,22 +213,28 @@ public sealed class EndpointExtensionsTests : IDisposable
     }
 
     [Fact]
-    public async Task MissingBearer_Returns401()
+    public async Task WhitespaceAuthorization_ValidXApiKey_Returns200()
     {
-        var method = SeedMethod(1, "noKey", "return 1;");
+        // IsNullOrWhiteSpace fall-through: a PRESENT but whitespace-only Authorization
+        // header is treated as absent, so a valid X-API-Key in the same request must
+        // still authenticate (200). This pins the IsNullOrWhiteSpace check: without
+        // it, a non-null-but-blank Authorization value would be passed straight to
+        // the verifier (which would fail), and the X-API-Key would never be consulted.
+        var method = SeedMethod(1, "echo", "return Parameters[\"value\"];",
+            """[{"name":"value","type":"Integer","required":true}]""");
 
         using var host = await BuildHostAsync(method);
-        await SeedKeyAsync(host, "key1", "noKey-caller", new[] { "noKey" });
+        var token = await SeedKeyAsync(host, keyId: "key1", displayName: "echo-caller",
+            scopes: new[] { "echo" });
         var client = host.GetTestClient();
 
-        // No Authorization header — auth should reject with 401.
-        var request = new HttpRequestMessage(HttpMethod.Post, "/api/noKey")
-        {
-            Content = new StringContent("{}", Encoding.UTF8, "application/json"),
-        };
+        var request = BuildPostWithApiKeyHeader("echo", """{"value":7}""", token);
+        request.Headers.TryAddWithoutValidation("Authorization", "   ");
         var response = await client.SendAsync(request);
+        var body = await response.Content.ReadAsStringAsync();
 
-        Assert.Equal(HttpStatusCode.Unauthorized, response.StatusCode);
+        Assert.Equal(HttpStatusCode.OK, response.StatusCode);
+        Assert.Contains("7", body);
     }
 
     [Fact]
@@ -553,7 +559,7 @@ public sealed class EndpointExtensionsTests : IDisposable
     }
 
     /// <summary>
-    /// X-API-Key restore: builds a POST carrying the credential in the legacy
+    /// X-API-Key restore: builds a POST carrying the credential in the alternate
     /// <c>X-API-Key: sbk_&lt;keyId&gt;_&lt;secret&gt;</c> header (the RAW token, no
     /// "Bearer " prefix) instead of Authorization. The endpoint must extract this
     /// header value and feed it to the SAME shared verifier.