diff --git a/src/Aevatar.AI.Core/Chat/ChatRuntimeRequestBuilder.cs b/src/Aevatar.AI.Core/Chat/ChatRuntimeRequestBuilder.cs
index 0e5ff65ad..544229d16 100644
--- a/src/Aevatar.AI.Core/Chat/ChatRuntimeRequestBuilder.cs
+++ b/src/Aevatar.AI.Core/Chat/ChatRuntimeRequestBuilder.cs
@@ -77,12 +77,14 @@ public static LLMRequest Build(
             catalogProof?.AssertMatchesExactTools(exactTools ?? []);
         }
 
+        var callerContext = ResolveCallerContext(baseRequest.CallerContext, effectiveToolContext);
+
         return new LLMRequest
         {
             Messages = baseRequest.Messages,
             RequestId = string.IsNullOrWhiteSpace(requestId) ? baseRequest.RequestId : requestId.Trim(),
             Metadata = AgentToolExecutionContextMapper.StripOwnedControlKeys(mergedMetadata),
-            CallerContext = baseRequest.CallerContext,
+            CallerContext = callerContext,
             ToolContext = effectiveToolContext,
             RoutingContext = effectiveLlmControl?.ToRoutingContext(baseRequest.RoutingContext) ?? baseRequest.RoutingContext,
             LlmControl = effectiveLlmControl,
@@ -181,6 +183,47 @@ internal static AuthorizationFence CaptureAuthorizationFence(LLMRequest request)
         return merged;
     }
 
+    private static LLMRequestCallerContext? ResolveCallerContext(
+        LLMRequestCallerContext? baseCallerContext,
+        AgentToolExecutionContext toolContext)
+    {
+        var credential = string.IsNullOrWhiteSpace(baseCallerContext?.Credentials?.NyxIdBearer)
+            ? ResolvePromotableNyxIdCredential(toolContext.Credentials)
+            : baseCallerContext.Credentials.NyxIdBearer.Trim();
+        var credentials = string.IsNullOrWhiteSpace(credential)
+            ? baseCallerContext?.Credentials
+            : new LLMRequestCallerCredentials(credential);
+        if (baseCallerContext is not null)
+        {
+            return baseCallerContext with
+            {
+                Credentials = credentials,
+            };
+        }
+
+        if (credentials is null &&
+            string.IsNullOrWhiteSpace(toolContext.Caller.ScopeId) &&
+            string.IsNullOrWhiteSpace(toolContext.Caller.OwnerSubject) &&
+            string.IsNullOrWhiteSpace(toolContext.Caller.ResponseId))
+        {
+            return null;
+        }
+
+        return new LLMRequestCallerContext(
+            Normalize(toolContext.Caller.ScopeId) ?? string.Empty,
+            Normalize(toolContext.Caller.OwnerSubject) ?? string.Empty,
+            Normalize(toolContext.Caller.ResponseId),
+            credentials);
+    }
+
+    private static string? ResolvePromotableNyxIdCredential(AgentToolCredentials credentials) =>
+        credentials.NyxIdCredentialKind == AgentToolNyxIdCredentialKind.AgentKey
+            ? Normalize(credentials.NyxIdAccessToken)
+            : null;
+
+    private static string? Normalize(string? value) =>
+        string.IsNullOrWhiteSpace(value) ? null : value.Trim();
+
     internal sealed class AuthorizationFence
     {
         private readonly IReadOnlyDictionary<string, IAgentTool> _schemaTools;
diff --git a/test/Aevatar.AI.Tests/ChatRuntimeRequestBuilderCredentialTests.cs b/test/Aevatar.AI.Tests/ChatRuntimeRequestBuilderCredentialTests.cs
new file mode 100644
index 000000000..e60173840
--- /dev/null
+++ b/test/Aevatar.AI.Tests/ChatRuntimeRequestBuilderCredentialTests.cs
@@ -0,0 +1,52 @@
+using Aevatar.AI.Abstractions.LLMProviders;
+using Aevatar.AI.Abstractions.ToolProviders;
+using Aevatar.AI.Core.Chat;
+using FluentAssertions;
+
+namespace Aevatar.AI.Tests;
+
+public sealed class ChatRuntimeRequestBuilderCredentialTests
+{
+    [Fact]
+    public void Build_WhenToolContextHasAgentKeyCredential_ShouldPromoteCallerBearer()
+    {
+        var request = BuildRequest(AgentToolNyxIdCredentialKind.AgentKey);
+
+        request.CallerContext.Should().NotBeNull();
+        request.CallerContext!.Credentials.Should().NotBeNull();
+        request.CallerContext.Credentials!.NyxIdBearer.Should().Be("nyxid_ag_alpha");
+    }
+
+    [Fact]
+    public void Build_WhenToolContextCredentialKindIsUnspecified_ShouldNotPromoteCallerBearer()
+    {
+        var request = BuildRequest(AgentToolNyxIdCredentialKind.Unspecified);
+
+        request.CallerContext.Should().NotBeNull();
+        request.CallerContext!.Credentials.Should().BeNull();
+    }
+
+    private static LLMRequest BuildRequest(AgentToolNyxIdCredentialKind credentialKind)
+    {
+        var toolContext = AgentToolExecutionContext.Empty with
+        {
+            Credentials = new AgentToolCredentials(
+                " nyxid_ag_alpha ",
+                null,
+                null,
+                credentialKind),
+            Caller = new AgentToolCallerContext(" scope-alpha ", " owner-alpha ", " response-alpha "),
+        };
+
+        return ChatRuntimeRequestBuilder.Build(
+            new LLMRequest
+            {
+                Messages = [new ChatMessage { Role = "user", Content = "hello" }],
+            },
+            null,
+            null,
+            toolContext,
+            null,
+            null);
+    }
+}
diff --git a/test/Aevatar.Workflow.Core.Tests/Modules/WorkflowRoleGAgentMappingTests.cs b/test/Aevatar.Workflow.Core.Tests/Modules/WorkflowRoleGAgentMappingTests.cs
index bc5d2bc51..1389226a1 100644
--- a/test/Aevatar.Workflow.Core.Tests/Modules/WorkflowRoleGAgentMappingTests.cs
+++ b/test/Aevatar.Workflow.Core.Tests/Modules/WorkflowRoleGAgentMappingTests.cs
@@ -158,6 +158,9 @@ await agent.HandleWorkflowLlmExecutionIntent(new WorkflowLlmExecutionIntent
         provider.LastRequest.LlmControl.Should().NotBeNull();
         provider.LastRequest.LlmControl!.NyxIdAccessToken.Should().BeNull(
             "the durable Agent Key should only enter the ephemeral tool context");
+        provider.LastRequest.CallerContext.Should().NotBeNull();
+        provider.LastRequest.CallerContext!.Credentials.Should().NotBeNull();
+        provider.LastRequest.CallerContext.Credentials!.NyxIdBearer.Should().Be(agentKey);
     }
 
     [Fact]
@@ -217,6 +220,9 @@ await agent.HandleWorkflowLlmExecutionIntent(new WorkflowLlmExecutionIntent
         provider.LastRequest.LlmControl.Should().NotBeNull();
         provider.LastRequest.LlmControl!.NyxIdAccessToken.Should().BeNull(
             "the durable Agent Key should only enter the ephemeral tool context");
+        provider.LastRequest.CallerContext.Should().NotBeNull();
+        provider.LastRequest.CallerContext!.Credentials.Should().NotBeNull();
+        provider.LastRequest.CallerContext.Credentials!.NyxIdBearer.Should().Be(agentKey);
     }
 
     [Fact]