diff --git a/docs/runbooks/containerization.md b/docs/runbooks/containerization.md
index e3bd6f5..a83ae5a 100644
--- a/docs/runbooks/containerization.md
+++ b/docs/runbooks/containerization.md
@@ -23,6 +23,8 @@ docker run --rm -p 8080:8080 --name restaurant-admin-bff agilewebs/restaurant-ad
 ## Runtime Notes
 
 - Exposes REST control-plane endpoints for admin configuration updates.
+- Requires `ThalosAuth__BaseAddress` to resolve Thalos session introspection endpoint.
+- Returns standardized auth failures (`401|403|503`) with `x-correlation-id` propagation.
 
 ## Health Endpoint Consistency
 
diff --git a/docs/security/auth-enforcement.md b/docs/security/auth-enforcement.md
index 1e91f16..be6edad 100644
--- a/docs/security/auth-enforcement.md
+++ b/docs/security/auth-enforcement.md
@@ -38,8 +38,13 @@ Standard auth error payload:
 
 - `401`: missing or invalid session
 - `403`: permission denied by identity service
+- `503`: identity service unavailable or timeout (`identity_unavailable|identity_timeout`)
 
 ## Correlation
 
 - Incoming/outgoing correlation header: `x-correlation-id`
 - Correlation ID is forwarded to Thalos session validation call.
+
+## Validation Rule
+
+- Successful session introspection must also include `isAuthenticated=true` in Thalos response payload.
diff --git a/src/Restaurant.Admin.Bff.Rest/Program.cs b/src/Restaurant.Admin.Bff.Rest/Program.cs
index b7d1417..6a9c16d 100644
--- a/src/Restaurant.Admin.Bff.Rest/Program.cs
+++ b/src/Restaurant.Admin.Bff.Rest/Program.cs
@@ -3,6 +3,7 @@ using Microsoft.Extensions.Primitives;
 using Restaurant.Admin.Bff.Application.Adapters;
 using Restaurant.Admin.Bff.Application.Handlers;
 using Restaurant.Admin.Bff.Contracts.Requests;
+using Restaurant.Admin.Bff.Rest.Security;
 
 const string CorrelationHeaderName = "x-correlation-id";
 const string SessionAccessCookieName = "thalos_session";
@@ -109,21 +110,50 @@ async Task<IResult?> EnforceSessionAsync(
         request.Headers.TryAddWithoutValidation("Cookie", cookieHeader);
     }
 
-    using var response = await httpClientFactory.CreateClient("ThalosAuth").SendAsync(request, ct);
-
-    if (response.StatusCode == HttpStatusCode.Forbidden)
+    HttpResponseMessage response;
+    try
     {
-        return ErrorResponse(StatusCodes.Status403Forbidden, "forbidden", "Permission denied.", correlationId);
+        response = await httpClientFactory.CreateClient("ThalosAuth").SendAsync(request, ct);
+    }
+    catch (HttpRequestException)
+    {
+        return ErrorResponse(
+            StatusCodes.Status503ServiceUnavailable,
+            "identity_unavailable",
+            "Identity service is temporarily unavailable.",
+            correlationId);
+    }
+    catch (TaskCanceledException)
+    {
+        return ErrorResponse(
+            StatusCodes.Status503ServiceUnavailable,
+            "identity_timeout",
+            "Identity service did not respond in time.",
+            correlationId);
     }
 
-    if (response.StatusCode == HttpStatusCode.Unauthorized)
+    using (response)
     {
-        return ErrorResponse(StatusCodes.Status401Unauthorized, "unauthorized", "Unauthorized request.", correlationId);
-    }
+        if (response.StatusCode == HttpStatusCode.Forbidden)
+        {
+            return ErrorResponse(StatusCodes.Status403Forbidden, "forbidden", "Permission denied.", correlationId);
+        }
 
-    if (!response.IsSuccessStatusCode)
-    {
-        return ErrorResponse(StatusCodes.Status401Unauthorized, "session_invalid", "Session validation failed.", correlationId);
+        if (response.StatusCode == HttpStatusCode.Unauthorized)
+        {
+            return ErrorResponse(StatusCodes.Status401Unauthorized, "unauthorized", "Unauthorized request.", correlationId);
+        }
+
+        if (!response.IsSuccessStatusCode)
+        {
+            return ErrorResponse(StatusCodes.Status401Unauthorized, "session_invalid", "Session validation failed.", correlationId);
+        }
+
+        var payload = await response.Content.ReadAsStringAsync(ct);
+        if (!SessionMePayloadParser.IsAuthenticated(payload))
+        {
+            return ErrorResponse(StatusCodes.Status401Unauthorized, "session_invalid", "Session validation failed.", correlationId);
+        }
     }
 
     return null;
diff --git a/src/Restaurant.Admin.Bff.Rest/Security/SessionMePayloadParser.cs b/src/Restaurant.Admin.Bff.Rest/Security/SessionMePayloadParser.cs
new file mode 100644
index 0000000..40f5f4e
--- /dev/null
+++ b/src/Restaurant.Admin.Bff.Rest/Security/SessionMePayloadParser.cs
@@ -0,0 +1,29 @@
+using System.Text.Json;
+
+namespace Restaurant.Admin.Bff.Rest.Security;
+
+public static class SessionMePayloadParser
+{
+    public static bool IsAuthenticated(string payload)
+    {
+        if (string.IsNullOrWhiteSpace(payload))
+        {
+            return false;
+        }
+
+        try
+        {
+            using var document = JsonDocument.Parse(payload);
+            if (!document.RootElement.TryGetProperty("isAuthenticated", out var value))
+            {
+                return false;
+            }
+
+            return value.ValueKind == JsonValueKind.True;
+        }
+        catch (JsonException)
+        {
+            return false;
+        }
+    }
+}