diff --git a/EnvelopeGenerator.API/Documentation/AuthProxyDocumentFilter.cs b/EnvelopeGenerator.API/Documentation/AuthProxyDocumentFilter.cs
index d4ae7480..8cb9c6c0 100644
--- a/EnvelopeGenerator.API/Documentation/AuthProxyDocumentFilter.cs
+++ b/EnvelopeGenerator.API/Documentation/AuthProxyDocumentFilter.cs
@@ -16,6 +16,12 @@ public sealed class AuthProxyDocumentFilter : IDocumentFilter
     /// <param name="swaggerDoc"></param>
     /// <param name="context"></param>
     public void Apply(OpenApiDocument swaggerDoc, DocumentFilterContext context)
+    {
+        AddLoginOperation(swaggerDoc, context);
+        AddEnvelopeReceiverLoginOperation(swaggerDoc, context);
+    }
+
+    private static void AddLoginOperation(OpenApiDocument swaggerDoc, DocumentFilterContext context)
     {
         const string path = "/api/auth";
 
@@ -67,4 +73,51 @@ public sealed class AuthProxyDocumentFilter : IDocumentFilter
             }
         };
     }
+
+    private static void AddEnvelopeReceiverLoginOperation(OpenApiDocument swaggerDoc, DocumentFilterContext context)
+    {
+        const string path = "/api/Auth/envelope-receiver/{key}";
+
+        var bodySchema = context.SchemaGenerator.GenerateSchema(typeof(EnvelopeReceiverLogin), context.SchemaRepository);
+
+        var operation = new OpenApiOperation
+        {
+            Summary = "Envelope receiver login (auth-hub proxy)",
+            Description = "Proxies the envelope receiver login to the auth service. " +
+                          "The `cookie` query parameter is always forwarded as `true` so the auth service sets the per-envelope cookie automatically.",
+            Tags = [new() { Name = "Auth" }],
+            Parameters =
+            {
+                new OpenApiParameter
+                {
+                    Name = "key",
+                    In = ParameterLocation.Path,
+                    Required = true,
+                    Schema = new OpenApiSchema { Type = "string" },
+                    Description = "The unique envelope receiver key."
+                }
+            },
+            RequestBody = new OpenApiRequestBody
+            {
+                Required = false,
+                Content =
+                {
+                    ["multipart/form-data"] = new OpenApiMediaType { Schema = bodySchema }
+                }
+            },
+            Responses =
+            {
+                ["200"] = new OpenApiResponse { Description = "OK – per-envelope cookie set by auth service." },
+                ["401"] = new OpenApiResponse { Description = "Unauthorized – invalid or missing access code." }
+            }
+        };
+
+        swaggerDoc.Paths[path] = new OpenApiPathItem
+        {
+            Operations =
+            {
+                [OperationType.Post] = operation
+            }
+        };
+    }
 }
\ No newline at end of file
diff --git a/EnvelopeGenerator.API/Models/EnvelopeReceiverLogin.cs b/EnvelopeGenerator.API/Models/EnvelopeReceiverLogin.cs
new file mode 100644
index 00000000..fa53ec61
--- /dev/null
+++ b/EnvelopeGenerator.API/Models/EnvelopeReceiverLogin.cs
@@ -0,0 +1,7 @@
+namespace EnvelopeGenerator.API.Models;
+
+/// <summary>
+/// Request body for the envelope-receiver login endpoint.
+/// </summary>
+/// <param name="AccessCode">The access code sent to the receiver.</param>
+public record EnvelopeReceiverLogin(string? AccessCode = null);
diff --git a/EnvelopeGenerator.API/yarp.json b/EnvelopeGenerator.API/yarp.json
index dc38a955..cd16812a 100644
--- a/EnvelopeGenerator.API/yarp.json
+++ b/EnvelopeGenerator.API/yarp.json
@@ -10,6 +10,17 @@
         "Transforms": [
           { "PathSet": "/api/auth/sign-flow" }
         ]
+      },
+      "auth-envelope-receiver-login": {
+        "ClusterId": "auth-hub",
+        "Match": {
+          "Path": "/api/Auth/envelope-receiver/{key}",
+          "Methods": [ "POST" ]
+        },
+        "Transforms": [
+          { "PathPattern": "/api/auth/envelope-receiver/{key}" },
+          { "QueryValueParameter": "cookie", "Set": "true" }
+        ]
       }
     },
     "Clusters": {