diff --git a/src/libs/OpenRouter/Generated/OpenRouter.ISubpackageAnthropicMessagesClient.CreateMessages.g.cs b/src/libs/OpenRouter/Generated/OpenRouter.ISubpackageAnthropicMessagesClient.CreateMessages.g.cs
index b86ce9e..809db19 100644
--- a/src/libs/OpenRouter/Generated/OpenRouter.ISubpackageAnthropicMessagesClient.CreateMessages.g.cs
+++ b/src/libs/OpenRouter/Generated/OpenRouter.ISubpackageAnthropicMessagesClient.CreateMessages.g.cs
@@ -68,7 +68,7 @@ public partial interface ISubpackageAnthropicMessagesClient
         /// </param>
         /// <param name="serviceTier"></param>
         /// <param name="sessionId">
-        /// A unique identifier for grouping related requests (e.g., a conversation or agent workflow) for observability. If provided in both the request body and the x-session-id header, the body value takes precedence. Maximum of 256 characters.
+        /// A unique identifier for grouping related requests (e.g., a conversation or agent workflow). When provided, OpenRouter uses it as the sticky routing key, routing all requests in the session to the same provider to maximize prompt cache hits. Also used for observability grouping. If provided in both the request body and the x-session-id header, the body value takes precedence. Maximum of 256 characters.
         /// </param>
         /// <param name="speed"></param>
         /// <param name="stopSequences"></param>
diff --git a/src/libs/OpenRouter/Generated/OpenRouter.ISubpackageBetaResponsesClient.CreateResponses.g.cs b/src/libs/OpenRouter/Generated/OpenRouter.ISubpackageBetaResponsesClient.CreateResponses.g.cs
index 454ee26..7370856 100644
--- a/src/libs/OpenRouter/Generated/OpenRouter.ISubpackageBetaResponsesClient.CreateResponses.g.cs
+++ b/src/libs/OpenRouter/Generated/OpenRouter.ISubpackageBetaResponsesClient.CreateResponses.g.cs
@@ -86,7 +86,7 @@ public partial interface ISubpackageBetaResponsesClient
         /// <param name="safetyIdentifier"></param>
         /// <param name="serviceTier"></param>
         /// <param name="sessionId">
-        /// A unique identifier for grouping related requests (e.g., a conversation or agent workflow) for observability. If provided in both the request body and the x-session-id header, the body value takes precedence. Maximum of 256 characters.
+        /// A unique identifier for grouping related requests (e.g., a conversation or agent workflow). When provided, OpenRouter uses it as the sticky routing key, routing all requests in the session to the same provider to maximize prompt cache hits. Also used for observability grouping. If provided in both the request body and the x-session-id header, the body value takes precedence. Maximum of 256 characters.
         /// </param>
         /// <param name="stopServerToolsWhen">
         /// Stop conditions for the server-tool agent loop. Any condition firing halts the loop (OR logic). When set, this overrides `max_tool_calls`.
diff --git a/src/libs/OpenRouter/Generated/OpenRouter.ISubpackageChatClient.SendChatCompletionRequest.g.cs b/src/libs/OpenRouter/Generated/OpenRouter.ISubpackageChatClient.SendChatCompletionRequest.g.cs
index 5cc9865..37aaf8c 100644
--- a/src/libs/OpenRouter/Generated/OpenRouter.ISubpackageChatClient.SendChatCompletionRequest.g.cs
+++ b/src/libs/OpenRouter/Generated/OpenRouter.ISubpackageChatClient.SendChatCompletionRequest.g.cs
@@ -110,7 +110,7 @@ public partial interface ISubpackageChatClient
         /// The service tier to use for processing this request.
         /// </param>
         /// <param name="sessionId">
-        /// A unique identifier for grouping related requests (e.g., a conversation or agent workflow) for observability. If provided in both the request body and the x-session-id header, the body value takes precedence. Maximum of 256 characters.
+        /// A unique identifier for grouping related requests (e.g., a conversation or agent workflow). When provided, OpenRouter uses it as the sticky routing key, routing all requests in the session to the same provider to maximize prompt cache hits. Also used for observability grouping. If provided in both the request body and the x-session-id header, the body value takes precedence. Maximum of 256 characters.
         /// </param>
         /// <param name="stop">
         /// Stop sequences (up to 4)
diff --git a/src/libs/OpenRouter/Generated/OpenRouter.ISubpackagePresetsClient.CreatePresetsChatCompletions.g.cs b/src/libs/OpenRouter/Generated/OpenRouter.ISubpackagePresetsClient.CreatePresetsChatCompletions.g.cs
index e8eb854..4cb84f6 100644
--- a/src/libs/OpenRouter/Generated/OpenRouter.ISubpackagePresetsClient.CreatePresetsChatCompletions.g.cs
+++ b/src/libs/OpenRouter/Generated/OpenRouter.ISubpackagePresetsClient.CreatePresetsChatCompletions.g.cs
@@ -104,7 +104,7 @@ public partial interface ISubpackagePresetsClient
         /// The service tier to use for processing this request.
         /// </param>
         /// <param name="sessionId">
-        /// A unique identifier for grouping related requests (e.g., a conversation or agent workflow) for observability. If provided in both the request body and the x-session-id header, the body value takes precedence. Maximum of 256 characters.
+        /// A unique identifier for grouping related requests (e.g., a conversation or agent workflow). When provided, OpenRouter uses it as the sticky routing key, routing all requests in the session to the same provider to maximize prompt cache hits. Also used for observability grouping. If provided in both the request body and the x-session-id header, the body value takes precedence. Maximum of 256 characters.
         /// </param>
         /// <param name="stop">
         /// Stop sequences (up to 4)
diff --git a/src/libs/OpenRouter/Generated/OpenRouter.ISubpackagePresetsClient.CreatePresetsMessages.g.cs b/src/libs/OpenRouter/Generated/OpenRouter.ISubpackagePresetsClient.CreatePresetsMessages.g.cs
index 5fbb4fb..ab97476 100644
--- a/src/libs/OpenRouter/Generated/OpenRouter.ISubpackagePresetsClient.CreatePresetsMessages.g.cs
+++ b/src/libs/OpenRouter/Generated/OpenRouter.ISubpackagePresetsClient.CreatePresetsMessages.g.cs
@@ -62,7 +62,7 @@ public partial interface ISubpackagePresetsClient
         /// </param>
         /// <param name="serviceTier"></param>
         /// <param name="sessionId">
-        /// A unique identifier for grouping related requests (e.g., a conversation or agent workflow) for observability. If provided in both the request body and the x-session-id header, the body value takes precedence. Maximum of 256 characters.
+        /// A unique identifier for grouping related requests (e.g., a conversation or agent workflow). When provided, OpenRouter uses it as the sticky routing key, routing all requests in the session to the same provider to maximize prompt cache hits. Also used for observability grouping. If provided in both the request body and the x-session-id header, the body value takes precedence. Maximum of 256 characters.
         /// </param>
         /// <param name="speed"></param>
         /// <param name="stopSequences"></param>
diff --git a/src/libs/OpenRouter/Generated/OpenRouter.ISubpackagePresetsClient.CreatePresetsResponses.g.cs b/src/libs/OpenRouter/Generated/OpenRouter.ISubpackagePresetsClient.CreatePresetsResponses.g.cs
index 9d60250..2e1d5fb 100644
--- a/src/libs/OpenRouter/Generated/OpenRouter.ISubpackagePresetsClient.CreatePresetsResponses.g.cs
+++ b/src/libs/OpenRouter/Generated/OpenRouter.ISubpackagePresetsClient.CreatePresetsResponses.g.cs
@@ -80,7 +80,7 @@ public partial interface ISubpackagePresetsClient
         /// <param name="safetyIdentifier"></param>
         /// <param name="serviceTier"></param>
         /// <param name="sessionId">
-        /// A unique identifier for grouping related requests (e.g., a conversation or agent workflow) for observability. If provided in both the request body and the x-session-id header, the body value takes precedence. Maximum of 256 characters.
+        /// A unique identifier for grouping related requests (e.g., a conversation or agent workflow). When provided, OpenRouter uses it as the sticky routing key, routing all requests in the session to the same provider to maximize prompt cache hits. Also used for observability grouping. If provided in both the request body and the x-session-id header, the body value takes precedence. Maximum of 256 characters.
         /// </param>
         /// <param name="stopServerToolsWhen">
         /// Stop conditions for the server-tool agent loop. Any condition firing halts the loop (OR logic). When set, this overrides `max_tool_calls`.
diff --git a/src/libs/OpenRouter/Generated/OpenRouter.Models.ChatRequest.g.cs b/src/libs/OpenRouter/Generated/OpenRouter.Models.ChatRequest.g.cs
index 91ab068..b91af1e 100644
--- a/src/libs/OpenRouter/Generated/OpenRouter.Models.ChatRequest.g.cs
+++ b/src/libs/OpenRouter/Generated/OpenRouter.Models.ChatRequest.g.cs
@@ -145,7 +145,7 @@ public sealed partial class ChatRequest
         public global::OpenRouter.OneOf<global::OpenRouter.ChatRequestServiceTier?, object>? ServiceTier { get; set; }
 
         /// <summary>
-        /// A unique identifier for grouping related requests (e.g., a conversation or agent workflow) for observability. If provided in both the request body and the x-session-id header, the body value takes precedence. Maximum of 256 characters.
+        /// A unique identifier for grouping related requests (e.g., a conversation or agent workflow). When provided, OpenRouter uses it as the sticky routing key, routing all requests in the session to the same provider to maximize prompt cache hits. Also used for observability grouping. If provided in both the request body and the x-session-id header, the body value takes precedence. Maximum of 256 characters.
         /// </summary>
         [global::System.Text.Json.Serialization.JsonPropertyName("session_id")]
         public string? SessionId { get; set; }
@@ -293,7 +293,7 @@ public sealed partial class ChatRequest
         /// The service tier to use for processing this request.
         /// </param>
         /// <param name="sessionId">
-        /// A unique identifier for grouping related requests (e.g., a conversation or agent workflow) for observability. If provided in both the request body and the x-session-id header, the body value takes precedence. Maximum of 256 characters.
+        /// A unique identifier for grouping related requests (e.g., a conversation or agent workflow). When provided, OpenRouter uses it as the sticky routing key, routing all requests in the session to the same provider to maximize prompt cache hits. Also used for observability grouping. If provided in both the request body and the x-session-id header, the body value takes precedence. Maximum of 256 characters.
         /// </param>
         /// <param name="stop">
         /// Stop sequences (up to 4)
diff --git a/src/libs/OpenRouter/Generated/OpenRouter.Models.MessagesRequest.g.cs b/src/libs/OpenRouter/Generated/OpenRouter.Models.MessagesRequest.g.cs
index 396119d..1b919f7 100644
--- a/src/libs/OpenRouter/Generated/OpenRouter.Models.MessagesRequest.g.cs
+++ b/src/libs/OpenRouter/Generated/OpenRouter.Models.MessagesRequest.g.cs
@@ -83,7 +83,7 @@ public sealed partial class MessagesRequest
         public string? ServiceTier { get; set; }
 
         /// <summary>
-        /// A unique identifier for grouping related requests (e.g., a conversation or agent workflow) for observability. If provided in both the request body and the x-session-id header, the body value takes precedence. Maximum of 256 characters.
+        /// A unique identifier for grouping related requests (e.g., a conversation or agent workflow). When provided, OpenRouter uses it as the sticky routing key, routing all requests in the session to the same provider to maximize prompt cache hits. Also used for observability grouping. If provided in both the request body and the x-session-id header, the body value takes precedence. Maximum of 256 characters.
         /// </summary>
         [global::System.Text.Json.Serialization.JsonPropertyName("session_id")]
         public string? SessionId { get; set; }
@@ -202,7 +202,7 @@ public sealed partial class MessagesRequest
         /// </param>
         /// <param name="serviceTier"></param>
         /// <param name="sessionId">
-        /// A unique identifier for grouping related requests (e.g., a conversation or agent workflow) for observability. If provided in both the request body and the x-session-id header, the body value takes precedence. Maximum of 256 characters.
+        /// A unique identifier for grouping related requests (e.g., a conversation or agent workflow). When provided, OpenRouter uses it as the sticky routing key, routing all requests in the session to the same provider to maximize prompt cache hits. Also used for observability grouping. If provided in both the request body and the x-session-id header, the body value takes precedence. Maximum of 256 characters.
         /// </param>
         /// <param name="speed"></param>
         /// <param name="stopSequences"></param>
diff --git a/src/libs/OpenRouter/Generated/OpenRouter.Models.ResponsesRequest.g.cs b/src/libs/OpenRouter/Generated/OpenRouter.Models.ResponsesRequest.g.cs
index d671a81..6560a1e 100644
--- a/src/libs/OpenRouter/Generated/OpenRouter.Models.ResponsesRequest.g.cs
+++ b/src/libs/OpenRouter/Generated/OpenRouter.Models.ResponsesRequest.g.cs
@@ -156,7 +156,7 @@ public sealed partial class ResponsesRequest
         public global::OpenRouter.OneOf<global::OpenRouter.ResponsesRequestServiceTier?, object>? ServiceTier { get; set; }
 
         /// <summary>
-        /// A unique identifier for grouping related requests (e.g., a conversation or agent workflow) for observability. If provided in both the request body and the x-session-id header, the body value takes precedence. Maximum of 256 characters.
+        /// A unique identifier for grouping related requests (e.g., a conversation or agent workflow). When provided, OpenRouter uses it as the sticky routing key, routing all requests in the session to the same provider to maximize prompt cache hits. Also used for observability grouping. If provided in both the request body and the x-session-id header, the body value takes precedence. Maximum of 256 characters.
         /// </summary>
         [global::System.Text.Json.Serialization.JsonPropertyName("session_id")]
         public string? SessionId { get; set; }
@@ -291,7 +291,7 @@ public sealed partial class ResponsesRequest
         /// <param name="safetyIdentifier"></param>
         /// <param name="serviceTier"></param>
         /// <param name="sessionId">
-        /// A unique identifier for grouping related requests (e.g., a conversation or agent workflow) for observability. If provided in both the request body and the x-session-id header, the body value takes precedence. Maximum of 256 characters.
+        /// A unique identifier for grouping related requests (e.g., a conversation or agent workflow). When provided, OpenRouter uses it as the sticky routing key, routing all requests in the session to the same provider to maximize prompt cache hits. Also used for observability grouping. If provided in both the request body and the x-session-id header, the body value takes precedence. Maximum of 256 characters.
         /// </param>
         /// <param name="stopServerToolsWhen">
         /// Stop conditions for the server-tool agent loop. Any condition firing halts the loop (OR logic). When set, this overrides `max_tool_calls`.
diff --git a/src/libs/OpenRouter/Generated/OpenRouter.SubpackageAnthropicMessagesClient.CreateMessages.g.cs b/src/libs/OpenRouter/Generated/OpenRouter.SubpackageAnthropicMessagesClient.CreateMessages.g.cs
index fb8a6a6..d9d9a01 100644
--- a/src/libs/OpenRouter/Generated/OpenRouter.SubpackageAnthropicMessagesClient.CreateMessages.g.cs
+++ b/src/libs/OpenRouter/Generated/OpenRouter.SubpackageAnthropicMessagesClient.CreateMessages.g.cs
@@ -741,7 +741,7 @@ partial void ProcessCreateMessagesResponseContent(
         /// </param>
         /// <param name="serviceTier"></param>
         /// <param name="sessionId">
-        /// A unique identifier for grouping related requests (e.g., a conversation or agent workflow) for observability. If provided in both the request body and the x-session-id header, the body value takes precedence. Maximum of 256 characters.
+        /// A unique identifier for grouping related requests (e.g., a conversation or agent workflow). When provided, OpenRouter uses it as the sticky routing key, routing all requests in the session to the same provider to maximize prompt cache hits. Also used for observability grouping. If provided in both the request body and the x-session-id header, the body value takes precedence. Maximum of 256 characters.
         /// </param>
         /// <param name="speed"></param>
         /// <param name="stopSequences"></param>
diff --git a/src/libs/OpenRouter/Generated/OpenRouter.SubpackageBetaResponsesClient.CreateResponses.g.cs b/src/libs/OpenRouter/Generated/OpenRouter.SubpackageBetaResponsesClient.CreateResponses.g.cs
index cd52068..9801eff 100644
--- a/src/libs/OpenRouter/Generated/OpenRouter.SubpackageBetaResponsesClient.CreateResponses.g.cs
+++ b/src/libs/OpenRouter/Generated/OpenRouter.SubpackageBetaResponsesClient.CreateResponses.g.cs
@@ -944,7 +944,7 @@ partial void ProcessCreateResponsesResponseContent(
         /// <param name="safetyIdentifier"></param>
         /// <param name="serviceTier"></param>
         /// <param name="sessionId">
-        /// A unique identifier for grouping related requests (e.g., a conversation or agent workflow) for observability. If provided in both the request body and the x-session-id header, the body value takes precedence. Maximum of 256 characters.
+        /// A unique identifier for grouping related requests (e.g., a conversation or agent workflow). When provided, OpenRouter uses it as the sticky routing key, routing all requests in the session to the same provider to maximize prompt cache hits. Also used for observability grouping. If provided in both the request body and the x-session-id header, the body value takes precedence. Maximum of 256 characters.
         /// </param>
         /// <param name="stopServerToolsWhen">
         /// Stop conditions for the server-tool agent loop. Any condition firing halts the loop (OR logic). When set, this overrides `max_tool_calls`.
diff --git a/src/libs/OpenRouter/Generated/OpenRouter.SubpackageChatClient.SendChatCompletionRequest.g.cs b/src/libs/OpenRouter/Generated/OpenRouter.SubpackageChatClient.SendChatCompletionRequest.g.cs
index 1ab53d7..c1e2c4b 100644
--- a/src/libs/OpenRouter/Generated/OpenRouter.SubpackageChatClient.SendChatCompletionRequest.g.cs
+++ b/src/libs/OpenRouter/Generated/OpenRouter.SubpackageChatClient.SendChatCompletionRequest.g.cs
@@ -968,7 +968,7 @@ partial void ProcessSendChatCompletionRequestResponseContent(
         /// The service tier to use for processing this request.
         /// </param>
         /// <param name="sessionId">
-        /// A unique identifier for grouping related requests (e.g., a conversation or agent workflow) for observability. If provided in both the request body and the x-session-id header, the body value takes precedence. Maximum of 256 characters.
+        /// A unique identifier for grouping related requests (e.g., a conversation or agent workflow). When provided, OpenRouter uses it as the sticky routing key, routing all requests in the session to the same provider to maximize prompt cache hits. Also used for observability grouping. If provided in both the request body and the x-session-id header, the body value takes precedence. Maximum of 256 characters.
         /// </param>
         /// <param name="stop">
         /// Stop sequences (up to 4)
diff --git a/src/libs/OpenRouter/Generated/OpenRouter.SubpackagePresetsClient.CreatePresetsChatCompletions.g.cs b/src/libs/OpenRouter/Generated/OpenRouter.SubpackagePresetsClient.CreatePresetsChatCompletions.g.cs
index 067f2a4..50b4cb2 100644
--- a/src/libs/OpenRouter/Generated/OpenRouter.SubpackagePresetsClient.CreatePresetsChatCompletions.g.cs
+++ b/src/libs/OpenRouter/Generated/OpenRouter.SubpackagePresetsClient.CreatePresetsChatCompletions.g.cs
@@ -734,7 +734,7 @@ partial void ProcessCreatePresetsChatCompletionsResponseContent(
         /// The service tier to use for processing this request.
         /// </param>
         /// <param name="sessionId">
-        /// A unique identifier for grouping related requests (e.g., a conversation or agent workflow) for observability. If provided in both the request body and the x-session-id header, the body value takes precedence. Maximum of 256 characters.
+        /// A unique identifier for grouping related requests (e.g., a conversation or agent workflow). When provided, OpenRouter uses it as the sticky routing key, routing all requests in the session to the same provider to maximize prompt cache hits. Also used for observability grouping. If provided in both the request body and the x-session-id header, the body value takes precedence. Maximum of 256 characters.
         /// </param>
         /// <param name="stop">
         /// Stop sequences (up to 4)
diff --git a/src/libs/OpenRouter/Generated/OpenRouter.SubpackagePresetsClient.CreatePresetsMessages.g.cs b/src/libs/OpenRouter/Generated/OpenRouter.SubpackagePresetsClient.CreatePresetsMessages.g.cs
index 18a7057..35c47c9 100644
--- a/src/libs/OpenRouter/Generated/OpenRouter.SubpackagePresetsClient.CreatePresetsMessages.g.cs
+++ b/src/libs/OpenRouter/Generated/OpenRouter.SubpackagePresetsClient.CreatePresetsMessages.g.cs
@@ -692,7 +692,7 @@ partial void ProcessCreatePresetsMessagesResponseContent(
         /// </param>
         /// <param name="serviceTier"></param>
         /// <param name="sessionId">
-        /// A unique identifier for grouping related requests (e.g., a conversation or agent workflow) for observability. If provided in both the request body and the x-session-id header, the body value takes precedence. Maximum of 256 characters.
+        /// A unique identifier for grouping related requests (e.g., a conversation or agent workflow). When provided, OpenRouter uses it as the sticky routing key, routing all requests in the session to the same provider to maximize prompt cache hits. Also used for observability grouping. If provided in both the request body and the x-session-id header, the body value takes precedence. Maximum of 256 characters.
         /// </param>
         /// <param name="speed"></param>
         /// <param name="stopSequences"></param>
diff --git a/src/libs/OpenRouter/Generated/OpenRouter.SubpackagePresetsClient.CreatePresetsResponses.g.cs b/src/libs/OpenRouter/Generated/OpenRouter.SubpackagePresetsClient.CreatePresetsResponses.g.cs
index d03015e..3871fb8 100644
--- a/src/libs/OpenRouter/Generated/OpenRouter.SubpackagePresetsClient.CreatePresetsResponses.g.cs
+++ b/src/libs/OpenRouter/Generated/OpenRouter.SubpackagePresetsClient.CreatePresetsResponses.g.cs
@@ -710,7 +710,7 @@ partial void ProcessCreatePresetsResponsesResponseContent(
         /// <param name="safetyIdentifier"></param>
         /// <param name="serviceTier"></param>
         /// <param name="sessionId">
-        /// A unique identifier for grouping related requests (e.g., a conversation or agent workflow) for observability. If provided in both the request body and the x-session-id header, the body value takes precedence. Maximum of 256 characters.
+        /// A unique identifier for grouping related requests (e.g., a conversation or agent workflow). When provided, OpenRouter uses it as the sticky routing key, routing all requests in the session to the same provider to maximize prompt cache hits. Also used for observability grouping. If provided in both the request body and the x-session-id header, the body value takes precedence. Maximum of 256 characters.
         /// </param>
         /// <param name="stopServerToolsWhen">
         /// Stop conditions for the server-tool agent loop. Any condition firing halts the loop (OR logic). When set, this overrides `max_tool_calls`.
diff --git a/src/libs/OpenRouter/openapi.yaml b/src/libs/OpenRouter/openapi.yaml
index ec9225b..4b5bef2 100644
--- a/src/libs/OpenRouter/openapi.yaml
+++ b/src/libs/OpenRouter/openapi.yaml
@@ -11672,7 +11672,7 @@
           },
           "session_id": {
             "type": "string",
-            "description": "A unique identifier for grouping related requests (e.g., a conversation or agent workflow) for observability. If provided in both the request body and the x-session-id header, the body value takes precedence. Maximum of 256 characters."
+            "description": "A unique identifier for grouping related requests (e.g., a conversation or agent workflow). When provided, OpenRouter uses it as the sticky routing key, routing all requests in the session to the same provider to maximize prompt cache hits. Also used for observability grouping. If provided in both the request body and the x-session-id header, the body value takes precedence. Maximum of 256 characters."
           },
           "stop_server_tools_when": {
             "$ref": "#/components/schemas/StopServerToolsWhen"
@@ -18600,7 +18600,7 @@
           },
           "session_id": {
             "type": "string",
-            "description": "A unique identifier for grouping related requests (e.g., a conversation or agent workflow) for observability. If provided in both the request body and the x-session-id header, the body value takes precedence. Maximum of 256 characters."
+            "description": "A unique identifier for grouping related requests (e.g., a conversation or agent workflow). When provided, OpenRouter uses it as the sticky routing key, routing all requests in the session to the same provider to maximize prompt cache hits. Also used for observability grouping. If provided in both the request body and the x-session-id header, the body value takes precedence. Maximum of 256 characters."
           },
           "stop": {
             "$ref": "#/components/schemas/ChatRequestStop",
@@ -25817,7 +25817,7 @@
           },
           "session_id": {
             "type": "string",
-            "description": "A unique identifier for grouping related requests (e.g., a conversation or agent workflow) for observability. If provided in both the request body and the x-session-id header, the body value takes precedence. Maximum of 256 characters."
+            "description": "A unique identifier for grouping related requests (e.g., a conversation or agent workflow). When provided, OpenRouter uses it as the sticky routing key, routing all requests in the session to the same provider to maximize prompt cache hits. Also used for observability grouping. If provided in both the request body and the x-session-id header, the body value takes precedence. Maximum of 256 characters."
           },
           "speed": {
             "$ref": "#/components/schemas/AnthropicSpeed"