language_models: Add thinking support to OpenRouter provider (#32541)

Did some bit cleanup of code for loading models for settings as that is
not required as we are fetching all the models from openrouter so it's
better to maintain one source of truth

Release Notes:

- Add thinking support to OpenRouter provider

crates/open_router/src/open_router.rs

@@ -53,6 +53,18 @@ pub struct Model {
     pub max_tokens: u64,
     pub supports_tools: Option<bool>,
     pub supports_images: Option<bool>,
+    #[serde(default)]
+    pub mode: ModelMode,
+}
+
+#[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
+#[derive(Clone, Debug, Default, Serialize, Deserialize, PartialEq)]
+pub enum ModelMode {
+    #[default]
+    Default,
+    Thinking {
+        budget_tokens: Option<u32>,
+    },
 }
 
 impl Model {
@@ -63,6 +75,7 @@ impl Model {
             Some(2000000),
             Some(true),
             Some(false),
+            Some(ModelMode::Default),
         )
     }
 
@@ -76,6 +89,7 @@ impl Model {
         max_tokens: Option<u64>,
         supports_tools: Option<bool>,
         supports_images: Option<bool>,
+        mode: Option<ModelMode>,
     ) -> Self {
         Self {
             name: name.to_owned(),
@@ -83,6 +97,7 @@ impl Model {
             max_tokens: max_tokens.unwrap_or(2000000),
             supports_tools,
             supports_images,
+            mode: mode.unwrap_or(ModelMode::Default),
         }
     }
 
@@ -127,6 +142,8 @@ pub struct Request {
     pub parallel_tool_calls: Option<bool>,
     #[serde(default, skip_serializing_if = "Vec::is_empty")]
     pub tools: Vec<ToolDefinition>,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub reasoning: Option<Reasoning>,
     pub usage: RequestUsage,
 }
 
@@ -160,6 +177,18 @@ pub struct FunctionDefinition {
     pub parameters: Option<Value>,
 }
 
+#[derive(Debug, Serialize, Deserialize)]
+pub struct Reasoning {
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub effort: Option<String>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub max_tokens: Option<u32>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub exclude: Option<bool>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub enabled: Option<bool>,
+}
+
 #[derive(Serialize, Deserialize, Debug, Eq, PartialEq)]
 #[serde(tag = "role", rename_all = "lowercase")]
 pub enum RequestMessage {
@@ -299,6 +328,7 @@ pub struct FunctionContent {
 pub struct ResponseMessageDelta {
     pub role: Option<Role>,
     pub content: Option<String>,
+    pub reasoning: Option<String>,
     #[serde(default, skip_serializing_if = "is_none_or_empty")]
     pub tool_calls: Option<Vec<ToolCallChunk>>,
 }
@@ -591,6 +621,16 @@ pub async fn list_models(client: &dyn HttpClient, api_url: &str) -> Result<Vec<M
                         .map(|arch| arch.input_modalities.contains(&"image".to_string()))
                         .unwrap_or(false),
                 ),
+                mode: if entry
+                    .supported_parameters
+                    .contains(&"reasoning".to_string())
+                {
+                    ModelMode::Thinking {
+                        budget_tokens: Some(4_096),
+                    }
+                } else {
+                    ModelMode::Default
+                },
             })
             .collect();