language_model: Add supported_effort_levels method to LanguageModel (#48523)

This PR adds a new `supported_effort_levels` method to the
`LanguageModel` trait.

This can be used to retrieve the list of effort levels that the model
supports, which will eventually be used to drive the UI for selecting
the thinking effort.

Right now this list will only be populated for Cloud models.

Release Notes:

- N/A

crates/cloud_llm_client/src/cloud_llm_client.rs

@@ -297,6 +297,7 @@ pub struct LanguageModel {
     pub supports_tools: bool,
     pub supports_images: bool,
     pub supports_thinking: bool,
+    pub supported_effort_levels: Vec<SupportedEffortLevel>,
     #[serde(default)]
     pub supports_streaming_tools: bool,
     /// Only used by OpenAI and xAI.
@@ -304,6 +305,12 @@ pub struct LanguageModel {
     pub supports_parallel_tool_calls: bool,
 }
 
+#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
+pub struct SupportedEffortLevel {
+    pub name: Arc<str>,
+    pub value: Arc<str>,
+}
+
 #[derive(Debug, Serialize, Deserialize)]
 pub struct ListModelsResponse {
     pub models: Vec<LanguageModel>,

crates/language_model/src/language_model.rs

@@ -573,6 +573,12 @@ impl Default for LanguageModelTextStream {
     }
 }
 
+#[derive(Debug, Clone)]
+pub struct LanguageModelEffortLevel {
+    pub name: SharedString,
+    pub value: SharedString,
+}
+
 pub trait LanguageModel: Send + Sync {
     fn id(&self) -> LanguageModelId;
     fn name(&self) -> LanguageModelName;
@@ -591,11 +597,16 @@ pub trait LanguageModel: Send + Sync {
         None
     }
 
-    /// Whether this model supports extended thinking.
+    /// Whether this model supports thinking.
     fn supports_thinking(&self) -> bool {
         false
     }
 
+    /// Returns the list of supported effort levels that can be used when thinking.
+    fn supported_effort_levels(&self) -> Vec<LanguageModelEffortLevel> {
+        Vec::new()
+    }
+
     /// Whether this model supports images
     fn supports_images(&self) -> bool;
 

crates/language_models/src/provider/cloud.rs

@@ -19,11 +19,11 @@ use http_client::http::{HeaderMap, HeaderValue};
 use http_client::{AsyncBody, HttpClient, HttpRequestExt, Method, Response, StatusCode};
 use language_model::{
     AuthenticateError, IconOrSvg, LanguageModel, LanguageModelCacheConfiguration,
-    LanguageModelCompletionError, LanguageModelCompletionEvent, LanguageModelId, LanguageModelName,
-    LanguageModelProvider, LanguageModelProviderId, LanguageModelProviderName,
-    LanguageModelProviderState, LanguageModelRequest, LanguageModelToolChoice,
-    LanguageModelToolSchemaFormat, LlmApiToken, NeedsLlmTokenRefresh, PaymentRequiredError,
-    RateLimiter, RefreshLlmTokenListener,
+    LanguageModelCompletionError, LanguageModelCompletionEvent, LanguageModelEffortLevel,
+    LanguageModelId, LanguageModelName, LanguageModelProvider, LanguageModelProviderId,
+    LanguageModelProviderName, LanguageModelProviderState, LanguageModelRequest,
+    LanguageModelToolChoice, LanguageModelToolSchemaFormat, LlmApiToken, NeedsLlmTokenRefresh,
+    PaymentRequiredError, RateLimiter, RefreshLlmTokenListener,
 };
 use release_channel::AppVersion;
 use schemars::JsonSchema;
@@ -577,6 +577,17 @@ impl LanguageModel for CloudLanguageModel {
         self.model.supports_thinking
     }
 
+    fn supported_effort_levels(&self) -> Vec<LanguageModelEffortLevel> {
+        self.model
+            .supported_effort_levels
+            .iter()
+            .map(|effort_level| LanguageModelEffortLevel {
+                name: effort_level.name.clone().into(),
+                value: effort_level.value.clone().into(),
+            })
+            .collect()
+    }
+
     fn supports_streaming_tools(&self) -> bool {
         self.model.supports_streaming_tools
     }