language_models: Improve token counting for providers (#32853)

We push the usage data whenever we receive it from the provider to make
sure the counting is correct after the turn has ended.

- [x] Ollama 
- [x] Copilot 
- [x] Mistral 
- [x] OpenRouter 
- [x] LMStudio

Put all the changes into a single PR open to move these to separate PR
if that makes the review and testing easier.

Release Notes:

- N/A

crates/language_models/src/provider/open_router.rs

@@ -12,7 +12,7 @@ use language_model::{
     LanguageModelId, LanguageModelName, LanguageModelProvider, LanguageModelProviderId,
     LanguageModelProviderName, LanguageModelProviderState, LanguageModelRequest,
     LanguageModelToolChoice, LanguageModelToolResultContent, LanguageModelToolUse, MessageContent,
-    RateLimiter, Role, StopReason,
+    RateLimiter, Role, StopReason, TokenUsage,
 };
 use open_router::{Model, ResponseStreamEvent, list_models, stream_completion};
 use schemars::JsonSchema;
@@ -467,6 +467,7 @@ pub fn into_open_router(
         } else {
             None
         },
+        usage: open_router::RequestUsage { include: true },
         tools: request
             .tools
             .into_iter()
@@ -581,6 +582,15 @@ impl OpenRouterEventMapper {
             }
         }
 
+        if let Some(usage) = event.usage {
+            events.push(Ok(LanguageModelCompletionEvent::UsageUpdate(TokenUsage {
+                input_tokens: usage.prompt_tokens,
+                output_tokens: usage.completion_tokens,
+                cache_creation_input_tokens: 0,
+                cache_read_input_tokens: 0,
+            })));
+        }
+
         match choice.finish_reason.as_deref() {
             Some("stop") => {
                 events.push(Ok(LanguageModelCompletionEvent::Stop(StopReason::EndTurn)));
@@ -609,7 +619,7 @@ impl OpenRouterEventMapper {
                 events.push(Ok(LanguageModelCompletionEvent::Stop(StopReason::ToolUse)));
             }
             Some(stop_reason) => {
-                log::error!("Unexpected OpenAI stop_reason: {stop_reason:?}",);
+                log::error!("Unexpected OpenRouter stop_reason: {stop_reason:?}",);
                 events.push(Ok(LanguageModelCompletionEvent::Stop(StopReason::EndTurn)));
             }
             None => {}