tweak: tell the model what model it is in environment section of prompt

packages/opencode/src/session/prompt.ts

@@ -598,7 +598,7 @@ export namespace SessionPrompt {
         agent,
         abort,
         sessionID,
-        system: [...(await SystemPrompt.environment()), ...(await SystemPrompt.custom())],
+        system: [...(await SystemPrompt.environment(model)), ...(await SystemPrompt.custom())],
         messages: [
           ...MessageV2.toModelMessages(sessionMessages, model),
           ...(isLastStep

packages/opencode/src/session/system.ts

@@ -52,10 +52,11 @@ export namespace SystemPrompt {
     return [PROMPT_ANTHROPIC_WITHOUT_TODO]
   }
 
-  export async function environment() {
+  export async function environment(model: Provider.Model) {
     const project = Instance.project
     return [
       [
+        `You are powered by the model named ${model.api.id}. The exact model ID is ${model.providerID}/${model.api.id}`,
         `Here is some useful information about the environment you are running in:`,
         `<env>`,
         `  Working directory: ${Instance.directory}`,