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

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}`,