diff --git a/src/agents/system-prompt.ts b/src/agents/system-prompt.ts
index 40ecd8607..16e12fe10 100644
--- a/src/agents/system-prompt.ts
+++ b/src/agents/system-prompt.ts
@@ -547,13 +547,17 @@ export function buildAgentSystemPrompt(params: {
     );
   }
 
-  lines.push("## Runtime", buildRuntimeLine(runtimeInfo, runtimeChannel, runtimeCapabilities, params.defaultThinkLevel), `Reasoning: ${reasoningLevel} (hidden unless on/stream). Toggle /reasoning; /status shows Reasoning when enabled.`);
+  lines.push(
+    "## Runtime",
+    buildRuntimeLine(runtimeInfo, runtimeChannel, runtimeCapabilities, params.defaultThinkLevel),
+    `Reasoning: ${reasoningLevel} (hidden unless on/stream). Toggle /reasoning; /status shows Reasoning when enabled.`,
+  );
 
   return lines.filter(Boolean).join("\n");
 }
 
 export function buildRuntimeLine(
-  runtimeInfo: {
+  runtimeInfo?: {
     agentId?: string;
     host?: string;
     os?: string;
diff --git a/src/types/cli-highlight.d.ts b/src/types/cli-highlight.d.ts
new file mode 100644
index 000000000..ab4ad92fb
--- /dev/null
+++ b/src/types/cli-highlight.d.ts
@@ -0,0 +1,10 @@
+declare module "cli-highlight" {
+  export type HighlightOptions = {
+    language?: string;
+    theme?: unknown;
+    ignoreIllegals?: boolean;
+  };
+
+  export function highlight(code: string, options?: HighlightOptions): string;
+  export function supportsLanguage(language: string): boolean;
+}