fix: mutate prefixContext object instead of reassigning for closure correctness

src/auto-reply/reply/agent-runner-execution.ts

@@ -127,9 +127,6 @@ export async function runAgentTurnWithFallback(params: {
         run: (provider, model) => {
           // Notify that model selection is complete (including after fallback).
           // This allows responsePrefix template interpolation with the actual model.
-          logVerbose(
-            `[prefix-debug] onModelSelected firing: provider=${provider} model=${model} thinkLevel=${params.followupRun.run.thinkLevel}`,
-          );
           params.opts?.onModelSelected?.({
             provider,
             model,