diff --git a/src/outputFormat.ts b/src/outputFormat.ts
index e57579de..fe3c30f9 100644
--- a/src/outputFormat.ts
+++ b/src/outputFormat.ts
@@ -19,7 +19,23 @@ export class OutputFormat {
     this.quiet = opts.quiet;
     this.dataArr = [];
   }
-  onInit(opts: {
+  async write(data: string): Promise<void> {
+    return new Promise((resolve, reject) => {
+      const result = process.stdout.write(data, (error) => {
+        if (error) {
+          reject(error);
+        } else {
+          resolve();
+        }
+      });
+      // If the buffer is full, wait for the 'drain' event
+      if (!result) {
+        process.stdout.once('drain', resolve);
+      }
+    });
+  }
+
+  async onInit(opts: {
     text: string;
     sessionId: string;
     cwd: string;
@@ -39,23 +55,25 @@ export class OutputFormat {
       tools: opts.tools.map((tool) => tool.name),
     };
     if (this.format === 'stream-json') {
-      console.log(JSON.stringify(data));
+      await this.write(JSON.stringify(data) + '\n');
     } else if (this.format === 'json') {
       this.dataArr.push(data);
     }
   }
-  onMessage(opts: { message: any }) {
+
+  async onMessage(opts: { message: any }) {
     if (!this.quiet) {
       return;
     }
     const data = { ...opts.message };
     if (this.format === 'stream-json') {
-      console.log(JSON.stringify(data));
+      await this.write(JSON.stringify(data) + '\n');
     } else if (this.format === 'json') {
       this.dataArr.push(data);
     }
   }
-  onEnd(opts: { result: LoopResult; sessionId: string }) {
+
+  async onEnd(opts: { result: LoopResult; sessionId: string }) {
     if (!this.quiet) {
       return;
     }
@@ -78,15 +96,15 @@ export class OutputFormat {
       };
     }
     if (this.format === 'stream-json') {
-      console.log(JSON.stringify(data));
+      await this.write(JSON.stringify(data) + '\n');
     } else if (this.format === 'json') {
       this.dataArr.push(data);
-      console.log(JSON.stringify(this.dataArr));
+      await this.write(JSON.stringify(this.dataArr) + '\n');
     } else if (this.format === 'text') {
-      console.log(
-        opts.result.success
+      await this.write(
+        (opts.result.success
           ? opts.result.data?.text || ''
-          : opts.result.error.message,
+          : opts.result.error.message) + '\n',
       );
     }
   }
diff --git a/src/project.ts b/src/project.ts
index e95d71d8..57492548 100644
--- a/src/project.ts
+++ b/src/project.ts
@@ -167,7 +167,6 @@ export class Project {
       format: this.context.config.outputFormat!,
       quiet: this.context.config.quiet,
     });
-
     const jsonlLogger = new JsonlLogger({
       filePath: this.context.paths.getSessionLogPath(this.session.id),
     });
@@ -280,7 +279,7 @@ export class Project {
 
     // Output model info for initial message
     if (message !== null) {
-      outputFormat.onInit({
+      await outputFormat.onInit({
         text: message,
         sessionId: this.session.id,
         tools,
@@ -306,7 +305,7 @@ export class Project {
           ...message,
           sessionId: this.session.id,
         };
-        outputFormat.onMessage({
+        await outputFormat.onMessage({
           message: normalizedMessage,
         });
         jsonlLogger.addMessage({
@@ -452,14 +451,14 @@ export class Project {
       ],
       type: PluginHookType.Series,
     });
-    outputFormat.onEnd({
+
+    await outputFormat.onEnd({
       result,
       sessionId: this.session.id,
     });
     if (result.success && result.data.history) {
       this.session.updateHistory(result.data.history);
     }
-
     return result;
   }
 }