diff --git a/src/core/agent/AntigravityProvider.ts b/src/core/agent/AntigravityProvider.ts
index e641442..3c7ddce 100644
--- a/src/core/agent/AntigravityProvider.ts
+++ b/src/core/agent/AntigravityProvider.ts
@@ -117,8 +117,11 @@ export class AntigravityProvider implements AgentProvider {
       child.kill();
     }, 5 * 60 * 1000);
 
+    const stdoutDecoder = new TextDecoder('utf-8');
+    const stderrDecoder = new TextDecoder('utf-8');
+
     child.stdout!.on('data', (chunk: Buffer) => {
-      const text = chunk.toString();
+      const text = stdoutDecoder.decode(chunk, { stream: true });
       stdoutFull += text;
       stdoutBuffer += text;
       const lines = stdoutBuffer.split(/\r?\n/);
@@ -129,7 +132,7 @@ export class AntigravityProvider implements AgentProvider {
       }
     });
     child.stderr!.on('data', (chunk: Buffer) => {
-      const text = chunk.toString();
+      const text = stderrDecoder.decode(chunk, { stream: true });
       stderrFull += text;
       stderrBuffer += text;
     });
@@ -138,6 +141,8 @@ export class AntigravityProvider implements AgentProvider {
       done = true;
     });
     child.on('close', (code) => {
+      stdoutFull += stdoutDecoder.decode();
+      stderrFull += stderrDecoder.decode();
       exitCode = code;
       window.clearTimeout(timeout);
       if (code && code !== 0) {
diff --git a/src/core/cli/ExternalCliRunner.ts b/src/core/cli/ExternalCliRunner.ts
index 4c8b595..fbab03f 100644
--- a/src/core/cli/ExternalCliRunner.ts
+++ b/src/core/cli/ExternalCliRunner.ts
@@ -151,22 +151,27 @@ function runProcess(command: string, args: string[], env: NodeJS.ProcessEnv, cwd
       windowsHide: false,
     });
 
+    const stdoutDecoder = new TextDecoder('utf-8');
+    const stderrDecoder = new TextDecoder('utf-8');
+
     const timeout = globalThis.setTimeout(() => {
       child.kill('SIGTERM');
       reject(new Error(`${path.basename(command)} timed out after ${Math.round(timeoutMs / 1000)} seconds`));
     }, timeoutMs);
 
     child.stdout?.on('data', (chunk: Buffer) => {
-      stdout += chunk.toString();
+      stdout += stdoutDecoder.decode(chunk, { stream: true });
     });
     child.stderr?.on('data', (chunk: Buffer) => {
-      stderr += chunk.toString();
+      stderr += stderrDecoder.decode(chunk, { stream: true });
     });
     child.on('error', (error) => {
       globalThis.clearTimeout(timeout);
       reject(error);
     });
     child.on('close', (code) => {
+      stdout += stdoutDecoder.decode();
+      stderr += stderrDecoder.decode();
       globalThis.clearTimeout(timeout);
       if (code && code !== 0) {
         reject(new Error(`${path.basename(command)} exited with code ${code}\n${stderr || stdout}`.trim()));