diff --git a/nanobot/apps/cli/service.py b/nanobot/apps/cli/service.py
index 90c0e099..8c5d6391 100644
--- a/nanobot/apps/cli/service.py
+++ b/nanobot/apps/cli/service.py
@@ -961,6 +961,8 @@ class CliAppManager:
             argv,
             capture_output=True,
             text=True,
+            encoding="utf-8",
+            errors="replace",
             timeout=timeout,
         )
         logger.info("CLI Apps: command exited with code {}: {}", result.returncode, command)
@@ -1364,6 +1366,8 @@ Use the `run_cli_app` tool with `name="{name}"` for command execution. Do not in
                 cwd=str(cwd),
                 capture_output=True,
                 text=True,
+                encoding="utf-8",
+                errors="replace",
                 timeout=effective_timeout,
                 env=os.environ.copy(),
             )
diff --git a/tests/cli_apps/test_service.py b/tests/cli_apps/test_service.py
index 9a8d60be..7b0a312a 100644
--- a/tests/cli_apps/test_service.py
+++ b/tests/cli_apps/test_service.py
@@ -423,10 +423,14 @@ def test_run_argv_logs_command_exit_and_output(
         *,
         capture_output: bool,
         text: bool,
+        encoding: str,
+        errors: str,
         timeout: int,
     ) -> subprocess.CompletedProcess[str]:
         assert capture_output is True
         assert text is True
+        assert encoding == "utf-8"
+        assert errors == "replace"
         assert timeout == 5
         return subprocess.CompletedProcess(argv, 0, stdout="installed ok", stderr="")
 
@@ -441,6 +445,22 @@ def test_run_argv_logs_command_exit_and_output(
     assert any("installed ok" in record for record in records)
 
 
+def test_run_argv_decodes_utf8_output(tmp_path: Path) -> None:
+    manager = _manager(tmp_path)
+
+    result = manager._run_argv(
+        [
+            sys.executable,
+            "-c",
+            "import sys; sys.stdout.buffer.write(chr(0x2713).encode('utf-8'))",
+        ],
+        timeout=5,
+    )
+
+    assert result.returncode == 0
+    assert result.stdout == "\u2713"
+
+
 def test_install_records_available_cli_without_reinstalling(
     tmp_path: Path,
     monkeypatch: pytest.MonkeyPatch,
@@ -863,6 +883,9 @@ def test_run_installed_cli_uses_argv_without_shell(
 
     def fake_run(argv: list[str], **kwargs: object) -> subprocess.CompletedProcess[str]:
         assert "shell" not in kwargs or kwargs["shell"] is False
+        assert kwargs["text"] is True
+        assert kwargs["encoding"] == "utf-8"
+        assert kwargs["errors"] == "replace"
         return subprocess.CompletedProcess(
             argv,
             0,