From 5d24d33536d1041b4d9f107a5f5813bd43177530 Mon Sep 17 00:00:00 2001 From: Andrew Branson Date: Tue, 2 Jun 2026 00:18:14 +0200 Subject: Harden MCP transport error handling Normalize timeout output to text, convert tool exceptions into tool errors, and keep stdio running after response serialization failures. --- src/sailfish_devel_mcp/runner.py | 20 +++++++++++++++----- 1 file changed, 15 insertions(+), 5 deletions(-) (limited to 'src/sailfish_devel_mcp/runner.py') diff --git a/src/sailfish_devel_mcp/runner.py b/src/sailfish_devel_mcp/runner.py index b0b88bf..74748f4 100644 --- a/src/sailfish_devel_mcp/runner.py +++ b/src/sailfish_devel_mcp/runner.py @@ -4,7 +4,7 @@ from dataclasses import dataclass from pathlib import Path import shlex import subprocess -from typing import Iterable, Sequence +from typing import Any, Iterable, Sequence from .config import DeviceConfig @@ -39,6 +39,16 @@ def truncate(text: str, limit: int) -> tuple[str, bool]: return text[:limit] + f"\n[truncated after {limit} characters]", True +def ensure_text(value: Any) -> str: + if value is None: + return "" + if isinstance(value, str): + return value + if isinstance(value, bytes): + return value.decode("utf-8", errors="replace") + return str(value) + + def run( argv: Sequence[str], *, @@ -57,15 +67,15 @@ def run( return CommandResult( argv=tuple(str(arg) for arg in argv), returncode=completed.returncode, - stdout=completed.stdout, - stderr=completed.stderr, + stdout=ensure_text(completed.stdout), + stderr=ensure_text(completed.stderr), ) except subprocess.TimeoutExpired as exc: return CommandResult( argv=tuple(str(arg) for arg in argv), returncode=124, - stdout=exc.stdout or "", - stderr=(exc.stderr or "") + f"\ncommand timed out after {timeout}s", + stdout=ensure_text(exc.stdout), + stderr=ensure_text(exc.stderr) + f"\ncommand timed out after {timeout}s", ) -- cgit v1.2.3