Port two improvements inspired by Kilo-Org/kilocode analysis:
1. Error classifier: add context overflow patterns for vLLM, Ollama,
and llama.cpp/llama-server. These local inference servers return
different error formats than cloud providers (e.g., 'exceeds the
max_model_len', 'context length exceeded', 'slot context'). Without
these patterns, context overflow errors from local servers are
misclassified as format errors, causing infinite retries instead
of triggering compression.
2. MCP initial connection retry: previously, if the very first
connection attempt to an MCP server failed (e.g., transient DNS
blip at startup), the server was permanently marked as failed with
no retry. Post-connect reconnection had 5 retries with exponential
backoff, but initial connection had zero. Now initial connections
retry up to 3 times with backoff before giving up, matching the
resilience of post-connect reconnection.
(Inspired by Kilo Code's MCP server disappearing fix in v1.3.3)
Tests: 6 new error classifier tests, 4 new MCP retry tests, 1
updated existing test. All 276 affected tests pass.
Four fixes for MCP server stability issues reported by community member
(terminal lockup, zombie processes, escape sequence pollution, startup hang):
1. MCP reload timeout guard (cli.py): _check_config_mcp_changes now runs
_reload_mcp in a separate daemon thread with a 30s hard timeout. Previously,
a hung MCP server could block the process_loop thread indefinitely, freezing
the entire TUI (user can type but nothing happens, only Ctrl+D/Ctrl+\ work).
2. MCP stdio subprocess PID tracking (mcp_tool.py): Tracks child PIDs spawned
by stdio_client via before/after snapshots of /proc children. On shutdown,
_stop_mcp_loop force-kills any tracked PIDs that survived the SDK's graceful
SIGTERM→SIGKILL cleanup. Prevents zombie MCP server processes from
accumulating across sessions.
3. MCP event loop exception handler (mcp_tool.py): Installs
_mcp_loop_exception_handler on the MCP background event loop — same pattern
as the existing _suppress_closed_loop_errors on prompt_toolkit's loop.
Suppresses benign 'Event loop is closed' RuntimeError from httpx transport
__del__ during MCP shutdown. Salvaged from PR #2538 (acsezen).
4. MCP OAuth non-blocking (mcp_oauth.py): Replaces blocking input() call in
_wait_for_callback with OAuthNonInteractiveError raise. Adds _is_interactive()
TTY detection. In non-interactive environments, build_oauth_auth() still
returns a provider (cached tokens + refresh work), but the callback handler
raises immediately instead of blocking the MCP event loop for 120s. Re-raises
OAuth setup failures in _run_http so failed servers are reported cleanly
without blocking others. Salvaged from PRs #4521 (voidborne-d) and #4465
(heathley).
Closes#2537, closes#4462
Related: #4128, #3436
