Zero-dependency, single-file MCP server for AI agents, natively running on Termux (Android), Raspberry Pi, and Linux.

🚀 Quick Start

Local (Termux / Linux)

bash

cd /path/to/nano-mcp-termux
python3 nano_mcp_termux.py

Docker

bash

docker build -t nano-mcp-termux .
docker run -i --rm nano-mcp-termux

Health check (one-shot, no MCP handshake)

bash

python3 nano_mcp_termux.py --health

🛠️ Features

✅ Zero-dependency: No external packages required
✅ Single-file: All logic in one Python script
✅ Cross-platform: Works in Termux (Android), on Raspberry Pi, Linux, and inside Docker
✅ Container-ready: Dockerfile at repo root for Glama introspection
✅ Standard stdio framing: Newline-delimited JSON-RPC (official MCP transport)
✅ Version negotiation: Echoes client protocolVersion (2024-11-05 / 2025-06-18 / 2025-11-25), falls back to highest supported
✅ Graceful degradation: device_status never fails; unavailable inputs are marked, not crashed
✅ [lifecycle] No orphaned processes: every command runs in its own process group; timeouts kill the whole tree (SIGTERM → SIGKILL), never just the shell
✅ [lifecycle] Self-terminating: parent-process watchdog + stdin-EOF detection + optional idle timeout, so a dead client never leaves a zombie server behind
✅ [lifecycle] Phantom Process Killer aware: reports Android 12+ child-count risk with concrete mitigations
✅ [paths] Android/Termux path adapter: resolves /sdcard ↔ /storage/emulated/0 ↔ $HOME/storage/shared, detects noexec mounts, case-insensitive filesystems, and shell-quoting hazards

🧩 Tools Overview

Tool	Description
`device_status`	Aggregate device info: battery / storage / arch / memory (degraded fields marked unavailable)
`server_health`	Runtime health: pid/ppid/env, uptime, request counters, live children, reaping policy, RSS, Phantom Process Killer risk
`resolve_path`	Resolve an Android/Termux path: canonical form, mount point, `noexec`/read-only flags, case sensitivity, equivalent spellings, quoting warnings
`path_adapter`	Environment profile: runtime class, `$HOME`/`$PREFIX`/`$TMPDIR`, Android storage roots with mount summaries, `noexec` mount list

🔗 Protocol Surface

Method	Behavior
`initialize`	Echoes supported client version (2024-11-05 / 2025-06-18 / 2025-11-25), else responds with highest supported per MCP spec; declares `{"tools": {}}`
`notifications/initialized`	Silent (no response)
`ping`	Returns `{}`
`tools/list`	Returns tool catalog
`tools/call`	Returns `{"content": [{"type": "text", ...}]}`
Unknown method / tool	`-32601` / `-32602` JSON-RPC errors
Malformed JSON	`-32700` parse error

🔄 Why 1.1.0: the orphan-process bug

Version 1.0.0 ran commands with subprocess.run(..., timeout=...). On timeout, Python terminates only the direct child — the sh -c wrapper. Anything the shell had already spawned is reparented to init and survives forever. On Android that is the exact leak class that trips the Phantom Process Killer and can get the whole app group killed.

1.1.0 fixes this at the root: commands are spawned with start_new_session=True and torn down with os.killpg(pgid, SIGTERM) → SIGKILL, so the entire process tree dies together.

The repository ships a reproducible A/B regression test for it:

bash

python3 test_lifecycle_orphan.py
# current  nano_mcp_termux.py           leaked_grandchildren=0
# legacy   nano_mcp_termux_v10_backup.py leaked_grandchildren=1   <- the bug
# PASS: current server leaves 0 orphaned grandchildren after timeout

✅ Tests

bash

python3 test_client.py            # 32 protocol / tool / lifecycle assertions
python3 test_lifecycle_orphan.py  # orphan-leak A/B regression (1.0.0 vs 1.1.0)

⚙️ Environment variables

Variable	Default	Purpose
`NANO_IDLE_TIMEOUT`	`0` (off)	Seconds of inactivity before the server exits on its own
`NANO_NO_WATCHDOG`	unset	Set to `1` to disable the parent-process watchdog thread