---
summary: Heartbeat disabled by default — stdio servers no longer self-terminate in dev mode or simple harnesses without a client
breaking: false
---

# 0.2.8 — 2026-03-28

Heartbeat disabled by default — opt-in only.

## Fixed

- **Heartbeat default changed to disabled** — `MCP_HEARTBEAT_INTERVAL_MS` now defaults to `0` (off). The 30s default caused stdio servers to self-terminate when run without a client (dev mode, manual testing, simple harnesses). Set `MCP_HEARTBEAT_INTERVAL_MS=30000` to enable.
