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Sweep 22 Oct 2026 · 21:04Z Build v2.1.309 528 read Stable v2.1.308 Latest v2.1.309 Next v2.1.309 Feeds RSS JSON llms.txt llms-full.txt Unofficial

Claude Code v2.1.228 ·

MCP SSE liveness callback renamed to heartbeat

An MCP connection-liveness callback was renamed to heartbeat; nothing behaves differently.

Under the hood Internal Changes
JSON All of v2.1.228
Under the hoodTier: how much it should matter to you
1Useful: my rating, 1 to 5
0Signal: worth watching, 1 to 5
MCPArea: what it touches
Internal ChangesKind: in v2.1.228,
Internal ChangesSection of the release
What

The SSE transport's liveness probe callback, its setter and its error log were renamed to heartbeat. The log now reads "SSETransport: onHeartbeatProbe handler threw". No behaviour change.

Evidence

SSETransport: onHeartbeatProbe handler threw:

Strings lifted out of the shipped bundle, so the claim above can be checked against them.

See this entry in the whole of v2.1.228 →

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