[BUG] Claude Desktop reports a fixed MCP clientInfo.version (0.1.0 for chat, 1.0.0 for Cowork) regardless of app version

What's wrong

In the MCP initialize request, Claude Desktop always sends the same clientInfo.version, whatever version of the app is installed:

| Connection | clientInfo.name | clientInfo.version |
|---|---|---|
| Chat | claude-ai | 0.1.0 |
| Cowork | local-agent-mode-<extension name> | 1.0.0 |

On this machine Claude Desktop is 2.31226.0 (macOS), and the handshake still says 0.1.0 / 1.0.0. Across the installs of an MCP server I maintain, every Claude Desktop start over the past week reported exactly these two values, on both macOS and Windows, although users run many different app versions. The same "clientInfo":{"name":"claude-ai","version":"0.1.0"} also appears in logs other people pasted into reports a year apart (e.g. modelcontextprotocol discussion #325, April 2025; homeassistant-ai/ha-mcp#1506, May 2026).

Why it matters

clientInfo is the only way an MCP server learns which client it is talking to. With a constant version, a server cannot:

• tell which Claude Desktop release a user runs when supporting them (we currently have to ask users to look it up);
• work around a known bug in a specific Desktop release, or stop working around it once a release fixes it;
• see in its own telemetry which Desktop versions are in use.

Other clients send their real version; Codex, for example, reports codex-mcp-client with its actual release (0.162.0-alpha.2).

Expected

clientInfo.version is the Claude Desktop app version (e.g. 2.31226.0), for both the chat and the Cowork connections. If the two connections should stay distinguishable, the name already does that (claude-ai vs local-agent-mode-…).

Environment

• Claude Desktop 2.31226.0, macOS (also observed on Windows)
• MCP server: stdio, installed as a desktop extension (.mcpb)