codegraph upgrade should run automatically on MCP server start (or offer a check)

[PancakeZik]

Problem

The recommended MCP config points at the local codegraph binary:

{
  "command": "codegraph",
  "args": ["serve", "--mcp"]
}

This means the MCP server stays on whatever version was last manually upgraded via codegraph upgrade. There is no mechanism to notify the user that a newer version is available, or to self-update on startup.

In practice this leads to version drift: users discover they're running an old version only when something breaks or when they happen to check manually. The codegraph prompt-hook (which also uses the local binary) compounds this, since both the MCP server and the hook silently stay on the old version together.

A common workaround is to use npx @colbymchenry/codegraph@latest serve --mcp in the MCP config, but this diverges from the official docs, adds cold-start latency (npm registry check), and splits the install from the prompt-hook binary (which still uses the local codegraph).

Expected behavior

One of:

1. Check on serve start: when codegraph serve --mcp starts, check the latest release in the background. If a newer version exists, emit a notice in the MCP server instructions or log (not blocking). Something like "CodeGraph X.Y.Z available, run codegraph upgrade to update."

2. Auto-upgrade option: a flag like codegraph serve --mcp --auto-upgrade that runs the upgrade logic before starting the server, so the MCP config always launches the latest version without needing npx.

3. Startup hook in codegraph upgrade: register a systemd user timer, cron job, or similar that periodically checks for updates (opt-in during codegraph install).

Option 1 seems lowest-friction: no behavioral change, just visibility.

Environment

• CodeGraph 1.4.0, bundle install (Linux x64)
• MCP config: "command": "codegraph", "args": ["serve", "--mcp"]
• Also uses codegraph prompt-hook in Claude Code UserPromptSubmit hooks