Make multiple inspector tabs work correctly, avoid infinitely respawning MCP server

[ezyang]

This is actually I think reported in #293 but I think the original authors didn't understand the problem so I'm refiling the issue with a better name until someone renames the other issue.

When you have multiple inspector tabs open, you end up with a log that looks like this:

Stdio transport: command=/opt/homebrew/bin/uv, args=run,--with,mcp,mcp,run,codemcp/__main__.py
Spawned stdio transport
Connected MCP client to backing server transport
Created web app transport
Created web app transport
Set up MCP proxy
New SSE connection
Query parameters: {
  transportType: 'stdio',
  command: 'uv',
  args: 'run --with mcp mcp run codemcp/__main__.py',
  env: '{"HOME":"/Users/ezyang","LOGNAME":"ezyang","PATH":"/Users/ezyang/.npm/_npx/5a9d879542beca3a/node_modules/.bin:/Users/ezyang/Dev/codemcp/node_modules/.bin:/Users/ezyang/Dev/node_modules/.bin:/Users/ezyang/node_modules/.bin:/Users/node_modules/.bin:/node_modules/.bin:/Users/ezyang/.nvm/versions/node/v22.12.0/lib/node_modules/npm/node_modules/@npmcli/run-script/lib/node-gyp-bin:/Users/ezyang/Dev/codemcp/.venv/bin:/Users/ezyang/.cargo/bin:/Users/ezyang/.cabal/bin:/Users/ezyang/.ghcup/bin:/Users/ezyang/.bun/bin:/opt/homebrew/bin/:/Users/ezyang/.nvm/versions/node/v22.12.0/bin:/Users/ezyang/.local/bin:/usr/local/bin:/System/Cryptexes/App/usr/bin:/usr/bin:/bin:/usr/sbin:/sbin:/var/run/com.apple.security.cryptexd/codex.system/bootstrap/usr/local/bin:/var/run/com.apple.security.cryptexd/codex.system/bootstrap/usr/bin:/var/run/com.apple.security.cryptexd/codex.system/bootstrap/usr/appleinternal/bin:/Library/Apple/usr/bin","SHELL":"/bin/zsh","TERM":"xterm-256color","USER":"ezyang"}'
}
Stdio transport: command=/opt/homebrew/bin/uv, args=run,--with,mcp,mcp,run,codemcp/__main__.py
Spawned stdio transport
Connected MCP client to backing server transport
Created web app transport
Created web app transport
Set up MCP proxy
New SSE connection
Query parameters: {
  transportType: 'stdio',
  command: 'uv',
  args: 'run --with mcp mcp run codemcp/__main__.py',
  env: '{"HOME":"/Users/ezyang","LOGNAME":"ezyang","PATH":"/Users/ezyang/.npm/_npx/5a9d879542beca3a/node_modules/.bin:/Users/ezyang/Dev/codemcp/node_modules/.bin:/Users/ezyang/Dev/node_modules/.bin:/Users/ezyang/node_modules/.bin:/Users/node_modules/.bin:/node_modules/.bin:/Users/ezyang/.nvm/versions/node/v22.12.0/lib/node_modules/npm/node_modules/@npmcli/run-script/lib/node-gyp-bin:/Users/ezyang/Dev/codemcp/.venv/bin:/Users/ezyang/.cargo/bin:/Users/ezyang/.cabal/bin:/Users/ezyang/.ghcup/bin:/Users/ezyang/.bun/bin:/opt/homebrew/bin/:/Users/ezyang/.nvm/versions/node/v22.12.0/bin:/Users/ezyang/.local/bin:/usr/local/bin:/System/Cryptexes/App/usr/bin:/usr/bin:/bin:/usr/sbin:/sbin:/var/run/com.apple.security.cryptexd/codex.system/bootstrap/usr/local/bin:/var/run/com.apple.security.cryptexd/codex.system/bootstrap/usr/bin:/var/run/com.apple.security.cryptexd/codex.system/bootstrap/usr/appleinternal/bin:/Library/Apple/usr/bin","SHELL":"/bin/zsh","TERM":"xterm-256color","USER":"ezyang"}'
}
Stdio transport: command=/opt/homebrew/bin/uv, args=run,--with,mcp,mcp,run,codemcp/__main__.py
Spawned stdio transport
Connected MCP client to backing server transport
Created web app transport
Created web app transport
Set up MCP proxy
New SSE connection
Query parameters: {
  transportType: 'stdio',
  command: 'uv',
  args: 'run --with mcp mcp run codemcp/__main__.py',
  env: '{"HOME":"/Users/ezyang","LOGNAME":"ezyang","PATH":"/Users/ezyang/.npm/_npx/5a9d879542beca3a/node_modules/.bin:/Users/ezyang/Dev/codemcp/node_modules/.bin:/Users/ezyang/Dev/node_modules/.bin:/Users/ezyang/node_modules/.bin:/Users/node_modules/.bin:/node_modules/.bin:/Users/ezyang/.nvm/versions/node/v22.12.0/lib/node_modules/npm/node_modules/@npmcli/run-script/lib/node-gyp-bin:/Users/ezyang/Dev/codemcp/.venv/bin:/Users/ezyang/.cargo/bin:/Users/ezyang/.cabal/bin:/Users/ezyang/.ghcup/bin:/Users/ezyang/.bun/bin:/opt/homebrew/bin/:/Users/ezyang/.nvm/versions/node/v22.12.0/bin:/Users/ezyang/.local/bin:/usr/local/bin:/System/Cryptexes/App/usr/bin:/usr/bin:/bin:/usr/sbin:/sbin:/var/run/com.apple.security.cryptexd/codex.system/bootstrap/usr/local/bin:/var/run/com.apple.security.cryptexd/codex.system/bootstrap/usr/bin:/var/run/com.apple.security.cryptexd/codex.system/bootstrap/usr/appleinternal/bin:/Library/Apple/usr/bin","SHELL":"/bin/zsh","TERM":"xterm-256color","USER":"ezyang"}'
}
Stdio transport: command=/opt/homebrew/bin/uv, args=run,--with,mcp,mcp,run,codemcp/__main__.py
Spawned stdio transport
Connected MCP client to backing server transport
Created web app transport
Created web app transport
Set up MCP proxy
New SSE connection
Query parameters: {
  transportType: 'stdio',
  command: 'uv',
  args: 'run --with mcp mcp run codemcp/__main__.py',
  env: '{"HOME":"/Users/ezyang","LOGNAME":"ezyang","PATH":"/Users/ezyang/.npm/_npx/5a9d879542beca3a/node_modules/.bin:/Users/ezyang/Dev/codemcp/node_modules/.bin:/Users/ezyang/Dev/node_modules/.bin:/Users/ezyang/node_modules/.bin:/Users/node_modules/.bin:/node_modules/.bin:/Users/ezyang/.nvm/versions/node/v22.12.0/lib/node_modules/npm/node_modules/@npmcli/run-script/lib/node-gyp-bin:/Users/ezyang/Dev/codemcp/.venv/bin:/Users/ezyang/.cargo/bin:/Users/ezyang/.cabal/bin:/Users/ezyang/.ghcup/bin:/Users/ezyang/.bun/bin:/opt/homebrew/bin/:/Users/ezyang/.nvm/versions/node/v22.12.0/bin:/Users/ezyang/.local/bin:/usr/local/bin:/System/Cryptexes/App/usr/bin:/usr/bin:/bin:/usr/sbin:/sbin:/var/run/com.apple.security.cryptexd/codex.system/bootstrap/usr/local/bin:/var/run/com.apple.security.cryptexd/codex.system/bootstrap/usr/bin:/var/run/com.apple.security.cryptexd/codex.system/bootstrap/usr/appleinternal/bin:/Library/Apple/usr/bin","SHELL":"/bin/zsh","TERM":"xterm-256color","USER":"ezyang"}'
}
Stdio transport: command=/opt/homebrew/bin/uv, args=run,--with,mcp,mcp,run,codemcp/__main__.py
Spawned stdio transport
Connected MCP client to backing server transport
Created web app transport
Created web app transport
Set up MCP proxy
New SSE connection
Query parameters: {
  transportType: 'stdio',
  command: 'uv',
  args: 'run --with mcp mcp run codemcp/__main__.py',
  env: '{"HOME":"/Users/ezyang","LOGNAME":"ezyang","PATH":"/Users/ezyang/.npm/_npx/5a9d879542beca3a/node_modules/.bin:/Users/ezyang/Dev/codemcp/node_modules/.bin:/Users/ezyang/Dev/node_modules/.bin:/Users/ezyang/node_modules/.bin:/Users/node_modules/.bin:/node_modules/.bin:/Users/ezyang/.nvm/versions/node/v22.12.0/lib/node_modules/npm/node_modules/@npmcli/run-script/lib/node-gyp-bin:/Users/ezyang/Dev/codemcp/.venv/bin:/Users/ezyang/.cargo/bin:/Users/ezyang/.cabal/bin:/Users/ezyang/.ghcup/bin:/Users/ezyang/.bun/bin:/opt/homebrew/bin/:/Users/ezyang/.nvm/versions/node/v22.12.0/bin:/Users/ezyang/.local/bin:/usr/local/bin:/System/Cryptexes/App/usr/bin:/usr/bin:/bin:/usr/sbin:/sbin:/var/run/com.apple.security.cryptexd/codex.system/bootstrap/usr/local/bin:/var/run/com.apple.security.cryptexd/codex.system/bootstrap/usr/bin:/var/run/com.apple.security.cryptexd/codex.system/bootstrap/usr/appleinternal/bin:/Library/Apple/usr/bin","SHELL":"/bin/zsh","TERM":"xterm-256color","USER":"ezyang"}'
}

i.e. it is spawning the MCP client over and over. The net effect is that it's impossible to interact with the MCP client as the connection is always dropped. This occurs if you have two inspector tabs, if you close all but one the problem goes away. It would be good if it didn't do that.

[kavinkumar807]

Adding #310 here for reference

[olaservo]

I'm trying to understand the use case better here - are we trying to connect to a different server in each tab, or authorize a different user in each tab, or...?

[ezyang]

For me, it's actually super dumb; we have too many tabs in the browser, we manually restarted inspector and forgot we already had an inspector tab buried in the tab list

[avez-fsd]

Took me a while to figure out the issue 😂, it is fixed after closing other tabs. SSE also has a limit of 6 tabs.

[BBBmau]

For me, it's actually super dumb; we have too many tabs in the browser, we manually restarted inspector and forgot we already had an inspector tab buried in the tab list

was having the same issue, it was only until i went in and removed the one browser which had the connected state still.

[olaservo]

From what I'm seeing here I think we're OK to close this as 'not planned' at the moment, since it sounds like more of an unintentional state than a necessary feature.

If this is something that happens to people fairly often it could be worth adding to a troubleshooting section of the docs.