A failed stdio launch had no useful diagnostic surface: the message log
(History) is cleared on the error transition and there are no HTTP
requests (Network), so the auto-opened monitoring column was empty. The
process's stderr — which explains the failure (e.g. "No module named
mcp_server_time") — was captured in StderrLogState but never displayed.
- New ConsoleScreen renders the captured stderr stream (search / sort /
clear / export; embeddable in the monitoring column), wired through App
via the existing useStderrLog hook + StderrLogState.
- Console is a pinnable monitor tab like Logs/History/Network, gated to
stdio servers (HTTP has no child process). It lives in the header menu
when the column isn't pinned, and moves into the column when it is.
- The failure column now picks its tabs by which diagnostic actually
captured content (stderr → Console, fetch requests → Network), not by
the active server's transport: a connect failure fires the client
`disconnect` event, which clears `activeServer`, so transport can't be
read back there. The memo re-runs as stderr/fetch entries stream in, so
the diagnostic tab appears as soon as the failing process prints.
Verified live against a failing `python -m mcp_server_time` stdio server:
the column auto-opens to Console showing the real ModuleNotFoundError.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01BrihGWcrM9JGRyu41nzZYw
219298b24d