Docker stdio MCP servers duplicated on /new and /resume (v1.0.68)

[rjvq85]

Summary

On v1.0.68, running /new or /resume (resuming a session not started during the current CLI run) spawns a fresh set of stdio MCP docker run clients without tearing down the previous set. Duplicates accumulate within the same CLI process for its entire lifetime.

This looks related to #3440 but is a different code path: #3440 was about session.disconnect() not killing stdio processes (fixed in 1.0.51). Here, no disconnect happens at all — the CLI re-initializes MCP servers on /new//resume and spawns a new set while the old set stays connected, so the kill-on-disconnect logic never runs.

Environment

• Copilot CLI 1.0.68
• macOS (Darwin arm64)
• MCP servers configured as stdio Docker containers (docker run -i --rm …) in ~/.copilot/mcp-config.json — one github-mcp-server + three grafana instances

Actual behavior

Every configured stdio MCP server is duplicated per /new or /resume. docker ps shows 2× (or more) of every server, all parented to the same live copilot process. Because the containers run with --rm, they only self-remove when the whole CLI exits — so they pile up for the entire CLI session.

Affected version

1.0.68

Steps to reproduce the behavior

1. Configure one or more stdio Docker-based MCP servers.
2. Start the CLI (session A) → one set of docker run clients spawns.
3. Run /new, or /resume a session that was not opened during the current CLI run.
4. A second set of clients spawns; the first set is not disconnected.

Expected behavior

On /new or /resume, the CLI should either reuse the existing MCP server connections or disconnect the outgoing session's stdio MCP servers before starting new ones.

Additional context

Evidence

Single copilot PID 71692, alive ~19 min, holding two full sets spawned ~2 min apart — none orphaned, all share that PID as parent:

$ ps -eo pid,ppid,etime,command | grep '[d]ocker run'
72222 71692 19:12 docker run -i --rm --network host … github-mcp-server
72225 71692 19:11 docker run -i --rm … grafana/mcp-grafana -t stdio
72226 71692 19:11 docker run -i --rm … grafana/mcp-grafana -t stdio
72227 71692 19:11 docker run -i --rm … grafana/mcp-grafana -t stdio
72869 71692 17:32 docker run -i --rm --network host … github-mcp-server
72870 71692 17:31 docker run -i --rm … grafana/mcp-grafana -t stdio
72871 71692 17:31 docker run -i --rm … grafana/mcp-grafana -t stdio
72880 71692 17:30 docker run -i --rm … grafana/mcp-grafana -t stdio

$ docker ps --format '{{.Image}}' | sort | uniq -c
   6 grafana/mcp-grafana
   2 nexus…/github/github-mcp-server

Impact

Resource leak: duplicated containers consume memory/CPU and, for named containers, cause container "x" already exists errors on the next spawn. The only reliable cleanup today is fully exiting the CLI.

Related

• session.disconnect() does not kill stdio MCP server processes spawned for that session #3440 (fixed the disconnect path in 1.0.51; this is the /new + /resume re-init path, still leaking on 1.0.68)