cli: proxy env routes localhost service discovery through proxy, concurrent spawns fail with "port already in use" #57020

Description

Summary

When a system proxy is active (WSL2 networkingMode=Mirrored auto-syncs HTTP_PROXY/no_proxy into every WSL process), service discovery can transiently fail and multiple concurrently starting CLI instances each spawn serve --service; the losers die with Managed service port 49375 ... already in use.

Two related defects:

1. Without NO_PROXY, requests to 127.0.0.1 are routed through the proxy — loopback should be excluded unconditionally.
2. Concurrent service spawns are not mutually exclusive, so a transient discovery failure surfaces as a confusing "port already in use" error.

Actual Behavior

Log timeline (2026-10-19, ~/.local/share/opencode/log/opencode.log; 49 occurrences between 10-12 and 10-19 on versions 2.0.29–2.0.32):

06:53:13       event stream disconnected (socket closed unexpectedly)
06:53:18/23/36 three serve --service spawned within 18s
06:53:31       background service starting reason=missing
06:53:34~51    all three die: "Managed service port 49375 on 127.0.0.1 is already in
                use by another process ... (cause: ServeError: Failed to start server.
                Is port 49375 in use?)"
06:54~07:04    external fetches (models.opencode.ai) fail while proxy restarts

Second occurrence the same day:

07:43:48 background service starting reason=missing → spawn #1 (succeeds)
07:43:53 spawn #2 five seconds later
07:44:09 spawn #2 dies: "Managed service port 49375 ... already in use"

Expected Behavior

• Health/discovery requests to 127.0.0.1 should never go through a proxy, even when NO_PROXY is absent or malformed.
• Concurrent service starts should be mutually exclusive (per-port spawn lock); losing starters should wait and attach to the already-running service instead of erroring.

Probe experiment

With a deliberately dead proxy (HTTP_PROXY=http://127.0.0.1:1), running opencode api get /api/info:

Additional Context

• Environment: WSL2 with networkingMode=Mirrored; Windows Clash system proxy at 127.0.0.1:7890; the registry ProxyOverride bypass list only affects WinINET consumers, not Node/Bun programs reading HTTP_PROXY.
• Workarounds: pin NO_PROXY=127.0.0.1,localhost,::1 in the shell profile; avoid toggling the proxy while starting opencode; avoid launching multiple instances simultaneously.
• Suggested fix: unconditionally exclude loopback in the HTTP client used for service discovery, and guard spawn with a per-port lock so losers poll-attach.

Plugins

none

OpenCode version

2.0.32 (also reproduced on 2.0.29–2.0.31)

Steps to reproduce

1. Enable a system HTTP proxy on Windows (e.g. Clash at 127.0.0.1:7890); WSL2 mirrored networking syncs HTTP_PROXY/no_proxy into every WSL process.
2. Toggle/restart the proxy (a few seconds of connectivity loss), and/or start several opencode instances at once during that window.
3. A CLI logs background service starting reason=missing.
4. Multiple serve --service processes race; the first binds port 49375, the rest fail with EADDRINUSE.

Screenshot

No response

Operating System

Linux 6.6.87.2-microsoft-standard-WSL2 (WSL2, networkingMode=Mirrored), x86_64 — Windows host

Terminal

Windows Terminal / xterm-256color, shell /bin/bash