Boot blocks for minutes on project .opencode/ dir + any plugin when IPv6 is advertised but unroutable (registry install: no timeout, AAAA-first)

Note: written by an AI assistant (opencode + GLM) at the user's request, based on a live debugging session on the affected machine. Kept concise per the template guidance.

Description

Boot blocks for minutes when the project has an .opencode/ directory and any plugin is configured, on hosts where DNS returns AAAA records but IPv6 is unroutable (router advertises RA, upstream dead). The registry install triggered by the .opencode/ dir has no timeout and prefers IPv6, so each fetch stalls in SYN-SENT for the kernel retry window (~130s) before falling back to IPv4.

Measured trigger matrix (opencode run, v1.18.31):

.opencode/ dir	plugin(s) in config	result
yes	yes	stalled >70s (killed)
no	yes	~9s, OK
yes	no	~9s, OK
--pure	—	OK

Plugins

Any plugin reproduces it (tested with user's local file:// plugins and a minimal empty plugin).

OpenCode version

1.18.31 (Linux, Bun-compiled binary)

Steps to reproduce

Precondition: broken IPv6 (verifiable with curl -6 -m5 https://registry.npmjs.org/ timing out while curl -4 returns 200 quickly).

mkdir repro && cd repro && git init -q
mkdir .opencode && printf '{ "lsp": false }\n' > .opencode/opencode.json
# any plugin in global config, e.g.:
#   printf 'export const P = async () => ({})\n' > /tmp/p.js
#   add "file:///tmp/p.js" to "plugin" in ~/.config/opencode/opencode.json
time opencode run "Reply OK"
# stalls after the "loading path=..." config log lines
# control: rm -rf .opencode -> boots in ~9s

Expected behavior

Boot does not block on background dependency installation; a dead network path degrades to a warning (as background dependency install failed already does on fast failures).

Actual behavior

During the stall: zero CPU, no child processes, and TCP sockets stuck in SYN-SENT to 2606:4700::6810:* (registry.npmjs.org AAAA records):

SYN-SENT  0  1 [2804:...]:55696 [2606:4700::6810:822]:443
SYN-SENT  0  1 [2804:...]:37796 [2606:4700::6810:722]:443

Root cause chain (v1.18.31 source):

• packages/opencode/src/config/config.ts:452 forks npmSvc.install(dir, {add: ["@opencode-ai/plugin"]}) for every existing config dir, including the project .opencode/ (included by ConfigPaths.directories only when it exists)
• packages/core/src/npm.ts:149-152 runs arborist reify() whenever that dir lacks node_modules — a live registry install triggered by merely having project config
• config.ts:634 / tui.ts:266 (waitForDependencies) block boot until those installs finish
• the fetch prefers AAAA with no timeout and no happy-eyeballs fallback; dns-result-order=ipv4first in ~/.npmrc does not help (ignored by the Bun runtime)

Environment

• OS: Linux x86_64 (Ubuntu-ish, Kernel 6.x)
• Network: RA-advertised IPv6 default route, IPv6 transit dead, IPv4 fine

Screenshot and/or share link

n/a (headless repro above; can provide full ss/log captures on request)

Workarounds

Remove the project .opencode/ dir (global config install is satisfied by existing node_modules + lockfile, no fetch), or repair/disable host IPv6 (sysctl net.ipv6.conf.all.disable_ipv6=1).

Related: #48147 (plugin loading waits for install) and #30337 (.opencode install side effects).