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Describe the enhancement you want to request

Problem

OpenCode makes several outbound connections that are not directly related to LLM inference:

• Auto-update checks (opencode.ai/install)
• Session sharing (opncd.ai)
• Web UI proxy (app.opencode.ai)

These are fine in normal usage, but users in privacy-sensitive or restricted-network environments (corporate firewalls, VPNs, regulated industries) want a way to disable them without resorting to OS-level firewall rules or environment-variable guesswork.

Related but distinct from #2224 (which covers installation in fully air-gapped environments where even Bun package resolution fails).

Solution

Add a single offline kill switch that disables all non-essential outbound connections.

Config (opencode.json)

{
  "$schema": "https://opencode.ai/config.json",
  "offline": true
}

Environment variable

OPENCODE_OFFLINE=true opencode

CLI flag

opencode --offline
opencode run --offline "fix the tests"
opencode serve --offline

Behavior when enabled

The flag also acts as a superset of the existing granular flags (OPENCODE_DISABLE_AUTOUPDATE, OPENCODE_DISABLE_SHARE, OPENCODE_DISABLE_APP_PROXY) — enabling offline mode implies all of them.