MCP local server env block not propagated to child process #30892

Description

OpenCode does not pass the env block from mcp.<name>.env in opencode.json to locally spawned MCP server processes.

When configuring a local MCP server (e.g., mcp-searxng) with an env block like:

"mcp": {
  "searxng": {
    "type": "local",
    "command": ["npx", "-y", "mcp-searxng"],
    "enabled": true,
    "env": {
      "SEARXNG_URL": "http://localhost:47820"
    }
  }
}

The child process inherits OpenCode's own environment instead of receiving the configured SEARXNG_URL. This causes the MCP server to start successfully (stdio connection established, tools registered), but fail at runtime when it tries to read process.env.SEARXNG_URL and finds it undefined.

I verified this by:

1. Confirming SEARXNG_URL is present in the opencode.json config.
2. Checking /proc/<opencode_pid>/environ — SEARXNG_URL is not present in OpenCode's own environment.
3. Checking /proc/<mcp-searxng_pid>/environ — SEARXNG_URL is not present in the spawned MCP server either.
4. Manually setting export SEARXNG_URL=http://localhost:47820 before starting OpenCode resolves the issue, confirming the bug is in env propagation, not the MCP server itself.

Plugins

None

OpenCode version

1.16.0

Steps to reproduce

1. Configure a local MCP server in opencode.json with an env block:

   {
     "mcp": {
       "searxng": {
         "type": "local",
         "command": ["npx", "-y", "mcp-searxng"],
         "enabled": true,
         "env": {
           "SEARXNG_URL": "http://localhost:47820"
         }
       }
     }
   }

2. Ensure the SEARXNG_URL environment variable is not set in your shell before starting OpenCode.
3. Start OpenCode and try to use the MCP tool (e.g., searxng_searxng_web_search).
4. Observe the error: ⚠️ Configuration Issues: SEARXNG_URL not set...
5. Check the spawned MCP process environment: cat /proc/$(pgrep -f mcp-searxng)/environ | tr '\0' '\n' | grep SEARXNG — it will be empty.
6. Stop OpenCode, run export SEARXNG_URL=http://localhost:47820, restart OpenCode — the tool now works.

Screenshot and/or share link

N/A

Operating System

WSL Linux (Ubuntu 24.04.4 LTS)

Terminal

Windows Terminal