OpenCode

OpenCode loads context-mode as a native TypeScript plugin rather than JSON stdin/stdout hooks:

• The plugin array registers all 11 ctx_* tools in-process and wires the hooks, so there is no separate MCP child per session.
• The plugin keeps the bulk of raw payload bytes out of your window by routing data-heavy output into the sandbox and answering from the FTS5 knowledge base.

Hooks run as in-process functions. OpenCode exposes no real SessionStart hook (#14808), so context-mode uses two surrogates:

Install

OpenCode has no plugin marketplace, so install the package globally first, then point the host config at it.

node --version

npm install -g context-mode

{
  "$schema": "https://opencode.ai/config.json",
  "plugin": ["context-mode"]
}

cp node_modules/context-mode/configs/opencode/AGENTS.md AGENTS.md

Configure

The plugin-only config above needs no extra environment variable:

• The native plugin already exposes the ctx_* tools in-process.
• It sets CONTEXT_MODE_EMBEDDED_PLUGIN_TOOLS=1 for itself.

If you ever run the standalone MCP server alongside the plugin (for example, a leftover mcp.context-mode entry), set this variable where the spawned server can read it — an env block in the opencode.json MCP entry, not a transient shell export — so the duplicate copy of each tool is suppressed:

{
  "$schema": "https://opencode.ai/config.json",
  "plugin": ["context-mode"],
  "mcp": {
    "context-mode": {
      "type": "local",
      "command": ["context-mode"],
      "env": { "CONTEXT_MODE_EMBEDDED_PLUGIN_TOOLS": "1" }
    }
  }
}

For the normal plugin-only install, prefer removing the mcp entry entirely (run context-mode upgrade) over running both. See /docs/configuration for the full list of environment variables, storage paths, and permission rules.

Verify

Confirm the install with the doctor. It checks language runtimes (including the Linux Node 22.5+ SIGSEGV gate), the FTS5 knowledge base, the hooks configuration, and plugin registration, then reports anything that needs attention.

context-mode doctor

A clean run means the plugin is loaded and context-mode is ready to route your next data-heavy command.

Verify your savings

These two checks confirm context-mode is actually saving you tokens, not just that the tools loaded.

ctx stats

context-mode doctor

OpenCode has no persistent status line, so ctx stats in chat is the quickest read on your live savings.

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