Custom tools via symlinks fail to resolve @opencode-ai/plugin module #11001

Description

When a custom tool in .opencode/tools/ is a symlink pointing to another location, Bun resolves the symlink and tries to import @opencode-ai/plugin relative to the symlink target path instead of the .opencode/ directory where node_modules actually lives.

Steps to Reproduce

1. Create a tool file at /some/path/my-tool.ts:

import { tool } from "@opencode-ai/plugin"

export default tool({
  description: "Test tool",
  args: {},
  async execute(args, context) {
    return "Hello"
  },
})

2. Create a symlink in .opencode/tools/:

ln -s /some/path/my-tool.ts .opencode/tools/my-tool.ts

3. Ensure @opencode-ai/plugin is installed in .opencode/node_modules/

4. Start OpenCode

Expected Behavior

The tool loads successfully, resolving @opencode-ai/plugin from .opencode/node_modules/.

Actual Behavior

Error: Cannot find module '@opencode-ai/plugin' from '/some/path/my-tool.ts'

Bun follows the symlink and tries to resolve the module relative to the symlink target (/some/path/), where no node_modules exists.

Root Cause

In packages/opencode/src/tool/registry.ts, line 44:

const mod = await import(match)

When match is a symlink, Bun resolves it to the real path before importing, causing module resolution to fail.

Possible Solutions

1. Read the file content and use a data URL import instead of importing the path directly
2. Copy the file to a temp location before importing
3. Use fs.realpathSync() to detect symlinks and handle them differently
4. Document that symlinks are not supported for custom tools

Workaround

Copy tool files directly into .opencode/tools/ instead of using symlinks.

Environment

• OpenCode version: 1.1.39
• OS: macOS
• Bun version: (current)