Custom tools don't receive project directory in ToolContext #10477

Description

Custom tools defined via @opencode-ai/plugin have no way to access the project's working directory at execution time. The ToolContext passed to execute() contains sessionID, messageID, agent, abort, callID, extra, metadata(), and ask() - but no directory or worktree.

This works fine when running opencode directly in a project directory (where process.cwd() happens to be correct), but fails when using opencode web as a daemon serving multiple projects.

Steps to reproduce

1. Run opencode web as a daemon (e.g., via launchd with a fixed WorkingDirectory)
2. Create a custom tool that needs the project directory:

   import { tool } from "@opencode-ai/plugin";
   
   export default tool({
     description: "Get git status",
     args: {},
     async execute(args, context) {
       // context has no directory property
       // process.cwd() returns the daemon's cwd, not the project
       const result = await Bun.$`git status`.text();
       return result;
     },
   });

3. Open a project in the web UI and invoke the tool
4. The tool runs in the wrong directory

Debug output

Logging the full context and environment from a custom tool shows:

{
  "context": {
    "sessionID": "ses_...",
    "messageID": "msg_...",
    "agent": "build",
    "callID": "toolu_...",
    "extra": { "model": {...} },
    "allKeys": ["sessionID", "abort", "messageID", "callID", "extra", "agent", "metadata", "ask"]
  },
  "cwd": "/Users/rick",
  "env": {
    "OPENCODE": "1",
    "HOME": "/Users/rick"
  }
}

Note: cwd is the daemon's working directory, not the project. No directory in context, no OPENCODE_DIRECTORY env var.

Expected behavior

Custom tools should receive directory and worktree in ToolContext, matching what plugins receive in PluginInput at initialization:

export type ToolContext = {
  sessionID: string
  messageID: string
  agent: string
  abort: AbortSignal
  directory: string    // <- add this
  worktree: string     // <- add this
  // ...
}

Workaround

None currently. Built-in tools work because they import Instance.directory directly, but custom tools can't access that module.

OpenCode version

1.0.x (current dev branch)

Operating System

macOS (but applies to any OS when running as daemon)