nixos/shared/linked-dotfiles/opencode/plugin/file-proxy.js

import { tool } from "@opencode-ai/plugin";
import { readFile, writeFile, mkdir } from "fs/promises";
import { resolve, normalize, join, dirname } from "path";
import { homedir } from "os";

const CONFIG_BASE = resolve(homedir(), ".config/opencode");

function resolvePath(filePath) {
  if (!filePath.startsWith('/') && !filePath.startsWith('~')) {
    filePath = join(CONFIG_BASE, filePath);
  }
  
  if (filePath.startsWith('~/')) {
    filePath = filePath.replace('~/', homedir() + '/');
  }
  
  const normalized = normalize(resolve(filePath));
  
  if (!normalized.startsWith(CONFIG_BASE)) {
    throw new Error(
      `Access denied: Path must be within ~/.config/opencode\n` +
      `Attempted: ${normalized}\n` +
      `Use config_read/config_write/config_edit ONLY for opencode config files.`
    );
  }
  
  return normalized;
}

export const FileProxyPlugin = async () => {
  return {
    tool: {
      config_read: tool({
        description: `Read files from OpenCode config directory (~/.config/opencode).

**REQUIRED when reading config files from outside ~/.config/opencode directory.**

Use this tool when:
- Reading agent definitions (agent/*.md)
- Reading skills (skills/*/SKILL.md)
- Reading workflows (OPTIMIZATION_WORKFLOW.md, etc.)
- Current working directory is NOT ~/.config/opencode

Do NOT use if already in ~/.config/opencode - use standard 'read' tool instead.`,
        
        args: {
          filePath: tool.schema.string()
            .describe("Path to file (e.g., 'agent/optimize.md' or '~/.config/opencode/skills/skill-name/SKILL.md')")
        },
        
        async execute(args) {
          try {
            const validPath = resolvePath(args.filePath);
            const content = await readFile(validPath, "utf-8");
            return content;
          } catch (error) {
            if (error.code === 'ENOENT') {
              return `❌ File not found: ${args.filePath}\nCheck path and try again.`;
            }
            if (error.code === 'EACCES') {
              return `❌ Permission denied: ${args.filePath}`;
            }
            if (error.message.includes('Access denied')) {
              return `❌ ${error.message}`;
            }
            return `❌ Error reading file: ${error.message}`;
          }
        }
      }),

      config_write: tool({
        description: `Write/create files in OpenCode config directory (~/.config/opencode).

**REQUIRED when creating/writing config files from outside ~/.config/opencode directory.**

Use this tool when:
- Creating new skills (skills/new-skill/SKILL.md)
- Creating new agent definitions
- Writing workflow documentation
- Current working directory is NOT ~/.config/opencode

Common use case: Optimize agent creating skills or updating workflows from project directories.

Do NOT use if already in ~/.config/opencode - use standard 'write' tool instead.`,
        
        args: {
          filePath: tool.schema.string()
            .describe("Path to file (e.g., 'skills/my-skill/SKILL.md')"),
          content: tool.schema.string()
            .describe("Complete file content to write")
        },
        
        async execute(args) {
          try {
            const validPath = resolvePath(args.filePath);
            await mkdir(dirname(validPath), { recursive: true });
            await writeFile(validPath, args.content, "utf-8");
            return `✅ Successfully wrote to ${args.filePath}`;
          } catch (error) {
            if (error.code === 'EACCES') {
              return `❌ Permission denied: ${args.filePath}`;
            }
            if (error.message.includes('Access denied')) {
              return `❌ ${error.message}`;
            }
            return `❌ Error writing file: ${error.message}`;
          }
        }
      }),

      config_edit: tool({
        description: `Edit existing files in OpenCode config directory (~/.config/opencode).

**REQUIRED when editing config files from outside ~/.config/opencode directory.**

Use this tool when:
- Updating agent definitions (adding sections to optimize.md)
- Enhancing existing skills
- Modifying workflow docs
- Current working directory is NOT ~/.config/opencode

Operations: append (add to end), prepend (add to beginning), replace (find and replace text).

Do NOT use if already in ~/.config/opencode - use standard 'edit' tool instead.`,
        
        args: {
          filePath: tool.schema.string()
            .describe("Path to file to edit"),
          operation: tool.schema.enum(["append", "prepend", "replace"])
            .describe("Edit operation to perform"),
          content: tool.schema.string()
            .describe("Content to add or replacement text"),
          searchPattern: tool.schema.string()
            .optional()
            .describe("Regex pattern to find (required for 'replace' operation)")
        },
        
        async execute(args) {
          try {
            const validPath = resolvePath(args.filePath);
            let fileContent = await readFile(validPath, "utf-8");
            
            switch (args.operation) {
              case "append":
                fileContent += "\n" + args.content;
                break;
              case "prepend":
                fileContent = args.content + "\n" + fileContent;
                break;
              case "replace":
                if (!args.searchPattern) {
                  throw new Error("searchPattern required for replace operation");
                }
                fileContent = fileContent.replace(new RegExp(args.searchPattern, "g"), args.content);
                break;
            }
            
            await writeFile(validPath, fileContent, "utf-8");
            return `✅ Successfully edited ${args.filePath} (${args.operation})`;
          } catch (error) {
            if (error.code === 'ENOENT') {
              return `❌ File not found: ${args.filePath}\nUse config_write to create new files.`;
            }
            if (error.code === 'EACCES') {
              return `❌ Permission denied: ${args.filePath}`;
            }
            if (error.message.includes('Access denied')) {
              return `❌ ${error.message}`;
            }
            return `❌ Error editing file: ${error.message}`;
          }
        }
      })
    }
  };
};