MCP-TY

Instructions

Implementation Reference

• src/mcp_ty/server.py:728-782 (handler)

  The get_edit_preview tool handler that retrieves code actions and previews their edits.

  async def get_edit_preview(
      file_path: str, line: int, column: int, action_index: int
  ) -> str:
      """Preview changes a code action would make."""
      client = _get_client()
  
      path = Path(file_path).resolve()
      if not path.exists():
          return _error(f"File not found: {file_path}")
  
      try:
          await client.open_document(path)
  
          import asyncio
          await asyncio.sleep(0.3)
  
          diagnostics = client.get_diagnostics(path)
          relevant_diags = [
              d for d in diagnostics
              if d.range.start.line <= line - 1 <= d.range.end.line
          ]
  
          actions = await client.get_code_actions(
              path, line - 1, column - 1, line - 1, column, relevant_diags
          )
  
          if not actions:
              return _not_found(f"No actions at {path.name}:{line}:{column}")
  
          if action_index < 1 or action_index > len(actions):
              return _error(f"Invalid index. Choose 1-{len(actions)}")
  
          action = actions[action_index - 1]
  
          if not action.edit:
              return _error(f"Action '{action.title}' has no edits")
  
          all_edits = action.edit.get_all_edits()
          total_edits = sum(len(e) for e in all_edits.values())
  
          preview = []
          for uri, edits in all_edits.items():
              edit_path = _uri_to_path(uri)
              for e in edits:
                  text_preview = e.new_text[:80].replace("\n", "\\n") if e.new_text else "(delete)"
                  preview.append({
                      "file": edit_path.name,
                      "line": e.range.start.line + 1,
                      "column": e.range.start.character + 1,
                      "new_text": text_preview
                  })
  
          return _ok({
              "action": action.title,
              "edits_count": total_edits,