mcp-neovim-server

Instructions

Implementation Reference

• src/neovim.ts:532-546 (handler)

  Core handler function that validates the register name and uses Neovim's setreg API to store the provided content in the specified register.

  public async setRegister(register: string, content: string): Promise<string> {
    const validRegisters = [...'abcdefghijklmnopqrstuvwxyz"'];
    if (!validRegisters.includes(register)) {
      return 'Invalid register name';
    }
  
    try {
      const nvim = await this.connect();
      await nvim.eval(`setreg('${register}', '${content.replace(/'/g, "''")}')`);
      return `Register ${register} set`;
    } catch (error) {
      console.error('Error setting register:', error);
      return 'Error setting register';
    }
  }

• src/index.ts:243-268 (registration)

  MCP server.tool registration for 'vim_register', including Zod input schema validation and thin async handler wrapper that delegates to NeovimManager.setRegister.

  server.tool(
    "vim_register",
    "Manage Neovim register contents",
    {
      register: z.string().regex(/^[a-z"]$/).describe("Register name - a lowercase letter [a-z] or double-quote [\"] for the unnamed register"),
      content: z.string().describe("The text content to store in the specified register")
    },
    async ({ register, content }) => {
      try {
        const result = await neovimManager.setRegister(register, content);
        return {
          content: [{
            type: "text",
            text: result
          }]
        };
      } catch (error) {
        return {
          content: [{
            type: "text",
            text: error instanceof Error ? error.message : 'Error setting register'
          }]
        };
      }
    }
  );

• src/index.ts:246-249 (schema)

  Zod schema defining the input parameters: register (a-z or ") and content (string).

  {
    register: z.string().regex(/^[a-z"]$/).describe("Register name - a lowercase letter [a-z] or double-quote [\"] for the unnamed register"),
    content: z.string().describe("The text content to store in the specified register")
  },

• src/neovim.ts:356-369 (helper)

  Helper code in getNeovimStatus that reads current register contents using getreg for status reporting.

  const registers: { [key: string]: string } = {};
  const registerNames = [...'abcdefghijklmnopqrstuvwxyz', '"', ...Array(10).keys()];
  for (const reg of registerNames) {
    try {
      const content = String(await nvim.eval(`getreg('${reg}')`));
      // Only include registers that have content
      if (content && content.trim().length > 0) {
        registers[String(reg)] = content;
      }
    } catch (e) {
      // Register empty or error
    }
  }