obsidian-mcp-pro

Instructions

Implementation Reference

• src/lib/vault.ts:96-118 (handler)

  The implementation of the prepend_to_note logic which reads the file, detects frontmatter, and prepends the new content either after the frontmatter or at the start of the file.

  export async function prependToNote(
    vaultPath: string,
    relativePath: string,
    content: string,
  ): Promise<void> {
    const fullPath = resolveVaultPath(vaultPath, relativePath);
    const existing = await fs.readFile(fullPath, "utf-8");
  
    // Detect frontmatter block (starts with --- on first line)
    const frontmatterMatch = existing.match(/^---\r?\n[\s\S]*?\r?\n---\r?\n?/);
  
    let result: string;
    if (frontmatterMatch) {
      const frontmatter = frontmatterMatch[0];
      const rest = existing.slice(frontmatter.length);
      const separator = frontmatter.endsWith("\n") ? "" : "\n";
      result = frontmatter + separator + content + "\n" + rest;
    } else {
      result = content + "\n" + existing;
    }
  
    await fs.writeFile(fullPath, result, "utf-8");
  }

• src/tools/write.ts:129-149 (registration)

  The MCP tool registration for 'prepend_to_note', which validates inputs and calls the prependToNote handler.

  // 3. prepend_to_note
  server.registerTool(
    "prepend_to_note",
    {
      description: "Prepend content to a note, after frontmatter if present",
      inputSchema: {
        path: z.string().min(1).describe("Relative path to the note"),
        content: z.string().describe("Content to prepend"),
      },
    },
    async ({ path: notePath, content }) => {
      try {
        const resolvedPath = ensureMdExtension(notePath);
        await prependToNote(vaultPath, resolvedPath, content);
        return textResult(`Prepended content to '${resolvedPath}'.`);
      } catch (err) {
        console.error("prepend_to_note error:", err);
        return errorResult(`Error prepending to note: ${err instanceof Error ? err.message : String(err)}`);
      }
    },
  );