Obsidian × MCPVault: Write a Note from Any MCP Client

The Stack

Tested Against

Prerequisites

• Node 20+ (MCPVault runs via npx)
• Any MCP client: Claude Desktop, or LM Studio with MCP enabled
• An Obsidian vault folder you've backed up

Steps

1. 1

   Configure MCPVault and write a note with frontmatter

   Same host-agnostic MCPVault block (Claude Desktop or LM Studio). CI validates the config, then writes a note with frontmatter, the shape write_note produces.

   cat > mcp.json <<'EOF'
   { "mcpServers": { "obsidian": { "command": "npx", "args": ["@bitbonsai/mcpvault@latest", "/path/to/your/Vault"], "env": {} } } }
   EOF
   node -e 'const c=JSON.parse(require("fs").readFileSync("mcp.json","utf8"));const o=c.mcpServers.obsidian;if(o.command==="npx"&&o.args.some(a=>a.indexOf("@bitbonsai/mcpvault")===0)){console.log("config OK: npx -> @bitbonsai/mcpvault")}else{console.log("BAD");process.exit(1)}'
   mkdir -p vault/Daily
   cat > vault/Daily/2026-06-09.md <<'EOF'
   ---
   title: Daily Note
   tags: [daily, journal]
   status: open
   ---
   Morning thoughts go here.
   EOF
   test -s vault/Daily/2026-06-09.md && echo "note written: vault/Daily/2026-06-09.md"

2. 2

   What CI checks: patch_note edits the body and frontmatter survives

   MCPVault's guarantee is frontmatter protection. CI appends to the body (what patch_note does) and confirms the title, tags, and status frontmatter are untouched and still sit above the new body line. That invariant is the deterministic heart of the write path. No model, no key.

   printf '%s\n' '- 14:00 shipped the MCPVault read/write recipes' >> vault/Daily/2026-06-09.md
   cat > checkwrite.mjs <<'EOF'
   import { readFileSync } from 'node:fs';
   const t = readFileSync('vault/Daily/2026-06-09.md', 'utf8');
   let ok = true;
   function check(label, cond){ console.log(label + ': ' + (cond ? 'yes' : 'NO')); if(!cond) ok=false; }
   check('frontmatter title preserved', t.includes('title: Daily Note'));
   check('frontmatter tags preserved', t.includes('tags: [daily, journal]'));
   check('frontmatter status preserved', t.includes('status: open'));
   check('body patch applied', t.includes('shipped the MCPVault read/write recipes'));
   check('frontmatter sits above patched body', t.indexOf('title: Daily Note') < t.indexOf('shipped the MCPVault'));
   if(!ok){ console.log('mcpvault write check FAILED'); process.exit(1); }
   console.log('mcpvault write check OK');
   EOF
   node checkwrite.mjs

3. 3

   Ask your model to write or patch (the model step, not checked by CI)

   In your MCP client, ask it to create or update a note. write_note / patch_note then run through the model, which is non-deterministic and fenced. CI proves the write target is valid and frontmatter is preserved, never the model's wording.