Obsidian MCP for ChatGPT Web

This project connects an Obsidian vault to a ChatGPT custom MCP app through Cloudflare.

The recommended always-on, no-domain setup keeps one fixed ChatGPT URL and continues working while the Windows PC is off:

ChatGPT web
  -> fixed Cloudflare Worker URL (*.workers.dev)
  -> current Cloudflare quick tunnel on an OCI Always Free VM
  -> filesystem MCP bridge on 127.0.0.1:8000
  -> rclone OneDrive mount
  -> OneDrive/Obsidian Vault
  -> Windows Obsidian when the PC is online

The random trycloudflare.com origin can change after a reboot. A systemd supervisor publishes the new origin to the Worker, so the workers.dev URL saved in ChatGPT does not change. The original Windows launcher remains a manual fallback.

Modes

The primary MCP transport is Streamable HTTP at /mcp. Legacy GET SSE remains available, but quick tunnels buffer it, so ChatGPT must use the URL ending in /mcp.

Related MCP server: obsidian-local-mcp

Security properties

• The bridge listens only on loopback. The OCI VM requires no public inbound application port; cloudflared makes an outbound-only connection.

• In worker-proxy and quick-tunnel modes, every MCP path is below /t/<64-hex-secret>/; other paths return 404.

• The path comparison at the local bridge and the Worker administrator-token comparison are timing-safe.

• The Worker administrator route accepts only authenticated updates containing a valid https://*.trycloudflare.com origin.

• Local secrets are encrypted with Windows DPAPI in ignored config.local.json; Cloudflare stores the Worker administrator token as a Worker secret. On OCI, the two bridge environment files are root-owned, group-readable only by the dedicated service user, and excluded from Git.

• /healthz is local-only. The Worker does not forward it.

The full MCP URL is a credential. Anyone who obtains it can use the vault tools, including write tools. Do not share it or commit it.

Prerequisites for the Windows fallback and one-time Worker setup

• Windows PowerShell 5.1 or PowerShell 7

• Python 3.11+ and uv

• Node.js and npm (for one-time Worker deployment)

• Obsidian with the Local REST API plugin

• cloudflared

• A free Cloudflare account; no purchased domain is required for worker-proxy

Install the Python dependencies:

uv sync

Always-on OCI Free Tier setup

The deployed Linux layout, systemd units, OneDrive mount, recovery commands, and free-tier constraints are documented in OCI_ALWAYS_FREE_SETUP.md. The relevant source files are:

• src/obsidian_chatgpt_bridge/filesystem_server.py - direct vault backend exposing the same 12 MCP tools without running the Obsidian desktop app.

• deploy/oci/*.service - OneDrive mount, MCP bridge, and tunnel units.

• scripts/oci_tunnel_supervisor.py - quick-tunnel restart and stable Worker origin update.

The Windows task Obsidian MCP ChatGPT must remain disabled while OCI is the primary host. Otherwise a Windows login could replace the Worker origin with a PC-local tunnel.

Windows fallback setup without a domain

1. Install the Obsidian Local REST API plugin if needed:

   .\scripts\install_obsidian_local_rest_api.ps1 -VaultPath "<VAULT_PATH>"

2. Deploy the stable Worker. The first run opens one Cloudflare authorization page:

   .\scripts\setup_stable_worker_proxy.ps1

3. Start and verify the full route:

   .\scripts\launch_servers.ps1

4. Optionally register automatic startup 30 seconds after Windows logon only when Windows is the primary host:

   .\scripts\install_autostart_task.ps1

5. Create or update the ChatGPT custom app:

   • MCP URL: the value printed by the launcher and stored in runtime\last_chatgpt_mcp_url.txt

   • Authentication: None

The URL stays fixed across reboots. Do not enable the Windows logon task at the same time as the OCI services.

Status

.\scripts\check_status.ps1

This checks the Windows fallback services, configured mode, fixed origin, and a real public MCP initialize request. OCI service status is checked with the commands in OCI_ALWAYS_FREE_SETUP.md.

Other modes

For a temporary changing URL, set mode to quick-tunnel and run the launcher. After each tunnel restart, update ChatGPT from runtime\last_chatgpt_mcp_url.txt.

For a custom domain with per-user OAuth, follow CLOUDFLARE_ACCESS_SETUP.md, run scripts\setup_cloudflare_access.ps1, and set ChatGPT authentication to OAuth.

Never expose a bridge started with -AuthMode disabled through any public tunnel.

Tests

uv run python -m unittest discover -s tests -v
cd cloudflare\stable-proxy
npm test
npm run check

Secret rotation

• Path secret: remove pathSecretProtected from config.local.json, switch temporarily to quick-tunnel, run the launcher once to generate a new secret, then rerun setup_stable_worker_proxy.ps1. Update ChatGPT with the new fixed URL path.

• Worker administrator token: rerun setup_stable_worker_proxy.ps1; the path secret is preserved and the administrator token is replaced.

• Named-tunnel credentials: rotate them in Cloudflare and rerun setup_cloudflare_access.ps1.