Nextcloud for ChatGPT & Codex

An open-source, tenant-isolated bridge that lets ChatGPT and Codex work with files in a user-owned Nextcloud workspace. The bridge keeps its OAuth identity separate from Nextcloud credentials and uses standards-based providers when native Nextcloud MCP capabilities are absent.

Product website: nextcloud-for-chatgpt.v4t0r.chatgpt.site

Release status

v0.3.0 is the public-app and production-deployment release candidate.

The repository contains the application-side pieces required for a universal OAuth-protected MCP service:

• request-scoped bridge identity and pseudonymous tenant isolation

• Nextcloud Login Flow v2 without collecting a user's Nextcloud password

• tenant-scoped metadata plus encrypted PostgreSQL credential storage

• root-bound WebDAV and OCS providers with explicit read/write tools

• conservative household invoice review that never approves, books, pays, or transmits

• rate limiting, request limits, security headers, trusted-host checks, and stateless MCP transport

• a DNS-rebinding-resistant HTTPS egress proxy and network-isolated production composition

• database migrations, readiness checks, maintenance cleanup, and release preflight

• a Codex plugin package plus reviewer-ready OpenAI listing and test material

• a production landing site with privacy, terms, support, and security pages

The source release does not claim an active public service or OpenAI approval. Public availability still requires an operator-controlled production domain, external OAuth configuration, reviewer fixture, verified publisher identity, and successful OpenAI review.

The MCP bridge itself works without directory publication. Codex CLI, ChatGPT desktop, and the Codex IDE extension can connect directly; compatible remote MCP hosts can use a deployed HTTPS endpoint. ChatGPT web requires developer-mode access for an unpublished connection or installation of a published plugin. See deployment modes.

Related MCP server: codex-chatgpt-bridge

Real Nextcloud validation

The standards-based fallback path passed a live integration run against Nextcloud 33.0.7:

• authenticated OCS discovery

• WebDAV listing, create, upload, download, metadata lookup, move, and cleanup

• user-visible app inventory and root-bound share inventory

• isolated synthetic household workspace and invoice-review flow

Native Nextcloud Context Agent MCP was unavailable on that instance. The successful fallback run is therefore direct evidence that native MCP is optional rather than a hidden dependency. No credentials or instance-identifying values are recorded. See the compatibility matrix.

Architecture

ChatGPT / Codex
       |
       | OAuth access token
       v
Public stateless MCP boundary
       |
       | verified issuer + subject + scopes
       v
BridgeSessionContext
       |
       | pseudonymous tenant scope
       v
ConnectionService
       |-- PostgreSQL connection metadata
       `-- AES-256-GCM credential store
       |
       | Nextcloud Login Flow v2 credential
       v
Root-bound provider core
       |-- WebDAV files
       |-- OCS capabilities, apps, shares, revocation
       `-- Native Nextcloud MCP discovery when available

The bridge identity never contains a Nextcloud username or credential. Every connection, pending flow, household profile, and credential operation is scoped by the verified tenant context.

Public MCP tools

Read and discovery

• get_nextcloud_capabilities

• get_nextcloud_app_accesses

• probe_native_nextcloud_mcp

• list_files, search_files, list_nextcloud_shares

• get_file_info, read_text_file, download_file_base64

• list_nextcloud_connections, list_household_accounts, list_household_invoices

• review_household_invoice

Create or modify private Nextcloud state

• write_text_file, upload_file_base64, create_folder, move_file, delete_file

• begin_nextcloud_connection, poll_nextcloud_connection, set_nextcloud_root

• disconnect_nextcloud

• configure_household_account, prepare_household_workspace

• save_household_invoice_review

Every hosted tool has an explicit title, description, input schema, output schema, and risk annotations. The production tool contract is locked by automated tests and documented in submission/TOOL_ANNOTATIONS.md.

Security defaults

• account root / and parent traversal are rejected before provider access

• every returned WebDAV path is rechecked against the configured root

• HTTPS and TLS verification are mandatory for hosted Nextcloud targets

• public targets are resolved, validated, and IP-pinned by a CONNECT-only egress proxy

• bearer tokens, app passwords, share tokens, raw invoice text, and full IBANs are excluded from model-visible results

• credential ciphertext is tenant-bound through AES-GCM authenticated data

• overwrite is opt-in; the configured root cannot be deleted

• request body and transfer sizes are bounded

• write, overwrite, move, delete, disconnect, and credential-revocation risks are explicit

• hosted access is stateless and derives a fresh identity for every MCP request

Read SECURITY.md before deployment. Report vulnerabilities through GitHub private vulnerability reporting, never through a public issue containing secrets or private data.

Local development

Requires Python 3.11 or newer.

python -m venv .venv
source .venv/bin/activate  # Windows: .venv\Scripts\activate
pip install -e ".[dev,hosted]"
ruff check .
pytest

Copy .env.example to .env only for local testing. Use a dedicated Nextcloud account and app password, keep the root narrow, and never commit the resulting file.

Run the local stdio server:

nextcloud-chatgpt-bridge

Run sanitized read-only diagnostics or the explicit temporary write/cleanup smoke test:

nextcloud-chatgpt-diagnose
nextcloud-chatgpt-diagnose --write-test

Production deployment

The reference composition is in deploy/compose.production.yml. It separates PostgreSQL, the bridge, maintenance, egress, and TLS termination, and keeps the bridge off the direct external network.

cp deploy/.env.production.example deploy/.env.production
docker compose --env-file deploy/.env.production \
  -f deploy/compose.production.yml config
docker compose --env-file deploy/.env.production \
  -f deploy/compose.production.yml up -d

Supply database and encryption secrets as files outside Git. Apply migrations through the dedicated migrate service, then run nextcloud-chatgpt-preflight against the exact public MCP, OAuth, website, support, privacy, and terms URLs before any reviewer access.

See docs/PRODUCTION_DEPLOYMENT.md and docs/HOSTED_ACCEPTANCE.md.

OpenAI submission package

Repository-side review material lives in submission/:

• canonical listing copy and starter prompts

• positive and negative reviewer cases

• reviewer fixture and runbook

• exact tool-annotation inventory

• release notes and final operational checklist

The final OpenAI submission remains an owner-controlled action. See docs/PLUGIN_SUBMISSION.md.

Project documents

• Authentication and credential boundaries

• Private, hosted, and no-store deployment modes

• MCP tools and provider behavior

• Household and invoice boundary

• Privacy model

• Terms and service boundary

• Release process

• Roadmap

License

Licensed under the Apache License 2.0. This independent project is not affiliated with or endorsed by Nextcloud GmbH or OpenAI.