dsh-stitch-mcp

English | 简体中文

Google Stitch as native mcp__stitch__* tools inside DeepSeek Harness, with an in-panel card for the API key and an optional proxy.

Stitch is a remote MCP endpoint. This plugin connects to it directly with the Streamable HTTP transport and authenticates with an API key header, which is the shape Google documents for MCP clients:

{
  "servers": {
    "stitch": {
      "url": "https://stitch.googleapis.com/mcp",
      "type": "http",
      "headers": {
        "Accept": "application/json",
        "X-Goog-Api-Key": "YOUR-API-KEY"
      }
    }
  }
}

There is no helper process, no local port and no launcher script: the plugin adds the row above to the harness and reads the credential from the card.

Tools

The endpoint exposes 16 tools; they register as mcp__stitch__*:

Tool	Purpose
list_projects / get_project / create_project / delete_project	Projects
list_screens / get_screen / download_file	Screens and their files
generate_screen_from_text / edit_screens / generate_variants	Generate and edit UI
list_design_systems / create_design_system / create_design_system_from_design_md / update_design_system / apply_design_system	Design systems
upload_design_md	Upload a DESIGN.md

Install

dsh plugin --profile web add dsh-stitch-mcp@latest

Use your own profile name when the harness is launched with another one.

Credentials

Settings → Plugins → Google Stitch → paste the key → Save. The widget has two tabs:

• API Key — the documented shape, X-Goog-Api-Key.
• OAuth — Authorization: Bearer <access token>, optionally pinned to a project with X-Goog-User-Project.

Create a key at https://stitch.withgoogle.com/settings → API key → Create key. The full key is shown only once. The OAuth tab takes an access token, e.g. the output of gcloud auth print-access-token.

Values are stored through the host credentials service; the Host half resolves them into ~/.dsh/dsh-runtimes/stitch-mcp/config.json, which the MCP row reads when its headers are composed. Saving in the card therefore triggers a reload of that one entry, so the new credential applies without restarting the harness.

Endpoint and proxy

The default is a direct connection, and a network that reaches Google needs no configuration at all.

The card's Use a proxy switch is the only valve. Switching it on stores http://<ip>:<port> and routes only this plugin's Stitch requests through it: everything else in the harness — the model API, web search, other MCP servers — keeps the route it already had. The change applies inside the running process within a few seconds, so there is no restart, and nothing is written to ~/.dsh/.env.

Switching it off stores nothing and takes the plugin out of the path again: Stitch then connects directly, or follows the proxy policy you exported for the harness yourself.

If nothing can reach the endpoint, nothing is faked: the MCP row reports its own transport error, and ~/.dsh/dsh-runtimes/stitch-mcp/status.json says what failed:

{ "ok": false, "endpoint": "https://stitch.googleapis.com/mcp",
  "credential": "api-key", "proxy": null, "route": "direct", "reachable": false,
  "error": "UND_ERR_CONNECT_TIMEOUT", "checkedAt": "..." }

A healthy one looks like:

{ "ok": true, "endpoint": "https://stitch.googleapis.com/mcp",
  "credential": "api-key", "proxy": "http://127.0.0.1:7897", "route": "proxy",
  "reachable": true, "tools": 16, "checkedAt": "..." }

Troubleshooting

Symptom	Meaning
server is disconnected	The transport cannot reach stitch.googleapis.com at all. status.json → error names the reason (UND_ERR_CONNECT_TIMEOUT, fetch failed, …). Give the process a proxy and restart.
Tools listed, calls answer “Request is missing required authentication credential”	No credential saved yet — paste an API key in the card. The handshake itself needs no key, which is why the tools appear first.
status.json says credential: null	The card has nothing stored; the host credentials service is unreachable.
Proxy on but still unreachable	Check the address in the card, then status.json → proxyError / error. Switching the proxy off hands Stitch back to the harness policy.
status.json says route: "direct" with the switch on	undici could not be resolved in this profile, so the switch stays inert; proxyError says so. Reinstall the plugin.
Row gave up after many attempts	The MCP client stops retrying permanently; saving a credential reloads the entry, and restarting the harness also re-arms it.

Layout

File	Role
cordis.patch.yml	Inserts the host entry and the dsh-mcp-client row (direct HTTPS transport, credential headers, reconnect)
index.js	Host half: resolves credentials, keeps config.json / status.json, installs the per-origin proxy wrapper, reloads the row on a change
proxy.js	Per-origin dispatcher wrapper: routes stitch.googleapis.com only, and only while the card's switch is on
client.js	Client half: the credential card in plugins.bundle.config, with I18N dictionaries
locale/{en,zh}.json	Plugin title and description per locale
CHANGELOG.md	Release history
market/listing.json	DSH Plugin Market submission entry

License

MIT.