DeepSeek Harness

1Install Node.js

Install Node.js 22 LTS or newer from nodejs.org, then check the version:

node --version

2Start the Web UI

In your project directory, run:

cd your-project
npx @deepseek-ai/dsh web

It starts at http://127.0.0.1:3080 and opens your browser; add --no-open to start the server only. dsh uses the launch directory as its default file-system location.

git clone https://github.com/deepseek-ai/deepseek-harness.git
cd deepseek-harness
pnpm install
pnpm run build
pnpm dsh web

3Create a Codelux account and API key

1. Go to Codelux Portal and create an account (existing users sign in).
2. Pick a subscription plan or top up in Billing — any balance works for every agent.
3. Open API Keys in the left menu and click Create New Key. Give it a name you will recognise, such as the agent's name.
4. After it is created, copy the API key (starts with sk-) and the API base URL. The key is shown in full only once, so keep it somewhere safe.

4Add a custom model API

1. Open Settings → Models and click Add model provider.
2. Switch the card from Third-party model provider to Custom model API.
3. Provider ID: codelux (lowercase; it can't be renamed later). Display name: Codelux.
4. API URL: https://codelux.io/v1.
5. API protocol: OpenAI Chat Completions (Codelux also supports OpenAI Responses and Anthropic Messages; one provider uses one protocol).
6. API key: paste your Codelux key. It is write-only and stored in $DSH_HOME/.credentials.yaml.

5Fetch and add models

Under Model catalog, click Fetch available models. dsh asks Codelux for its model list; search, tick the models you want, click Add selected, then save the provider. If fetching fails, typing model IDs from Portal → AI Hub works just the same.

6(If requests are rejected) Adjust compatibility

If the URL and key are correct but requests are still rejected, add compatibility settings to the Codelux route in $DSH_HOME/profiles/web/cordis.patch.yml (or click Open config file at the top of Settings):

- id: llm-pi-ai
  config:
    providers:
      codelux:
        apiKeyEnv: CODELUX_API_KEY
        api: openai-completions
        baseURL: https://codelux.io/v1
        compat:
          supportsDeveloperRole: false
          maxTokensField: max_tokens
        models:
          - id: deepseek-v4-flash
          - id: claude-sonnet-5

For models that think by default (such as DeepSeek V4) behind an OpenAI-compatible gateway, set compat.thinkingFormat: deepseek on the model so the “off” reasoning level really turns thinking off.

7Choose a workspace

Click Select workspace, add the project directory you launched dsh from and select it. The input box is disabled until a workspace is selected.

8Pick a model and run a task

Pick a Codelux model in the model selector (it becomes the default for new sessions), then send a task, for example:

Summarize this repository and identify its main packages.

The agent reads and edits files, runs commands and keeps a plan; actions that need approval ask you first. Usage and charges for each request are in Portal → Logs.