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Configure DeepSeek Harness to call the Modellix LLM gateway. DeepSeek Harness is a plugin-based agent harness whose llm-pi-ai adapter accepts a custom provider for any OpenAI-compatible endpoint, so Modellix needs no plugin—only configuration.
Modellix model IDs are provider/name (for example openai/gpt-5.5). Put the full string as each model id in your custom provider so DeepSeek Harness sends it unchanged in the request body. See Models & Pricing.

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Prerequisites

  • DeepSeek Harness Web UI started via the root README
  • A Modellix API key from the console—not a vendor platform key
Model changes take effect on the next request; you do not need to restart the server.

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Add Modellix as a Custom Provider

1

Open the Models Page

Open Settings → Models.
2

Add a Custom Provider

Choose Add a custom provider and fill in the form:The Provider ID is permanent because requests, saved sessions, model defaults, and credential references use it. The display name, base URL, protocol, credential, and models remain editable.Keys are write-only: after saving, the page shows only a redacted descriptor, and the key is stored in $DSH_HOME/.credentials.yaml.
3

Add Models

Under Model catalog, choose Fetch available models. Modellix serves the OpenAI-compatible GET /v1/models endpoint, so the form lists the current Model IDs. Select the ones you want, or enter them by hand.Each model id must be a full Modellix Model ID, for example:
The provider is not stored until you save. Full catalog: Models & Pricing.
4

Select a Model

Save the provider, then choose a Modellix model in the model picker. Selecting a model also makes it the default for new sessions.

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Configure Directly in settings.yaml

You can declare the same provider in $DSH_HOME/settings.yaml instead of the form. Credentials stay out of this file—apiKeyEnv is a reference resolved per request (or provide the key through the Models page):
The models list replaces the route’s catalog, so every model the route should serve must appear in it—an entry with only id is enough. name is optional and shown in selectors. Add or remove entries as needed; a model the route does not configure fails with UNKNOWN_MODEL.

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Use the Anthropic Messages Protocol

Most setups should keep openai-completions: every Modellix model, including anthropic/..., works over Chat Completions at https://llm.modellix.ai/v1. If you prefer the Anthropic wire protocol, set api: anthropic-messages and baseURL: https://llm.modellix.ai (no /v1)—but model discovery (Fetch available models) only reads OpenAI-compatible GET /models endpoints, so enter models by hand in that case.

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Troubleshooting