DSH Custom Provider Settings Plugin

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A WebUI plugin for DeepSeek Harness that adds request headers, image-input declarations, and reasoning-level settings to user-defined custom model providers. It loads through the DSH plugin system and does not modify Harness source files.

The plugin applies only to providers carrying the Custom tag. DeepSeek official providers and built-in third-party providers retain their original configuration and request behavior.

Features

• Configure User-Agent and additional HTTP request headers for each custom provider.
• Apply the same custom headers to normal model requests and Fetch available models.
• Declare each custom model as text-only or text-and-image capable.
• Configure the reasoning levels exposed for each model and map every level to the value sent to its API.
• Set a provider-level default reasoning level.
• Configure the reasoning parameter format for openai-completions providers.
• Restore the original Harness request-header behavior by clearing all custom headers.

Demo

Custom provider settings

The plugin inserts request-header and model-capability fields into the existing custom-provider form. The highlighted areas show User-Agent, additional headers, image input, the default reasoning level, and per-model reasoning mappings.

Reasoning selector

Enabled reasoning levels appear in the conversation composer. The example exposes Default, Off, Low, Medium, High, Xhigh, and Max, with Xhigh selected.

Installation

Prerequisites

• Node.js ^22.19.0 or >=24.0.0; Node.js 24 LTS is recommended.
• Git, used to install the plugin from GitHub.
• pnpm. dsh plugin invokes pnpm in the Web profile directory to manage plugins.
• DeepSeek Harness 0.1.0-rc.6 or a compatible release with the web profile.

Check the environment in PowerShell:

node --version
npx --version
git --version
corepack enable
pnpm --version

If corepack enable fails because of insufficient permissions, run it once from an administrator PowerShell or follow the pnpm installation guide.

Stop the running WebUI before installing, upgrading, or removing the plugin, then restart it when the command completes.

Option 1: Install a release TGZ (recommended)

This installs a tested, fixed version that does not change with the main branch. To install v0.4.0:

npx --yes -p @deepseek-ai/dsh dsh plugin --profile web add https://github.com/supersealwqas/dsh-custom-provider-settings/releases/download/v0.4.0/dsh-custom-provider-settings-0.4.0.tgz

Start the WebUI after installation:

npx --yes -p @deepseek-ai/dsh dsh web

The WebUI listens on http://127.0.0.1:3080 by default. If dsh is installed globally, the shorter dsh plugin ... and dsh web forms are equivalent.

Option 2: Install from the GitHub main branch

This installs the current main branch and is suitable for users who want the newest changes immediately. On first use, npx downloads the official DSH NPM package and its dependencies:

npx --yes -p @deepseek-ai/dsh dsh plugin --profile web add github:supersealwqas/dsh-custom-provider-settings

Start the WebUI after installation:

npx --yes -p @deepseek-ai/dsh dsh web

Option 3: Install from a local checkout

Use this method when changing or debugging the plugin. Create a TGZ package in the repository and install it into the Web profile:

New-Item -ItemType Directory -Force .\dist
npm pack --pack-destination .\dist
npx --yes -p @deepseek-ai/dsh dsh plugin --profile web add .\dist\dsh-custom-provider-settings-0.4.0.tgz
npx --yes -p @deepseek-ai/dsh dsh web

The dist directory and TGZ files are ignored by .gitignore and are not uploaded to the repository.

Upgrade

Stop the WebUI and run the matching add command again. DSH updates the installed plugin without requiring a separate removal. For a TGZ installation, replace the version and filename in the command with the target release. Restart the WebUI afterward.

Uninstall

npx --yes -p @deepseek-ai/dsh dsh plugin --profile web remove dsh-custom-provider-settings

Restart the WebUI to remove the plugin controls and behavior. Provider extension fields already stored in settings.yaml are not deleted automatically.

Usage

1. Open Settings > Models.
2. Edit a provider carrying the Custom tag that already contains a model, or choose Add provider > Add a custom provider and enter its models.
3. In the inserted Request headers area, enter a User-Agent and any other headers required by the endpoint. Leave the fields empty to retain the Harness defaults.
4. Under Model capabilities, choose each model's input and reasoning capabilities. Select Text and images only when both the API and model support image input.
5. Select the enabled reasoning levels and enter the exact API value for each one. Choose a default level if required.
6. Use the original Apply or Create provider button. The plugin saves its fields after the Harness form succeeds.
7. Start a new conversation, select the custom model, and choose one of its configured reasoning levels.

Fetch available models uses the request-header values currently entered in the same form, including values that have not been saved yet. This allows model discovery to work with endpoints that require a particular User-Agent or another custom header.

Verify image input

1. Set the model's input capability to Text and images and save the provider.
2. Start a new conversation with that model.
3. Upload a PNG or JPEG containing a unique string such as VISION-7392.
4. Ask the model to return only the string visible in the image.

A correct response confirms that Harness accepted the attachment and the endpoint processed it. This setting declares model capability to Harness; it cannot add vision support to an API or model that does not already provide it.

Stored settings

The UI writes these fields under llm-pi-ai.providers.<provider>:

headers:
  User-Agent: my-client/1.0
  X-Client-Name: my-client
reasoning: high
models:
  - id: example-model
    input: [text, image]
    reasoningEfforts:
      low: low
      medium: medium
      high: high

Header values are stored as ordinary text in settings.yaml. Keep API keys and other secrets in the Harness credential field instead of custom headers.

Clearing every custom header removes the override and restores the original Harness request-header behavior.

Troubleshooting

The plugin settings do not appear

Confirm that the plugin is installed in the web profile and restart the WebUI after installation. The plugin mounts only on user-defined custom providers, and a provider without models has no editable model settings.

Fetch available models still fails

Confirm the Base URL, API key, and API protocol first, then check every User-Agent or additional header required by the endpoint. The plugin includes unsaved header values from the active form in the discovery request.

Reasoning levels or image upload are missing in a conversation

Save the provider, start a new conversation, and select the model again. Reasoning levels must be enabled for that model, and image upload requires the model to be declared as Text and images.

Compatibility and limitations

• The current release targets the public plugin interfaces and WebUI in DeepSeek Harness 0.1.0-rc.6.
• The plugin mounts only on user-defined providers reported by Harness with declared: true.
• DeepSeek official providers and built-in third-party providers are not mounted or modified.
• Model names, context windows, maximum output values, and other fields owned by the original form are preserved when plugin settings are saved.
• The current Models page has no provider-form plugin slot. This plugin locates the original accessible labels and mounts its React controls at runtime, so a future Harness form change may require a plugin update.
• The plugin does not patch DeepSeek Harness source files.

Development and verification

npm test
node --check client.js
npm pack --dry-run

Attribution

The reasoning-settings client logic is adapted from JuneLearn/dsh-reasoning-settings under the MIT License.

License

MIT. See LICENSE. The license retains the copyright notices for this repository and its adapted upstream source.