Introduction

The plugin-based architecture of DeepSeek Harness (DSH) allows developers to integrate external capabilities into workflows. For developers who need to reuse a ChatGPT Codex subscription (Plus / Pro / Business / Edu), calling it directly from DSH requires solving authentication and context management issues. This plugin connects through the OAuth flow to a ChatGPT subscription and replaces the context compression logic with Codex’s native mechanism, resolving context overflow and compression efficiency issues in multi-turn conversations.

What Is This

This is a plugin for DeepSeek Harness (DSH), maintained by thaning0. It exposes the ChatGPT Codex subscription as the DSH model provider codex-oauth, and integrates native compression and image input capabilities.

Core Features

  • Subscription model access: Registers the OpenAI Codex provider as codex-oauth and exposes models such as gpt-5.3-codex-spark.
  • OAuth device-code login: Uses auth.openai.com for device-code login, without requiring a local callback server.
  • Credential security: Refresh / Access Tokens are stored only in the DSH credential store $DSH_HOME/.credentials.yaml (permissions 0600), and are not included in configuration files, session logs, or the plugin repository.
  • Login and subscription usage: Supports login and logout, and displays the remaining usage percentage through commands in the settings page and conversations.
  • Multi-turn conversations: Fully preserves provider-native replay metadata and supports multi-turn requests across rounds.
  • Transient error recovery: Classifies WebSocket, DNS, rate-limit, and service-unavailable errors into DSH’s TRANSPORT, RATE_LIMIT, or SERVER retry backoff.
  • Multimodal image input: Supports image input for models that declare image capability.
  • Native compression: Provides a manual /compact command and automatic compression triggered at 80% pressure, using an opaque native checkpoint.

Installation

Installation must use the file: prefix; otherwise dependency loading will fail.

dsh plugin --profile web add file:/path/to/dsh-llm-codex-auth-native-compact-image

After installation, restart DSH Web to activate the new bundle. Before installation, make sure pnpm is installed (dsh plugin forwards dependencies) or use the provided script for cross-platform installation.

Typical Usage

  1. Login: After restarting dsh, open the Settings page, select “Codex Subscription (ChatGPT)” in the sidebar, and log in. After logging in, you can view the remaining usage percentage for the 5-hour and 7-day windows on the Settings page.
  2. Create a conversation: When creating a new conversation, select the Codex Native agent preset, and choose a model under codex-oauth on the Models settings page.
  3. Manual compaction: Enter /compact in the conversation to manually compact the context.
  4. Status queries: Enter /codex-status in the conversation to view login status, enter /codex-usage to view remaining usage, and enter /codex-logout to log out.

Applicable Scenarios and Notes

  • Compatibility: The original OAuth plugin and this plugin must not be loaded at the same time, otherwise the same provider will be registered twice.
  • Security and compliance: This plugin uses unpublished ChatGPT backend endpoints (chatgpt.com/backend-api). There is a real risk of violating OpenAI’s terms of service, which may result in account restrictions. Use it only after your own assessment.
  • Plugin maintenance: The repository does not contain any secrets. Before pushing to GitHub, make sure .gitignore is working, and never commit $DSH_HOME/.credentials.yaml.
  • Limitations: Automatic native compaction only applies to codex-oauth; other providers will not fall back to compaction-basic.

Conclusion

This plugin provides DSH users with a direct way to call Codex subscriptions and optimizes the context compression process. For developers who need to handle large amounts of context or multimodal capabilities, this is a viable integration solution.

Catalog | GitHub Repository