[xy3xy3]

Closes #1057

Summary

Add native support for the official DeepSeek Harness (DSH) through its first-party ACP server ("dsh --profile acp").

Codeg currently supports DeepSeek Harness through the community-maintained "deepseek-acp" adapter. Since the official DeepSeek Harness now provides an ACP interface, this PR introduces it as a separate built-in agent while preserving the existing integration and its session history.

Changes

1. Official DSH ACP integration

• Add "deepseek_official" as a new built-in agent.
• Launch the official ACP server using "dsh --profile acp".
• Configure the managed npm distribution with "@deepseek-ai/dsh@0.2.1-rc.4" and Node.js >= 24.9.0.
• Integrate with Codeg's existing ACP connection and session infrastructure.

2. Agent registration and UI

• Register the new agent in the Rust agent model and ACP registry.
• Add its display name, icon, and agent picker entry.
• Include the agent in default settings and supported-agent lists.
• Enable selection through Codeg's multi-agent delegation interface.

3. Session and skill integration

• Use Codeg-owned ACP transcripts for sessions created through the official DSH integration.
• Integrate with session listing and import infrastructure.
• Reuse the existing DeepSeek Harness skill directory conventions.
• Preserve the existing "deepseek" agent identity and historical session data.

4. Documentation and regression tests

• Add "docs/agents/deepseek-official.md" with installation instructions, supported features, and known limitations.
• Add Rust tests covering agent identity, registry mapping, distribution metadata, and launch arguments.

Compatibility

The official DSH ACP server is designed primarily for automation and currently exposes a different feature set from the community "deepseek-acp" adapter.

Supported by the official ACP server:

• Session creation, listing, resumption, and closing
• Prompt execution and cancellation
• Model selection and reasoning effort configuration
• Session-scoped MCP servers (stdio and Streamable HTTP)
• Standard ACP permission requests and semantic updates

Currently unsupported by the official ACP server:

• "session/load" transcript replay
• Session forking and deletion
• Additional working directories
• SSE MCP transport
• Editor-specific presentation features and interactive plan/terminal interfaces

For this reason, the official implementation is provided as a separate agent instead of replacing the existing community adapter.

Existing "deepseek" sessions, settings, and custom agent registrations remain unaffected.

Testing

The implementation includes regression tests for the new agent identity and launch configuration.

The following checks still need to be executed:

• "cargo check"
• "cargo test --features test-utils"
• "pnpm lint ."
• "pnpm test"
• End-to-end ACP handshake and session smoke test using the pinned DSH release
• Verify MCP integration and session resumption

These checks have not yet been run in the development environment. Runtime compatibility should be verified before merging.

References

• Related issue: [FR] Support official deepseek-harness #1057
• "Official DeepSeek Harness repository" (https://github.com/deepseek-ai/deepseek-harness)
• "Official ACP protocol documentation" (https://github.com/deepseek-ai/deepseek-harness/blob/master/packages/acp/acp/README.md)
• "DSH CLI documentation" (https://github.com/deepseek-ai/deepseek-harness/blob/master/apps/cli/README.md)