acp-extension-dsh

ACP session controls and a pinned coding profile for DeepSeek Harness.

The package is a Cordis plugin, not a replacement for Harness. It adds ACP model, reasoning-effort, permission, and agent-preset selectors, accepts inline images when DeepSeek-V4-Flash-Vision-Exp is selected, and mounts ACP-provided stdio or Streamable HTTP MCP servers into each Harness Agent scope. Harness continues to own model execution, sandbox enforcement, persistence, preset composition, tool execution, and one-shot approvals.

The adapter advertises Core's _meta.lody.compaction capability and translates Harness compaction/start and compaction/end events into a standard ACP tool lifecycle carrying _meta.lody.activity. Manual and automatic compaction remain distinguishable, and failed compactions keep the Harness error reason. Committed assistant images are read back through the attachment store and sent as ACP image blocks. Prompt completion and cancellation wait for admission, Harness idle, and ordered output delivery before releasing the session's prompt slot.

ACP model choices are discovered from Harness when each session is created and returned through both the standard model config option and the legacy ACP models response. Exact per-model metadata controls the reasoning selector and image admission, and the legacy response carries model[effort] entries so a host can cache the reasoning choices for every model rather than only the model that happened to be active during the probe. Permission choices use the composed Harness preset table. When DEEPSEEK_BASE_URL is set, the adapter requests its OpenAI-compatible GET /models endpoint once per ACP connection, resolves every advertised id through Harness, and selects the first result initially. Discovery is bounded, does not follow redirects, and reports an actionable startup failure when the endpoint cannot provide a usable list. Without an endpoint, the Harness catalog remains advisory: an explicitly configured or selected model is still resolved even when it is not listed.

Exports

• acp-extension-dsh exports the Cordis plugin: apply, inject, and name.
• acp-extension-dsh/capabilities exports the selector vocabulary for host UIs.
• acp-extension-dsh/profile exports the pinned Harness package set and ACP host-composition builder.

The host launches the pinned dsh-acp-demo executable with the generated composition and stages this package's official standard/code/minimal/cordis preset snapshot beside the ACP adapter. Harness mounts the selected preset per session and also discovers user presets below $DSH_HOME/.agent-presets. MCP tools use Harness's native mcp__<server>__<tool> naming and are removed with their owning ACP session.

The generated profile defaults session persistence to upstream's zstd encoding. A host that reuses an existing Harness session root may pass none to the profile builder only after verifying that the root contains raw session.jsonl artifacts and no session.jsonl.zstd artifacts. Harness roots are single-encoding stores: hosts must refuse mixed roots without moving, rewriting, or deleting user artifacts.

The ACP profile keeps the session-query service mounted for exact reads but sets its full-text SQLite index to openAt: never. This composition does not expose the session-search tool, and public Node distributions cannot be assumed to include SQLite FTS5. Disabling the unused index prevents ACP startup from depending on that optional SQLite build feature.

Development

npm install
npm run build
npm test
npm run format:check

Node.js 22 or newer is required.