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 the selected model declares image input (the default deepseek-flash / DeepSeek-V41-Flash does), 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.

With bilateral Core subagentEvents v1, scoped Harness subagent/start and subagent/end events establish owned executions. Local descendants stream committed assistant messages, live reasoning and the existing rich tool projection; non-local runs expose lifecycle and final summaries only. Scope-carrier identity, not tool titles, establishes ancestry. Child approvals keep run-scoped tool IDs on the root ACP connection; delegated questionnaires remain outside the root bridge. Normalized runs offer no cancellation/output query controls. Existing clients are unchanged. Core 0.1.9 supplies the subagent event contract and helper.

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.

The ACP host mounts Harness's file-backed settings provider. It reads $DSH_HOME/settings.yaml, falling back to ~/.dsh/settings.yaml, and exposes user sections to settings-aware plugins. Missing settings preserve composition defaults; malformed settings documents fail startup instead of being silently ignored. The llm-deepseek.models array replaces the local catalog in full, so retain any default models and their vision metadata that should remain selectable. For example:

llm-deepseek:
  models:
    - id: deepseek-flash
      name: DeepSeek-V41-Flash
      inputModalities: [text, image]
    - id: deepseek-v4-flash
      name: DeepSeek-V4-Flash
    - id: deepseek-v4-pro
      name: DeepSeek-V4-Pro
    - id: deepseek-v4-flash-vision-exp
      name: DeepSeek-V4-Flash-Vision-Exp
      inputModalities: [text, image]
    - id: custom-model
      name: Custom model

The provider watches file edits, but ACP model choices are cached per connection. Reconnect and refresh the host's model capabilities after catalog edits. DEEPSEEK_BASE_URL still selects endpoint discovery: this setting does not merge local-only model IDs into an endpoint's /models response. API credentials remain in the host environment; generated compositions contain no credentials.

The host also mounts dsh-llm-pi-ai with an empty base profile. It remains dormant until settings.yaml adds a supported route, for example alongside the unchanged DeepSeek configuration:

llm-pi-ai:
  providers:
    acme-gateway:
      displayName: Acme Gateway
      apiKeyEnv: ACME_GATEWAY_API_KEY
      api: openai-completions
      baseURL: https://gateway.example/v1
      models:
        - id: shared-model
          name: Shared model
          contextWindow: 65536
          maxTokens: 4096

apiKeyEnv is a reference resolved by Harness for each request. The key itself is not copied into settings, the generated profile, ACP capability data, or Lody's workspace state. Removing a route or leaving its named credential unavailable fails that selection explicitly; the adapter does not switch back to DeepSeek. Reconnect and refresh capabilities after changing the route catalog.

Token and USD accounting

Core's usage capability reports committed request usage, cumulative per-model totals and already-included deltas. The pinned Harness 0.1.1-rc.2 supplies usage on assistant/message and actual route metadata on request/context; raw stream chunks are not counted again. No model request or transcript is needed by tests. Only reported activity in the ACP-owned Harness session is counted; separate background agents or internal operations without usage events are not invented.

Official DeepSeek prices, checked directly on 2026-09-13, are estimated per request at completion time. Off-peak USD/million tokens (cache miss / hit / output): Flash 0.15 / 0.003 / 0.6; V4 Pro 0.66 / 0.022 / 1.98. Weekday 01:00–04:00 and 06:00–10:00 UTC are twice those rates. deepseek-v4-flash and deepseek-v4-flash-vision-exp now alias the new deepseek-flash price. Unknown models/custom endpoints have no estimated cost. These are list-price estimates, not invoices; cross-boundary requests can differ. Only the registered deepseek-official route at the official endpoint is priced; an arbitrary provider named deepseek is not evidence of official billing. Publish Core 0.1.5 before releasing this adapter dependency.

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 version, the same-release npx package closure, and createDeepSeekHarnessProfileFiles, which renders the generated dsh profile files.

The host launches the pinned dsh executable with --profile lody-acp, writing the generated profile (the @deepseek-ai/dsh-base bundle plus the Lody cordis.patch.yml overlay) under $DSH_HOME/profiles/lody-acp. It stages this package's official standard/ptc/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.

The optional real-runtime settings regression test uses a preinstalled profile closure. Install every specifier createDeepSeekHarnessNpxSpecifiers() returns in a separate directory first, then run:

DSH_TEST_RUNTIME_ROOT=/absolute/runtime/node_modules npm run test:settings-profile

The test itself uses isolated temporary homes, synthetic settings, and ACP initialization/session creation only. It does not install packages, use API keys, send model requests, or edit the user's Harness home. It checks first-request catalog visibility, absent settings, invalid YAML, non-mapping settings documents, and preservation of the settings document. The profile's ACP entry explicitly waits for settings so catalog discovery cannot race the initial file read.

Plan configuration

Core’s boolean plan_mode option is available only when the current Agent preset mounts the native Plan service. It calls planMode.set, preserves sandbox/approval settings, and publishes durable Plan changes as config updates. A pending selection is reflected until its next-step commit; Plan is guidance, not a sandbox policy.

User questions

Each ACP-owned Agent mounts an answerer for Harness user-questions/request. The standard, ptc, and cordis presets expose ask_user_question; minimal still does not. Clients must advertise standard elicitation.form. The adapter sends elicitation/create with Core _meta.lody.elicitation and restores the original Harness question ids and selected option labels in the tool result. Free text and single-select Other use the existing replacement-answer flow.

For multi-select, clients advertising Core 0.1.6 answerNotes receive a separate Other note alongside their selections. A collision-free Other option permits custom-only answers; this synthetic label never reaches the tool result. Clients without answer notes retain replacement-only Other. Plan-review questions display the question and full plan detail, preserve the declared approval label, and do not change Plan Mode or permissions.

Harness owns exact-live/root-agent admission (CALLER_NOT_LIVE and DELEGATED_CALLER). Requests queue independently per ACP session. Abort, session cancel/close, and connection disposal reject pending tools with ASK_ABORTED; decline returns ASK_DECLINED, transport failure ANSWER_FAILED, and malformed accepted answers INVALID_ANSWER. Cancelled queued requests do not dispatch. SDK 1.3's AgentSideConnection has no per-request cancellation API: an already sent form may remain visible until the host dismisses it or cancels the turn. The adapter ignores late answers and releases its local queue immediately.

Run the native tool/service/Cordis/ACP boundary test against the pinned installed closure (no model requests or credentials):

npm run build
DSH_TEST_RUNTIME_ROOT=/absolute/runtime/node_modules node --test scripts/user-questions-smoke.mjs

Tool calls

The adapter projects durable Harness tool/call and tool/result events into standard ACP tool lifecycles. Each row keeps the tool name, parsed arguments (or the original malformed JSON), completion/failure status, and native result payload. Text and stored images become ACP content; unsupported blocks remain inspectable as JSON. Unavailable attachments produce a visible placeholder. Permission requests wait for the preceding call notification and include its name, title, kind, arguments and locations.

Agent-scoped tool presenters supply titles, categories, file locations, terminal output and successful result-time diffs. Broken or absent presenters fall back to native data. Call-time diffs are deliberately not published as evidence of an applied edit, and failed calls retain their native error output. tool/ptc-dispatch-start / tool/ptc-dispatch also expose tools inside run_code as separate rows, with native sub-call IDs; result payloads retain their root and parent IDs. The adapter does not invent a host-specific nesting protocol.

Only the exact ACP-owned session contributes rows. Ordered delivery includes attachment reads, and prompt settlement drains it before releasing the slot. A turn that ends without a recorded tool result closes the remaining row as failed with an explicit unknown-outcome explanation, never invented success. This does not add child-agent transcript forwarding, token-level tool argument streaming, or subprocess stdout streaming that the durable tool events lack.

Session titles

The managed profile enables the upstream first-prompt LLM title plugin. Initialize advertises Core 0.1.7's _meta.lody.sessionTitle: { version: 1 }; clients can skip a separate title process. Native session/title events use the ordered ACP output queue and map provider/user/fallback provenance to generated/explicit/fallback titleSource metadata. Harness owns generation, persistence and user-name protection. A failed generation leaves the fallback title; it does not fail the prompt.