Files
deepseek-harness/packages/llm-deepseek
Tianyi Cui ab19fed77c Add two DeepSeek LLM adapters: dsh-llm-deepseek and dsh-llm-pi-ai
The first real LlmAdapter implementations, shipped as a deliberate pair:
same models and wire protocol, completely different internals, so the
StreamChunk protocol is verified across independent implementations.

- dsh-llm-deepseek: hand-rolled fetch + SSE parser + chunk-translation
  state machine against the official chat-completions format (thinking
  mode via top-level thinking/reasoning_effort; the empty-string
  reasoning_content first chunk; usage attached to the finish chunk or
  trailing; reasoning_content passback on tool-call turns; disjoint
  cache-token accounting).
- dsh-llm-pi-ai: the same endpoint through @earendil-works/pi-ai,
  mapping its event vocabulary (parsed tool arguments, in-stream error
  events, folded reasoning tokens) onto the same chunks.

The agent loop now honors the in-band error path: an adapter that ends
its stream with finish {kind:error|aborted} (the only option for
adapters that can't throw mid-stream, like pi-ai) is translated into a
step error, so the turn ends error/aborted with a logged error event
instead of a normal completed assistant message. This makes the
StreamChunk error contract real for both adapters; docs/architecture.md
and the StreamChunk doc are updated accordingly.

New yarn test:e2e (vitest.e2e.config.ts, *.e2e.ts) runs key-gated
real-API matrices for both adapters across V4 Flash/Pro and all
thinking/effort levels; it self-skips without DEEPSEEK_API_KEY. Unit
suites run against local node:http mock SSE servers at 100% per-file
coverage.
2026-06-13 18:30:03 +08:00
..

@deepseek-ai/dsh-llm-deepseek

DeepSeek chat-completions adapter for the harness LLM seam: hand-rolled fetch + SSE translation from the official wire format (source of truth: the API docs — guides/thinking_mode, guides/tool_calls, api/create-chat-completion) into the StreamChunk protocol.

A second, independent implementation of the same seam exists in @deepseek-ai/dsh-llm-pi-ai (library-backed). Same Config shape — pick one per context (registering both for the same model names throws by design).

Config

- id: llm-deepseek
  name: '@deepseek-ai/dsh-llm-deepseek'
  config:
    apiKey: !!js process.env.DEEPSEEK_API_KEY    # or rely on the env fallback
    baseURL: !!js process.env.DEEPSEEK_BASE_URL  # default: https://api.deepseek.com
    models: [deepseek-v4-flash, deepseek-v4-pro] # one adapter, registered for each name
    thinking: enabled        # optional; provider default is enabled
    reasoningEffort: high    # optional; high | max — omitted ⇒ not sent

models lists every model name this one adapter instance serves: the adapter registers itself for each (the harness model name IS the wire model string), so a generate/stream call routes to it whenever options.model is any of them. Registering a second adapter for a name already taken throws LlmError('DUPLICATE_ADAPTER') (the LLM service enforces one adapter per model, all-or-nothing).

reasoningEffort is omitted by default — when unset, the reasoning_effort wire field is not sent and the server applies its own default for the model. The only accepted values are high and max (DeepSeek's official effort levels). It is meaningful only with thinking enabled (the provider default).

thinking/reasoningEffort are adapter-level request defaults serialized as the official top-level thinking: {type} / reasoning_effort wire fields. They live in adapter config (not GenerateOptions) to keep the core vocabulary provider-neutral.

Wire-format notes (verified live + against the official docs)

  • Streaming only (stream_options.include_usage always on). usage may arrive attached to the finish chunk or as a trailing usage-only chunk — the translator defers both to [DONE], so usage always precedes finish and nothing follows finish.
  • The first thinking-mode chunk carries reasoning_content: "" — handled (no spurious reasoning block).
  • Reasoning passback rule: on assistant turns that carried tool calls, reasoning_content is serialized back in history (required by the API in thinking mode); on tool-call-free turns it is dropped (ignored anyway — saves tokens).
  • strict on tool schemas passes through (officially Beta; the public API wants the /beta base URL for it, the internal endpoint accepts it directly).
  • Cache accounting: cacheReadTokensprompt_cache_hit_tokens / prompt_tokens_details.cached_tokens; DeepSeek reports no cache-write metric.

Limitations (MVP, documented deliberately)

  • prefill throws LlmError('UNSUPPORTED') — DeepSeek's chat-prefix completion is a Beta feature on the /beta base URL; future work.
  • image blocks are skipped (no vision support on these models).
  • tool_choice is not mapped (not part of the core vocabulary).

Errors

Non-2xx responses throw LlmError with stable codes: AUTH (401/403), RATE_LIMIT (429), INVALID_REQUEST (400), SERVER (5xx), HTTP_<status> otherwise. Protocol violations throw STREAM_CLOSED (no [DONE]) or MALFORMED_RESPONSE (bad JSON payload). Unknown wire finish_reasons (e.g. content_filter, insufficient_system_resource) become finish {kind: 'error', code: <REASON>} chunks.

Testing

Unit suites run against a local node:http mock SSE server (no network). Real-API coverage lives in tests/adapter.e2e.ts (yarn test:e2e, key-gated): V4 Flash + V4 Pro across thinking enabled/disabled and both official effort levels, including the thinking+tools round trip with reasoning passback.