Files
deepseek-harness/packages/subagent/subagent-fork
Tianyi Cui dafb81be7b subagent: implement structured output for in-process backends
The seam vocabulary (SubagentStartRequest.outputSchema, SubagentResult
.structured) existed but no in-process backend honored it — spawn/fork
advertised outputSchema: false. This lands the missing half:

- dsh-tools gains a structured-output JSON Schema subset (json-schema.ts):
  StructuredOutputSchema, assertSupportedOutputSchema (rejects loud outside
  the enforced subset, every violation listed), validateStructuredValue
  (path-qualified issues, total). outputSchema's seam type becomes this raw
  JSON-Schema subset instead of the author-facing SchemaSpec DSL — the schema
  travels verbatim to the model as a forced tool's parameters.
- dsh-subagent-inprocess gains the shared structured runtime: one global
  structured_output capture tool (placeholder parameters) + a prepend:true
  agent/request listener doing FINAL-REQUEST enforcement (strip for plain
  agents, per-run schema for structured children — survives downstream
  request-replacing listeners) + an agent/turn-continuation veto that stops
  a child's turn once captured (no wasted extra model step). Lifetime is
  refcounted by backends (plugin lifetime) AND live runs (start→settle).
- startInProcessRun drives the capture: subset asserted before the child
  exists, instruction appended to the child's system prompt, clean-finish
  nudge loop (structuredNudgeRetries, backend Config, default 1), captured
  value on result.structured; a clean finish without a capture settles
  'error' (never a silent success with a missing field).
- spawn + fork flip outputSchema: true and inject 'tools'.
2026-07-05 11:35:39 +08:00
..

@deepseek-ai/dsh-subagent-fork

The in-process fork subagent backend: a SubagentProvider that runs each child as a child Agent seeded with a prefix of the parent's session log — so the child inherits the parent's conversation context instead of starting fresh. Shares the run driver (startInProcessRun) with dsh-subagent-spawn; the only difference is the seed.

The seed boundary (the crux)

At the moment a subagent tool's execute runs, the parent's CURRENT turn is open and unbalanced: the log holds the assistant/message carrying this spawn's tool-call and the dangling tool/call with no tool/result yet. Seeding that raw prefix would give the child an open turn that the session constructor and the dev-mode invariants replay reject.

So the fork seeds only the balanced completed-turn prefix — the parent's log up to and including its last turn/end, excluding the in-flight turn entirely (completedTurnPrefix). Because the live log keeps seq === index, the slice is contiguous-from-0 and a valid seed. A parent on its very first (not-yet-complete) turn forks an empty seed — i.e. effectively a fresh child.

The seam this rides on: CreateAgentOptions.seed (added on dsh-agent, threaded through AgentLoop.createAgentctx.sessions.prepare({ seed })), the same primitive resume uses.

Capabilities

{ outputSchema: true, depthLimit: true, toolFilter: false } — identical to spawn (the depth/model/structured-output behavior is the shared driver's).

Config

Key Meaning
providerName Registry name on ctx.subagents (default fork).
structuredNudgeRetries How many times a structured run re-prompts a child that finished cleanly without calling structured_output (default 1).

See dsh-subagent-spawn for the run lifecycle, model inheritance, and depth tracking — all shared.