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'.
25 lines
2.0 KiB
Markdown
25 lines
2.0 KiB
Markdown
# @deepseek-ai/dsh-subagent-fork
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The in-process **fork** subagent backend: a [`SubagentProvider`](../subagent/README.md) that runs each child as a child [`Agent`](../../core/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`](../subagent-spawn/README.md); the only difference is the seed.
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## The seed boundary (the crux)
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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](../../support/invariants) replay **reject**.
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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.
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The seam this rides on: `CreateAgentOptions.seed` (added on `dsh-agent`, threaded through `AgentLoop.createAgent` → `ctx.sessions.prepare({ seed })`), the same primitive `resume` uses.
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## Capabilities
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`{ outputSchema: true, depthLimit: true, toolFilter: false }` — identical to spawn (the depth/model/structured-output behavior is the shared driver's).
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## Config
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| Key | Meaning |
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|---|---|
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| `providerName` | Registry name on `ctx.subagents` (default `fork`). |
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| `structuredNudgeRetries` | How many times a structured run re-prompts a child that finished cleanly without calling `structured_output` (default 1). |
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See [`dsh-subagent-spawn`](../subagent-spawn/README.md) for the run lifecycle, model inheritance, and depth tracking — all shared.
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