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'.
A fork subagent seeds its child session with a prefix of the parent's log, and
that seed becomes the child's persisted log — so a fork child's .jsonl begins
with the PARENT's events, including the parent's assistant/chunk events. The
snapshot replay harness derived a child's script from its whole log, which would
replay the parent's recorded responses as the child's model calls. Spawn-only
scenarios never hit it, but a fork snapshot would mis-route silently.
Record the seed boundary and skip the inherited prefix at replay:
- SessionHeader gains an optional `seedLength` (how many leading events were
inherited via a seed), threaded through CreateSessionOptions/CreateAgentOptions
meta and stamped by the fork backend (= seeded-prefix length; absent for spawn).
It is EXPLICIT, never inferred from seed.length: a resume seeds the whole stored
log, so the resume path passes the persisted boundary back.
- Both persistence backends round-trip it: JSONL header line, SQLite seed_length
column. The SQLite table change bumps SCHEMA_VERSION 2->3; per the pre-release
stance the backend rejects an older user_version on open with NO migration.
- llm-replay's parseSessionHeader reads seedLength and loadSessionScripts derives
a child script from events AFTER the boundary. seedLength is 0 for spawn, so
spawn replay is byte-for-byte unchanged.
Closes the routing-correctness gap the per-session snapshot replay RFC under-
stated; a recorded fork scenario remains a future addition but now derives
correctly. RFC: docs/rfc/implemented/testing/2026-06-22-fork-child-replay-seed-boundary.md.
Regression coverage: a fork child fixture whose seeded prefix carries a parent
chunk (derived script must exclude it, proven red without the slice); a seedLength
persistence round-trip through the shared coordinator contract (both backends);
the fork backend stamping it; resume preserving it from the persisted header.
The shared run driver lived inside dsh-subagent-spawn, so the spawn package
carried fork-aware seeding logic and dsh-subagent-fork depended backward on
dsh-subagent-spawn — the two in-process backends were not independent.
Move the driver (startInProcessRun, depthOf, SubagentDepthError,
InProcessRunOptions) into a new pure-library package
@deepseek-ai/dsh-subagent-inprocess that registers nothing. spawn and fork now
both depend only on that driver and neither knows about the other; spawn no
longer re-exports it and fork no longer imports from spawn.
Also wire BOTH backends in examples/coding-agent/cordis.yml (config-only): load
dsh-subagent-spawn + dsh-subagent-fork + two dsh-tool-subagent instances with
distinct toolNames (subagent → spawn, subagent_fork → fork), demonstrating that
exposing multiple transports needs no code change.
