b82c310db3
Two merge-blocking bugs in the shared in-process run driver, both rooted in `readResult` scanning the whole child session and deriving the stop reason only from `turn/end`: - A pre-turn `cancel()` cleared the queued prompt before any `turn/end` was logged, so the run settled `error` instead of `aborted`, violating the `SubagentRun.cancel()` contract. The driver now tracks that a cancel was requested and maps the no-turn case to `aborted`. - A fork child whose own turn produced no `assistant/message` returned the SEEDED parent's last message as a `completed` success. `readResult` now scopes to the child's OWN events (after the seed prefix), so a message-less child yields empty output. Both fixes carry a regression test proven to go red on the pre-fix driver. Also: correct the `SubagentRun.id` / event-payload docs (it is the child AGENT id, not a session id — the backend mints distinct tokens); refresh the stale `coding-agent` welcome string (subagent is now a tool); and replace the stale `TODO(sub-agents)` "deferred" prose in the Agent interface, core.md, and architecture.md with an accurate pointer to the realized seam.
@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.createAgent → ctx.sessions.prepare({ seed })), the same primitive resume uses.
Capabilities
{ outputSchema: false, depthLimit: true, toolFilter: false } — identical to spawn (the depth/model/output behavior is the shared driver's).
Config
| Key | Meaning |
|---|---|
providerName |
Registry name on ctx.subagents (default fork). |
See dsh-subagent-spawn for the run lifecycle, model inheritance, and depth tracking — all shared.