af9616f47d
The regression's script spun immediately after calling agent(), but the agent() continuation (which posts the child-start RPC) only runs on a microtask tick — the spin seized the worker's loop before the post, so the host never saw a child inside the waitFor window. A few await-null yields before the spin let the RPC out; the posted message needs no further worker-loop turns to reach the host, so the wedge still holds for the Cancel message the test is about.
workflow/ — dynamic-workflow capability family
The workflow seam: a model-written JavaScript orchestration script that fans out subagents at scale (phases, structured per-agent results, concurrency caps), modeled on Claude Code's dynamic workflows. A capability seam (see capability seams) in the bash shape: ONE engine implementation per context registers as ctx.workflows; the model-facing tool consumes it.
| Package | Role | ctx key |
|---|---|---|
workflow/ |
Abstract workflow seam: service base class + run vocabulary + workflow/* events |
ctx.workflows |
workflow-workerthread/ |
node:worker_threads engine: one worker per run; the script's vm context lives inside the worker, agent() bridges to ctx.subagents over the message port |
(provides ctx.workflows) |
tool-workflow/ |
Model-facing workflow tool over ctx.workflows |
(registers on ctx.tools) |
The interface lives at workflow/workflow/. The engine's agent() hook rides the subagent seam (any registered provider; the shipped examples use spawn), and agent({ schema }) rides the structured-output support the in-process backends implement. The worker thread isolates the SCRIPT — the host never blocks on it, and a cancelled run's post-grace termination is real — but it is NOT a security boundary; an isolated-vm/separate-process engine (actual sandboxing) swaps in behind the same interface if that ever matters.
The proposal, decisions, and deferred work: docs/rfc/implemented/feature/2026-07-05-dynamic-workflows.md.