In-place port of dsh-workflow-vm from the in-process node:vm execution
to one worker thread per run (the workflow-workerthread engine of
PR #215, adopted as THE engine): the script's vm context moves inside
the worker, agent() bridges to ctx.subagents over the message port
(host.ts/protocol.ts/session.ts/worker.ts are new; runtime.ts loses the
abandon channel — the host's grace timer force-settles and TERMINATES
instead), start() pre-parses the body host-side to keep the seam's
synchronous SCRIPT_PARSE throw, and a ready→go handshake keeps a run
cancelled before start from ever executing the body. start() no longer
blocks the host, termination is real, and the value boundary is
serialization by construction. The package keeps its name until the
follow-up rename commit; scripts see the identical hook surface, and
the seam-contract tests hardened ahead of this swap pass unchanged.
The run and child-RPC surfaces are class-shaped rather than literal
bundles: WorkerRun IMPLEMENTS the seam's WorkflowRun (id/meta are its
own clone, separate from event payloads') and start() returns the
instance directly — interface parity with the seam is compiler-checked;
worker-side, ChildRpcBridge (implements ChildPort; callId allocation +
pending book-keeping settled by onChild* entry points) and
RpcChildHandle (every member an RPC keyed by its callId) carry names in
stacks. ChildPort's method is startAgent — it names what it starts,
matching the script-side agent() hook and the agentsStarted /
workflow/agent-* vocabulary; the Child* type names deliberately stay
(the worker side is cordis- and subagent-free; these are reduced JSON
projections, not the seam's types).
Review findings from the reference PR are folded in rather than
re-introduced:
- cancel() drives BOTH child-cancel channels host-side: the request
signal aborts AND each registered child's explicit cancel() is
called — a worker wedged in a synchronous spin cannot relay its own
ChildCancel RPCs (regression: cancel-only provider + wedged worker).
- All host warn paths render through the total renderThrown; a child
dispose() rejecting a value whose coercion throws still acks
ChildDisposed instead of wedging the script's finally (regression).
- built-worker.e2e.ts is wired into builtBinSmokeGate and the AGENTS.md
CI sequence — the built lib/worker.js resolution contract now runs in
an automated gate.
- workflow/end payload pinned on the worker-death path (with the
cancelled and grace-force-settle pins riding the ported spec).
- Real-Worker scripted timing budgets widened (50-300ms → 150-1000ms)
for starved CI hosts.
Workspace plumbing: the "./worker" subpath export sanctions the second
runtime bundle (check-workspace-constraints), tsdown builds two
single-entry passes, tsx becomes a devDependency for the unbuilt worker
spawn.
A new capability family at packages/workflow/ in the bash seam shape,
modeled on Claude Code's dynamic workflows: the model writes a JavaScript
orchestration script (export const meta = {...} + plain-JS body), a runtime
executes it, and the script — not the conversation — holds the loop, the
branching, and the intermediate results.
- dsh-workflow (ctx.workflows): abstract WorkflowService + run vocabulary
(WorkflowRun whose result NEVER rejects) + observe-only workflow/* events
carrying data snapshots (id + meta, never the live run), per-listener
contained like subagent/*.
- dsh-workflow-vm: in-process node:vm engine. Meta extraction via a
string/comment-aware scanner (template interpolation rejected; literal
evaluated alone in an empty timed context; statement blanked line-
preservingly so stacks keep script line numbers). Hooks: agent(prompt,
{label, phase, schema, model}) over ctx.subagents, parallel(), pipeline()
(no cross-stage barrier), phase(), log(), args. Fatal-vs-null discipline:
hook misuse (unknown/deferred options, bad arguments, unsupported
schemas, tripped caps, seam start failures, cancellation) throws fatal
WorkflowErrors the combinators RE-THROW — never dissolved into the
per-item null reserved for child failures. Realm boundary: inbound values
materialized by descriptor walks that never invoke accessors (defineProperty
copies, __proto__-safe); outbound values rebuilt in-realm via the
context's own JSON.parse. Determinism bans (Date.now/Math.random/argless
new Date) kept so future resume support cannot break scripts. Caps and
timeouts are validated Config. Every hook promise carries a no-op
rejection consumer (app-boot exits on unhandled rejections).
- dsh-tool-workflow: the model-facing workflow tool, synchronous like
dsh-tool-subagent (start → await → try/finally dispose; abort bridged;
non-completed → isError). Generic render card titled by a textual
meta.name sniff. The tool description carries the authoring contract.
Wired into examples/{coding-agent,acp-agent} with explicit-ask-only
guidance. Coverage at every tier: unit (meta scanner, materializer incl.
counting-getter and __proto__ regressions, combinator semantics,
concurrency ceiling, caps, cancellation, no-unhandled-rejection abandon),
integration over the real spawn stack, with-key e2e (real two-phase run +
the tool through the registry pipeline), and a recorded ACP snapshot
scenario (workflow-run, 1 child session). RFC:
docs/rfc/implemented/feature/2026-07-05-dynamic-workflows.md (deferred
work explicitly listed). AGENTS.md budget 1575 → 1590 for the new group's
layout line.
