Codex code-review round 5: agent()/parallel()/pipeline() returned HOST Promise
objects into the script realm — Object.getPrototypeOf(agent('x')) reached host
Promise.prototype, contradicting the realm contract (correctness containment,
not the accepted sandbox stance). The rejection channel had the same leak one
hop away: a caught hook failure was a host WorkflowError (host Error.prototype
chain), and phase()/log() threw host errors synchronously.
All three surfaces are realm-built now:
- hook promises: the realm's own Promise.resolve (bound at context setup)
assimilates the host promise, so the script-visible promise carries realm
prototypes; the realm promise gets the same no-op rejection consumer as the
host one (a script may drop it).
- hook failures: rejections and phase/log sync throws are translated at the
boundary into realm-built clones (name/code/message/fatal via an in-realm
factory); non-WorkflowError host failures become generic realm Errors
carrying their describeThrown rendering.
- the combinators recognize FATAL clones structurally
(isFatalWorkflowErrorClone: proxy-guarded descriptor reads), preserving the
fatal-vs-null discipline across the boundary; a script forging the shape
kills only its own run. drive() maps any post-cancel failure to 'cancelled'
by run state (a CANCELLED clone deliberately fails the host instanceof).
Tests: realm-promise identity for all three hooks + host Promise.prototype
pollution unreachable; clone shape (instanceof realm Error, name/code/fatal/
message) with prototype-chain mutation staying realm-side; a rejecting
provider result crossing as a generic clone; phase/log sync-throw clones;
combinator catch branches (string throw, proxy throw, shape-miss forgery →
null; forged fatal → kills own run); existing fatal-propagation, cancellation,
and unhandled-rejection tests as canaries.
Codex code-review round 4 flagged the return channel: an async IIFE
Promise-assimilates a returned thenable, so its then() runs past the sync
slice and the RESOLUTION replaces the raw object. Verified against the real
engine and judged behavior, not defect:
- Assimilation is standard JavaScript (an async function's returned thenable
resolves before the caller sees it) and is load-bearing ergonomics: an
un-awaited 'return agent(...)' / 'return parallel(...)' resolves to the
intended value precisely because of it. Rejecting callable-then returns
would break that; intercepting pre-assimilation is spec-impossible (the
Get(v,'then') and job enqueue are internal to promise resolution).
- The realm-boundary guard applies to the RESOLUTION (a thenable resolving to
non-JSON is still RESULT_UNSERIALIZABLE), so nothing crosses unmaterialized.
- A spin inside a returned thenable's then() is the same accepted class as any
post-slice spin (it runs on the microtask queue, past the vm timeout's
reach); the docs previously said 'after the first await', which was too
narrow — reworded to 'past the initial synchronous slice (an await
continuation, or a thenable's then invoked by promise resolution)'.
Pinned with an engine test (un-awaited return agent(); custom thenable
resolution as the return value; thenable resolving to non-JSON rejects), and
the limitation wording updated in the module doc, README, and RFC.
Codex code-review round 3: the round-2 'contained stack getter' still let a
script escape the vm sync-slice timeout — throw { get stack() { while(true){} } }
put the spin on the HOST catch path, where no timeout applies (verified: a
direct sync-slice spin dies by the timeout; the getter-hidden one hung the
process). Identity-trusting the native getter is also insufficient: V8 stack
formatting reads script-controllable hooks at format time (Error.prepareStackTrace,
a subclass name getter — both empirically confirmed), so ANY host-side
formatting of a realm error can run realm code.
The fix moves rendering into the realm itself: the compiled body (and the meta
literal) is wrapped in a realm-side catch that pre-renders the thrown value to
a string (REALM_THROWN_RENDERER_SOURCE) — a hostile accessor/toString now runs
as ordinary script code, killed by the sync-slice timeout or falling under the
documented post-await spin limitation; host WorkflowErrors pass through for
the CANCELLED mapping. The host catch descriptor-reads the pre-rendered string
(thrownRendering) or falls back to describeThrown, which invokes no getter
whose identity is not the host realm's own native stack getter.
Tests: hostile-table expectations updated for realm-side rendering; new
regressions for the getter-hidden sync spin dying by the vm timeout (engine +
meta paths) and for a hostile thenable rejection that bypasses the realm
wrapper (renders host-side, proxy labelled, traps never run); describeThrown/
thrownRendering unit tables including the realm-error identity-mismatch case.
Codex code-review round 2: errorText() read .stack/.message as plain property
gets and fell back to String(error) — a script throwing a value with a
throwing accessor (or toString/Symbol.toPrimitive) ran realm code in drive()'s
catch and made WorkflowRun.result REJECT, which the detached workflow/end hook
turned into an unhandledRejection (process death under dsh-app-boot).
Replaced with describeThrown in dsh-workflow-vm/realm: total (never throws),
proxy-labelling before any inspection, own-descriptor reads, String() only on
primitives, and a CONTAINED stack-getter invocation — modern V8 (Node >= 22)
makes stack an own ACCESSOR on genuine Errors, so refusing all accessors would
lose every real stack and the lineOffset line numbers; a hostile getter's
throw is swallowed and rendering falls back to message. The meta-literal
eval catch had the same String(error) exposure and now uses the same renderer.
Regression tests: a hostile-thrown-values table through the real engine
(throwing stack/message getters, data stack, setter-only stack, proxy,
Symbol.toPrimitive, function, null) asserting result resolves 'error' with the
expected rendering and NO unhandledRejection fires; a meta-path hostile throw
mapping to META_INVALID.
Six verified A-findings from the code-stage review, each with a regression test:
- parallel()/pipeline() resolved to HOST arrays inside the vm realm, exposing
host Array.prototype to scripts; combinator results are now realm-built
(in-realm Array.from bound at context setup).
- materializeFromRealm ran proxy traps (ownKeys/getOwnPropertyDescriptor/
getPrototypeOf) during the descriptor walk — realm code on the host stack,
outside the vm timeout, escaping as raw errors; proxies (root, nested, and
in the prototype position) are now rejected trap-free via util.types.isProxy
before any inspection.
- an already-aborted signal or an immediate cancel() no longer reports
'completed' for a hook-free script: drive() checks cancellation before
running the body and again when the script settles.
- dispose() now waits (bounded by disposeGraceMs) for stray agent() children
to FINISH disposing, not just for the script to settle: every agent() call
is tracked and quiesce() drains the in-flight set.
- workflow/* event payloads were live mutable aliases shared across emissions;
emitWorkflowEvent now hands each listener its own structural clone.
- the structured-output turn-continuation veto is now prepend: true, so an
earlier-registered force-continue listener cannot short-circuit it.
Docs updated in the same change (READMEs, core-data-structures/workflow.md,
the dynamic-workflows RFC, regenerated cordis catalogs).
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.
Tianyi Cui