# @deepseek-ai/dsh-workflow

English | [中文](README.zh.md)

The workflow seam (`ctx.workflows`) executes a model-written orchestration script that can fan out subagents. The seam defines the script, run, result, error, and event contracts; an engine decides how to isolate and execute the script.

`@deepseek-ai/dsh-workflow-workerthread` is the current engine and `@deepseek-ai/dsh-tool-workflow` is the model-facing consumer. A future process or sandbox engine can replace the implementation without changing the tool.

## Service and run contract

`WorkflowService.start(request): WorkflowRun` validates enough synchronously to reject a malformed meta block, unparseable script, unavailable provider route, or unsupported per-run limit before a run exists. Once returned, `WorkflowRun.result` never rejects: execution failures resolve with `stopReason: 'error'`, and cancellation resolves with `cancelled` within the engine's bounded grace.

A run is holder-owned. Engine-plugin unload prevents new starts but does not revoke accepted runs. The holder must call `dispose()` on every path; disposal cancels remaining work and reaches or abandons quiescence within the documented bound.

`WorkflowStartRequest` contains `{ meta, script, args?, subagentProvider?, maxTotalAgents?, parent, signal? }`. `parent` attributes every child agent to the invoking agent. `subagentProvider` optionally routes every child in that run without exposing provider choice to the script; omission uses the engine's configured provider. `maxTotalAgents` optionally lowers the engine's deployment ceiling for one run and is likewise invisible to the script. An implementation rejects invalid routes and limits synchronously. `meta` and `args` are plain data, not script fragments.

`WorkflowRun` exposes `{ id, meta, result, cancel(reason?), dispose() }`. `WorkflowResult` contains `{ value, stopReason, error?, agentsStarted }`; `value` is plain JSON data or `null`.

## Events

Workflow events are observe-only. They carry `WorkflowRunInfo` (`id` plus `meta`) rather than the live run, so listeners cannot acquire cancellation or disposal authority.

- `workflow/start` / `workflow/end` pair the run.
- `workflow/phase` and `workflow/log` expose script narration.
- `workflow/agent-start` / `workflow/agent-end` pair each child call by `seq`; a child whose async provider start rejects emits neither.

Same-process event payloads are borrowed immutable values. Every listener is independently contained: a synchronous throw or rejected returned promise is logged without starving peers or changing execution.

## Failure discipline

`WorkflowError` carries a code and a `fatal` flag. Fatal errors always escape `parallel()` and `pipeline()` instead of becoming an ordinary per-item `null`:

- `SCRIPT_PARSE` / `META_INVALID` — the workflow cannot start.
- `INVALID_ARGUMENT` / `UNSUPPORTED_OPTION` / `UNSUPPORTED_SCHEMA` — a hook call violates the engine contract.
- `AGENT_CAP` / `ITEM_CAP` — configured safety limits were exceeded.
- `AGENT_START` — the provider's async start rejected.
- `AGENT_RESULT` — a published child's result rejected with an infrastructure fault.
- `RESULT_UNSERIALIZABLE` — a script/worker value is not plain JSON data.
- `CANCELLED` — cancellation owns the run and pending/future hooks reject.

A child that resolves normally with a non-completed stop reason is not an infrastructure exception: `agent()` returns `null`, allowing the script to handle an ordinary child failure.

## Model Experience

Indirectly, through `dsh-tool-workflow` and a workflow engine, which create child-agent requests and return a retained parent tool result.

#### KV Cache effect

No direct invalidation; the named consumer owns any request-prefix changes.

## Known Limitations and Deferred Work

- **Foreground collection only** — the caller owns one live run and awaits it; background start/poll, spill handles, and detached collection are deferred.
- **No journaling or resume** — scripts, child progress, and intermediate values are not checkpointed, so a process restart cannot continue a run.
- **No saved or nested workflows** — the seam starts caller-supplied scripts only, and a workflow script receives no `workflow()` hook for recursive orchestration.
- **No token-budget vocabulary** — engines cap concurrency, items, and children, but neither the request nor result accounts for model tokens across children.
- **Runs are holder-owned, not service-tracked** — unloading the engine does not discover independent live handles; every consumer must dispose the run it started.

See the [dynamic-workflows Agent Note](../../../.agents/notes/implemented/feature/2026-07-05-dynamic-workflows.md) for the deferred workflow surface.
