workflow: dynamic workflows — script-driven multi-agent orchestration

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.

scripts/gen-tool-catalog.ts

@@ -51,6 +51,8 @@ import * as ToolFs from '@deepseek-ai/dsh-tool-fs'
 import * as ToolTodo from '@deepseek-ai/dsh-tool-todo'
 import * as ToolSubagent from '@deepseek-ai/dsh-tool-subagent'
 import * as ToolWeb from '@deepseek-ai/dsh-tool-web'
+import VmWorkflowEngine from '@deepseek-ai/dsh-workflow-vm'
+import * as ToolWorkflow from '@deepseek-ai/dsh-tool-workflow'
 
 const root = resolve(import.meta.dirname, '..')
 const OUT = 'docs/tool-catalog/tools.md'
@@ -138,6 +140,20 @@ const TOOL_PACKAGES: ToolPackage[] = [
       await ctx.plugin(ToolTodo)
     },
   },
+  {
+    pkg: '@deepseek-ai/dsh-tool-workflow',
+    dir: 'tool-workflow',
+    source: 'packages/workflow/tool-workflow/src/index.ts',
+    async mount(ctx) {
+      // The tool injects `workflows`; boot the vm engine over a scripted
+      // subagent provider to satisfy it. The schema does not depend on which
+      // provider backs the engine.
+      await ctx.plugin(SubagentService)
+      await ctx.plugin(SubagentMock, { name: 'mock' })
+      await ctx.plugin(VmWorkflowEngine, { provider: 'mock' })
+      await ctx.plugin(ToolWorkflow)
+    },
+  },
   {
     pkg: '@deepseek-ai/dsh-tool-web',
     dir: 'tool-web',