review: drop the structured-output nudge; FIXME the context-global registry constraint

Two human review directives:

- No re-prompt. A structured child that finishes a turn cleanly without
  calling structured_output settles error to the parent immediately —
  readResult already carried that mapping; the nudge loop only delayed it.
  Deletes the loop, its cancellation-window guard, STRUCTURED_OUTPUT_NUDGE,
  and the structuredNudgeRetries Config on both backends.

- FIXME in the structured module doc: per-agent/per-session tool registry and
  prompt assembly would dissolve the final-assembly enforcement dance (the
  placeholder tool, the swap, the strip, the global-registration lifetime).

packages/subagent/subagent-fork/README.md

@@ -19,6 +19,5 @@ The seam this rides on: `CreateAgentOptions.seed` (added on `dsh-agent`, threade
 | Key | Meaning |
 |---|---|
 | `providerName` | Registry name on `ctx.subagents` (default `fork`). |
-| `structuredNudgeRetries` | How many times a structured run re-prompts a child that finished cleanly without calling `structured_output` (default 1). |
 
 See [`dsh-subagent-spawn`](../subagent-spawn/README.md) for the run lifecycle, model inheritance, and depth tracking — all shared.

packages/subagent/subagent-fork/src/index.ts

@@ -34,20 +34,14 @@ export const name = 'subagent-fork'
 // model-visible tool list) is unchanged by structured output.
 export const inject = ['subagents', 'agents']
 
-/** Config: the registry name to register the provider under, plus structured-run tuning. */
+/** Config: the registry name to register the provider under. */
 export interface Config {
   /** Provider name on `ctx.subagents` (default `fork`). */
   providerName: string
-  /**
-   * How many times a structured run re-prompts a child that finished cleanly
-   * without calling `structured_output` before giving up (default 1).
-   */
-  structuredNudgeRetries: number
 }
 
 export const Config: z<Config> = z.object({
   providerName: z.string().default('fork'),
-  structuredNudgeRetries: z.natural().default(1),
 })
 
 /**
@@ -76,17 +70,12 @@ class ForkProvider implements SubagentProvider {
   // Context contract: a forked child IS seeded with the parent's completed-turn prefix.
   readonly inheritsParentContext = true
 
-  constructor(
-    readonly name: string,
-    private readonly ctx: Context,
-    private readonly structuredNudgeRetries: number,
-  ) {}
+  constructor(readonly name: string, private readonly ctx: Context) {}
 
   start(request: SubagentStartRequest) {
     const seed = completedTurnPrefix(request.parent)
     return startInProcessRun(this.ctx, request, {
       providerName: this.name,
-      structuredNudgeRetries: this.structuredNudgeRetries,
       // Only pass a seed when there's a completed turn to inherit; an empty seed
       // is equivalent to a fresh child, so omit it to keep the session unseeded.
       ...seed.length > 0 ? { seed } : {},
@@ -102,5 +91,5 @@ export function apply(ctx: Context, config: Config): void {
     const acquisition = acquireStructuredRuntime(ctx)
     return () => { acquisition.release() }
   }, 'subagent-fork structured runtime')
-  ctx.subagents.registerProvider(new ForkProvider(config.providerName, ctx, config.structuredNudgeRetries))
+  ctx.subagents.registerProvider(new ForkProvider(config.providerName, ctx))
 }

packages/subagent/subagent-fork/tests/multi-subagent.spec.ts

@@ -30,8 +30,8 @@ async function setup(script: Script) {
   await ctx.plugin(Invariants)
   await ctx.plugin(AgentLoop, { agents: [] })
   await ctx.plugin(SubagentService)
-  await ctx.plugin(Spawn, { providerName: 'spawn', structuredNudgeRetries: 1 })
-  await ctx.plugin(fork, { providerName: 'fork', structuredNudgeRetries: 1 })
+  await ctx.plugin(Spawn, { providerName: 'spawn' })
+  await ctx.plugin(fork, { providerName: 'fork' })
   ctx.llm.registerAdapter(['mock'], new MockAdapter(script))
   const parent = ctx.agentLoop.create(AgentId('parent'), { model: 'mock' })
   return { ctx, parent }

packages/subagent/subagent-fork/tests/subagent-fork.spec.ts

@@ -37,7 +37,7 @@ async function setup(script: Script) {
   await ctx.plugin(Invariants)
   await ctx.plugin(AgentLoop, { agents: [] })
   await ctx.plugin(SubagentService)
-  await ctx.plugin(fork, { providerName: 'fork', structuredNudgeRetries: 1 })
+  await ctx.plugin(fork, { providerName: 'fork' })
   ctx.llm.registerAdapter(['mock'], new MockAdapter(script))
   const parent = ctx.agentLoop.create(AgentId('parent'), { model: 'mock' })
   return { ctx, parent }
@@ -176,7 +176,7 @@ describe('dsh-subagent-fork', () => {
     // the registries are loaded here so the runtime registers eagerly anyway.
     await ctx.plugin(SystemPrompt)
     await ctx.plugin(ToolRegistry)
-    const fiber = await ctx.plugin(fork, { providerName: 'fork', structuredNudgeRetries: 1 })
+    const fiber = await ctx.plugin(fork, { providerName: 'fork' })
     expect(ctx.subagents.list()).toEqual(['fork'])
     await fiber.dispose()
     expect(ctx.subagents.list()).toEqual([])