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-spawn/README.md

@@ -6,7 +6,7 @@ The run mechanics live in the shared [`@deepseek-ai/dsh-subagent-inprocess`](../
 
 ## What it does
 
-`start(request)` delegates to `startInProcessRun(ctx, request, { providerName, structuredNudgeRetries })` with no seed: a fresh child agent with the parent's `cwd`/`parentSession` lineage and (by default) the parent's model. See the [driver README](../subagent-inprocess/README.md) for the full lifecycle (depth check, one-shot drive, result read, dispose).
+`start(request)` delegates to `startInProcessRun(ctx, request, { providerName })` with no seed: a fresh child agent with the parent's `cwd`/`parentSession` lineage and (by default) the parent's model. See the [driver README](../subagent-inprocess/README.md) for the full lifecycle (depth check, one-shot drive, result read, dispose).
 
 ## Capabilities
 
@@ -17,4 +17,3 @@ The run mechanics live in the shared [`@deepseek-ai/dsh-subagent-inprocess`](../
 | Key | Meaning |
 |---|---|
 | `providerName` | Registry name on `ctx.subagents` (default `spawn`). |
-| `structuredNudgeRetries` | How many times a structured run re-prompts a child that finished cleanly without calling `structured_output` (default 1). |

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

@@ -32,20 +32,14 @@ export const name = 'subagent-spawn'
 // structured output existed.
 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 `spawn`). */
   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('spawn'),
-  structuredNudgeRetries: z.natural().default(1),
 })
 
 /**
@@ -59,20 +53,13 @@ class SpawnProvider implements SubagentProvider {
   // Context contract: a spawned child starts fresh — it never sees the parent conversation.
   readonly inheritsParentContext = false
 
-  constructor(
-    readonly name: string,
-    private readonly ctx: Context,
-    private readonly structuredNudgeRetries: number,
-  ) {}
+  constructor(readonly name: string, private readonly ctx: Context) {}
 
   start(request: SubagentStartRequest) {
     // Fresh child: no seed. The shared driver mints ids, stamps cwd/lineage/
-    // depth, drives the one-shot (including the structured capture/nudge loop
-    // when the request carries an outputSchema), and maps the result.
-    return startInProcessRun(this.ctx, request, {
-      providerName: this.name,
-      structuredNudgeRetries: this.structuredNudgeRetries,
-    })
+    // depth, drives the one-shot (including the structured capture when the
+    // request carries an outputSchema), and maps the result.
+    return startInProcessRun(this.ctx, request, { providerName: this.name })
   }
 }
 
@@ -85,5 +72,5 @@ export function apply(ctx: Context, config: Config): void {
     const acquisition = acquireStructuredRuntime(ctx)
     return () => { acquisition.release() }
   }, 'subagent-spawn structured runtime')
-  ctx.subagents.registerProvider(new SpawnProvider(config.providerName, ctx, config.structuredNudgeRetries))
+  ctx.subagents.registerProvider(new SpawnProvider(config.providerName, ctx))
 }

packages/subagent/subagent-spawn/tests/harness.ts

@@ -34,7 +34,7 @@ export async function spawnHarness(workdir: string): Promise<Context> {
   await ctx.plugin(LocalBashExecutor, { cwd: workdir, timeoutMs: 30_000 })
   await ctx.plugin(ToolBash)
   await ctx.plugin(SubagentService)
-  await ctx.plugin(Spawn, { providerName: 'spawn', structuredNudgeRetries: 1 })
+  await ctx.plugin(Spawn, { providerName: 'spawn' })
   // The model-facing subagent tool, bound to the spawn backend.
   await ctx.plugin(ToolSubagent, { provider: 'spawn' })
   return ctx

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

@@ -34,7 +34,7 @@ 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(spawn, { providerName: 'spawn' })
   ctx.llm.registerAdapter(['mock'], adapter)
   const parent = ctx.agentLoop.create(AgentId('parent'), { model: 'mock' })
   return { ctx, parent, adapter }
@@ -257,7 +257,7 @@ describe('dsh-subagent-spawn', () => {
     // the registries are loaded here so the runtime registers eagerly anyway.
     await ctx.plugin(SystemPrompt)
     await ctx.plugin(ToolRegistry)
-    const fiber = await ctx.plugin(spawn, { providerName: 'spawn', structuredNudgeRetries: 1 })
+    const fiber = await ctx.plugin(spawn, { providerName: 'spawn' })
     expect(ctx.subagents.list()).toEqual(['spawn'])
     await fiber.dispose()
     expect(ctx.subagents.list()).toEqual([])