feat(subagent): deliver continuable child settlement to parents

A continuable child that stopped without reporting — an error, a token
ceiling, cancellation, teardown — left its parent nothing to act on.
The continuation manager now delivers an unconditional settlement
notice to the durable direct parent before releasing ownership, folding
consumed work (foldConsumedWork supersedes findLastMessageTurnEnd) so a
claimed-but-unrun prompt reads as aborted rather than completed, waking
an idle parent, steering a busy one, and never waking a closing tree.

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

@@ -13,8 +13,9 @@
 
 import { randomUUID } from 'node:crypto'
 import type { Context } from '@deepseek-ai/cordis'
+import { foldConsumedWork } from '@deepseek-ai/dsh-agent'
 import type { Agent, AgentHandle } from '@deepseek-ai/dsh-agent'
-import { findLastMessageTurnEnd, SessionId, type SessionEvent, type TurnEndReason } from '@deepseek-ai/dsh-session'
+import { SessionId, type SessionEvent, type TurnEndReason } from '@deepseek-ai/dsh-session'
 import { createUserMessage, type ContentBlock } from '@deepseek-ai/dsh-llm'
 import {
   appendDelegatedPolicyOverrides,
@@ -52,6 +53,10 @@ function toStopReason(reason: TurnEndReason | undefined): SubagentStopReason {
       return 'max-tokens'
     case 'aborted':
       return 'aborted'
+    // A pre-step rejection discarded the claimed prompt: the task was
+    // declined, and the caller must not read the run as done.
+    case 'blocked':
+      return 'refusal'
     case 'error':
     case 'interrupted':
     default:
@@ -207,7 +212,11 @@ function readResult(
   structured?: { captured?: { value: unknown } | undefined },
 ): SubagentResult {
   const own = child.session.events.slice(boundary)
-  const lastEnd = findLastMessageTurnEnd(own)
+  // `droppedUnrun` is deliberately unread: a one-shot prompt is claimed by its
+  // awaited first turn almost immediately, and the owner's own teardown is the
+  // `cancelled` flag below. A cancellation with no accounting turn resolves
+  // `error` through `toStopReason(undefined)`, which never overstates success.
+  const lastEnd = foldConsumedWork(own).end
   // The seam's canonical selection rule; a partial answer survives cancel and truncation.
   const output: ContentBlock[] = finalAssistantOutput(own) ?? []
   const recorded = toStopReason(lastEnd?.data.reason)