fix(tui): route prompts by next-step capability

packages/core/agent/src/types.ts

@@ -147,6 +147,12 @@ export interface Agent {
   readonly session: Session
   /** The current lifecycle state, mirrored on every `agent/status` transition. */
   readonly status: AgentStatus
+  /**
+   * Whether a `next-step` send currently stages for prompt admission or the
+   * open turn. Unlike {@link status}, this excludes admission exit and turn
+   * settlement, when a waking `next-step` send becomes a queued follow-up.
+   */
+  readonly acceptsNextStep: boolean
   /** Agent-scoped context; its contributions are agent-local, unwind on disposal, and reject registration afterward. */
   readonly ctx: Context
 

packages/core/agent/tests/agent.spec.ts

@@ -17,11 +17,12 @@ import type {
 
 function stubAgent(rawId: string, overrides: Partial<Agent> = {}): Agent {
   const id = SessionId(rawId)
-  return {
+  const agent: Agent = {
     id,
     options: {},
     session: new Session(id),
     status: 'idle',
+    acceptsNextStep: false,
     ctx: new Context(),
     send: () => AgentMessageId('stub'),
     followup: () => AgentMessageId('stub'),
@@ -30,8 +31,8 @@ function stubAgent(rawId: string, overrides: Partial<Agent> = {}): Agent {
     cancel() {},
     retry() {},
     whenIdle() { return Promise.resolve() },
-    ...overrides,
   }
+  return Object.assign(agent, overrides)
 }
 
 describe('AgentRegistry', () => {