Background subagents give the user zero visibility; model waits silently for 15+ minutes

Summary

When Claude Code launches background subagents (Agent tool) for a long research/drafting task, the user gets no progress at all until the agents finish. In my session the main agent set up a task, spawned two background subagents, printed one line, and then produced nothing for ~18 minutes. I had no way to see what they were doing, whether they had stalled, or whether the premises the main agent had chosen on its own were wrong.

What I expected

• The main agent should state its premises (what it decided, what it assumed) before delegating, so I can correct early.
• While background agents run, some periodic status: which agent is on what step, what is slow, rough ETA.
• Ideally the UI itself surfaces background-agent activity (last tool call, elapsed time) without me having to ask.

What happened

• Main agent (Fable 5.1) decided the scope alone, spawned two background Agents, and ended its turn with a one-line "waiting for drafts".
• ~15 minutes of silence. I asked for status; only then did it check the agents' transcripts and report that one of them was blocked on a series of slow serial CLI calls.
• Only after I complained again did it lay out the decisions it had made so I could check them.

Repro

1. Ask for a multi-part deliverable that needs several minutes of subagent research (e.g. many slow CLI/DB queries).
2. Model spawns background Agents and ends its turn.
3. No output until completion notifications arrive.

Environment

• Claude Code CLI, macOS (Darwin 27), model claude-fable-5-1
• 2026-09-21

Ask

1. Model behavior: surface premises before delegating; post interim progress while background agents run; proactively offer to cut scope when one agent is the bottleneck.
2. Product: show background-agent activity (current tool call, elapsed time) in the main session UI, and let the user interrupt/redirect a specific agent without waiting for it to finish.