Cowork emits a blank session "index" handoff on focus when a CLI session is paused awaiting input

Environment:

• Claude Desktop (Cowork) on Windows
• claude-code 2.1.149
• Anthropic Filesystem extension installed (ant.dir.ant.anthropic.filesystem)

Summary:
When I click back into a Claude Code (CLI) conversation that is paused waiting on user input (i.e. the session asked a question and is idle), Cowork generates and hands off an empty index for that session. It repeats every time I refocus the session. The payload is blank — no deliverables, no files, no tasks — so nothing is actually being passed off. It's a no-op handoff firing on a focus/visibility event.

Steps to reproduce:

1. Start a Claude Code session in Cowork.
2. Get the session into a "waiting for input" state (it asks a question and pauses).
3. Click away to another session/window, then click back into the paused session.
4. Observe Cowork create/hand off an index for the session.
5. Inspect it — it's empty.

Expected:
No index/handoff should be created or transmitted unless the session has produced genuine content to hand off (≥1 real deliverable, output file, or task result). A paused-on-a-question session with zero outputs should produce nothing.

Actual:
A blank index is generated and handed off on every refocus of the paused session, with no real payload.

Proposed fix:
Gate the index handoff on non-empty content — skip emission entirely when the computed index has no deliverables/tasks. At minimum, suppress re-emission when the session state is unchanged since the last handoff (debounce on focus events so refocusing an idle session doesn't re-fire).

Impact:
Cosmetic but persistent noise; makes it look like work is being passed off when it isn't, and adds churn on every focus. Low severity, but the repeated empty handoffs are confusing and erode trust in the handoff signal.