[BUG] Long silent stretches during large tasks; harness repeatedly prompts for status

During a multi-hour review the model went long periods with no user-visible update. The harness had to inject "user hasn't heard from you" reminders several times.

Repro steps

1. Start a long task that needs many tool calls (e.g. review several large pull requests, or run a multi-phase benchmark).
2. Let the model work without interrupting it.
3. Observe stretches of many consecutive tool calls with no text to the user, until the harness injects a status reminder.

Expected

Brief progress notes at a reasonable cadence without needing harness nudges.

Actual

Long silent stretches; the harness reminder is what triggers an update.

Recreated from #97131 (closed by the bot for missing repro steps).

Environment

Claude Code CLI, macOS, Opus model, long sessions with context compaction.