TUI attention sound plays repeatedly while idle with no events (WSL2)

Description

When a session is idle — no prompts, no tool calls, no permission requests —
the TUI plays the default attention sound (bip-bop, ~3 beeps) repeatedly at
irregular intervals, completely unrelated to any event. The sound is not
triggered by question/permission/error/done events: at the moment it plays,
the log shows zero new entries, process CPU is flat, and there is no UI
activity. Sound stops as soon as opencode exits.

Plugins

None

OpenCode version

1.18.14

Steps to reproduce

1. Windows 11 + WSL2 (Ubuntu), opencode 1.18.14 (latest)
2. Enable attention sound in ~/.config/opencode/tui.json:
   { "attention": { "enabled": true, "sound": true, "notifications": false, "volume": 0.4 } }
3. Use opencode normally until the agent completes a task and becomes idle
4. Leave the session idle without touching the terminal
5. After a short wait the default attention sound plays with no prompting,
   and repeats at irregular intervals (observed plays ~40s apart at
   22:49:10 / 22:49:50, then a longer gap)

Screenshot and/or share link

No response

Operating System

Windows 11 (opencode runs on WSL2 - Ubuntu)

Terminal

Windows Terminal (WSLg)

Reproduce the idle session with attention sound enabled under Windows 11/WSL2 Ubuntu and confirm that beeps occur without prompts, tool calls, permission requests, errors, or completion events. Then trace the TUI attention-sound event and timer paths. Done means idle sessions remain silent while genuine attention events still play the configured sound.