[FEATURE] Desktop app: option to notify only when attention is needed or a session finishes (not on every turn end)

Problem

In the Claude Code desktop app (macOS), OS notifications (with sound) fire whenever a session finishes a response while the app is unfocused — not only when the session actually stops or needs the user.

Long-running sessions produce many intermediate turn-ends: background subagents reporting back, scheduled wakeups, background builds re-invoking the session, interim status messages. Each of these ends a turn and triggers a notification, even though the session immediately continues working and nothing is needed from the user.

For users who run several parallel sessions and want to focus on other work while they run, this makes notifications noise instead of signal: a beep no longer means "come back", it means "a turn ended somewhere".

Current workarounds (all lossy)

• macOS System Settings → Notifications → Claude: turning off the sound or the alerts silences everything, including the genuinely useful "session is blocked on a permission decision" ping.
• "preferredNotifChannel": "notifications_disabled" in ~/.claude/settings.json: same problem — all or nothing.

There is no setting that filters by notification reason.

Proposed feature

A notification-granularity option (desktop app settings and/or settings.json), e.g.:

• All (current behavior): every turn-end while unfocused
• Attention needed + session finished (requested): notify only when a session is waiting on the user (permission prompt, question, blocked) or when it has fully stopped — not on intermediate turn-ends while background work continues

The hooks system already distinguishes these internally (permission_prompt / idle_prompt notification types), so the reason-level granularity appears to exist — it's just not exposed as a user-facing notification filter.

Environment

• Claude Code desktop app, macOS (Darwin 25.6.0)
• preferredNotifChannel: "auto"