feat(tui): add terminal notifications via OSC escape sequences

[dexion]

Issue for this PR

Closes #23446

Type of change

• Bug fix
• New feature
• Refactor / code improvement
• Documentation

What does this PR do?

macOS desktop notifications from OpenCode appear as "Script Editor" alerts with no click-to-focus. This happens because the app uses osascript -e 'display notification...' which macOS attributes to the Script Editor process.

This PR adds terminal-native notifications via OSC escape sequences that work directly through the terminal emulator (iTerm2, Kitty, etc.), requiring no external tools.

How it works:

• New util/notify.ts — resolves notification method per terminal and formats OSC sequences
• New util/osc.ts — shared helper that wraps OSC sequences for tmux/screen passthrough
• Modified app.tsx — subscribes to session.idle, permission.asked, question.asked events
• Modified clipboard.ts — refactors OSC 52 clipboard to reuse the shared wrapOscSequence helper
• Modified tui-schema.ts + tui-migrate.ts — adds configurable notification_method option

Terminal detection ("auto" — default):

Terminal	Method	Why
iTerm2, Ghostty, Apple Terminal, Warp	OSC 9 (\x1b]9;msg\x07)	Native notification support with click-to-focus
Kitty, WezTerm, VTE-based	OSC 777 (\x1b]777;notify;title;body\x07)	Supported via xterm OSC 777
VS Code, Windows Terminal	Bell (\x07)	No OSC notification support
Other	Bell (\x07)	Safe fallback

Adapted from @kitlangton's draft PR #23212, but without the large provider.ts Effect/Schema refactor that caused merge conflicts.

How did you verify your code works?

Manual testing on macOS with iTerm2:

# OSC 9 — shows native iTerm2 notification, click focuses the tab
printf '\e]9;OpenCode: Response ready\a'

# OSC 777 — Kitty/WezTerm format
printf '\e]777;notify;OpenCode;Response ready\a'

# Bell fallback
printf '\a'

# tmux passthrough — wraps sequence correctly
TMUX=1 node -e "process.stdout.write('\x1b]9;test\x07')"

Verified that:

• iTerm2 shows native macOS notification with correct attribution
• Clicking notification focuses the correct iTerm2 tab
• notification_method: "off" suppresses all notifications
• notification_method: "bell" works as fallback in unsupported terminals

Screenshots / recordings

N/A — terminal behavior change, no UI changes in the TUI itself.

Checklist

• I have tested my changes locally
• I have not included unrelated changes in this PR

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[github-actions]

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Potential Duplicate PRs Found

1. #23212 — "feat(tui): add terminal notifications"

• Status: Related draft PR (mentioned in current PR description)
• Why: This is the original PR by @kitlangton that has merge conflicts. The current PR (feat(tui): add terminal notifications via OSC escape sequences #23447) is explicitly described as a focused, minimal implementation adapted from this PR's work, avoiding the large provider.ts refactor that caused conflicts.

2. #20963 — "feat(tui): built-in system notifications for session completion"

• Status: Potentially related earlier work
• Why: Addresses system notifications for TUI, which overlaps with the session.idle notification feature in the current PR.

The current PR (#23447) is the proper approach as it avoids the merge conflicts from #23212 while implementing the same terminal notification functionality using OSC escape sequences.

[github-actions]

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