Mark tabs and split action buttons for host hint modes

[teamleaderleo]

cmux's hint mode (Cmd-J) labels every clickable control in the window so typing a label clicks it. It walks the window in process, and there SwiftUI shows the tab bar only as unknown accessibility elements, so the pane tab bar's tabs and split action buttons got no labels.

• New public BonsplitHintTargetView: a transparent, click-through, non-accessibility view at a control's frame, with a title.
• Each tab carries one named by its title. Each split action button carries one, applied once in splitButtonRow so it covers all three button styles, named by its tooltip.

Nothing changes for clicks or VoiceOver: the view returns nil from hitTest and is not an accessibility element.

Tests: Tests/BonsplitTests/BonsplitHintTargetTests.swift hosts a two-tab BonsplitView and expects targets named after both tabs and the default New Terminal and Split Right tooltips.

Used by manaflow-ai/cmux cx-zjtn.7 (hint mode labels for the pane tab bar). The cmux pin bump that adopts this also brings #272, #273 and #275; #272's fields are opt-in, so cmux's buttons keep their current behavior.

🤖 Generated with Claude Code

---

^{Need help on this PR? Tag @codesmith-bot with what you need. Autofix is disabled.}

---

Summary by cubic

Marks pane tab bar tabs and split action buttons with a new BonsplitHintTargetView so a host's keyboard hint mode (like cmux's Cmd-J) can label them. SwiftUI shows the tab bar only as unknown accessibility elements in process, so hosts couldn't name these controls before.

The target view is transparent and click-through—it returns nil from hitTest and isn't an accessibility element—so clicks and VoiceOver behavior are unchanged. Each tab carries a target named by its title; each split action button carries one named by its tooltip. Tests cover a two-tab BonsplitView and expect targets for both tabs and the default New Terminal and Split Right tooltips.

^{Written for commit 9a48db6. Summary will update on new commits.}

Summary by CodeRabbit

• New Features
  • Keyboard hint mode can now identify tabs by their titles and split actions by their existing tooltip text.
  • Hint targets do not intercept mouse interactions or appear as separate accessibility elements.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

• Configuration used: defaults
• Review profile: CHILL
• Plan: Advanced
• Run ID: 5c54ca4d-7bfd-464a-949c-18e785ed4529

---

📥 Commits

Reviewing files that changed from the base of the PR and between 5e441ac and 9a48db6.

---

📒 Files selected for processing (4)

• Sources/Bonsplit/Internal/Views/TabBarView.swift
• Sources/Bonsplit/Internal/Views/TabItemView.swift
• Sources/Bonsplit/Public/BonsplitHintTarget.swift
• Tests/BonsplitTests/BonsplitHintTargetTests.swift

---

Included review availability: This review used your included allowance. Your plan provides up to 1 included review per hour; 0 remain after this review.

---

---

📝 Walkthrough

Walkthrough

The change adds BonsplitHintTargetView and a SwiftUI modifier, then applies hint targets to tab titles and split-action tooltip text. Tests verify the target titles and hit-test behavior.

Changes

Keyboard hint targets

Layer / File(s)	Summary
Hint target view and modifier Sources/Bonsplit/Public/BonsplitHintTarget.swift	Adds an NSView subclass that stores a title, does not handle hit tests, and is not an accessibility element. A SwiftUI representable updates the title, and a view modifier attaches it as a background.
Register tab and split-action titles Sources/Bonsplit/Internal/Views/TabItemView.swift, Sources/Bonsplit/Internal/Views/TabBarView.swift, Tests/BonsplitTests/BonsplitHintTargetTests.swift	Tab views use their title as a hint target. Split-action buttons use their tooltip text. Tests check expected target titles and confirm that targets return nil from hit testing.

Priority: ➖ Normal

Estimated code review effort: 2 (Simple) | ~10 minutes

Change: Feature

Suggested reviewers: lawrencecchen

---

Merge Risk: ⚪ Minimal · up to 9a48d

This change adds a transparent, click-through view that marks tabs and split-action buttons for hint modes. Existing click and VoiceOver behavior is not expected to change, and no merge-blocking risk was found.

Pre-merge checks | 4 | 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage		Docstring coverage is 14.29% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 7 functions across 4 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check		Check skipped - CodeRabbit’s high-level summary is enabled.
Title check		The title clearly summarizes the main change: marking tabs and split action buttons for host hint modes.
Linked Issues check		Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check		Check skipped because no linked issues were found for this pull request.

---

• Fix all pre-merge checks with AI

✨ Finishing Touches 💡 1

📝 Generate docstrings 💡

• Commit to this branch
• Create a new PR

---

---

🧪 Generate unit tests (beta)

• Commit to this branch
• Create a new PR

---

• Autofix · Keep fixing CodeRabbit findings and required CI, and resolving merge conflicts

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

---

_{Comment @coderabbitai help to get the list of available commands.}

[teamleaderleo]

Parking this: Leo decided hint mode in cmux stays opt-in (manaflow-ai/cmux#19538 closed), so the tab-bar labels are on hold. Tests passed here (Hint targets suite). The branch leo/hint-targets stays for when the work resumes; the cmux side is on leo/cx-zjtn-7-tabbar-hints (red test 0/7 recorded).