sidebar scrollbar always visible — should only appear when content overflows

[lawrencecchen]

Addresses #3241

Generated by cmux-loader.

Codex final message:

Implemented the sidebar scrollbar fix with a narrow change in the workspace sidebar scroll setup:

• Updated Sources/ContentView.swift in workspaceScrollArea’s SidebarScrollViewResolver callback:
  • scrollView?.autohidesScrollers = true
  • scrollView?.scrollerStyle = .overlay

Summary:

• This should make the workspace sidebar scrollbar adopt native behavior (hidden until needed/interaction), removing the permanent track when content fits.

Verification performed:

• ./scripts/reload.sh --tag loader-issue-3241-sidebar-scrollbar (failed: mkdir: /Users/runner/.cache/cmux: Operation not permitted)
• HOME=/tmp/cmux-home ./scripts/reload.sh --tag loader-issue-3241-sidebar-scrollbar (failed: cannot resolve github.com while fetching prebuilt GhosttyKit)
• HOME=/tmp/cmux-home CMUX_SKIP_ZIG_BUILD=1 ./scripts/reload.sh --tag loader-issue-3241-sidebar-scrollbar (failed same network/DNS issue resolving github.com)

Issue context:

• sidebar scrollbar always visible — should only appear when content overflows #3241

Recorded videos:

• None. Build/runtime environment could not complete a tagged launch/reload with network and cache access, so GUI capture wasn’t performed here.

---

Summary by cubic

Fixes #3241 by enabling native auto‑hiding, overlay scrollbars in the workspace sidebar. The scrollbar now stays hidden when content fits and appears on interaction or overflow.

^{Written for commit aafc1cb. Summary will update on new commits. Review in cubic}

Summary by CodeRabbit

• Bug Fixes
  • Improved sidebar scrollbar behavior to use overlay scrollers that automatically hide when not actively in use.

[vercel]

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Project	Deployment	Actions	Updated (UTC)
cmux	Ready	Preview, Comment	Apr 29, 2026 0:33am
cmux-staging	Building	Preview, Comment	Apr 29, 2026 0:33am

[coderabbitai]

Caution

Review failed

Pull request was closed or merged during review

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: 86cd8b84-8416-422a-96eb-5403de259977

📥 Commits

Reviewing files that changed from the base of the PR and between 84bc711 and aafc1cb.

📒 Files selected for processing (1)

• Sources/ContentView.swift

---

📝 Walkthrough

Walkthrough

The sidebar's ScrollView configuration now enables overlay scrollers and autohides the scroller UI through SidebarScrollViewResolver, while maintaining existing drag autoscroll attachment behavior.

Changes

Cohort / File(s)	Summary
Sidebar Scroll Configuration Sources/ContentView.swift	Configure NSScrollView with overlay scroller style and autohide behavior for the sidebar's main scroll view.

Estimated code review effort

🎯 1 (Trivial) | ⏱️ ~2 minutes

Possibly related PRs

• Keep selected workspace visible in sidebar #3152: Both PRs modify NSScrollView configuration in the sidebar (main PR adds overlay scrollers + autohide; retrieved PR adds insets and scroll-to-visible behavior).
• Disable right sidebar horizontal scroll #3202: Both PRs configure sidebar NSScrollView properties (main PR sets overlay scrollers + autohide via SidebarScrollViewResolver; retrieved PR disables horizontal elasticity).
• Fix feedback editor scrolling #3182: Both PRs modify NSScrollView scrollbar behavior in ContentView.swift (setting scrollerStyle = .overlay and autohidesScrollers).

Poem

🐰 Scrollers hide and dance with grace,
Overlay style takes their place,
The sidebar glides so smooth and clean,
The prettiest scroll I've ever seen! ✨

🚥 Pre-merge checks | ✅ 3 | ❌ 2

❌ Failed checks (2 warnings)

Check name	Status	Explanation	Resolution
Description check	⚠️ Warning	The description is missing key sections from the template: no manual testing verification, no demo video (though explained why), incomplete checklist items, and no review bot trigger comment included.	Add explicit testing steps performed, include the review trigger block, and complete the checklist with status updates for the verification attempts made.
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (3 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title accurately describes the main change: configuring the sidebar scrollbar to use overlay style and autohide, making it appear only when content overflows.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch loader/issue-3241-sidebar-scrollbar-video

---

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[lawrencecchen]

Closing this second dogfood attempt because Codex could not write cmux cache/DerivedData inside the sandbox, so it still could not reload or record before/after videos. Rerunning from a fresh branch with the sandbox writable dirs fixed in https://github.com/manaflow-ai/cmux-loader/pull/2.

[greptile-apps]

Greptile Summary

This PR fixes the workspace sidebar scrollbar always being visible by setting autohidesScrollers = true and scrollerStyle = .overlay on the underlying NSScrollView via the existing SidebarScrollViewResolver hook. The two-line change is consistent with identical settings applied to other scroll views in ContentView.swift (lines 5120–5121, 10999–11000).

Confidence Score: 5/5

Safe to merge — minimal, targeted, idiomatic change with no logic or security concerns.

Two-line addition using the same autohidesScrollers/scrollerStyle pattern already established in multiple other scroll views in the codebase. No new logic, no new state, fully idempotent on re-renders.

No files require special attention.

Important Files Changed

Filename	Overview
Sources/ContentView.swift	Adds autohidesScrollers = true and scrollerStyle = .overlay to the workspace sidebar scroll view resolver callback, matching the pattern used by other scroll views in the same file.

Sequence Diagram

sequenceDiagram
    participant SwiftUI as SwiftUI (workspaceScrollArea)
    participant Resolver as SidebarScrollViewResolver
    participant NSView as SidebarScrollViewResolverView
    participant ScrollView as NSScrollView (sidebar)

    SwiftUI->>Resolver: updateNSView(_:context:)
    Resolver->>NSView: resolveScrollView()
    NSView->>NSView: DispatchQueue.main.async
    NSView->>ScrollView: enclosingScrollView
    NSView->>ScrollView: autohidesScrollers = true
    NSView->>ScrollView: scrollerStyle = .overlay
    NSView->>ScrollView: dragAutoScrollController.attach(scrollView:)

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_{Reviews (1): Last reviewed commit: "Address https://github.com/manaflow-ai/c..." | Re-trigger Greptile}