[juliusmarminge]

Picking up a sidebar thread near the bottom of the list ran the list away to the end, even with the pointer held still. Pinned threads left the screen before you could drop.

Fixes #27669

The cause is dnd-kit's default autoscroll: a 20% edge zone at full speed, and a scroll intent that stays on after one pixel of downward movement. The sidebar's DndContext now uses a 5% vertical edge zone and acceleration 3. Dragging to the edge still scrolls the list, at about 400 px/s. Context (tag) drags still turn autoscroll off.

This PR first also fixed a second cause: the Settled drop hint called scrollIntoView on every drag start. #30346 has since fixed that on main, so the takeover removed that part and its tests. Those tests failed against current main.

Measured in the web dev app, 1280×800, sidebar viewport y 100–756, about 500 seeded threads with Settled expanded. Each row: press a row, move as listed, hold still, sample scrollTop every 250 ms.

Gesture	Before (main)	After
Press at y 700, 8px down, then 3px	13 → 332 → 533 → end in under 1 s	0 throughout
Press at y 700, 10px up, then 1px down	10 → 265 → 425 → 610 → end	0 throughout
Drag a row out to the composer (tag)	sidebar left at 342	0
Deliberate drag to the bottom edge (y 750)	end in about 0.5 s	13 → 140 → 265 → … → end over 2 s

vp run check:changed passes on the merged head.

Not verified: touch input, trackpad feel by hand, the Electron app, and mobile (separate code).

Original work by @juliusmarminge. Takeover (merge with main, removal of the part #30346 covers, verification) by Claude Opus 5.5 in T3 Code (Claude Code harness).

🤖 Generated with Claude Code

[macroscopeapp]

Approvability

Verdict: Needs Human Approval

Macroscope's review found this PR requires human approval — This changes the default sidebar drag auto-scrolling to a narrower edge zone with lower acceleration, while keeping context-drag scrolling disabled. A human must confirm the new default interaction.

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[coderabbitai]

No actionable comments were generated in the recent review.

Walkthrough

The sidebar now uses custom auto-scroll settings for non-context drags. Sortable marker hints scroll into view only when their current or transformed bounds overlap the scroll viewport. Browser tests cover hint visibility during drag.

Changes: Sidebar drag scrolling

Layer / File(s)	Summary
Configure sidebar auto-scroll apps/web/src/components/Sidebar.tsx	Non-context drags use a 5% vertical edge threshold and acceleration of 3. Context drags continue to disable auto-scroll.
Guard sortable hint reveal during drag apps/web/src/components/sidebar/SidebarListMarkers.tsx, apps/web/src/components/sidebar/SidebarListMarkers.browser.test.tsx	The marker scrolls its hint into view only when its current or transformed bounds overlap the scroll viewport. Browser tests cover off-screen, clipped, and shifted hints.

Estimated code review effort: 2 (Simple) | ~15 minutes

Change: Bug fix · Severity of issue fixed: Low

Possibly related PRs

• pingdotgg/t3code#26736: This PR also changes when a settled drop hint scrolls into view during a drag.
• pingdotgg/t3code#28119: This PR changes which sidebar drag mode Working threads use, affecting whether the configured auto-scroll behavior applies.

Suggested reviewers: t3dotgg

Merge Risk: Minimal · up to 556e4

No actionable merge-blocking risk was identified in the changed sidebar drag-scrolling paths.

Pre-merge checks: 3 · 1

Failed checks: 1 inconclusive

Check name	Status	Explanation	Resolution
Description check		The description conflicts with the supplied changes. It says the Settled hint fix and tests were removed, but both appear in the file summaries. It also lacks the required UI screenshots and recording…	Confirm the final diff and update the description and verification results to match it. Add the template headings, before-and-after screenshots, and a recording of the drag behavior. Confirm that the linked issue is triaged, link maintainer…

Passed checks: 3 passed

Check name	Status	Explanation
Title check		The title clearly identifies the sidebar drag-scrolling fix and follows the repository’s conventional commit style.
Linked Issues check		Issue #27669 requires three coding changes: (1) the sidebar list must not scroll when a thread drag starts with a stationary pointer away from the edge; (2) edge scrolling must remain, at a controllab…
Out of Scope Changes check		The whole-PR diff against the merge base changes three areas, all in apps/web. (a) Sidebar.tsx: adds SIDEBAR_AUTO_SCROLL and the AutoScrollOptions import, and changes the autoScroll prop on …

Full details: Linked Issues check

Explanation

Issue #27669 requires three coding changes: (1) the sidebar list must not scroll when a thread drag starts with a stationary pointer away from the edge; (2) edge scrolling must remain, at a controllable speed; (3) the Settled drop hint must not pull the list to an off-screen position. The reviewed head meets each one.

(1) and (3): In SidebarListMarkers.tsx, SortableSidebarMarker calls scrollIntoView only when the hint rect, or the rect minus transform.y (its resting position), overlaps the first scrollable ancestor's rect. A clipped hint still overlaps, so it is still revealed. An entirely off-screen hint is not scrolled to.

(2): In Sidebar.tsx, SIDEBAR_AUTO_SCROLL sets threshold.y to 0.05 and acceleration to 3. This replaces dnd-kit's 20% zone and default speed. Context drags still get autoScroll={false}. These are the values the issue suggests. The PR transcript reports 0px scroll during the stationary-pointer gestures from the issue, and continued scrolling at the bottom edge (about 440 px/s) and top edge (about 400 px/s). The issue says the speed needs a real feel test. That is a validation step, not a coding requirement, and the PR states it was not done.

The focused browser tests in SidebarListMarkers.browser.test.tsx cover the off-screen case, the clipped case, and both transform directions. The issue's coding requirements are met by the code in the reviewed head.

Full details: Out of Scope Changes check

Explanation

The whole-PR diff against the merge base changes three areas, all in apps/web. (a) Sidebar.tsx: adds SIDEBAR_AUTO_SCROLL and the AutoScrollOptions import, and changes the autoScroll prop on DndContext. (b) SidebarListMarkers.tsx: changes the useLayoutEffect reveal logic and adds a getScrollableAncestors import. (c) SidebarListMarkers.browser.test.tsx: adds browser tests for these cases. Each change serves issue #27669. The PR does not change useScrollIntent, focus handling, or unrelated sidebar behavior. The added tests support the Settled hint change. No unrelated behavior change was found in the diff.

Full details: Description check

Explanation

The description conflicts with the supplied changes. It says the Settled hint fix and tests were removed, but both appear in the file summaries. It also lacks the required UI screenshots and recording.

Resolution

Confirm the final diff and update the description and verification results to match it. Add the template headings, before-and-after screenshots, and a recording of the drag behavior. Confirm that the linked issue is triaged, link maintainer approval, or explain why the fix qualifies without prior approval.

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Recent review info

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• Source mode: Auto
• Repository: pingdotgg/t3code
• Branch: fix/issue-27669
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• Commit: 556e47f
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Files selected for processing: 1

• apps/web/src/components/Sidebar.tsx

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[juliusmarminge]

Taking over this one