fix(web): stop follow-ups from leaving giant blank space

[t3dotgg]

Sending a follow-up could leave thousands of pixels of blank space below the thread. Chromium rounds temporary LegendList padding, so the cleanup compared different strings and never removed it.

Store the browser-normalized padding before the cleanup check in both LegendList web builds. The 3,233.83px reproduction now clears, and all 45 focused timeline tests pass.

Built by GPT-5.6 Sol with Codex.

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Note

Medium Risk
Touches virtualized list scroll padding and end-anchor sizing via a vendor patch, so leftover space or jumpiness is possible if cleanup still mismatches.

Overview
Fixes a web thread bug where sending a follow-up could leave thousands of pixels of blank space below the list.

Chromium rounds LegendList’s temporary end padding, so cleanup compared a different string and never removed it. The patch now stores the browser-normalized padding after applying it (react.js / react.mjs ScrollAdjust).

Also caps anchored end space while tail sizes are still unknown and applies shrinks even before the space is “ready,” so leftover blank height does not stick around.

^{Reviewed by Cursor Bugbot for commit 5393885. Bugbot is set up for automated code reviews on this repo. Configure here.}

Note

Fix blank space in follow-ups by patching ScrollAdjust in @legendapp/list

• Patches ScrollAdjust in @legendapp__list@3.3.5.patch so temporaryPaddingRef.current is set after the contentNode.style[axis.paddingEndProp] mutation and reads the actual applied value from that style property.
• This ensures the recorded padding matches what the browser applied, preventing leftover blank space in follow-up scroll layouts.
• Risk: temporaryPaddingRef.current.value now reflects contentNode.style[axis.paddingEndProp] rather than the pre-mutation local temporaryPaddingEnd; any code relying on the old timing or value source may see different padding references.

^{Macroscope summarized 5393885.}

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[github-actions]

Thread transfer impact

✅ Thread transfer remains within every enforced ceiling.

Provider	Metric	Main baseline	This PR	Impact	PR ceiling
Codex	Total thread wire	13.4 KiB	13.4 KiB	+13 B (+0.1%)	15.1 KiB	✅
Codex	Thread snapshot wire	6.9 KiB	6.9 KiB	0 B (0.0%)	7.3 KiB	✅
Codex	Live turn WebSocket wire	6.5 KiB	6.5 KiB	+13 B (+0.2%)	7.8 KiB	✅
Codex	Live turn WebSocket decoded	55.0 KiB	55.0 KiB	0 B (0.0%)	66.4 KiB	✅
Codex	Live turn messages	16	16	0 (0.0%)	21	✅
Claude	Total thread wire	13.5 KiB	13.4 KiB	−12 B (−0.1%)	15.1 KiB	✅
Claude	Thread snapshot wire	6.9 KiB	6.9 KiB	−1 B (−0.0%)	7.3 KiB	✅
Claude	Live turn WebSocket wire	6.6 KiB	6.6 KiB	−11 B (−0.2%)	7.8 KiB	✅
Claude	Live turn WebSocket decoded	55.8 KiB	55.8 KiB	0 B (0.0%)	66.4 KiB	✅
Claude	Live turn messages	16	16	0 (0.0%)	21	✅

Baseline: e9f50c3 · PR result: 5393885 · Source CI: success

Scenario and decoded snapshot size

10 historical turns, 5 command tools per turn, 878.9 KiB retained MCP result per historical turn, and a 1.05 MiB retained result in the measured turn.

• Codex decoded thread snapshot: 109.4 KiB
• Claude decoded thread snapshot: 110.1 KiB

Updated in place by a trusted workflow. PR artifacts are strictly validated and never executed.

[t3dotgg]

Note

🤖 GPT-5.6 Sol responding on behalf of Theo

cursor review

[macroscopeapp]

Approvability

Verdict: Approved at 5393885

Macroscope's review found this PR approvable — This is a small, self-contained vendor patch that fixes temporary web scroll padding cleanup in both module formats, with the lockfile only recording the new patch hash. Its runtime effect is limited to the affected out-of-bounds scroll adjustment path and does not introduce new APIs, workflows, or infrastructure changes.

^{You can add or adjust custom eligibility rules. Learn more.}