fix(ui): preserve streaming chat scroll position

[marius-kilocode]

Problem

Streaming transcript layout changes can emit scroll events before the resize observer restores bottom-follow. The chat previously treated those browser and virtualizer events as user intent, so chart rendering, Bash output, tables, throughput updates, and other growing content could leave the transcript stuck above the bottom. Downward wheel input at the bottom could trigger the same state, and the initial input-aware fix did not cover native scrollbar drags or long touch gestures after the interaction grace period.

Fix

Auto-follow now distinguishes user movement from layout remeasurement:

• Scroll events caused by streaming reflow, virtualizer measurement, browser anchoring, or content growth no longer pause follow on their own.
• Downward wheel and trackpad input at the bottom does not mark the transcript as intentionally paused.
• Upward wheel input still pauses immediately.
• Native scrollbar movement and scroll-position changes with stable content height are treated as intentional user scrolling.
• Pointer, keyboard, and touch interaction protections remain in place, including long gestures that outlast the short activity grace period.

This keeps active streaming output pinned while preserving deliberate user scrolling.

Related Reports

• Setting to disable smart-scroll pause (always follow latest output) #13119, chat appears frozen mid-output when smart-scroll pauses.
• fix(vscode): chat auto-scroll won't detach from latest message on small upward wheel scroll #11485, small upward-wheel auto-scroll regression in the same hook.
• Auto-scroll lost on permission prompts and edit calls #10741, auto-scroll lost on streamed tool calls and permission prompts.
• Chat view does not auto-scroll to latest content #7879, original chat auto-scroll regression.

[kilo-code-bot]

Code Review Summary

Status: No Issues Found | Recommendation: Merge

Incremental review of 2acdb46; the previously reported warning (unmarked user-scroll channels no longer pausing auto-follow) is resolved by the stable-height position-change heuristic in handleScroll and covered by the new test.

Files Reviewed (2 files)

• packages/kilo-ui/src/hooks/create-auto-scroll.tsx
• packages/kilo-ui/src/hooks/create-auto-scroll.test.tsx

Previous Review Summary (commit cba6ebc)

Current summary above is authoritative. Previous snapshots are kept for context only.

Previous review (commit cba6ebc)

Status: 1 Issue Found | Recommendation: Address before merge

Overview

Severity	Count
CRITICAL	0
WARNING	1
SUGGESTION	0

Issue Details (click to expand)

WARNING

File	Line	Issue
packages/kilo-ui/src/hooks/create-auto-scroll.tsx	114	Unmarked user-scroll channels (native scrollbar drag, touch fling past grace window) no longer pause auto-follow

Files Reviewed (4 files)

• packages/kilo-ui/src/hooks/create-auto-scroll.tsx - 1 issue
• packages/kilo-ui/src/hooks/scroll-user-activity.ts
• packages/kilo-ui/src/hooks/create-auto-scroll.test.tsx
• .changeset/fix-streaming-scroll-follow.md

Fix these issues in Kilo Cloud

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_{Reviewed by kimi-k3 · Input: 37.2K · Output: 8K · Cached: 291.8K}

_{Review guidance: REVIEW.md from base branch main}