fix(agent-manager): preserve worktree list scroll on deletion

[marius-kilocode]

What Problem This Solves

Deleting a worktree from a long Agent Manager sidebar rebuilt the worktree rows from a complete state snapshot and reset the list to the top. This made repeated cleanup difficult because the selected position was lost after every deletion.

Why This Change Was Made

Agent Manager has different scroll owners in single-project and multi-project layouts. Preserve both containers before applying a state snapshot, restore their offsets after two animation frames, and cancel stale pending restores when another snapshot arrives. This keeps the fix scoped to the sidebar instead of changing project-state reconciliation.

User Impact

Worktree deletion keeps the current sidebar position in both supported layouts. Removed containers are ignored, and a shorter list naturally clamps to its new maximum scroll position.

Evidence

• Reproduced the unfixed behavior in an isolated VS Code self-test: deleting a real worktree reset scrollTop from 174 to 0.
• Verified the final fix with 26 real disposable worktrees: deleting one reduced the row count to 25 while scrollTop remained 320 before and after the deletion.
• Added focused coverage for worktree and project scroll owners, rapid successive snapshots, and disconnected containers.
• Passed extension compilation, typechecking, lint, Knip, the Kilo marker guard, and all 4,149 extension unit tests.

[kilo-code-bot]

Code Review Summary

Status: No Issues Found | Recommendation: Merge

Files Reviewed (3 files)

• packages/kilo-vscode/tests/unit/agent-manager-sidebar-scroll.test.ts
• packages/kilo-vscode/webview-ui/agent-manager/AgentManagerApp.tsx
• packages/kilo-vscode/webview-ui/agent-manager/sidebar-scroll.ts

Previous Review Summaries (2 snapshots, latest commit 71869fd)

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

Previous review (commit 71869fd)

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-vscode/webview-ui/agent-manager/sidebar-scroll.ts	30	scrollTop === 0 still loses to delayed scrollIntoView

Files Reviewed (3 files)

• packages/kilo-vscode/tests/unit/agent-manager-sidebar-scroll.test.ts - 0 issues
• packages/kilo-vscode/webview-ui/agent-manager/AgentManagerApp.tsx - 0 issues
• packages/kilo-vscode/webview-ui/agent-manager/sidebar-scroll.ts - 1 issue

Fix these issues in Kilo Cloud

Previous review (commit 5da8d6b)

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-vscode/webview-ui/agent-manager/sidebar-scroll.ts	30	Two-frame restore can undo the sidebar's selection scrollIntoView

Files Reviewed (4 files)

• .changeset/sidebar-scroll-preservation.md - 0 issues
• packages/kilo-vscode/tests/unit/agent-manager-sidebar-scroll.test.ts - 0 issues
• packages/kilo-vscode/webview-ui/agent-manager/AgentManagerApp.tsx - 0 issues
• packages/kilo-vscode/webview-ui/agent-manager/sidebar-scroll.ts - 1 issue

Fix these issues in Kilo Cloud

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_{Reviewed by grok-4.6 · Input: 59.2K · Output: 11.6K · Cached: 409.1K}

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