fix(agent-manager): batch worktree diff details

[marius-kilocode]

What Problem This Solves

Opening an Agent Manager worktree review starts separate Git size, content, and patch commands for each changed file. On a 12-file review with 10 tracked files, that means about 30 Git subprocesses, unnecessary disk contention, and a visible delay before every expanded diff is ready.

Why This Change Was Made

Use size-checked git cat-file --batch-check, binary-safe git cat-file --batch, and one path-scoped combined git diff to materialize eligible text files together. Keep complete file contents and hunk-bounded patches, preserve project ownership and source cancellation, and explicitly defer files that exceed the aggregate memory budget to the existing single-file path. Images, binary files, unsupported paths, failed batches, and non-bulk sources continue to use their existing behavior.

User Impact

Metric	Before	After	Improvement
Git subprocesses for 10 tracked files	30	3	90% fewer
Complete 12-file review	480 ms	290 ms	40% faster
12-file diff detail phase	200 ms	48 ms	76% faster
12-file Git detail generation	165 ms	39 ms	76% faster
17-file Git detail generation	164 ms	43 ms	74% faster

Cached worktree switching, full-screen review, scrolling, images, and complete expanded diffs remain available.

Evidence

• bun run test:unit: 4,210 passing tests on the rebased branch.
• bun run build:check, bun run knip, and bun run check-kilocode-change pass.
• Real isolated VS Code self-tests covered 12-file and 17-file reviews, rapid worktree switching, full-screen review, untracked files, and scrolling.
• Regression tests cover aggregate memory limits, explicit deferred fallback, binary and image content, project isolation, cancellation, stale summary snapshots, unchanged refreshes, nested paths, patch boundaries, and failed batch recovery.
• Interactive profiling was performed on macOS. Repository CI runs extension unit tests on Linux; Windows was not directly exercised.

Closes #13415

[kilo-code-bot]

Code Review Summary

Status: No Issues Found | Recommendation: Merge

Files Reviewed (2 files)

• packages/kilo-vscode/src/agent-manager/local-diff.ts
• packages/kilo-vscode/tests/unit/local-diff.test.ts

Previous Review Summary (commit 44395d3)

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

Previous review (commit 44395d3)

Status: 2 Issues Found | Recommendation: Address before merge

Overview

Severity	Count
CRITICAL	0
WARNING	2
SUGGESTION	0

Issue Details (click to expand)

WARNING

File	Line	Issue
packages/kilo-vscode/src/agent-manager/local-diff.ts	476	Bulk Git failures become null details with no single-file fallback
packages/kilo-vscode/src/agent-manager/local-diff.ts	514	Unchanged summary polls invalidate in-flight batches by object identity

Files Reviewed (27 files)

• .changeset/bulk-agent-manager-diff-details.md - 0 issues
• packages/kilo-vscode/src/agent-manager/AgentManagerProvider.ts - 0 issues
• packages/kilo-vscode/src/agent-manager/GitOps.ts - 0 issues
• packages/kilo-vscode/src/agent-manager/local-diff-batch.ts - 0 issues
• packages/kilo-vscode/src/agent-manager/local-diff.ts - 2 issues
• packages/kilo-vscode/src/agent-manager/types.ts - 0 issues
• packages/kilo-vscode/src/agent-manager/worktree-diff-controller.ts - 0 issues
• packages/kilo-vscode/src/diff/SourceController.ts - 0 issues
• packages/kilo-vscode/src/diff/sources/catalog.ts - 0 issues
• packages/kilo-vscode/src/diff/sources/types.ts - 0 issues
• packages/kilo-vscode/src/diff/sources/worktree.ts - 0 issues
• packages/kilo-vscode/src/diff/types.ts - 0 issues
• packages/kilo-vscode/tests/unit/agent-manager-arch.test.ts - 0 issues
• packages/kilo-vscode/tests/unit/agent-manager-worktree-diffs.test.ts - 0 issues
• packages/kilo-vscode/tests/unit/diff-preview-request.test.ts - 0 issues
• packages/kilo-vscode/tests/unit/diff-source-catalog.test.ts - 0 issues
• packages/kilo-vscode/tests/unit/git-ops.test.ts - 0 issues
• packages/kilo-vscode/tests/unit/local-diff.test.ts - 0 issues
• packages/kilo-vscode/tests/unit/source-controller.test.ts - 0 issues
• packages/kilo-vscode/tests/unit/worktree-diff-controller.test.ts - 0 issues
• packages/kilo-vscode/webview-ui/agent-manager/AgentManagerApp.tsx - 0 issues
• packages/kilo-vscode/webview-ui/agent-manager/DiffPanel.tsx - 0 issues
• packages/kilo-vscode/webview-ui/agent-manager/DiffPanelCache.tsx - 0 issues
• packages/kilo-vscode/webview-ui/agent-manager/worktree-diffs.ts - 0 issues
• packages/kilo-vscode/webview-ui/diff-viewer/FullScreenDiffView.tsx - 0 issues
• packages/kilo-vscode/webview-ui/diff-viewer/diff-requests.ts - 0 issues
• packages/kilo-vscode/webview-ui/src/types/messages/webview-messages.ts - 0 issues

Fix these issues in Kilo Cloud

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_{Reviewed by grok-4.6 · Input: 116.2K · Output: 11.4K · Cached: 322K}

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