Auto-open MergeConflictTab on git merge conflicts with complete resolution workflow

[Copilot]

When git merge encounters conflicts, the system now detects them and automatically opens the MergeConflictTab. Previously, conflicts only displayed a CLI error message without UI integration.

Implementation

MergeConflictDetector (gitOperations/mergeConflictDetector.ts)

• Compares base/ours/theirs trees via git.walk to identify modified files
• Reads blob content from git objects with binary file handling
• Returns structured conflict data for 3-way diff display

GitMergeOperations (gitOperations/merge.ts)

• Catches MergeNotSupportedError from isomorphic-git
• Invokes detector and opens tab with conflict data
• Uses useTabStore.getState() for non-React context access

MergeConflictTabType (tabs/builtins/MergeConflictTabType.tsx)

• Complete resolution flow:
  1. Save via fileRepository → IndexedDB
  2. Sync to GitFileSystem
  3. Stage files with git.add
  4. Create merge commit

Example Flow

// User runs: git merge feature-branch
// System detects conflict, automatically opens:
await openTab({
  conflicts: [
    {
      filePath: '/src/utils.ts',
      baseContent: '...',
      oursContent: '...',
      theirsContent: '...',
      resolvedContent: '...',
      isResolved: false
    }
  ],
  oursBranch: 'main',
  theirsBranch: 'feature-branch',
  projectId, projectName
}, { kind: 'merge-conflict' });

User resolves in UI → files save through fileRepository → merge commit created.

Original prompt

マージコンフリクト解決タブの実装

MergeConflictTab タイプの型定義を追加 (src/engine/tabs/types.ts)
MergeConflictTabType を実装 (src/engine/tabs/builtins/MergeConflictTabType.tsx)
タブコンポーネントUI MergeConflictResolutionTab.tsx を作成
ビルトインタブにエクスポートを追加
レジストリに登録
型のre-export
翻訳データを全言語に追加 (mergeConflict.*, common.editable)
ファイルリストの幅を調整 (w-64 → w-48)
を追加したは良いものの、git mergeのコマンドで、このシステムを使えていない。コンフリクトが起きたら開くように。

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