fix: diff view failed on edge cases

[sirily11]

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[vercel]

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Project	Deployment	Actions	Updated (UTC)
rxcode	Ready	Preview, Comment	May 26, 2026 4:13am

[Copilot]

Pull request overview

The PR fixes diff-view edge cases where a snapshot capture race produced originalContent == modifiedContent, causing the desktop "full file" diff to render as "No changes" even though the sidebar showed +N/-N from hunks. It introduces a shared DiffComputation.buildThreadEditDiff helper that prefers the snapshot-pair diff when it contains real +/- lines and otherwise falls back to the recorded hunks. It also includes unrelated MobileSync fan-out concurrency improvements (parallel relay broadcast and parallel APNs/FCM push) and skips .offline peers in broadcastMobileSnapshots.

Changes:

• New DiffComputation.buildThreadEditDiff helper with hunk fallback when the snapshot pair collapses; FileDiffView adopts it and the legacy disk fallback now also requires real +/- lines before short-circuiting.
• Parallel withTaskGroup fan-out for broadcastToAllClients, fanoutPush, and fanoutAPNs, plus offline-peer skipping in broadcastMobileSnapshots.
• New unit tests in DiffComputationTests covering snapshot-pair collapse for large deletes and new-file writes, missing modifiedContent, and the no-data case.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
Packages/Sources/DiffView/DiffComputation.swift	Adds buildThreadEditDiff that prefers snapshot diff but falls back to hunks when no real +/- lines exist.
Packages/Sources/RxCodeChatKit/FileDiffView.swift	Uses the new helper for snapshot-pair rendering and gates the legacy disk fallback on having real changes.
Packages/Tests/DiffViewTests/DiffComputationTests.swift	Adds tests for snapshot-pair collapse, new-file write collapse, preference of differing pair, missing modified content, and empty inputs.
RxCode/Services/MobileSyncService.swift	Parallelizes relay broadcast and APNs/FCM push fan-out via withTaskGroup.
RxCode/App/AppState+MobileSnapshots.swift	Skips peers in .offline state when broadcasting mobile snapshots.

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[sirily11]

🎉 This PR is included in version 1.12.0 🎉

The release is available on GitHub release

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