Function notifyVscodeSnapshotFilesUpdated

src/utils/fileHistory.ts:1054–1098

* Notifies VSCode about files that have changed between snapshots. * Compares the previous snapshot with the new snapshot and sends file_updated * notifications for any files whose content has changed. * Fire-and-forget (void-dispatched from fileHistoryMakeSnapshot).

(
  oldState: FileHistoryState,
  newState: FileHistoryState,
)

 * Fire-and-forget (void-dispatched from fileHistoryMakeSnapshot).
 */
async function notifyVscodeSnapshotFilesUpdated(
  oldState: FileHistoryState,
  newState: FileHistoryState,
): Promise<void> {
  const oldSnapshot = oldState.snapshots.at(-1)
  const newSnapshot = newState.snapshots.at(-1)

  if (!newSnapshot) {
    return
  }

  for (const trackingPath of newState.trackedFiles) {
    const filePath = maybeExpandFilePath(trackingPath)
    const oldBackup = oldSnapshot?.trackedFileBackups[trackingPath]
    const newBackup = newSnapshot.trackedFileBackups[trackingPath]

    // Skip if both backups reference the same version (no change)
    if (
      oldBackup?.backupFileName === newBackup?.backupFileName &&
      oldBackup?.version === newBackup?.version
    ) {
      continue
    }

    // Get old content from the previous backup
    let oldContent: string | null = null
    if (oldBackup?.backupFileName) {
      const backupPath = resolveBackupPath(oldBackup.backupFileName)
      oldContent = await readFileAsyncOrNull(backupPath)
    }

    // Get new content from the new backup or current file
    let newContent: string | null = null
    if (newBackup?.backupFileName) {
      const backupPath = resolveBackupPath(newBackup.backupFileName)
      newContent = await readFileAsyncOrNull(backupPath)
    }
    // If newBackup?.backupFileName === null, the file was deleted; newContent stays null.

    // Only notify if content actually changed
    if (oldContent !== newContent) {
      notifyVscodeFileUpdated(filePath, oldContent, newContent)
    }
  }
}

/** Async read that swallows all errors and returns null (best-effort). */
async function readFileAsyncOrNull(path: string): Promise<string | null> {