Function trackBulkFileChanges

src/utils/commitAttribution.ts:489–542

(
  state: AttributionState,
  changes: ReadonlyArray<{
    path: string
    type: 'modified' | 'created' | 'deleted'
    oldContent: string
    newContent: string
    mtime?: number
  }>,
)

 * large git diffs (e.g., jj operations that touch hundreds of thousands of files).
 */
export function trackBulkFileChanges(
  state: AttributionState,
  changes: ReadonlyArray<{
    path: string
    type: 'modified' | 'created' | 'deleted'
    oldContent: string
    newContent: string
    mtime?: number
  }>,
): AttributionState {
  // Create ONE copy of the Map, then mutate it for each file
  const newFileStates = new Map(state.fileStates)

  for (const change of changes) {
    const mtime = change.mtime ?? Date.now()
    if (change.type === 'deleted') {
      const normalizedPath = normalizeFilePath(change.path)
      const existingState = newFileStates.get(normalizedPath)
      const existingContribution = existingState?.claudeContribution ?? 0
      const deletedChars = change.oldContent.length

      newFileStates.set(normalizedPath, {
        contentHash: '',
        claudeContribution: existingContribution + deletedChars,
        mtime,
      })

      logForDebugging(
        `Attribution: Tracked deletion of ${normalizedPath} (${deletedChars} chars removed, total contribution: ${existingContribution + deletedChars})`,
      )
    } else {
      const newFileState = computeFileModificationState(
        newFileStates,
        change.path,
        change.oldContent,
        change.newContent,
        mtime,
      )
      if (newFileState) {
        const normalizedPath = normalizeFilePath(change.path)
        newFileStates.set(normalizedPath, newFileState)

        logForDebugging(
          `Attribution: Tracked ${newFileState.claudeContribution} chars for ${normalizedPath}`,
        )
      }
    }
  }

  return {
    ...state,
    fileStates: newFileStates,
  }
}

/**
 * Calculate final attribution for staged files.