Function inferFields

packages/shared-domain/src/database-csv.ts:192–230

(
  headers: string[],
  sampleRows: string[][],
  genId: GenId = defaultGenId
)

 * otherwise a leading `id` field is synthesized.
 */
export function inferFields(
  headers: string[],
  sampleRows: string[][],
  genId: GenId = defaultGenId
): InferredSchema {
  const usedNames = new Set<string>()
  const normalizedHeaders = headers.map((h, i) => dedupeHeader(h, usedNames, i))

  // Detect a usable id column.
  let idColIndex = -1
  const idHeaderIdx = normalizedHeaders.findIndex((h) => h.toLowerCase() === DEFAULT_ID_FIELD_NAME)
  if (idHeaderIdx >= 0) {
    const values = sampleRows.map((r) => r[idHeaderIdx] ?? '')
    const allPresent = values.length > 0 && values.every((v) => v.trim().length > 0)
    const unique = new Set(values).size === values.length
    if (sampleRows.length === 0 || (allPresent && unique)) idColIndex = idHeaderIdx
  }

  const fields: DbField[] = normalizedHeaders.map((name, i) => ({
    id: genId(),
    name,
    type:
      i === idColIndex
        ? 'text'
        : inferColumnType(sampleRows.map((r) => r[i] ?? ''))
  }))

  let idFieldId: string
  if (idColIndex >= 0) {
    idFieldId = fields[idColIndex].id
    fields[idColIndex].hidden = true
  } else {
    // Synthesize a leading id field.
    const idField: DbField = { id: genId(), name: DEFAULT_ID_FIELD_NAME, type: 'text', hidden: true }
    fields.unshift(idField)
    idFieldId = idField.id
  }
  return { idFieldId, fields }
}

/** A single default Table view (id hidden) covering all fields in order. */
export function buildDefaultViews(