fix: address seat count review feedback

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: asizikov

src/utils/seatCounts.test.ts

@@ -8,6 +8,9 @@ describe('seat count helpers', () => {
     expect(parseSeatCountInput('')).toBeNull()
     expect(parseSeatCountInput('  ')).toBeNull()
     expect(parseSeatCountInput('12.9')).toBeNull()
+    expect(parseSeatCountInput('1e3')).toBeNull()
+    expect(parseSeatCountInput('0x10')).toBeNull()
+    expect(parseSeatCountInput('+12')).toBeNull()
     expect(parseSeatCountInput('not-a-number')).toBeNull()
   })
 
@@ -17,6 +20,9 @@ describe('seat count helpers', () => {
     expect(getSeatCountInputError('', 10)).toBe(invalidInputError)
     expect(getSeatCountInputError('  ', 10)).toBe(invalidInputError)
     expect(getSeatCountInputError('12.9', 10)).toBe(invalidInputError)
+    expect(getSeatCountInputError('1e3', 10)).toBe(invalidInputError)
+    expect(getSeatCountInputError('0x10', 10)).toBe(invalidInputError)
+    expect(getSeatCountInputError('+12', 10)).toBe(invalidInputError)
     expect(getSeatCountInputError('not-a-number', 10)).toBe(invalidInputError)
     expect(getSeatCountInputError('10', 10)).toBeNull()
     expect(getSeatCountInputError(' 12 ', 10)).toBeNull()

src/utils/seatCounts.ts

@@ -8,10 +8,10 @@ export function normalizeSeatCount(value: number, minimum: number): number {
 
 export function parseSeatCountInput(raw: string): number | null {
   const trimmed = raw.trim()
-  if (trimmed === '') return null
+  if (!/^\d+$/.test(trimmed)) return null
 
   const parsed = Number(trimmed)
-  if (!Number.isFinite(parsed) || !Number.isInteger(parsed)) return null
+  if (!Number.isSafeInteger(parsed)) return null
 
   return parsed
 }

src/views/UsersView.tsx

@@ -11,7 +11,7 @@ import {
 import { calculateSavingsDifference } from '../utils/billingComparison'
 import { InfoTip, ValidationPopover } from '../components/InfoTip'
 import { formatAic, formatDifference } from '../utils/format'
-import { getSeatCountInputError, parseSeatCountInput } from '../utils/seatCounts'
+import { getSeatCountInputError, normalizeSeatCount, parseSeatCountInput } from '../utils/seatCounts'
 import { Trie } from '../utils/trie'
 import { th, thBase, thNum, td, tdNum, sortBtn } from '../components/ui/tableStyles'
 
@@ -77,8 +77,8 @@ export function UsersView({ users, seatOverrides = {}, onSeatOverridesChange, on
 
   const parsedDraftBusiness = parseSeatCountInput(draftBusiness)
   const parsedDraftEnterprise = parseSeatCountInput(draftEnterprise)
-  const displayBusiness = isEditing ? (parsedDraftBusiness ?? savedBusiness) : savedBusiness
-  const displayEnterprise = isEditing ? (parsedDraftEnterprise ?? savedEnterprise) : savedEnterprise
+  const displayBusiness = isEditing ? normalizeSeatCount(parsedDraftBusiness ?? savedBusiness, defaultBusiness) : savedBusiness
+  const displayEnterprise = isEditing ? normalizeSeatCount(parsedDraftEnterprise ?? savedEnterprise, defaultEnterprise) : savedEnterprise
   const businessSeatError = isEditing
     ? getSeatCountInputError(draftBusiness, defaultBusiness)
     : null