feat(ST-507): add code-helpers and CodeBadge component

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

components/shared/code-badge.tsx

@@ -0,0 +1,20 @@
+import { cn } from '@/lib/utils'
+
+interface CodeBadgeProps {
+  code: string | null | undefined
+  className?: string
+}
+
+export function CodeBadge({ code, className }: CodeBadgeProps) {
+  if (!code) return null
+  return (
+    <span
+      className={cn(
+        'inline-flex items-center rounded-md border border-border bg-surface-container px-1.5 py-0.5 font-mono text-[11px] leading-none text-muted-foreground',
+        className,
+      )}
+    >
+      {code}
+    </span>
+  )
+}

lib/code.ts

@@ -0,0 +1,54 @@
+import { prisma } from '@/lib/prisma'
+
+const STORY_AUTO_RE = /^ST-(\d+)$/
+const PBI_AUTO_RE = /^PBI-(\d+)$/
+
+const VALID_CODE_RE = /^[A-Za-z0-9._-]+$/
+
+export const MAX_CODE_LENGTH = 30
+
+export function isValidCode(code: string): boolean {
+  return code.length > 0 && code.length <= MAX_CODE_LENGTH && VALID_CODE_RE.test(code)
+}
+
+export function normalizeCode(input: string | null | undefined): string | null {
+  if (input == null) return null
+  const trimmed = input.trim()
+  return trimmed === '' ? null : trimmed
+}
+
+function nextSequential(existing: (string | null)[], pattern: RegExp): number {
+  let max = 0
+  for (const c of existing) {
+    if (!c) continue
+    const m = c.match(pattern)
+    if (m) {
+      const n = Number.parseInt(m[1], 10)
+      if (!Number.isNaN(n) && n > max) max = n
+    }
+  }
+  return max + 1
+}
+
+export async function generateNextStoryCode(productId: string): Promise<string> {
+  const stories = await prisma.story.findMany({
+    where: { product_id: productId },
+    select: { code: true },
+  })
+  const next = nextSequential(stories.map((s) => s.code), STORY_AUTO_RE)
+  return `ST-${String(next).padStart(3, '0')}`
+}
+
+export async function generateNextPbiCode(productId: string): Promise<string> {
+  const pbis = await prisma.pbi.findMany({
+    where: { product_id: productId },
+    select: { code: true },
+  })
+  const next = nextSequential(pbis.map((p) => p.code), PBI_AUTO_RE)
+  return `PBI-${next}`
+}
+
+export function deriveTaskCode(storyCode: string | null, indexOneBased: number): string | null {
+  if (!storyCode) return null
+  return `${storyCode}.${indexOneBased}`
+}