Sprint: Stories en taken krijgen één voorspelbare volgorde gekoppeld aan hun code; drag-and-drop herordening voor stories/taken verdwijnt, priority wordt puur label. (#201)

* feat(code): add parseCodeNumber helper to lib/code.ts

Pure helper that extracts the trailing numeric sequence from a code string
(ST-007 → 7, T-42 → 42). Non-conforming codes fall back to Number.MAX_SAFE_INTEGER
so they sort to the end. Includes 5 unit tests.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

* feat(tasks): add code field to BacklogTask type and all task selects

Adds `code: string | null` to BacklogTask interface and includes it in
all Prisma task.findMany selects (backlog API, stories tasks API, page
hydration routes). Updates coerceTaskPayload and test fixtures to match.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

* feat(sort-order): derive story/task sort_order from parseCodeNumber(code)

All create paths (createStoryAction, saveTask, createTaskAction,
materializeIdeaPlanAction) and code-edit paths (updateStoryAction, saveTask
update) now set sort_order = parseCodeNumber(code) instead of last+1.
Removes stale last-record queries from create paths.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

* fix(sort-order): decouple sprint membership actions from sort_order

createSprintAction and addStoryToSprintAction no longer write sort_order
when adding stories to a sprint. sort_order is derived from code via
parseCodeNumber, so membership should only set sprint_id + status.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

* refactor(ordering): remove priority from all story/task orderBy

Story- en taak-ordering is nu puur sort_order asc (created_at als
tiebreaker). PBI-ordering (priority + sort_order) blijft ongewijzigd.

Gewijzigd: backlog/route, pbis/stories/route, claude-context/route,
next-story/route, workspace/route, tasks/route, sprint-runs (query +
in-memory sort), solo-workspace-server, page.tsx (app + mobile + sprint),
store compareStory, actions/sprints story-query, next-story test.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

* refactor(dnd): remove drag-and-drop reorder for stories and tasks

- Remove reorderStoriesAction, reorderTasksAction, reorderSprintStoriesAction
- Delete REST route app/api/stories/[id]/tasks/reorder/route.ts
- Remove DnD from backlog story-panel and task-panel (flat list)
- Remove reorder-within-sprint branch from sprint-board-client handleDragEnd
- Switch SortableSprintRow to plain SprintRow using useDraggable (membership drag kept)
- Remove all DnD from task-list (status toggle + edit kept)
- Remove story-order/task-order/sprint-story-order/sprint-task-order mutation types and store handlers
- Remove related tests for deleted reorder route; fix sprint store tests

* feat(backlog): toon code-badge op backlog-taakkaarten

Geeft code={task.code} door aan <BacklogCard> in TaskCard (task-panel.tsx).
BacklogCard rendert de CodeBadge al conditionally — alleen de prop ontbrak.

* feat(migration): backfill story/task sort_order from code numeric suffix

One-time Prisma migration that sets sort_order = trailing numeric part
of code for all existing stories and tasks, consistent with
parseCodeNumber (fallback = Number.MAX_SAFE_INTEGER for non-conforming
codes). PBIs are intentionally excluded.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

* docs+tests(sort-order): update for code-binding order on stories/tasks

- Rewrite docs/patterns/sort-order.md: float-insertion PBI only; story/task
  sort_order = parseCodeNumber(code), never drag/membership mutated
- Update plan-to-pbi-flow.md: sort_order auto, sprint_id param, priority=label
- Update make-plan.md: priority=label, array order = execution order
- Update rest-contract.md: fix sprint-tasks ordering, remove reorder endpoint
- Add ADR-0011: code is bindende volgordesleutel voor stories/taken
- Regenerate docs/INDEX.md via npm run docs
- Remove reorderStoriesAction/reorderTasksAction mocks from backlog tests
- Remove dnd-kit mocks from task-panel test (panel no longer uses dnd)
- Extend materializeIdeaPlanAction test: assert sort_order=parseCodeNumber(code)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

---------

Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

actions/tasks.ts

@@ -10,7 +10,7 @@ import { productAccessFilter } from '@/lib/product-access'
 import { requireProductWriter } from '@/lib/auth'
 import { taskSchema as sharedTaskSchema, type TaskInput } from '@/lib/schemas/task'
 import { propagateStatusUpwards } from '@/lib/tasks-status-update'
-import { normalizeCode } from '@/lib/code'
+import { normalizeCode, parseCodeNumber } from '@/lib/code'
 import { createWithCodeRetry, generateNextTaskCode, isCodeUniqueConflict } from '@/lib/code-server'
 import { enforceUserRateLimit } from '@/lib/rate-limit'
 
@@ -80,6 +80,7 @@ export async function saveTask(
             description: description ?? null,
             implementation_plan: implementation_plan ?? null,
             priority,
+            ...(inputCode ? { code: inputCode, sort_order: parseCodeNumber(inputCode) } : {}),
           },
           select: { id: true, title: true, status: true },
         })
@@ -106,15 +107,8 @@ export async function saveTask(
     })
     if (!story) return { ok: false, code: 403, error: 'forbidden' }
 
-    const last = await prisma.task.findFirst({
-      where: { story_id: context.storyId },
-      orderBy: { sort_order: 'desc' },
-      select: { sort_order: true },
-    })
-
     const productId = story.product_id
     const sprintId = story.sprint_id ?? null
-    const sortOrder = (last?.sort_order ?? 0) + 1.0
     const storyId = context.storyId
 
     const task = await createWithCodeRetry(
@@ -130,7 +124,7 @@ export async function saveTask(
             description: description ?? null,
             implementation_plan: implementation_plan ?? null,
             priority,
-            sort_order: sortOrder,
+            sort_order: parseCodeNumber(code),
             status: 'TO_DO',
           },
           select: { id: true, title: true, status: true },
@@ -207,11 +201,6 @@ export async function createTaskAction(_prevState: unknown, formData: FormData)
   })
   if (!story) return { error: 'Story niet gevonden' }
 
-  const last = await prisma.task.findFirst({
-    where: { story_id: storyId },
-    orderBy: { sort_order: 'desc' },
-  })
-
   const productId = story.product_id
   const task = await createWithCodeRetry(
     () => generateNextTaskCode(productId),
@@ -225,7 +214,7 @@ export async function createTaskAction(_prevState: unknown, formData: FormData)
           title: parsed.data.title,
           description: parsed.data.description ?? null,
           priority: parsed.data.priority,
-          sort_order: (last?.sort_order ?? 0) + 1.0,
+          sort_order: parseCodeNumber(code),
           status: 'TO_DO',
         },
       }),
@@ -333,22 +322,3 @@ export async function updateTaskPlanAction(taskId: string, productId: string, im
   return { success: true }
 }
 
-export async function reorderTasksAction(storyId: string, orderedIds: string[]) {
-  const session = await getSession()
-  if (!session.userId) return { error: 'Niet ingelogd' }
-  if (session.isDemo) return { error: 'Niet beschikbaar in demo-modus' }
-
-  const story = await prisma.story.findFirst({
-    where: { id: storyId, product: productAccessFilter(session.userId) },
-  })
-  if (!story) return { error: 'Story niet gevonden' }
-
-  await prisma.$transaction(
-    orderedIds.map((id, i) =>
-      prisma.task.update({ where: { id }, data: { sort_order: i + 1.0 } })
-    )
-  )
-
-  revalidatePath(`/products/${story.product_id}/sprint/planning`)
-  return { success: true }
-}