Add Phase 4b: instructor blocked dates, store closures, and substitute instructors

- New tables: instructor_blocked_date, store_closure (migration 0034)
- substitute_instructor_id column added to lesson_session
- Session generation skips blocked instructor dates and store closure periods
- Substitute assignment validates sub is not blocked and has no conflicting slot
- Routes: POST/GET/DELETE /instructors/:id/blocked-dates, POST/GET/DELETE /store-closures
- 15 new integration tests covering blocked dates, store closures, and sub validation

packages/backend/src/routes/v1/lessons.ts

@@ -18,8 +18,10 @@ import {
   LessonPlanCreateSchema,
   LessonPlanUpdateSchema,
   LessonPlanItemUpdateSchema,
+  InstructorBlockedDateCreateSchema,
+  StoreClosureCreateSchema,
 } from '@lunarfront/shared/schemas'
-import { InstructorService, LessonTypeService, ScheduleSlotService, EnrollmentService, LessonSessionService, GradingScaleService, LessonPlanService, LessonPlanItemService } from '../../services/lesson.service.js'
+import { InstructorService, LessonTypeService, ScheduleSlotService, EnrollmentService, LessonSessionService, GradingScaleService, LessonPlanService, LessonPlanItemService, InstructorBlockedDateService, StoreClosureService } from '../../services/lesson.service.js'
 
 export const lessonRoutes: FastifyPluginAsync = async (app) => {
   // --- Instructors ---
@@ -252,9 +254,10 @@ export const lessonRoutes: FastifyPluginAsync = async (app) => {
     if (!parsed.success) {
       return reply.status(400).send({ error: { message: 'Validation failed', details: parsed.error.flatten(), statusCode: 400 } })
     }
-    const session = await LessonSessionService.update(app.db, id, parsed.data)
-    if (!session) return reply.status(404).send({ error: { message: 'Lesson session not found', statusCode: 404 } })
-    return reply.send(session)
+    const result = await LessonSessionService.update(app.db, id, parsed.data)
+    if (!result) return reply.status(404).send({ error: { message: 'Lesson session not found', statusCode: 404 } })
+    if ('error' in result) return reply.status(409).send({ error: { message: result.error, statusCode: 409 } })
+    return reply.send(result)
   })
 
   app.post('/lesson-sessions/:id/status', { preHandler: [app.authenticate, app.requirePermission('lessons.edit')] }, async (request, reply) => {
@@ -379,4 +382,58 @@ export const lessonRoutes: FastifyPluginAsync = async (app) => {
     if (!item) return reply.status(404).send({ error: { message: 'Lesson plan item not found', statusCode: 404 } })
     return reply.send(item)
   })
+
+  // --- Instructor Blocked Dates ---
+
+  app.post('/instructors/:id/blocked-dates', { preHandler: [app.authenticate, app.requirePermission('lessons.admin')] }, async (request, reply) => {
+    const { id } = request.params as { id: string }
+    const parsed = InstructorBlockedDateCreateSchema.safeParse(request.body)
+    if (!parsed.success) {
+      return reply.status(400).send({ error: { message: 'Validation failed', details: parsed.error.flatten(), statusCode: 400 } })
+    }
+    const instructor = await InstructorService.getById(app.db, id)
+    if (!instructor) return reply.status(404).send({ error: { message: 'Instructor not found', statusCode: 404 } })
+    const result = await InstructorBlockedDateService.create(app.db, id, parsed.data)
+    if ('error' in result) return reply.status(409).send({ error: { message: result.error, statusCode: 409 } })
+    return reply.status(201).send(result)
+  })
+
+  app.get('/instructors/:id/blocked-dates', { preHandler: [app.authenticate, app.requirePermission('lessons.view')] }, async (request, reply) => {
+    const { id } = request.params as { id: string }
+    const instructor = await InstructorService.getById(app.db, id)
+    if (!instructor) return reply.status(404).send({ error: { message: 'Instructor not found', statusCode: 404 } })
+    const dates = await InstructorBlockedDateService.list(app.db, id)
+    return reply.send(dates)
+  })
+
+  app.delete('/instructors/:instructorId/blocked-dates/:id', { preHandler: [app.authenticate, app.requirePermission('lessons.admin')] }, async (request, reply) => {
+    const { instructorId, id } = request.params as { instructorId: string; id: string }
+    const row = await InstructorBlockedDateService.delete(app.db, id, instructorId)
+    if (!row) return reply.status(404).send({ error: { message: 'Blocked date not found', statusCode: 404 } })
+    return reply.send(row)
+  })
+
+  // --- Store Closures ---
+
+  app.post('/store-closures', { preHandler: [app.authenticate, app.requirePermission('lessons.admin')] }, async (request, reply) => {
+    const parsed = StoreClosureCreateSchema.safeParse(request.body)
+    if (!parsed.success) {
+      return reply.status(400).send({ error: { message: 'Validation failed', details: parsed.error.flatten(), statusCode: 400 } })
+    }
+    const result = await StoreClosureService.create(app.db, parsed.data)
+    if ('error' in result) return reply.status(409).send({ error: { message: result.error, statusCode: 409 } })
+    return reply.status(201).send(result)
+  })
+
+  app.get('/store-closures', { preHandler: [app.authenticate, app.requirePermission('lessons.view')] }, async (_request, reply) => {
+    const closures = await StoreClosureService.list(app.db)
+    return reply.send(closures)
+  })
+
+  app.delete('/store-closures/:id', { preHandler: [app.authenticate, app.requirePermission('lessons.admin')] }, async (request, reply) => {
+    const { id } = request.params as { id: string }
+    const row = await StoreClosureService.delete(app.db, id)
+    if (!row) return reply.status(404).send({ error: { message: 'Store closure not found', statusCode: 404 } })
+    return reply.send(row)
+  })
 }