Add lessons Phase 2: schedule slots with conflict detection

Recurring weekly time slots linking instructors to lesson types.
Includes day/time overlap detection, instructor and day-of-week
filtering, and 17 new integration tests (40 total lessons tests).

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

@@ -5,8 +5,10 @@ import {
   InstructorUpdateSchema,
   LessonTypeCreateSchema,
   LessonTypeUpdateSchema,
+  ScheduleSlotCreateSchema,
+  ScheduleSlotUpdateSchema,
 } from '@lunarfront/shared/schemas'
-import { InstructorService, LessonTypeService } from '../../services/lesson.service.js'
+import { InstructorService, LessonTypeService, ScheduleSlotService } from '../../services/lesson.service.js'
 
 export const lessonRoutes: FastifyPluginAsync = async (app) => {
   // --- Instructors ---
@@ -92,4 +94,57 @@ export const lessonRoutes: FastifyPluginAsync = async (app) => {
     if (!lessonType) return reply.status(404).send({ error: { message: 'Lesson type not found', statusCode: 404 } })
     return reply.send(lessonType)
   })
+
+  // --- Schedule Slots ---
+
+  app.post('/schedule-slots', { preHandler: [app.authenticate, app.requirePermission('lessons.admin')] }, async (request, reply) => {
+    const parsed = ScheduleSlotCreateSchema.safeParse(request.body)
+    if (!parsed.success) {
+      return reply.status(400).send({ error: { message: 'Validation failed', details: parsed.error.flatten(), statusCode: 400 } })
+    }
+    const result = await ScheduleSlotService.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('/schedule-slots', { preHandler: [app.authenticate, app.requirePermission('lessons.view')] }, async (request, reply) => {
+    const query = request.query as Record<string, string | undefined>
+    const params = PaginationSchema.parse(query)
+    const filters = {
+      instructorId: query.instructorId,
+      dayOfWeek: query.dayOfWeek !== undefined ? Number(query.dayOfWeek) : undefined,
+    }
+    const result = await ScheduleSlotService.list(app.db, params, filters)
+    return reply.send(result)
+  })
+
+  app.get('/schedule-slots/:id', { preHandler: [app.authenticate, app.requirePermission('lessons.view')] }, async (request, reply) => {
+    const { id } = request.params as { id: string }
+    const slot = await ScheduleSlotService.getById(app.db, id)
+    if (!slot) return reply.status(404).send({ error: { message: 'Schedule slot not found', statusCode: 404 } })
+    return reply.send(slot)
+  })
+
+  app.patch('/schedule-slots/:id', { preHandler: [app.authenticate, app.requirePermission('lessons.admin')] }, async (request, reply) => {
+    const { id } = request.params as { id: string }
+    const parsed = ScheduleSlotUpdateSchema.safeParse(request.body)
+    if (!parsed.success) {
+      return reply.status(400).send({ error: { message: 'Validation failed', details: parsed.error.flatten(), statusCode: 400 } })
+    }
+    const result = await ScheduleSlotService.update(app.db, id, parsed.data)
+    if (!result) return reply.status(404).send({ error: { message: 'Schedule slot not found', statusCode: 404 } })
+    if ('error' in result) {
+      return reply.status(409).send({ error: { message: result.error, statusCode: 409 } })
+    }
+    return reply.send(result)
+  })
+
+  app.delete('/schedule-slots/:id', { preHandler: [app.authenticate, app.requirePermission('lessons.admin')] }, async (request, reply) => {
+    const { id } = request.params as { id: string }
+    const slot = await ScheduleSlotService.delete(app.db, id)
+    if (!slot) return reply.status(404).send({ error: { message: 'Schedule slot not found', statusCode: 404 } })
+    return reply.send(slot)
+  })
 }