Add multi-stage module support with progressive completion tracking

.gitignore

@@ -46,6 +46,10 @@ next-env.d.ts
 # CheerpJ build artifacts (built with: bun run build:cheerpj)
 /public/cheerpj/
 
+# Playwright
+/test-results/
+/playwright-report/
+
 # IDE
 .idea
 .vscode

app/api/analytics/event/route.ts

@@ -3,7 +3,12 @@ import { auth } from "@/auth"
 import { recordEvent } from "@/lib/analytics"
 import type { EventType } from "@/prisma/generated/prisma/client"
 
-const ALLOWED_TYPES: EventType[] = ["lesson_view", "hint_view", "solution_view"]
+const ALLOWED_TYPES: EventType[] = [
+  "lesson_view",
+  "hint_view",
+  "solution_view",
+  "stage_complete",
+]
 
 export async function POST(request: Request) {
   try {

app/api/progress/route.ts

@@ -1,6 +1,7 @@
 import { NextResponse } from "next/server"
 import { auth } from "@/auth"
 import { prisma } from "@/lib/prisma"
+import { isMultiStageProgressState } from "@/lib/types"
 
 export async function GET(request: Request) {
   const session = await auth()
@@ -28,11 +29,33 @@ export async function PUT(request: Request) {
     return NextResponse.json({ error: "Unauthorized" }, { status: 401 })
   }
 
-  const { lessonId, code } = await request.json() as { lessonId: string; code: string }
-  if (!lessonId || typeof code !== "string") {
+  const body = (await request.json()) as { lessonId?: unknown; code?: unknown }
+  const { lessonId, code } = body
+  if (typeof lessonId !== "string" || !lessonId || typeof code !== "string") {
     return NextResponse.json({ error: "Missing lessonId or code" }, { status: 400 })
   }
 
+  // If the payload looks like JSON, validate it against the multi-stage schema.
+  // Reject malformed JSON payloads that claim to be v2 but aren't well-formed.
+  if (code.startsWith("{")) {
+    try {
+      const parsed = JSON.parse(code) as unknown
+      if (
+        parsed &&
+        typeof parsed === "object" &&
+        (parsed as { __v?: unknown }).__v !== undefined &&
+        !isMultiStageProgressState(parsed)
+      ) {
+        return NextResponse.json(
+          { error: "Invalid multi-stage progress payload" },
+          { status: 400 }
+        )
+      }
+    } catch {
+      // Not JSON — treat as legacy plain-string code (no-op here)
+    }
+  }
+
   await prisma.userProgress.upsert({
     where: { userId_lessonId: { userId: session.user.id, lessonId } },
     create: { userId: session.user.id, lessonId, code },