diff --git a/convex/_generated/api.d.ts b/convex/_generated/api.d.ts
index e1069a3..38f1a07 100644
--- a/convex/_generated/api.d.ts
+++ b/convex/_generated/api.d.ts
@@ -9,7 +9,12 @@
  */
 
 import type * as auth from "../auth.js";
+import type * as canvases from "../canvases.js";
+import type * as credits from "../credits.js";
+import type * as edges from "../edges.js";
+import type * as helpers from "../helpers.js";
 import type * as http from "../http.js";
+import type * as nodes from "../nodes.js";
 
 import type {
   ApiFromModules,
@@ -19,7 +24,12 @@ import type {
 
 declare const fullApi: ApiFromModules<{
   auth: typeof auth;
+  canvases: typeof canvases;
+  credits: typeof credits;
+  edges: typeof edges;
+  helpers: typeof helpers;
   http: typeof http;
+  nodes: typeof nodes;
 }>;
 
 /**
diff --git a/convex/_generated/dataModel.d.ts b/convex/_generated/dataModel.d.ts
index a850cc1..f97fd19 100644
--- a/convex/_generated/dataModel.d.ts
+++ b/convex/_generated/dataModel.d.ts
@@ -8,29 +8,29 @@
  * @module
  */
 
-import { AnyDataModel } from "convex/server";
+import type {
+  DataModelFromSchemaDefinition,
+  DocumentByName,
+  TableNamesInDataModel,
+  SystemTableNames,
+} from "convex/server";
 import type { GenericId } from "convex/values";
-
-/**
- * No `schema.ts` file found!
- *
- * This generated code has permissive types like `Doc = any` because
- * Convex doesn't know your schema. If you'd like more type safety, see
- * https://docs.convex.dev/using/schemas for instructions on how to add a
- * schema file.
- *
- * After you change a schema, rerun codegen with `npx convex dev`.
- */
+import schema from "../schema.js";
 
 /**
  * The names of all of your Convex tables.
  */
-export type TableNames = string;
+export type TableNames = TableNamesInDataModel<DataModel>;
 
 /**
  * The type of a document stored in Convex.
+ *
+ * @typeParam TableName - A string literal type of the table name (like "users").
  */
-export type Doc = any;
+export type Doc<TableName extends TableNames> = DocumentByName<
+  DataModel,
+  TableName
+>;
 
 /**
  * An identifier for a document in Convex.
@@ -42,8 +42,10 @@ export type Doc = any;
  *
  * IDs are just strings at runtime, but this type can be used to distinguish them from other
  * strings when type checking.
+ *
+ * @typeParam TableName - A string literal type of the table name (like "users").
  */
-export type Id<TableName extends TableNames = TableNames> =
+export type Id<TableName extends TableNames | SystemTableNames> =
   GenericId<TableName>;
 
 /**
@@ -55,4 +57,4 @@ export type Id<TableName extends TableNames = TableNames> =
  * This type is used to parameterize methods like `queryGeneric` and
  * `mutationGeneric` to make them type-safe.
  */
-export type DataModel = AnyDataModel;
+export type DataModel = DataModelFromSchemaDefinition<typeof schema>;
diff --git a/convex/canvases.ts b/convex/canvases.ts
new file mode 100644
index 0000000..7221223
--- /dev/null
+++ b/convex/canvases.ts
@@ -0,0 +1,139 @@
+import { query, mutation } from "./_generated/server";
+import { v } from "convex/values";
+import { requireAuth } from "./helpers";
+
+// ============================================================================
+// Queries
+// ============================================================================
+
+/**
+ * Alle Canvases des eingeloggten Users, sortiert nach letzter Bearbeitung.
+ */
+export const list = query({
+  args: {},
+  handler: async (ctx) => {
+    const user = await requireAuth(ctx);
+    return await ctx.db
+      .query("canvases")
+      .withIndex("by_owner_updated", (q) => q.eq("ownerId", user.userId))
+      .order("desc")
+      .collect();
+  },
+});
+
+/**
+ * Einzelnen Canvas laden — mit Owner-Check.
+ */
+export const get = query({
+  args: { canvasId: v.id("canvases") },
+  handler: async (ctx, { canvasId }) => {
+    const user = await requireAuth(ctx);
+    const canvas = await ctx.db.get(canvasId);
+    if (!canvas || canvas.ownerId !== user.userId) {
+      return null;
+    }
+    return canvas;
+  },
+});
+
+// ============================================================================
+// Mutations
+// ============================================================================
+
+/**
+ * Neuen Canvas erstellen.
+ */
+export const create = mutation({
+  args: {
+    name: v.string(),
+    description: v.optional(v.string()),
+  },
+  handler: async (ctx, { name, description }) => {
+    const user = await requireAuth(ctx);
+    const now = Date.now();
+    const canvasId = await ctx.db.insert("canvases", {
+      name,
+      ownerId: user.userId,
+      description,
+      updatedAt: now,
+    });
+    return canvasId;
+  },
+});
+
+/**
+ * Canvas umbenennen oder Beschreibung ändern.
+ */
+export const update = mutation({
+  args: {
+    canvasId: v.id("canvases"),
+    name: v.optional(v.string()),
+    description: v.optional(v.string()),
+  },
+  handler: async (ctx, { canvasId, name, description }) => {
+    const user = await requireAuth(ctx);
+    const canvas = await ctx.db.get(canvasId);
+    if (!canvas || canvas.ownerId !== user.userId) {
+      throw new Error("Canvas not found");
+    }
+
+    const updates: Record<string, unknown> = { updatedAt: Date.now() };
+    if (name !== undefined) updates.name = name;
+    if (description !== undefined) updates.description = description;
+
+    await ctx.db.patch(canvasId, updates);
+  },
+});
+
+/**
+ * Canvas löschen — entfernt auch alle zugehörigen Nodes und Edges.
+ */
+export const remove = mutation({
+  args: { canvasId: v.id("canvases") },
+  handler: async (ctx, { canvasId }) => {
+    const user = await requireAuth(ctx);
+    const canvas = await ctx.db.get(canvasId);
+    if (!canvas || canvas.ownerId !== user.userId) {
+      throw new Error("Canvas not found");
+    }
+
+    // Alle Nodes dieses Canvas löschen
+    const nodes = await ctx.db
+      .query("nodes")
+      .withIndex("by_canvas", (q) => q.eq("canvasId", canvasId))
+      .collect();
+    for (const node of nodes) {
+      await ctx.db.delete(node._id);
+    }
+
+    // Alle Edges dieses Canvas löschen
+    const edges = await ctx.db
+      .query("edges")
+      .withIndex("by_canvas", (q) => q.eq("canvasId", canvasId))
+      .collect();
+    for (const edge of edges) {
+      await ctx.db.delete(edge._id);
+    }
+
+    // Canvas selbst löschen
+    await ctx.db.delete(canvasId);
+  },
+});
+
+/**
+ * Canvas-Thumbnail aktualisieren.
+ */
+export const setThumbnail = mutation({
+  args: {
+    canvasId: v.id("canvases"),
+    thumbnail: v.id("_storage"),
+  },
+  handler: async (ctx, { canvasId, thumbnail }) => {
+    const user = await requireAuth(ctx);
+    const canvas = await ctx.db.get(canvasId);
+    if (!canvas || canvas.ownerId !== user.userId) {
+      throw new Error("Canvas not found");
+    }
+    await ctx.db.patch(canvasId, { thumbnail, updatedAt: Date.now() });
+  },
+});
diff --git a/convex/credits.ts b/convex/credits.ts
new file mode 100644
index 0000000..dc7921d
--- /dev/null
+++ b/convex/credits.ts
@@ -0,0 +1,539 @@
+import { query, mutation, internalMutation } from "./_generated/server";
+import { v } from "convex/values";
+import { requireAuth } from "./helpers";
+
+// ============================================================================
+// Tier-Konfiguration
+// ============================================================================
+
+export const TIER_CONFIG = {
+  free: {
+    monthlyCredits: 50,           // €0,50 in Cent
+    dailyGenerationCap: 10,
+    concurrencyLimit: 1,
+    premiumModels: false,
+    topUpLimit: 0,                // Kein Top-Up für Free
+  },
+  starter: {
+    monthlyCredits: 630,          // €6,30 in Cent
+    dailyGenerationCap: 50,
+    concurrencyLimit: 2,
+    premiumModels: true,
+    topUpLimit: 2000,             // €20 pro Monat
+  },
+  pro: {
+    monthlyCredits: 3602,         // €36,02 in Cent (+5% Bonus)
+    dailyGenerationCap: 200,
+    concurrencyLimit: 2,
+    premiumModels: true,
+    topUpLimit: 10000,            // €100 pro Monat
+  },
+  business: {
+    monthlyCredits: 7623,         // €76,23 in Cent (+10% Bonus)
+    dailyGenerationCap: 500,
+    concurrencyLimit: 2,
+    premiumModels: true,
+    topUpLimit: 50000,            // €500 pro Monat
+  },
+} as const;
+
+export type Tier = keyof typeof TIER_CONFIG;
+
+// ============================================================================
+// Queries
+// ============================================================================
+
+/**
+ * Credit-Balance des eingeloggten Users abrufen.
+ * Gibt balance, reserved und computed available zurück.
+ */
+export const getBalance = query({
+  args: {},
+  handler: async (ctx) => {
+    const user = await requireAuth(ctx);
+    const balance = await ctx.db
+      .query("creditBalances")
+      .withIndex("by_user", (q) => q.eq("userId", user.userId))
+      .unique();
+
+    if (!balance) {
+      return { balance: 0, reserved: 0, available: 0, monthlyAllocation: 0 };
+    }
+
+    return {
+      balance: balance.balance,
+      reserved: balance.reserved,
+      available: balance.balance - balance.reserved,
+      monthlyAllocation: balance.monthlyAllocation,
+    };
+  },
+});
+
+/**
+ * Letzte Transaktionen des Users abrufen.
+ */
+export const listTransactions = query({
+  args: { limit: v.optional(v.number()) },
+  handler: async (ctx, { limit }) => {
+    const user = await requireAuth(ctx);
+    return await ctx.db
+      .query("creditTransactions")
+      .withIndex("by_user", (q) => q.eq("userId", user.userId))
+      .order("desc")
+      .take(limit ?? 50);
+  },
+});
+
+/**
+ * Aktuelle Subscription des Users abrufen.
+ */
+export const getSubscription = query({
+  args: {},
+  handler: async (ctx) => {
+    const user = await requireAuth(ctx);
+    return await ctx.db
+      .query("subscriptions")
+      .withIndex("by_user", (q) => q.eq("userId", user.userId))
+      .order("desc")
+      .first();
+  },
+});
+
+/**
+ * Heutige Nutzung des Users abrufen (für Abuse Prevention).
+ */
+export const getDailyUsage = query({
+  args: {},
+  handler: async (ctx) => {
+    const user = await requireAuth(ctx);
+    const today = new Date().toISOString().split("T")[0]; // "2026-03-25"
+
+    const usage = await ctx.db
+      .query("dailyUsage")
+      .withIndex("by_user_date", (q) =>
+        q.eq("userId", user.userId).eq("date", today)
+      )
+      .unique();
+
+    return usage ?? { generationCount: 0, concurrentJobs: 0 };
+  },
+});
+
+// ============================================================================
+// Mutations — Credit Balance Management
+// ============================================================================
+
+/**
+ * Credit-Balance für einen neuen User initialisieren.
+ * Wird beim ersten Login / Signup aufgerufen.
+ */
+export const initBalance = mutation({
+  args: {},
+  handler: async (ctx) => {
+    const user = await requireAuth(ctx);
+
+    // Prüfen ob schon existiert
+    const existing = await ctx.db
+      .query("creditBalances")
+      .withIndex("by_user", (q) => q.eq("userId", user.userId))
+      .unique();
+
+    if (existing) return existing._id;
+
+    // Free-Tier Credits als Startguthaben
+    const balanceId = await ctx.db.insert("creditBalances", {
+      userId: user.userId,
+      balance: TIER_CONFIG.free.monthlyCredits,
+      reserved: 0,
+      monthlyAllocation: TIER_CONFIG.free.monthlyCredits,
+      updatedAt: Date.now(),
+    });
+
+    // Initiale Subscription (Free)
+    await ctx.db.insert("subscriptions", {
+      userId: user.userId,
+      tier: "free",
+      status: "active",
+      currentPeriodStart: Date.now(),
+      currentPeriodEnd: Date.now() + 30 * 24 * 60 * 60 * 1000, // +30 Tage
+    });
+
+    // Initiale Transaktion loggen
+    await ctx.db.insert("creditTransactions", {
+      userId: user.userId,
+      amount: TIER_CONFIG.free.monthlyCredits,
+      type: "subscription",
+      status: "committed",
+      description: "Startguthaben — Free Tier",
+    });
+
+    return balanceId;
+  },
+});
+
+// ============================================================================
+// Mutations — Reservation + Commit (Kern des Credit-Systems)
+// ============================================================================
+
+/**
+ * Credits reservieren — vor einem KI-Call.
+ *
+ * Prüft: ausreichend verfügbare Credits, Daily Cap, Concurrency Limit.
+ * Gibt die Transaction-ID zurück (wird zum Commit/Release benötigt).
+ */
+export const reserve = mutation({
+  args: {
+    estimatedCost: v.number(),    // Geschätzte Kosten in Cent
+    description: v.string(),
+    nodeId: v.optional(v.id("nodes")),
+    canvasId: v.optional(v.id("canvases")),
+    model: v.optional(v.string()),
+  },
+  handler: async (ctx, args) => {
+    const user = await requireAuth(ctx);
+
+    // Balance laden
+    const balance = await ctx.db
+      .query("creditBalances")
+      .withIndex("by_user", (q) => q.eq("userId", user.userId))
+      .unique();
+    if (!balance) throw new Error("No credit balance found. Call initBalance first.");
+
+    const available = balance.balance - balance.reserved;
+    if (available < args.estimatedCost) {
+      throw new Error(
+        `Insufficient credits. Available: ${available}, required: ${args.estimatedCost}`
+      );
+    }
+
+    // Subscription laden für Tier-Checks
+    const subscription = await ctx.db
+      .query("subscriptions")
+      .withIndex("by_user", (q) => q.eq("userId", user.userId))
+      .order("desc")
+      .first();
+    const tier = (subscription?.tier ?? "free") as Tier;
+    const config = TIER_CONFIG[tier];
+
+    // Daily Cap prüfen
+    const today = new Date().toISOString().split("T")[0];
+    const dailyUsage = await ctx.db
+      .query("dailyUsage")
+      .withIndex("by_user_date", (q) =>
+        q.eq("userId", user.userId).eq("date", today)
+      )
+      .unique();
+
+    if (dailyUsage && dailyUsage.generationCount >= config.dailyGenerationCap) {
+      throw new Error(
+        `Daily generation limit reached (${config.dailyGenerationCap}/${tier})`
+      );
+    }
+
+    // Concurrency Limit prüfen
+    if (dailyUsage && dailyUsage.concurrentJobs >= config.concurrencyLimit) {
+      throw new Error(
+        `Concurrent job limit reached (${config.concurrencyLimit}/${tier})`
+      );
+    }
+
+    // Credits reservieren
+    await ctx.db.patch(balance._id, {
+      reserved: balance.reserved + args.estimatedCost,
+      updatedAt: Date.now(),
+    });
+
+    // Daily Usage aktualisieren
+    if (dailyUsage) {
+      await ctx.db.patch(dailyUsage._id, {
+        generationCount: dailyUsage.generationCount + 1,
+        concurrentJobs: dailyUsage.concurrentJobs + 1,
+      });
+    } else {
+      await ctx.db.insert("dailyUsage", {
+        userId: user.userId,
+        date: today,
+        generationCount: 1,
+        concurrentJobs: 1,
+      });
+    }
+
+    // Reservation-Transaktion erstellen
+    const transactionId = await ctx.db.insert("creditTransactions", {
+      userId: user.userId,
+      amount: -args.estimatedCost,
+      type: "reservation",
+      status: "reserved",
+      description: args.description,
+      nodeId: args.nodeId,
+      canvasId: args.canvasId,
+      model: args.model,
+    });
+
+    return transactionId;
+  },
+});
+
+/**
+ * Reservation committen — nach erfolgreichem KI-Call.
+ *
+ * Schreibt die tatsächlichen Kosten ab (können von Reservation abweichen).
+ */
+export const commit = mutation({
+  args: {
+    transactionId: v.id("creditTransactions"),
+    actualCost: v.number(),       // Tatsächliche Kosten in Cent
+    openRouterCost: v.optional(v.number()), // Echte API-Kosten
+  },
+  handler: async (ctx, { transactionId, actualCost, openRouterCost }) => {
+    const user = await requireAuth(ctx);
+    const transaction = await ctx.db.get(transactionId);
+    if (!transaction || transaction.userId !== user.userId) {
+      throw new Error("Transaction not found");
+    }
+    if (transaction.status !== "reserved") {
+      throw new Error(`Transaction is ${transaction.status}, expected reserved`);
+    }
+
+    const estimatedCost = Math.abs(transaction.amount);
+
+    // Balance aktualisieren
+    const balance = await ctx.db
+      .query("creditBalances")
+      .withIndex("by_user", (q) => q.eq("userId", user.userId))
+      .unique();
+    if (!balance) throw new Error("No credit balance found");
+
+    await ctx.db.patch(balance._id, {
+      balance: balance.balance - actualCost,
+      reserved: balance.reserved - estimatedCost,
+      updatedAt: Date.now(),
+    });
+
+    // Transaktion committen
+    await ctx.db.patch(transactionId, {
+      amount: -actualCost,
+      type: "usage",
+      status: "committed",
+      openRouterCost,
+    });
+
+    // Concurrent Jobs dekrementieren
+    const today = new Date().toISOString().split("T")[0];
+    const dailyUsage = await ctx.db
+      .query("dailyUsage")
+      .withIndex("by_user_date", (q) =>
+        q.eq("userId", user.userId).eq("date", today)
+      )
+      .unique();
+    if (dailyUsage && dailyUsage.concurrentJobs > 0) {
+      await ctx.db.patch(dailyUsage._id, {
+        concurrentJobs: dailyUsage.concurrentJobs - 1,
+      });
+    }
+  },
+});
+
+/**
+ * Reservation freigeben — bei fehlgeschlagenem KI-Call.
+ *
+ * Reservierte Credits werden komplett zurückgegeben.
+ */
+export const release = mutation({
+  args: {
+    transactionId: v.id("creditTransactions"),
+  },
+  handler: async (ctx, { transactionId }) => {
+    const user = await requireAuth(ctx);
+    const transaction = await ctx.db.get(transactionId);
+    if (!transaction || transaction.userId !== user.userId) {
+      throw new Error("Transaction not found");
+    }
+    if (transaction.status !== "reserved") {
+      throw new Error(`Transaction is ${transaction.status}, expected reserved`);
+    }
+
+    const estimatedCost = Math.abs(transaction.amount);
+
+    // Credits freigeben
+    const balance = await ctx.db
+      .query("creditBalances")
+      .withIndex("by_user", (q) => q.eq("userId", user.userId))
+      .unique();
+    if (!balance) throw new Error("No credit balance found");
+
+    await ctx.db.patch(balance._id, {
+      reserved: balance.reserved - estimatedCost,
+      updatedAt: Date.now(),
+    });
+
+    // Transaktion als released markieren
+    await ctx.db.patch(transactionId, {
+      status: "released",
+    });
+
+    // Concurrent Jobs dekrementieren
+    const today = new Date().toISOString().split("T")[0];
+    const dailyUsage = await ctx.db
+      .query("dailyUsage")
+      .withIndex("by_user_date", (q) =>
+        q.eq("userId", user.userId).eq("date", today)
+      )
+      .unique();
+    if (dailyUsage && dailyUsage.concurrentJobs > 0) {
+      await ctx.db.patch(dailyUsage._id, {
+        concurrentJobs: dailyUsage.concurrentJobs - 1,
+      });
+    }
+
+    // Generation Count NICHT zurücksetzen — der Versuch zählt
+  },
+});
+
+// ============================================================================
+// Mutations — Subscription & Top-Up (von Lemon Squeezy Webhooks aufgerufen)
+// ============================================================================
+
+/**
+ * Subscription aktivieren / ändern.
+ * Wird vom Lemon Squeezy Webhook aufgerufen.
+ */
+export const activateSubscription = internalMutation({
+  args: {
+    userId: v.string(),
+    tier: v.union(
+      v.literal("free"),
+      v.literal("starter"),
+      v.literal("pro"),
+      v.literal("business")
+    ),
+    lemonSqueezySubscriptionId: v.string(),
+    lemonSqueezyCustomerId: v.string(),
+    currentPeriodStart: v.number(),
+    currentPeriodEnd: v.number(),
+  },
+  handler: async (ctx, args) => {
+    const config = TIER_CONFIG[args.tier];
+
+    // Bestehende Subscription deaktivieren
+    const existing = await ctx.db
+      .query("subscriptions")
+      .withIndex("by_user", (q) => q.eq("userId", args.userId))
+      .order("desc")
+      .first();
+
+    if (existing) {
+      await ctx.db.patch(existing._id, { status: "cancelled" });
+    }
+
+    // Neue Subscription erstellen
+    await ctx.db.insert("subscriptions", {
+      userId: args.userId,
+      tier: args.tier,
+      status: "active",
+      currentPeriodStart: args.currentPeriodStart,
+      currentPeriodEnd: args.currentPeriodEnd,
+      lemonSqueezySubscriptionId: args.lemonSqueezySubscriptionId,
+      lemonSqueezyCustomerId: args.lemonSqueezyCustomerId,
+    });
+
+    // Credits gutschreiben
+    const balance = await ctx.db
+      .query("creditBalances")
+      .withIndex("by_user", (q) => q.eq("userId", args.userId))
+      .unique();
+
+    if (balance) {
+      await ctx.db.patch(balance._id, {
+        balance: balance.balance + config.monthlyCredits,
+        monthlyAllocation: config.monthlyCredits,
+        updatedAt: Date.now(),
+      });
+    } else {
+      await ctx.db.insert("creditBalances", {
+        userId: args.userId,
+        balance: config.monthlyCredits,
+        reserved: 0,
+        monthlyAllocation: config.monthlyCredits,
+        updatedAt: Date.now(),
+      });
+    }
+
+    // Transaktion loggen
+    await ctx.db.insert("creditTransactions", {
+      userId: args.userId,
+      amount: config.monthlyCredits,
+      type: "subscription",
+      status: "committed",
+      description: `Abo-Gutschrift — ${args.tier} Tier`,
+    });
+  },
+});
+
+/**
+ * Credits nachkaufen (Top-Up).
+ */
+export const topUp = mutation({
+  args: {
+    amount: v.number(), // Betrag in Cent
+  },
+  handler: async (ctx, { amount }) => {
+    const user = await requireAuth(ctx);
+    if (amount <= 0) throw new Error("Amount must be positive");
+
+    // Tier-Limit prüfen
+    const subscription = await ctx.db
+      .query("subscriptions")
+      .withIndex("by_user", (q) => q.eq("userId", user.userId))
+      .order("desc")
+      .first();
+    const tier = (subscription?.tier ?? "free") as Tier;
+    const config = TIER_CONFIG[tier];
+
+    if (config.topUpLimit === 0) {
+      throw new Error("Top-up not available for Free tier");
+    }
+
+    // Monatliches Top-Up-Limit prüfen
+    const monthStart = new Date();
+    monthStart.setDate(1);
+    monthStart.setHours(0, 0, 0, 0);
+
+    const monthlyTopUps = await ctx.db
+      .query("creditTransactions")
+      .withIndex("by_user_type", (q) =>
+        q.eq("userId", user.userId).eq("type", "topup")
+      )
+      .collect();
+
+    const thisMonthTopUps = monthlyTopUps
+      .filter((t) => t._creationTime >= monthStart.getTime())
+      .reduce((sum, t) => sum + t.amount, 0);
+
+    if (thisMonthTopUps + amount > config.topUpLimit) {
+      throw new Error(
+        `Monthly top-up limit reached. Limit: ${config.topUpLimit}, used: ${thisMonthTopUps}`
+      );
+    }
+
+    // Credits gutschreiben
+    const balance = await ctx.db
+      .query("creditBalances")
+      .withIndex("by_user", (q) => q.eq("userId", user.userId))
+      .unique();
+    if (!balance) throw new Error("No credit balance found");
+
+    await ctx.db.patch(balance._id, {
+      balance: balance.balance + amount,
+      updatedAt: Date.now(),
+    });
+
+    await ctx.db.insert("creditTransactions", {
+      userId: user.userId,
+      amount,
+      type: "topup",
+      status: "committed",
+      description: `Credit-Nachkauf — ${(amount / 100).toFixed(2)}€`,
+    });
+  },
+});
diff --git a/convex/edges.ts b/convex/edges.ts
new file mode 100644
index 0000000..8d5715c
--- /dev/null
+++ b/convex/edges.ts
@@ -0,0 +1,96 @@
+import { query, mutation } from "./_generated/server";
+import { v } from "convex/values";
+import { requireAuth } from "./helpers";
+
+// ============================================================================
+// Queries
+// ============================================================================
+
+/**
+ * Alle Edges eines Canvas laden.
+ */
+export const list = query({
+  args: { canvasId: v.id("canvases") },
+  handler: async (ctx, { canvasId }) => {
+    const user = await requireAuth(ctx);
+    const canvas = await ctx.db.get(canvasId);
+    if (!canvas || canvas.ownerId !== user.userId) {
+      return [];
+    }
+
+    return await ctx.db
+      .query("edges")
+      .withIndex("by_canvas", (q) => q.eq("canvasId", canvasId))
+      .collect();
+  },
+});
+
+// ============================================================================
+// Mutations
+// ============================================================================
+
+/**
+ * Neue Edge (Verbindung) zwischen zwei Nodes erstellen.
+ */
+export const create = mutation({
+  args: {
+    canvasId: v.id("canvases"),
+    sourceNodeId: v.id("nodes"),
+    targetNodeId: v.id("nodes"),
+    sourceHandle: v.optional(v.string()),
+    targetHandle: v.optional(v.string()),
+  },
+  handler: async (ctx, args) => {
+    const user = await requireAuth(ctx);
+    const canvas = await ctx.db.get(args.canvasId);
+    if (!canvas || canvas.ownerId !== user.userId) {
+      throw new Error("Canvas not found");
+    }
+
+    // Prüfen ob beide Nodes existieren und zum gleichen Canvas gehören
+    const source = await ctx.db.get(args.sourceNodeId);
+    const target = await ctx.db.get(args.targetNodeId);
+    if (!source || !target) {
+      throw new Error("Source or target node not found");
+    }
+    if (source.canvasId !== args.canvasId || target.canvasId !== args.canvasId) {
+      throw new Error("Nodes must belong to the same canvas");
+    }
+
+    // Keine Self-Loops
+    if (args.sourceNodeId === args.targetNodeId) {
+      throw new Error("Cannot connect a node to itself");
+    }
+
+    const edgeId = await ctx.db.insert("edges", {
+      canvasId: args.canvasId,
+      sourceNodeId: args.sourceNodeId,
+      targetNodeId: args.targetNodeId,
+      sourceHandle: args.sourceHandle,
+      targetHandle: args.targetHandle,
+    });
+
+    await ctx.db.patch(args.canvasId, { updatedAt: Date.now() });
+    return edgeId;
+  },
+});
+
+/**
+ * Edge löschen.
+ */
+export const remove = mutation({
+  args: { edgeId: v.id("edges") },
+  handler: async (ctx, { edgeId }) => {
+    const user = await requireAuth(ctx);
+    const edge = await ctx.db.get(edgeId);
+    if (!edge) throw new Error("Edge not found");
+
+    const canvas = await ctx.db.get(edge.canvasId);
+    if (!canvas || canvas.ownerId !== user.userId) {
+      throw new Error("Canvas not found");
+    }
+
+    await ctx.db.delete(edgeId);
+    await ctx.db.patch(edge.canvasId, { updatedAt: Date.now() });
+  },
+});
diff --git a/convex/helpers.ts b/convex/helpers.ts
new file mode 100644
index 0000000..772673e
--- /dev/null
+++ b/convex/helpers.ts
@@ -0,0 +1,34 @@
+import { QueryCtx, MutationCtx } from "./_generated/server";
+import { authComponent } from "./auth";
+
+type SafeAuthUser = NonNullable<
+  Awaited<ReturnType<typeof authComponent.safeGetAuthUser>>
+>;
+
+/** Better-Auth-User mit für die App garantierter userId (Convex-_id als Fallback). */
+export type AuthUser = Omit<SafeAuthUser, "userId"> & { userId: string };
+
+/**
+ * Erfordert einen authentifizierten User und gibt dessen userId zurück.
+ * Wirft einen Error wenn nicht eingeloggt — für Mutations und geschützte Queries.
+ */
+export async function requireAuth(
+  ctx: QueryCtx | MutationCtx
+): Promise<AuthUser> {
+  const user = await authComponent.safeGetAuthUser(ctx);
+  if (!user) {
+    throw new Error("Unauthenticated");
+  }
+  const userId = user.userId ?? String(user._id);
+  if (!userId) {
+    throw new Error("Unauthenticated");
+  }
+  return { ...user, userId };
+}
+
+/**
+ * Gibt den User zurück oder null — für optionale Auth-Checks (z.B. public Queries).
+ */
+export async function optionalAuth(ctx: QueryCtx | MutationCtx) {
+  return await authComponent.safeGetAuthUser(ctx);
+}
diff --git a/convex/nodes.ts b/convex/nodes.ts
new file mode 100644
index 0000000..7dab827
--- /dev/null
+++ b/convex/nodes.ts
@@ -0,0 +1,327 @@
+import { query, mutation, QueryCtx, MutationCtx } from "./_generated/server";
+import { v } from "convex/values";
+import { requireAuth } from "./helpers";
+import type { Doc, Id } from "./_generated/dataModel";
+
+// ============================================================================
+// Interne Helpers
+// ============================================================================
+
+/**
+ * Prüft ob der User Zugriff auf den Canvas hat und gibt ihn zurück.
+ */
+async function getCanvasOrThrow(
+  ctx: QueryCtx | MutationCtx,
+  canvasId: Id<"canvases">,
+  userId: string
+) {
+  const canvas = await ctx.db.get(canvasId);
+  if (!canvas || canvas.ownerId !== userId) {
+    throw new Error("Canvas not found");
+  }
+  return canvas;
+}
+
+// ============================================================================
+// Queries
+// ============================================================================
+
+/**
+ * Alle Nodes eines Canvas laden.
+ */
+export const list = query({
+  args: { canvasId: v.id("canvases") },
+  handler: async (ctx, { canvasId }) => {
+    const user = await requireAuth(ctx);
+    await getCanvasOrThrow(ctx, canvasId, user.userId);
+
+    return await ctx.db
+      .query("nodes")
+      .withIndex("by_canvas", (q) => q.eq("canvasId", canvasId))
+      .collect();
+  },
+});
+
+/**
+ * Einzelnen Node laden.
+ */
+export const get = query({
+  args: { nodeId: v.id("nodes") },
+  handler: async (ctx, { nodeId }) => {
+    const user = await requireAuth(ctx);
+    const node = await ctx.db.get(nodeId);
+    if (!node) return null;
+
+    await getCanvasOrThrow(ctx, node.canvasId, user.userId);
+    return node;
+  },
+});
+
+/**
+ * Nodes nach Typ filtern (z.B. alle ai-image Nodes eines Canvas).
+ */
+export const listByType = query({
+  args: {
+    canvasId: v.id("canvases"),
+    type: v.string(),
+  },
+  handler: async (ctx, { canvasId, type }) => {
+    const user = await requireAuth(ctx);
+    await getCanvasOrThrow(ctx, canvasId, user.userId);
+
+    return await ctx.db
+      .query("nodes")
+      .withIndex("by_canvas_type", (q) =>
+        q.eq("canvasId", canvasId).eq("type", type as Doc<"nodes">["type"])
+      )
+      .collect();
+  },
+});
+
+// ============================================================================
+// Mutations
+// ============================================================================
+
+/**
+ * Neuen Node auf dem Canvas erstellen.
+ */
+export const create = mutation({
+  args: {
+    canvasId: v.id("canvases"),
+    type: v.string(),
+    positionX: v.number(),
+    positionY: v.number(),
+    width: v.number(),
+    height: v.number(),
+    data: v.any(),
+    parentId: v.optional(v.id("nodes")),
+    zIndex: v.optional(v.number()),
+  },
+  handler: async (ctx, args) => {
+    const user = await requireAuth(ctx);
+    await getCanvasOrThrow(ctx, args.canvasId, user.userId);
+
+    const nodeId = await ctx.db.insert("nodes", {
+      canvasId: args.canvasId,
+      type: args.type as Doc<"nodes">["type"],
+      positionX: args.positionX,
+      positionY: args.positionY,
+      width: args.width,
+      height: args.height,
+      status: "idle",
+      data: args.data,
+      parentId: args.parentId,
+      zIndex: args.zIndex,
+    });
+
+    // Canvas updatedAt aktualisieren
+    await ctx.db.patch(args.canvasId, { updatedAt: Date.now() });
+
+    return nodeId;
+  },
+});
+
+/**
+ * Node-Position auf dem Canvas verschieben.
+ */
+export const move = mutation({
+  args: {
+    nodeId: v.id("nodes"),
+    positionX: v.number(),
+    positionY: v.number(),
+  },
+  handler: async (ctx, { nodeId, positionX, positionY }) => {
+    const user = await requireAuth(ctx);
+    const node = await ctx.db.get(nodeId);
+    if (!node) throw new Error("Node not found");
+
+    await getCanvasOrThrow(ctx, node.canvasId, user.userId);
+    await ctx.db.patch(nodeId, { positionX, positionY });
+    await ctx.db.patch(node.canvasId, { updatedAt: Date.now() });
+  },
+});
+
+/**
+ * Node-Größe ändern.
+ */
+export const resize = mutation({
+  args: {
+    nodeId: v.id("nodes"),
+    width: v.number(),
+    height: v.number(),
+  },
+  handler: async (ctx, { nodeId, width, height }) => {
+    const user = await requireAuth(ctx);
+    const node = await ctx.db.get(nodeId);
+    if (!node) throw new Error("Node not found");
+
+    await getCanvasOrThrow(ctx, node.canvasId, user.userId);
+    await ctx.db.patch(nodeId, { width, height });
+    await ctx.db.patch(node.canvasId, { updatedAt: Date.now() });
+  },
+});
+
+/**
+ * Mehrere Nodes gleichzeitig verschieben (Batch Move, z.B. nach Multiselect-Drag).
+ */
+export const batchMove = mutation({
+  args: {
+    moves: v.array(
+      v.object({
+        nodeId: v.id("nodes"),
+        positionX: v.number(),
+        positionY: v.number(),
+      })
+    ),
+  },
+  handler: async (ctx, { moves }) => {
+    const user = await requireAuth(ctx);
+    if (moves.length === 0) return;
+
+    // Canvas-Zugriff über den ersten Node prüfen
+    const firstNode = await ctx.db.get(moves[0].nodeId);
+    if (!firstNode) throw new Error("Node not found");
+    await getCanvasOrThrow(ctx, firstNode.canvasId, user.userId);
+
+    for (const { nodeId, positionX, positionY } of moves) {
+      await ctx.db.patch(nodeId, { positionX, positionY });
+    }
+
+    await ctx.db.patch(firstNode.canvasId, { updatedAt: Date.now() });
+  },
+});
+
+/**
+ * Node-Daten aktualisieren (typ-spezifische Payload).
+ */
+export const updateData = mutation({
+  args: {
+    nodeId: v.id("nodes"),
+    data: v.any(),
+  },
+  handler: async (ctx, { nodeId, data }) => {
+    const user = await requireAuth(ctx);
+    const node = await ctx.db.get(nodeId);
+    if (!node) throw new Error("Node not found");
+
+    await getCanvasOrThrow(ctx, node.canvasId, user.userId);
+    await ctx.db.patch(nodeId, { data });
+    await ctx.db.patch(node.canvasId, { updatedAt: Date.now() });
+  },
+});
+
+/**
+ * Node-Status aktualisieren (UX-Strategie: Status direkt am Node).
+ */
+export const updateStatus = mutation({
+  args: {
+    nodeId: v.id("nodes"),
+    status: v.union(
+      v.literal("idle"),
+      v.literal("analyzing"),
+      v.literal("clarifying"),
+      v.literal("executing"),
+      v.literal("done"),
+      v.literal("error")
+    ),
+    statusMessage: v.optional(v.string()),
+  },
+  handler: async (ctx, { nodeId, status, statusMessage }) => {
+    const user = await requireAuth(ctx);
+    const node = await ctx.db.get(nodeId);
+    if (!node) throw new Error("Node not found");
+
+    await getCanvasOrThrow(ctx, node.canvasId, user.userId);
+    await ctx.db.patch(nodeId, { status, statusMessage });
+  },
+});
+
+/**
+ * Node-Z-Index ändern (Layering).
+ */
+export const updateZIndex = mutation({
+  args: {
+    nodeId: v.id("nodes"),
+    zIndex: v.number(),
+  },
+  handler: async (ctx, { nodeId, zIndex }) => {
+    const user = await requireAuth(ctx);
+    const node = await ctx.db.get(nodeId);
+    if (!node) throw new Error("Node not found");
+
+    await getCanvasOrThrow(ctx, node.canvasId, user.userId);
+    await ctx.db.patch(nodeId, { zIndex });
+  },
+});
+
+/**
+ * Node in eine Gruppe/Frame verschieben oder aus Gruppe entfernen.
+ */
+export const setParent = mutation({
+  args: {
+    nodeId: v.id("nodes"),
+    parentId: v.optional(v.id("nodes")),
+  },
+  handler: async (ctx, { nodeId, parentId }) => {
+    const user = await requireAuth(ctx);
+    const node = await ctx.db.get(nodeId);
+    if (!node) throw new Error("Node not found");
+
+    await getCanvasOrThrow(ctx, node.canvasId, user.userId);
+
+    // Prüfen ob Parent existiert und zum gleichen Canvas gehört
+    if (parentId) {
+      const parent = await ctx.db.get(parentId);
+      if (!parent || parent.canvasId !== node.canvasId) {
+        throw new Error("Parent not found");
+      }
+    }
+
+    await ctx.db.patch(nodeId, { parentId });
+    await ctx.db.patch(node.canvasId, { updatedAt: Date.now() });
+  },
+});
+
+/**
+ * Node löschen — entfernt auch alle verbundenen Edges.
+ */
+export const remove = mutation({
+  args: { nodeId: v.id("nodes") },
+  handler: async (ctx, { nodeId }) => {
+    const user = await requireAuth(ctx);
+    const node = await ctx.db.get(nodeId);
+    if (!node) throw new Error("Node not found");
+
+    await getCanvasOrThrow(ctx, node.canvasId, user.userId);
+
+    // Alle Edges entfernen, die diesen Node als Source oder Target haben
+    const sourceEdges = await ctx.db
+      .query("edges")
+      .withIndex("by_source", (q) => q.eq("sourceNodeId", nodeId))
+      .collect();
+    for (const edge of sourceEdges) {
+      await ctx.db.delete(edge._id);
+    }
+
+    const targetEdges = await ctx.db
+      .query("edges")
+      .withIndex("by_target", (q) => q.eq("targetNodeId", nodeId))
+      .collect();
+    for (const edge of targetEdges) {
+      await ctx.db.delete(edge._id);
+    }
+
+    // Kind-Nodes aus Gruppe/Frame lösen (parentId auf undefined setzen)
+    const children = await ctx.db
+      .query("nodes")
+      .withIndex("by_parent", (q) => q.eq("parentId", nodeId))
+      .collect();
+    for (const child of children) {
+      await ctx.db.patch(child._id, { parentId: undefined });
+    }
+
+    // Node löschen
+    await ctx.db.delete(nodeId);
+    await ctx.db.patch(node.canvasId, { updatedAt: Date.now() });
+  },
+});
diff --git a/convex/schema.ts b/convex/schema.ts
new file mode 100644
index 0000000..2a8718f
--- /dev/null
+++ b/convex/schema.ts
@@ -0,0 +1,289 @@
+/* eslint-disable @typescript-eslint/no-unused-vars */
+import { defineSchema, defineTable } from "convex/server";
+import { v } from "convex/values";
+
+// ============================================================================
+// Node Types
+// ============================================================================
+
+// Phase 1 Node Types
+const phase1NodeTypes = v.union(
+  // Quelle
+  v.literal("image"),
+  v.literal("text"),
+  v.literal("prompt"),
+  // KI-Ausgabe
+  v.literal("ai-image"),
+  // Canvas & Layout
+  v.literal("group"),
+  v.literal("frame"),
+  v.literal("note"),
+  v.literal("compare")
+);
+
+// Alle Node Types (Phase 1 + spätere Phasen)
+// Phase 2+3 Typen sind hier schon definiert, damit das Schema nicht bei
+// jedem Phasenübergang migriert werden muss. Die UI zeigt nur die Typen
+// der jeweiligen Phase an.
+const nodeType = v.union(
+  // Quelle (Phase 1)
+  v.literal("image"),
+  v.literal("text"),
+  v.literal("prompt"),
+  // Quelle (Phase 2)
+  v.literal("color"),
+  v.literal("video"),
+  v.literal("asset"),
+  // KI-Ausgabe (Phase 1)
+  v.literal("ai-image"),
+  // KI-Ausgabe (Phase 2)
+  v.literal("ai-text"),
+  v.literal("ai-video"),
+  // KI-Ausgabe (Phase 3)
+  v.literal("agent-output"),
+  // Transformation (Phase 2)
+  v.literal("crop"),
+  v.literal("bg-remove"),
+  v.literal("upscale"),
+  // Transformation (Phase 3)
+  v.literal("style-transfer"),
+  v.literal("face-restore"),
+  // Steuerung (Phase 2)
+  v.literal("splitter"),
+  v.literal("loop"),
+  v.literal("agent"),
+  // Steuerung (Phase 3)
+  v.literal("mixer"),
+  v.literal("switch"),
+  // Canvas & Layout (Phase 1)
+  v.literal("group"),
+  v.literal("frame"),
+  v.literal("note"),
+  v.literal("compare"),
+  // Canvas & Layout (Phase 2)
+  v.literal("text-overlay"),
+  // Canvas & Layout (Phase 3)
+  v.literal("comment"),
+  v.literal("presentation")
+);
+
+// Node Status — direkt am Node sichtbar (UX-Strategie aus dem PRD)
+const nodeStatus = v.union(
+  v.literal("idle"),
+  v.literal("analyzing"),
+  v.literal("clarifying"),
+  v.literal("executing"),
+  v.literal("done"),
+  v.literal("error")
+);
+
+// ============================================================================
+// Node Data — typ-spezifische Payloads
+// ============================================================================
+
+// Bild-Node: Upload oder URL
+const imageNodeData = v.object({
+  storageId: v.optional(v.id("_storage")),       // Convex File Storage
+  url: v.optional(v.string()),                    // Externe URL
+  mimeType: v.optional(v.string()),               // image/png, image/jpeg, image/webp
+  originalFilename: v.optional(v.string()),
+  width: v.optional(v.number()),                  // Natürliche Bildbreite
+  height: v.optional(v.number()),                 // Natürliche Bildhöhe
+});
+
+// Text-Node: Freitext mit Markdown
+const textNodeData = v.object({
+  content: v.string(),
+});
+
+// Prompt-Node: Modellinstruktionen
+const promptNodeData = v.object({
+  content: v.string(),
+  model: v.optional(v.string()),                  // OpenRouter Model ID
+  modelTier: v.optional(v.union(
+    v.literal("budget"),
+    v.literal("standard"),
+    v.literal("premium")
+  )),
+});
+
+// KI-Bild-Node: Output einer Bildgenerierung
+const aiImageNodeData = v.object({
+  storageId: v.optional(v.id("_storage")),        // Generiertes Bild in Convex Storage
+  prompt: v.string(),                              // Verwendeter Prompt
+  model: v.string(),                               // OpenRouter Model ID
+  modelTier: v.union(
+    v.literal("budget"),
+    v.literal("standard"),
+    v.literal("premium")
+  ),
+  parameters: v.optional(v.any()),                 // Modell-spezifische Parameter
+  generationTimeMs: v.optional(v.number()),        // Latenz-Tracking
+  creditCost: v.optional(v.number()),              // Tatsächliche Kosten in Credits (Cent)
+  width: v.optional(v.number()),
+  height: v.optional(v.number()),
+  errorMessage: v.optional(v.string()),            // Bei status: "error"
+});
+
+// Frame-Node: Artboard mit definierter Auflösung
+const frameNodeData = v.object({
+  label: v.optional(v.string()),                   // Artboard-Name
+  exportWidth: v.number(),                         // Export-Auflösung
+  exportHeight: v.number(),
+  backgroundColor: v.optional(v.string()),         // Hex-Farbe
+});
+
+// Gruppe-Node: Container
+const groupNodeData = v.object({
+  label: v.optional(v.string()),
+  collapsed: v.boolean(),
+});
+
+// Notiz-Node: Annotation
+const noteNodeData = v.object({
+  content: v.string(),                             // Markdown
+  color: v.optional(v.string()),                   // Hintergrundfarbe
+});
+
+// Compare-Node: Zwei Bilder nebeneinander
+const compareNodeData = v.object({
+  leftNodeId: v.optional(v.id("nodes")),           // Referenz auf linkes Bild
+  rightNodeId: v.optional(v.id("nodes")),          // Referenz auf rechtes Bild
+  sliderPosition: v.optional(v.number()),          // 0-100, Default: 50
+});
+
+// ============================================================================
+// Schema Definition
+// ============================================================================
+
+export default defineSchema({
+
+  // ==========================================================================
+  // Canvas & Nodes
+  // ==========================================================================
+
+  canvases: defineTable({
+    name: v.string(),
+    ownerId: v.string(),                           // Better Auth User ID
+    description: v.optional(v.string()),
+    thumbnail: v.optional(v.id("_storage")),       // Canvas-Vorschaubild
+    updatedAt: v.number(),                         // Timestamp (ms)
+  })
+    .index("by_owner", ["ownerId"])
+    .index("by_owner_updated", ["ownerId", "updatedAt"]),
+
+  nodes: defineTable({
+    canvasId: v.id("canvases"),
+    type: nodeType,
+    // Position & Größe auf dem Canvas
+    positionX: v.number(),
+    positionY: v.number(),
+    width: v.number(),
+    height: v.number(),
+    // Node-Status (UX-Strategie: Status direkt am Node sichtbar)
+    status: nodeStatus,
+    statusMessage: v.optional(v.string()),         // z.B. "Timeout — Credits nicht abgebucht"
+    // Typ-spezifische Daten
+    // Convex empfiehlt v.any() für polymorphe data-Felder
+    // Type Safety wird über den `type`-Discriminator + Zod im Frontend sichergestellt
+    data: v.any(),
+    // Gruppierung
+    parentId: v.optional(v.id("nodes")),           // Für Nodes in Gruppen/Frames
+    zIndex: v.optional(v.number()),                // Layering-Reihenfolge
+  })
+    .index("by_canvas", ["canvasId"])
+    .index("by_canvas_type", ["canvasId", "type"])
+    .index("by_parent", ["parentId"]),
+
+  edges: defineTable({
+    canvasId: v.id("canvases"),
+    sourceNodeId: v.id("nodes"),
+    targetNodeId: v.id("nodes"),
+    // Edge-Metadaten
+    sourceHandle: v.optional(v.string()),          // Welcher Output-Port
+    targetHandle: v.optional(v.string()),          // Welcher Input-Port
+  })
+    .index("by_canvas", ["canvasId"])
+    .index("by_source", ["sourceNodeId"])
+    .index("by_target", ["targetNodeId"]),
+
+  // ==========================================================================
+  // Credit-System
+  // ==========================================================================
+
+  creditBalances: defineTable({
+    userId: v.string(),                            // Better Auth User ID
+    balance: v.number(),                           // Verfügbare Credits (Euro-Cent)
+    reserved: v.number(),                          // Gesperrte Credits (laufende Jobs)
+    // available = balance - reserved (computed, nicht gespeichert)
+    monthlyAllocation: v.number(),                 // Credits aus dem Abo (Cent)
+    updatedAt: v.number(),                         // Timestamp (ms)
+  })
+    .index("by_user", ["userId"]),
+
+  creditTransactions: defineTable({
+    userId: v.string(),                            // Better Auth User ID
+    amount: v.number(),                            // + = Gutschrift, - = Verbrauch (Cent)
+    type: v.union(
+      v.literal("subscription"),                   // Monatliche Abo-Gutschrift
+      v.literal("topup"),                          // Manueller Nachkauf
+      v.literal("usage"),                          // KI-Verbrauch
+      v.literal("reservation"),                    // Vorab-Reservierung
+      v.literal("refund")                          // Rückerstattung
+    ),
+    status: v.union(
+      v.literal("committed"),                      // Abgeschlossen
+      v.literal("reserved"),                       // Reserviert, Job läuft
+      v.literal("released"),                       // Reservierung aufgehoben (Fehler)
+      v.literal("failed")                          // Fehlgeschlagen
+    ),
+    description: v.string(),                       // z.B. "Bildgenerierung — Gemini 2.5 Flash Image"
+    nodeId: v.optional(v.id("nodes")),             // Auslösender Node
+    canvasId: v.optional(v.id("canvases")),        // Zugehöriger Canvas
+    openRouterCost: v.optional(v.number()),        // Tatsächliche API-Kosten (Cent)
+    model: v.optional(v.string()),                 // OpenRouter Model ID
+  })
+    .index("by_user", ["userId"])
+    .index("by_user_type", ["userId", "type"])
+    .index("by_user_status", ["userId", "status"])
+    .index("by_node", ["nodeId"]),
+
+  // ==========================================================================
+  // Subscriptions
+  // ==========================================================================
+
+  subscriptions: defineTable({
+    userId: v.string(),                            // Better Auth User ID
+    tier: v.union(
+      v.literal("free"),
+      v.literal("starter"),
+      v.literal("pro"),
+      v.literal("business")
+    ),
+    status: v.union(
+      v.literal("active"),
+      v.literal("cancelled"),
+      v.literal("past_due"),
+      v.literal("trialing")
+    ),
+    currentPeriodStart: v.number(),                // Timestamp (ms)
+    currentPeriodEnd: v.number(),                  // Timestamp (ms)
+    lemonSqueezySubscriptionId: v.optional(v.string()),
+    lemonSqueezyCustomerId: v.optional(v.string()),
+    cancelAtPeriodEnd: v.optional(v.boolean()),    // Kündigung zum Periodenende
+  })
+    .index("by_user", ["userId"])
+    .index("by_lemon_squeezy", ["lemonSqueezySubscriptionId"]),
+
+  // ==========================================================================
+  // Abuse Prevention
+  // ==========================================================================
+
+  dailyUsage: defineTable({
+    userId: v.string(),
+    date: v.string(),                              // ISO Date: "2026-03-25"
+    generationCount: v.number(),                   // Anzahl Generierungen heute
+    concurrentJobs: v.number(),                    // Aktuell laufende Jobs
+  })
+    .index("by_user_date", ["userId", "date"]),
+});