diff --git a/backlog/tasks/task-3 - Build-read-only-savings-agent-with-tool-calls.md b/backlog/tasks/task-3 - Build-read-only-savings-agent-with-tool-calls.md
new file mode 100644
index 0000000..6e1692f
--- /dev/null
+++ b/backlog/tasks/task-3 - Build-read-only-savings-agent-with-tool-calls.md	
@@ -0,0 +1,53 @@
+---
+id: TASK-3
+title: Build read-only savings agent with tool calls
+status: In Progress
+assignee: []
+created_date: '2026-06-15 19:02'
+updated_date: '2026-06-15 19:11'
+labels: []
+dependencies: []
+priority: high
+ordinal: 3000
+---
+
+## Description
+
+<!-- SECTION:DESCRIPTION:BEGIN -->
+Convert Talk to Savings from a prompt-packed chat into a read-only AI SDK tool-calling agent with deterministic transaction retrieval, spending summaries, forecasts, and compact frontend tool traces.
+<!-- SECTION:DESCRIPTION:END -->
+
+## Acceptance Criteria
+<!-- AC:BEGIN -->
+- [x] #1 Savings chat action uses AI SDK tool calls with a bounded multi-step loop and returns a compact tool trace
+- [x] #2 Read-only transaction retrieval tool supports selected scope, bounded custom ranges, account/category/search filters, exact totals, sanitized rows, and hasMore
+- [x] #3 Spending summary and cashflow forecast tools compute deterministic aggregates without model-invented math
+- [x] #4 Frontend remains localStorage-backed, loads legacy chats, and renders compact tool traces under assistant answers
+- [x] #5 Focused Convex tests, build, and targeted lint verification pass or known blockers are documented
+<!-- AC:END -->
+
+## Implementation Plan
+
+<!-- SECTION:PLAN:BEGIN -->
+1. Write failing Convex tests for read-only tool queries and traces
+2. Implement internal read-only savings agent tool queries
+3. Switch savingsChat.ask to AI SDK tool calling with bounded multi-step loop
+4. Update frontend chat messages and compact tool trace rendering
+5. Run focused tests, build, targeted lint, and record verification notes
+<!-- SECTION:PLAN:END -->
+
+## Implementation Notes
+
+<!-- SECTION:NOTES:BEGIN -->
+Implementation complete pending user confirmation.
+
+Subagents:
+- Frontend UX worker updated src/pages/SavingsChatPage.tsx for legacy-safe localStorage message normalization and compact assistant tool traces.
+- QA explorer reviewed Convex test strategy and confirmed mock AI SDK approach for ask() coverage.
+
+Verification:
+- PASS npx vitest convex/savingsChat.test.ts --run (8 tests)
+- PASS npx eslint convex/savingsChat.ts convex/savingsChat.test.ts src/pages/SavingsChatPage.tsx
+- PASS npm run build
+- BLOCKED npm run lint on pre-existing unrelated files: convex/bank/comdirectProvider.ts, convex/bank/config.ts, src/components/import/TanAwaitDialog.tsx, layout/ui fast-refresh exports, SettingsPage.tsx, generated eslint-disable warnings, and existing React compiler warnings. No TASK-3 touched file appears in the full-lint error list.
+<!-- SECTION:NOTES:END -->
diff --git a/convex/savingsChat.test.ts b/convex/savingsChat.test.ts
index b25be05..4725b63 100644
--- a/convex/savingsChat.test.ts
+++ b/convex/savingsChat.test.ts
@@ -1,14 +1,58 @@
 /// <reference types="vite/client" />
 
 import { convexTest } from "convex-test";
-import { describe, expect, test } from "vitest";
+import { generateText } from "ai";
+import { beforeEach, describe, expect, test, vi } from "vitest";
 import { api, internal } from "./_generated/api";
 import type { Id } from "./_generated/dataModel";
+import { buildToolTraceFromSteps } from "./savingsChat";
 import schema from "./schema";
 
+vi.mock("ai", async (importOriginal) => {
+  const actual = await importOriginal<typeof import("ai")>();
+  return {
+    ...actual,
+    generateText: vi.fn(async (options: {
+      tools: {
+        get_transactions: { execute: (input: unknown) => Promise<unknown> };
+        summarize_spending: { execute: (input: unknown) => Promise<unknown> };
+      };
+    }) => {
+      const transactionInput = { from: "2026-02-01", to: "2026-02-28", limit: 2 };
+      const summaryInput = { from: "2026-02-01", to: "2026-02-28" };
+      const transactionOutput = await options.tools.get_transactions.execute(transactionInput);
+      const summaryOutput = await options.tools.summarize_spending.execute(summaryInput);
+
+      return {
+        text: "Agenten-Antwort",
+        steps: [
+          {
+            toolResults: [
+              {
+                toolName: "get_transactions",
+                input: transactionInput,
+                output: transactionOutput,
+              },
+              {
+                toolName: "summarize_spending",
+                input: summaryInput,
+                output: summaryOutput,
+              },
+            ],
+          },
+        ],
+      };
+    }),
+  };
+});
+
 const modules = import.meta.glob("./**/*.ts");
 delete modules["./savingsChat.test.ts"];
 
+beforeEach(() => {
+  vi.clearAllMocks();
+});
+
 describe("savingsChat.getContext", () => {
   test("counts and sums every matching transaction before applying prompt limits", async () => {
     const t = convexTest(schema, modules);
@@ -192,3 +236,479 @@ describe("savingsChat.getContext", () => {
     expect(context.transactionLines.join("\n")).not.toContain("Other account should not appear");
   });
 });
+
+describe("savingsChat read-only agent tools", () => {
+  test("getTransactionsTool applies account scope, exact totals, limits, and sanitizes rows", async () => {
+    const t = convexTest(schema, modules);
+
+    const seeded = await t.run(async (ctx) => {
+      const userId = await ctx.db.insert("users", {
+        name: "Tool User",
+        email: "tool@example.com",
+      });
+      const categoryId = await ctx.db.insert("categories", {
+        userId,
+        name: "Lebensmittel",
+        kind: "ausgabe",
+        block: "variabel",
+        color: "#22c55e",
+        sortOrder: 1,
+        isSystem: false,
+      });
+      const giroAccountId = await ctx.db.insert("accounts", {
+        userId,
+        name: "Girokonto",
+        type: "checking",
+        openingBalance: 0,
+        currency: "EUR",
+        isArchived: false,
+      });
+      const savingsAccountId = await ctx.db.insert("accounts", {
+        userId,
+        name: "Tagesgeld",
+        type: "savings",
+        openingBalance: 0,
+        currency: "EUR",
+        isArchived: false,
+      });
+
+      await ctx.db.insert("transactions", {
+        userId,
+        accountId: giroAccountId,
+        categoryId,
+        bookingDate: "2026-01-05",
+        valueDate: "2026-01-05",
+        description: "Supermarkt",
+        counterparty: "Markt GmbH",
+        amount: -100,
+        isPending: false,
+        rawText: "RAW BANK PAYLOAD",
+        notes: "private note",
+        dedupHash: "secret-hash",
+        externalRef: "external-ref",
+        effectiveMonth: "2026-01",
+      });
+      await ctx.db.insert("transactions", {
+        userId,
+        accountId: giroAccountId,
+        bookingDate: "2026-01-07",
+        valueDate: "2026-01-07",
+        description: "Baecker",
+        amount: -15,
+        isPending: false,
+        effectiveMonth: "2026-01",
+      });
+      await ctx.db.insert("transactions", {
+        userId,
+        accountId: giroAccountId,
+        bookingDate: "2026-01-03",
+        valueDate: "2026-01-03",
+        description: "Kaffee",
+        amount: -5,
+        isPending: false,
+        effectiveMonth: "2026-01",
+      });
+      await ctx.db.insert("transactions", {
+        userId,
+        accountId: savingsAccountId,
+        bookingDate: "2026-01-08",
+        valueDate: "2026-01-08",
+        description: "Other account",
+        amount: 999,
+        isPending: false,
+        effectiveMonth: "2026-01",
+      });
+
+      return { userId, giroAccountId };
+    });
+
+    const asUser = t.withIdentity({
+      subject: `${seeded.userId}|test-session`,
+      tokenIdentifier: `test:${seeded.userId}`,
+    });
+
+    const result = await asUser.query(internal.savingsChat.getTransactionsTool, {
+      scope: {
+        from: "2026-01-01",
+        to: "2026-01-31",
+        accountId: seeded.giroAccountId as Id<"accounts">,
+        basis: "booking",
+      },
+      limit: 2,
+    });
+
+    expect(result.totalCount).toBe(3);
+    expect(result.hasMore).toBe(true);
+    expect(result.rows).toHaveLength(2);
+    expect(result.totals).toEqual({
+      transactionCount: 3,
+      income: 0,
+      expenses: -120,
+      balance: -120,
+    });
+    expect(result.rows[0].accountName).toBe("Girokonto");
+    expect(result.rows.find((row) => row.description === "Supermarkt")?.categoryName).toBe(
+      "Lebensmittel",
+    );
+    expect(Object.keys(result.rows[0])).not.toContain("rawText");
+    expect(Object.keys(result.rows[0])).not.toContain("notes");
+    expect(Object.keys(result.rows[0])).not.toContain("dedupHash");
+    expect(Object.keys(result.rows[0])).not.toContain("externalRef");
+    expect(Object.keys(result.rows[0])).not.toContain("userId");
+  });
+
+  test("getTransactionsTool includes legacy effective-month rows via booking fallback", async () => {
+    const t = convexTest(schema, modules);
+
+    const seeded = await t.run(async (ctx) => {
+      const userId = await ctx.db.insert("users", {
+        name: "Legacy User",
+        email: "legacy@example.com",
+      });
+      const accountId = await ctx.db.insert("accounts", {
+        userId,
+        name: "Girokonto",
+        type: "checking",
+        openingBalance: 0,
+        currency: "EUR",
+        isArchived: false,
+      });
+      await ctx.db.insert("transactions", {
+        userId,
+        accountId,
+        bookingDate: "2026-03-12",
+        valueDate: "2026-03-12",
+        description: "Legacy no effective month",
+        amount: -30,
+        isPending: false,
+      });
+      await ctx.db.insert("transactions", {
+        userId,
+        accountId,
+        bookingDate: "2026-03-20",
+        valueDate: "2026-03-20",
+        description: "Modern effective month",
+        amount: -20,
+        isPending: false,
+        effectiveMonth: "2026-03",
+      });
+      return { userId, accountId };
+    });
+
+    const asUser = t.withIdentity({
+      subject: `${seeded.userId}|test-session`,
+      tokenIdentifier: `test:${seeded.userId}`,
+    });
+
+    const result = await asUser.query(internal.savingsChat.getTransactionsTool, {
+      scope: {
+        from: "2026-03-01",
+        to: "2026-03-31",
+        accountId: seeded.accountId as Id<"accounts">,
+        basis: "effective",
+      },
+      limit: 10,
+    });
+
+    expect(result.totalCount).toBe(2);
+    expect(result.totals.expenses).toBe(-50);
+    expect(result.rows.map((row) => row.description)).toContain("Legacy no effective month");
+  });
+
+  test("summarizeSpendingTool computes exact monthly and category aggregates", async () => {
+    const t = convexTest(schema, modules);
+
+    const seeded = await t.run(async (ctx) => {
+      const userId = await ctx.db.insert("users", {
+        name: "Summary User",
+        email: "summary@example.com",
+      });
+      const accountId = await ctx.db.insert("accounts", {
+        userId,
+        name: "Girokonto",
+        type: "checking",
+        openingBalance: 0,
+        currency: "EUR",
+        isArchived: false,
+      });
+      const rentId = await ctx.db.insert("categories", {
+        userId,
+        name: "Miete",
+        kind: "ausgabe",
+        block: "wiederkehrend",
+        color: "#64748b",
+        sortOrder: 1,
+        isSystem: false,
+      });
+      const foodId = await ctx.db.insert("categories", {
+        userId,
+        name: "Lebensmittel",
+        kind: "ausgabe",
+        block: "variabel",
+        color: "#22c55e",
+        sortOrder: 2,
+        isSystem: false,
+      });
+      const salaryId = await ctx.db.insert("categories", {
+        userId,
+        name: "Gehalt",
+        kind: "einnahme",
+        color: "#0ea5e9",
+        sortOrder: 3,
+        isSystem: false,
+      });
+
+      for (const tx of [
+        { date: "2026-01-01", description: "Gehalt Januar", amount: 3000, categoryId: salaryId },
+        { date: "2026-01-02", description: "Miete Januar", amount: -1000, categoryId: rentId },
+        { date: "2026-01-10", description: "Supermarkt Januar", amount: -200, categoryId: foodId },
+        { date: "2026-02-01", description: "Gehalt Februar", amount: 3000, categoryId: salaryId },
+        { date: "2026-02-02", description: "Sonstiges Februar", amount: -50, categoryId: undefined },
+      ]) {
+        await ctx.db.insert("transactions", {
+          userId,
+          accountId,
+          categoryId: tx.categoryId,
+          bookingDate: tx.date,
+          valueDate: tx.date,
+          description: tx.description,
+          amount: tx.amount,
+          isPending: false,
+          effectiveMonth: tx.date.slice(0, 7),
+        });
+      }
+
+      return { userId, accountId };
+    });
+
+    const asUser = t.withIdentity({
+      subject: `${seeded.userId}|test-session`,
+      tokenIdentifier: `test:${seeded.userId}`,
+    });
+
+    const result = await asUser.query(internal.savingsChat.summarizeSpendingTool, {
+      scope: {
+        from: "2026-01-01",
+        to: "2026-02-28",
+        accountId: seeded.accountId as Id<"accounts">,
+        basis: "effective",
+      },
+    });
+
+    expect(result.totals).toEqual({
+      transactionCount: 5,
+      income: 6000,
+      expenses: -1250,
+      balance: 4750,
+    });
+    expect(result.fixedCosts).toBe(-1000);
+    expect(result.variableCosts).toBe(-200);
+    expect(result.monthlyTrend).toEqual([
+      { month: "2026-01", income: 3000, expenses: -1200, balance: 1800 },
+      { month: "2026-02", income: 3000, expenses: -50, balance: 2950 },
+    ]);
+    expect(result.categoryBreakdown.map((entry) => [entry.name, entry.amount])).toEqual([
+      ["Miete", -1000],
+      ["Lebensmittel", -200],
+      ["Ohne Kategorie", -50],
+    ]);
+  });
+
+  test("forecastCashflowTool excludes partial current month from the baseline", async () => {
+    const t = convexTest(schema, modules);
+
+    const seeded = await t.run(async (ctx) => {
+      const userId = await ctx.db.insert("users", {
+        name: "Forecast User",
+        email: "forecast@example.com",
+      });
+      const accountId = await ctx.db.insert("accounts", {
+        userId,
+        name: "Girokonto",
+        type: "checking",
+        openingBalance: 0,
+        currency: "EUR",
+        isArchived: false,
+      });
+
+      for (const tx of [
+        { date: "2026-04-01", description: "Gehalt April", amount: 3000 },
+        { date: "2026-04-10", description: "Kosten April", amount: -2000 },
+        { date: "2026-05-01", description: "Gehalt Mai", amount: 3200 },
+        { date: "2026-05-10", description: "Kosten Mai", amount: -2200 },
+        { date: "2026-06-01", description: "Gehalt Juni", amount: 3000 },
+        { date: "2026-06-10", description: "Teilkosten Juni", amount: -500 },
+      ]) {
+        await ctx.db.insert("transactions", {
+          userId,
+          accountId,
+          bookingDate: tx.date,
+          valueDate: tx.date,
+          description: tx.description,
+          amount: tx.amount,
+          isPending: false,
+          effectiveMonth: tx.date.slice(0, 7),
+        });
+      }
+
+      return { userId, accountId };
+    });
+
+    const asUser = t.withIdentity({
+      subject: `${seeded.userId}|test-session`,
+      tokenIdentifier: `test:${seeded.userId}`,
+    });
+
+    const result = await asUser.query(internal.savingsChat.forecastCashflowTool, {
+      scope: {
+        from: "2026-04-01",
+        to: "2026-06-30",
+        accountId: seeded.accountId as Id<"accounts">,
+        basis: "effective",
+      },
+      horizonMonths: 3,
+      asOf: "2026-06-15",
+    });
+
+    expect(result.baselineMonths).toEqual(["2026-04", "2026-05"]);
+    expect(result.excludedPartialMonth).toBe("2026-06");
+    expect(result.monthlyAverage).toEqual({ income: 3100, expenses: -2100, balance: 1000 });
+    expect(result.projection).toEqual([
+      { month: "2026-07", income: 3100, expenses: -2100, balance: 1000 },
+      { month: "2026-08", income: 3100, expenses: -2100, balance: 1000 },
+      { month: "2026-09", income: 3100, expenses: -2100, balance: 1000 },
+    ]);
+  });
+
+  test("buildToolTraceFromSteps returns compact summaries without raw tool output", () => {
+    const trace = buildToolTraceFromSteps([
+      {
+        toolResults: [
+          {
+            toolName: "get_transactions",
+            input: { from: "2026-01-01", to: "2026-01-31", limit: 50 },
+            output: {
+              totalCount: 2,
+              hasMore: false,
+              totals: { income: 0, expenses: -115, balance: -115, transactionCount: 2 },
+              rows: [
+                { description: "Supermarkt", amount: -100 },
+                { description: "Baecker", amount: -15 },
+              ],
+            },
+          },
+        ],
+      },
+    ]);
+
+    expect(trace).toEqual([
+      {
+        name: "get_transactions",
+        inputSummary: "2026-01-01 bis 2026-01-31, Limit 50",
+        resultSummary: "2 Umsätze, Saldo -115.00€, vollständig",
+      },
+    ]);
+  });
+
+  test("ask returns compact tool traces from executed read-only tools", async () => {
+    const t = convexTest(schema, modules);
+    const previousKey = process.env.OPENAI_API_KEY;
+    const previousModel = process.env.SAVINGS_CHAT_MODEL;
+
+    const seeded = await t.run(async (ctx) => {
+      const userId = await ctx.db.insert("users", {
+        name: "Ask User",
+        email: "ask@example.com",
+      });
+      const accountId = await ctx.db.insert("accounts", {
+        userId,
+        name: "Girokonto",
+        type: "checking",
+        openingBalance: 0,
+        currency: "EUR",
+        isArchived: false,
+      });
+      await ctx.db.insert("transactions", {
+        userId,
+        accountId,
+        bookingDate: "2026-02-01",
+        valueDate: "2026-02-01",
+        description: "Gehalt",
+        amount: 3000,
+        isPending: false,
+        effectiveMonth: "2026-02",
+        rawText: "RAW PAYLOAD SHOULD NOT LEAK",
+      });
+      await ctx.db.insert("transactions", {
+        userId,
+        accountId,
+        bookingDate: "2026-02-10",
+        valueDate: "2026-02-10",
+        description: "Supermarkt",
+        amount: -120,
+        isPending: false,
+        effectiveMonth: "2026-02",
+        notes: "private note should not leak",
+      });
+      return { userId, accountId };
+    });
+
+    try {
+      process.env.OPENAI_API_KEY = "test-key";
+      delete process.env.SAVINGS_CHAT_MODEL;
+      const asUser = t.withIdentity({
+        subject: `${seeded.userId}|test-session`,
+        tokenIdentifier: `test:${seeded.userId}`,
+      });
+
+      const result = await asUser.action(api.savingsChat.ask, {
+        messages: [{ role: "user", content: "Wie sieht Februar aus?" }],
+        from: "2026-02-01",
+        to: "2026-02-28",
+        accountId: seeded.accountId as Id<"accounts">,
+        basis: "effective",
+      });
+
+      expect(result.answer).toBe("Agenten-Antwort");
+      expect(result.model).toBe("gpt-5.4-mini");
+      expect(result.usedTransactions).toBe(2);
+      expect(result.usedBalance).toEqual({ income: 3000, expenses: -120, balance: 2880 });
+      expect(result.toolTrace).toEqual([
+        {
+          name: "get_transactions",
+          inputSummary: "2026-02-01 bis 2026-02-28, Limit 2",
+          resultSummary: "2 Umsätze, Saldo 2880.00€, vollständig",
+        },
+        {
+          name: "summarize_spending",
+          inputSummary: "2026-02-01 bis 2026-02-28",
+          resultSummary: "2 Umsätze, Saldo 2880.00€, 1 Kategorien",
+        },
+      ]);
+      expect(JSON.stringify(result.toolTrace)).not.toContain("RAW PAYLOAD");
+      expect(JSON.stringify(result.toolTrace)).not.toContain("private note");
+
+      expect(generateText).toHaveBeenCalledWith(
+        expect.objectContaining({
+          tools: expect.objectContaining({
+            get_transactions: expect.any(Object),
+            summarize_spending: expect.any(Object),
+            forecast_cashflow: expect.any(Object),
+          }),
+          stopWhen: expect.any(Function),
+        }),
+      );
+    } finally {
+      if (previousKey === undefined) {
+        delete process.env.OPENAI_API_KEY;
+      } else {
+        process.env.OPENAI_API_KEY = previousKey;
+      }
+      if (previousModel === undefined) {
+        delete process.env.SAVINGS_CHAT_MODEL;
+      } else {
+        process.env.SAVINGS_CHAT_MODEL = previousModel;
+      }
+    }
+  });
+});
diff --git a/convex/savingsChat.ts b/convex/savingsChat.ts
index 032230b..f372a11 100644
--- a/convex/savingsChat.ts
+++ b/convex/savingsChat.ts
@@ -1,9 +1,10 @@
 import { action, internalQuery, query } from "./_generated/server";
 import { v } from "convex/values";
-import { generateText } from "ai";
+import { generateText, stepCountIs, tool } from "ai";
 import { openai } from "@ai-sdk/openai";
 import { internal } from "./_generated/api";
-import { bookingMonth } from "./lib/month";
+import { z } from "zod";
+import { addMonthsToMonthKey, bookingMonth, monthKeyFromBasis } from "./lib/month";
 import { requireUserId } from "./lib/helpers";
 import type { Doc, Id } from "./_generated/dataModel";
 import type { QueryCtx } from "./_generated/server";
@@ -17,7 +18,9 @@ const chatMessageValidator = v.object({
 });
 
 const MAX_CONVERSATION_MESSAGES = 20;
-const MAX_PROMPT_CHARACTERS = 180_000;
+const DEFAULT_TOOL_ROW_LIMIT = 50;
+const MAX_TOOL_ROW_LIMIT = 200;
+const MAX_TOOL_RANGE_MONTHS = 18;
 
 type ChatContextArgs = {
   from: string;
@@ -42,6 +45,34 @@ type ChatAskResult = {
   answer: string;
   usedTransactions: number;
   usedBalance: { income: number; expenses: number; balance: number };
+  toolTrace: ToolTrace[];
+};
+type ToolTrace = { name: string; inputSummary: string; resultSummary: string };
+type TransactionTypeFilter = "income" | "expense";
+type AgentToolScope = ChatContextArgs;
+type TransactionToolArgs = {
+  scope: AgentToolScope;
+  from?: string;
+  to?: string;
+  accountId?: Id<"accounts">;
+  accountName?: string;
+  categoryIds?: Id<"categories">[];
+  categoryNames?: string[];
+  search?: string;
+  type?: TransactionTypeFilter;
+  limit?: number;
+};
+type ToolTransactionContext = {
+  from: string;
+  to: string;
+  basis: AgentToolScope["basis"];
+  accountId?: Id<"accounts">;
+  accountName?: string;
+  categories: Doc<"categories">[];
+  accounts: Doc<"accounts">[];
+  categoryById: Map<Id<"categories">, Doc<"categories">>;
+  accountById: Map<Id<"accounts">, Doc<"accounts">>;
+  transactions: Doc<"transactions">[];
 };
 
 function formatEuro(value: number): string {
@@ -51,37 +82,18 @@ function formatEuro(value: number): string {
 function buildSystemPrompt(context: { from: string; to: string; basis: string; accountName?: string }) {
   return [
     "Du bist ein präziser Finanz-Chat-Assistent für Privatanwender.",
-    "Nutze ausschließlich die gelieferten Umsätze als Kontext und beziehe dich nur auf die angegebenen Werte.",
+    "Nutze ausschließlich die bereitgestellten Werkzeuge und deren Ergebnisse als Finanzkontext.",
+    "Rufe Werkzeuge auf, wenn du Umsätze, Zusammenfassungen oder Prognosen brauchst; erfinde keine Beträge.",
     "Antworte auf Deutsch, kurz und handlungsorientiert.",
     `Zeitraum: ${context.from} bis ${context.to}.`,
     `Basis: ${context.basis}.`,
     context.accountName ? `Konto: ${context.accountName}.` : "Konto: Alle Konten.",
     "Wenn eine Aussage nur grob geschätzt werden kann, kennzeichne sie als Schätzung.",
+    "Nenne keine internen IDs und keine Rohdatenfelder.",
     "Verwende keine Links, keine HTML-Tags und keine Emojis.",
   ].join(" ");
 }
 
-function buildPrompt(context: ChatPromptContext, conversation: ChatMessage[]) {
-  return [
-    "Kontext der Auswertung:",
-    `Zeitraum: ${context.from} bis ${context.to}`,
-    `Basis: ${context.basis}`,
-    `Konto: ${context.accountName ?? "Alle Konten"}`,
-    `Anzahl Umsätze: ${context.totals.transactionCount}`,
-    `Einnahmen: ${formatEuro(context.totals.income)}`,
-    `Ausgaben: ${formatEuro(context.totals.expenses)}`,
-    `Saldo: ${formatEuro(context.totals.balance)}`,
-    "",
-    "Umsätze (neueste zuerst):",
-    ...(context.transactionLines.length > 0
-      ? context.transactionLines
-      : ["Keine Umsätze im Zeitraum."]),
-    "",
-    "Gesprächsverlauf:",
-    ...conversation.map((message) => `${message.role}: ${message.content}`),
-  ].join("\n");
-}
-
 function normalizeRole(role: ChatRole): "user" | "assistant" {
   return role;
 }
@@ -253,6 +265,55 @@ const contextSummaryValidator = v.object({
   isComplete: v.literal(true),
 });
 
+const toolTraceValidator = v.object({
+  name: v.string(),
+  inputSummary: v.string(),
+  resultSummary: v.string(),
+});
+
+const toolScopeValidator = v.object(contextArgsValidator);
+
+const transactionTypeFilterValidator = v.union(v.literal("income"), v.literal("expense"));
+
+const transactionToolArgsValidator = {
+  scope: toolScopeValidator,
+  from: v.optional(v.string()),
+  to: v.optional(v.string()),
+  accountId: v.optional(v.id("accounts")),
+  accountName: v.optional(v.string()),
+  categoryIds: v.optional(v.array(v.id("categories"))),
+  categoryNames: v.optional(v.array(v.string())),
+  search: v.optional(v.string()),
+  type: v.optional(transactionTypeFilterValidator),
+  limit: v.optional(v.number()),
+};
+
+const safeTransactionRowValidator = v.object({
+  date: v.string(),
+  bookingDate: v.optional(v.string()),
+  effectiveMonth: v.optional(v.string()),
+  description: v.string(),
+  counterparty: v.optional(v.string()),
+  amount: v.number(),
+  categoryName: v.string(),
+  accountName: v.string(),
+  isPending: v.boolean(),
+});
+
+const monthlyTrendValidator = v.object({
+  month: v.string(),
+  income: v.number(),
+  expenses: v.number(),
+  balance: v.number(),
+});
+
+const categoryBreakdownValidator = v.object({
+  categoryId: v.optional(v.id("categories")),
+  name: v.string(),
+  amount: v.number(),
+  block: v.optional(v.union(v.literal("wiederkehrend"), v.literal("variabel"))),
+});
+
 export const getContext = query({
   args: contextArgsValidator,
   returns: contextSummaryValidator,
@@ -263,6 +324,211 @@ export const getContext = query({
   },
 });
 
+function parseMonthIndex(month: string) {
+  const [year, monthNumber] = month.split("-").map(Number);
+  return year * 12 + monthNumber;
+}
+
+function rangeMonthSpan(from: string, to: string) {
+  return parseMonthIndex(to.slice(0, 7)) - parseMonthIndex(from.slice(0, 7)) + 1;
+}
+
+function clampToolLimit(limit: number | undefined) {
+  if (limit === undefined) return DEFAULT_TOOL_ROW_LIMIT;
+  return Math.max(1, Math.min(MAX_TOOL_ROW_LIMIT, Math.floor(limit)));
+}
+
+function normalizeToolRange(scope: AgentToolScope, from?: string, to?: string) {
+  const range = {
+    from: from?.trim() || scope.from,
+    to: to?.trim() || scope.to,
+  };
+  if (range.from > range.to) {
+    throw new Error("Ungültiger Zeitraum: von-Datum liegt nach bis-Datum.");
+  }
+  if (rangeMonthSpan(range.from, range.to) > MAX_TOOL_RANGE_MONTHS) {
+    throw new Error(`Der Tool-Zeitraum darf maximal ${MAX_TOOL_RANGE_MONTHS} Monate umfassen.`);
+  }
+  return range;
+}
+
+async function loadNameMaps(ctx: QueryCtx, userId: Id<"users">) {
+  const categories = await ctx.db
+    .query("categories")
+    .withIndex("by_user", (index) => index.eq("userId", userId))
+    .collect();
+  const accounts = await ctx.db
+    .query("accounts")
+    .withIndex("by_user", (index) => index.eq("userId", userId))
+    .collect();
+
+  return {
+    categories,
+    accounts,
+    categoryById: new Map(categories.map((category) => [category._id, category])),
+    accountById: new Map(accounts.map((account) => [account._id, account])),
+  };
+}
+
+function findAccountIdByName(
+  accounts: Doc<"accounts">[],
+  accountName: string | undefined,
+): Id<"accounts"> | undefined {
+  const normalized = accountName?.trim().toLocaleLowerCase("de-DE");
+  if (!normalized) return undefined;
+  return accounts.find((account) => account.name.toLocaleLowerCase("de-DE") === normalized)?._id;
+}
+
+function categoryNameSet(categoryNames: string[] | undefined) {
+  const normalized = categoryNames
+    ?.map((name) => name.trim().toLocaleLowerCase("de-DE"))
+    .filter(Boolean);
+  return normalized && normalized.length > 0 ? new Set(normalized) : null;
+}
+
+function transactionMatchesToolFilters(
+  tx: Doc<"transactions">,
+  args: TransactionToolArgs,
+  context: Pick<ToolTransactionContext, "categoryById" | "accountById">,
+) {
+  if (args.type === "income" && tx.amount <= 0) return false;
+  if (args.type === "expense" && tx.amount >= 0) return false;
+
+  if (args.categoryIds && args.categoryIds.length > 0) {
+    const categoryId = tx.categoryId;
+    if (!categoryId || !args.categoryIds.includes(categoryId)) return false;
+  }
+
+  const categoriesByName = categoryNameSet(args.categoryNames);
+  if (categoriesByName) {
+    const name = tx.categoryId ? context.categoryById.get(tx.categoryId)?.name : "Ohne Kategorie";
+    if (!categoriesByName.has((name ?? "Ohne Kategorie").toLocaleLowerCase("de-DE"))) {
+      return false;
+    }
+  }
+
+  const search = args.search?.trim().toLocaleLowerCase("de-DE");
+  if (search) {
+    const categoryName = tx.categoryId ? context.categoryById.get(tx.categoryId)?.name : "";
+    const accountName = tx.accountId ? context.accountById.get(tx.accountId)?.name : "";
+    const haystack = [
+      tx.description,
+      tx.counterparty,
+      categoryName,
+      accountName,
+    ]
+      .filter(Boolean)
+      .join(" ")
+      .toLocaleLowerCase("de-DE");
+    if (!haystack.includes(search)) return false;
+  }
+
+  return true;
+}
+
+async function buildToolTransactionContext(
+  ctx: QueryCtx,
+  userId: Id<"users">,
+  args: TransactionToolArgs,
+): Promise<ToolTransactionContext> {
+  const maps = await loadNameMaps(ctx, userId);
+  const range = normalizeToolRange(args.scope, args.from, args.to);
+  const accountId = args.accountId ?? findAccountIdByName(maps.accounts, args.accountName) ?? args.scope.accountId;
+  const account = accountId ? maps.accountById.get(accountId) : undefined;
+  const transactions = (await loadMatchingTransactions(ctx, userId, {
+    from: range.from,
+    to: range.to,
+    accountId,
+    basis: args.scope.basis,
+  })).filter((tx) => transactionMatchesToolFilters(tx, args, maps));
+
+  return {
+    ...maps,
+    ...range,
+    basis: args.scope.basis,
+    accountId,
+    accountName: account?.name,
+    transactions,
+  };
+}
+
+function safeTransactionRow(
+  tx: Doc<"transactions">,
+  context: Pick<ToolTransactionContext, "categoryById" | "accountById">,
+) {
+  return {
+    date: tx.valueDate || tx.bookingDate || tx.effectiveMonth || "n/a",
+    bookingDate: tx.bookingDate,
+    effectiveMonth: tx.effectiveMonth,
+    description: tx.description,
+    counterparty: tx.counterparty,
+    amount: Math.round(tx.amount * 100) / 100,
+    categoryName: tx.categoryId
+      ? context.categoryById.get(tx.categoryId)?.name ?? "Ohne Kategorie"
+      : "Ohne Kategorie",
+    accountName: tx.accountId
+      ? context.accountById.get(tx.accountId)?.name ?? "Ohne Konto"
+      : "Ohne Konto",
+    isPending: tx.isPending,
+  };
+}
+
+function roundMoney(value: number) {
+  return Math.round(value * 100) / 100;
+}
+
+function summarizeTransactions(context: ToolTransactionContext) {
+  const monthlyMap = new Map<string, { income: number; expenses: number }>();
+  const categoryMap = new Map<
+    string,
+    { categoryId?: Id<"categories">; name: string; amount: number; block?: "wiederkehrend" | "variabel" }
+  >();
+  let fixedCosts = 0;
+  let variableCosts = 0;
+
+  for (const tx of context.transactions) {
+    const month = monthKeyFromBasis(tx, context.basis);
+    if (month) {
+      const monthEntry = monthlyMap.get(month) ?? { income: 0, expenses: 0 };
+      if (tx.amount > 0) monthEntry.income += tx.amount;
+      if (tx.amount < 0) monthEntry.expenses += tx.amount;
+      monthlyMap.set(month, monthEntry);
+    }
+
+    if (tx.amount >= 0) continue;
+    const category = tx.categoryId ? context.categoryById.get(tx.categoryId) : undefined;
+    if (category?.block === "wiederkehrend") fixedCosts += tx.amount;
+    if (category?.block === "variabel") variableCosts += tx.amount;
+
+    const key = tx.categoryId ?? "none";
+    const categoryEntry = categoryMap.get(key) ?? {
+      categoryId: tx.categoryId,
+      name: category?.name ?? "Ohne Kategorie",
+      amount: 0,
+      block: category?.block,
+    };
+    categoryEntry.amount += tx.amount;
+    categoryMap.set(key, categoryEntry);
+  }
+
+  return {
+    totals: calculateTotals(context.transactions),
+    fixedCosts: roundMoney(fixedCosts),
+    variableCosts: roundMoney(variableCosts),
+    monthlyTrend: [...monthlyMap.entries()]
+      .sort(([a], [b]) => a.localeCompare(b))
+      .map(([month, data]) => ({
+        month,
+        income: roundMoney(data.income),
+        expenses: roundMoney(data.expenses),
+        balance: roundMoney(data.income + data.expenses),
+      })),
+    categoryBreakdown: [...categoryMap.values()]
+      .sort((a, b) => a.amount - b.amount)
+      .map((entry) => ({ ...entry, amount: roundMoney(entry.amount) })),
+  };
+}
+
 function toDisplayContextLine(
   tx: Doc<"transactions">,
   categoryById: Map<Id<"categories">, string>,
@@ -278,6 +544,135 @@ function toDisplayContextLine(
   }`;
 }
 
+export const getTransactionsTool = internalQuery({
+  args: transactionToolArgsValidator,
+  returns: v.object({
+    from: v.string(),
+    to: v.string(),
+    basis: v.union(v.literal("effective"), v.literal("booking")),
+    accountName: v.optional(v.string()),
+    totalCount: v.number(),
+    hasMore: v.boolean(),
+    totals: totalsValidator,
+    rows: v.array(safeTransactionRowValidator),
+  }),
+  handler: async (ctx, args) => {
+    const userId = await requireUserId(ctx);
+    const context = await buildToolTransactionContext(ctx, userId, args);
+    const limit = clampToolLimit(args.limit);
+    const rows = context.transactions
+      .slice(0, limit)
+      .map((tx) => safeTransactionRow(tx, context));
+
+    return {
+      from: context.from,
+      to: context.to,
+      basis: context.basis,
+      accountName: context.accountName,
+      totalCount: context.transactions.length,
+      hasMore: context.transactions.length > limit,
+      totals: calculateTotals(context.transactions),
+      rows,
+    };
+  },
+});
+
+export const summarizeSpendingTool = internalQuery({
+  args: {
+    scope: toolScopeValidator,
+    from: v.optional(v.string()),
+    to: v.optional(v.string()),
+    accountId: v.optional(v.id("accounts")),
+    accountName: v.optional(v.string()),
+    categoryIds: v.optional(v.array(v.id("categories"))),
+    categoryNames: v.optional(v.array(v.string())),
+    search: v.optional(v.string()),
+    type: v.optional(transactionTypeFilterValidator),
+  },
+  returns: v.object({
+    from: v.string(),
+    to: v.string(),
+    basis: v.union(v.literal("effective"), v.literal("booking")),
+    accountName: v.optional(v.string()),
+    totals: totalsValidator,
+    fixedCosts: v.number(),
+    variableCosts: v.number(),
+    monthlyTrend: v.array(monthlyTrendValidator),
+    categoryBreakdown: v.array(categoryBreakdownValidator),
+  }),
+  handler: async (ctx, args) => {
+    const userId = await requireUserId(ctx);
+    const context = await buildToolTransactionContext(ctx, userId, args);
+    const summary = summarizeTransactions(context);
+
+    return {
+      from: context.from,
+      to: context.to,
+      basis: context.basis,
+      accountName: context.accountName,
+      ...summary,
+    };
+  },
+});
+
+export const forecastCashflowTool = internalQuery({
+  args: {
+    scope: toolScopeValidator,
+    from: v.optional(v.string()),
+    to: v.optional(v.string()),
+    accountId: v.optional(v.id("accounts")),
+    accountName: v.optional(v.string()),
+    horizonMonths: v.optional(v.number()),
+    asOf: v.optional(v.string()),
+  },
+  returns: v.object({
+    from: v.string(),
+    to: v.string(),
+    basis: v.union(v.literal("effective"), v.literal("booking")),
+    accountName: v.optional(v.string()),
+    baselineMonths: v.array(v.string()),
+    excludedPartialMonth: v.union(v.string(), v.null()),
+    monthlyAverage: v.object({
+      income: v.number(),
+      expenses: v.number(),
+      balance: v.number(),
+    }),
+    projection: v.array(monthlyTrendValidator),
+  }),
+  handler: async (ctx, args) => {
+    const userId = await requireUserId(ctx);
+    const context = await buildToolTransactionContext(ctx, userId, args);
+    const summary = summarizeTransactions(context);
+    const asOfMonth = (args.asOf ?? new Date().toISOString().slice(0, 10)).slice(0, 7);
+    const baseline = summary.monthlyTrend.filter((month) => month.month < asOfMonth);
+    const excludedPartialMonth = summary.monthlyTrend.some((month) => month.month === asOfMonth)
+      ? asOfMonth
+      : null;
+    const horizonMonths = Math.max(1, Math.min(3, Math.floor(args.horizonMonths ?? 3)));
+    const denominator = baseline.length || 1;
+    const monthlyAverage = {
+      income: roundMoney(baseline.reduce((sum, month) => sum + month.income, 0) / denominator),
+      expenses: roundMoney(baseline.reduce((sum, month) => sum + month.expenses, 0) / denominator),
+      balance: roundMoney(baseline.reduce((sum, month) => sum + month.balance, 0) / denominator),
+    };
+    const projection = Array.from({ length: horizonMonths }, (_, index) => ({
+      month: addMonthsToMonthKey(asOfMonth, index + 1),
+      ...monthlyAverage,
+    }));
+
+    return {
+      from: context.from,
+      to: context.to,
+      basis: context.basis,
+      accountName: context.accountName,
+      baselineMonths: baseline.map((month) => month.month),
+      excludedPartialMonth,
+      monthlyAverage,
+      projection,
+    };
+  },
+});
+
 export const getPromptContext = internalQuery({
   args: contextArgsValidator,
   returns: v.object({
@@ -308,6 +703,117 @@ export const getPromptContext = internalQuery({
   },
 });
 
+function unknownRecord(value: unknown): Record<string, unknown> {
+  return value && typeof value === "object" && !Array.isArray(value)
+    ? (value as Record<string, unknown>)
+    : {};
+}
+
+function maybeString(value: unknown): string | undefined {
+  return typeof value === "string" && value.trim() ? value.trim() : undefined;
+}
+
+function maybeNumber(value: unknown): number | undefined {
+  return typeof value === "number" && Number.isFinite(value) ? value : undefined;
+}
+
+function summarizeToolInput(input: unknown) {
+  const record = unknownRecord(input);
+  const parts = [];
+  const from = maybeString(record.from);
+  const to = maybeString(record.to);
+  const search = maybeString(record.search);
+  const limit = maybeNumber(record.limit);
+  const horizonMonths = maybeNumber(record.horizonMonths);
+  const type = maybeString(record.type);
+  const categoryNames = Array.isArray(record.categoryNames)
+    ? record.categoryNames.filter((name): name is string => typeof name === "string")
+    : [];
+
+  if (from || to) parts.push(`${from ?? "?"} bis ${to ?? "?"}`);
+  if (search) parts.push(`Suche "${search}"`);
+  if (categoryNames.length > 0) parts.push(`Kategorien ${categoryNames.join(", ")}`);
+  if (type) parts.push(type === "income" ? "Einnahmen" : "Ausgaben");
+  if (horizonMonths) parts.push(`${horizonMonths} Monate Prognose`);
+  if (limit) parts.push(`Limit ${limit}`);
+
+  return parts.length > 0 ? parts.join(", ") : "Standard-Kontext";
+}
+
+function totalsFromOutput(output: Record<string, unknown>) {
+  const totals = unknownRecord(output.totals);
+  return {
+    count: maybeNumber(output.totalCount) ?? maybeNumber(totals.transactionCount) ?? 0,
+    balance: maybeNumber(totals.balance) ?? 0,
+  };
+}
+
+function summarizeToolOutput(toolName: string, output: unknown) {
+  const record = unknownRecord(output);
+  if (toolName === "get_transactions") {
+    const totals = totalsFromOutput(record);
+    const hasMore = record.hasMore === true;
+    return `${totals.count} Umsätze, Saldo ${formatEuro(totals.balance)}, ${
+      hasMore ? "weitere vorhanden" : "vollständig"
+    }`;
+  }
+
+  if (toolName === "summarize_spending") {
+    const totals = totalsFromOutput(record);
+    const categoryCount = Array.isArray(record.categoryBreakdown)
+      ? record.categoryBreakdown.length
+      : 0;
+    return `${totals.count} Umsätze, Saldo ${formatEuro(totals.balance)}, ${categoryCount} Kategorien`;
+  }
+
+  if (toolName === "forecast_cashflow") {
+    const projectionCount = Array.isArray(record.projection) ? record.projection.length : 0;
+    const average = unknownRecord(record.monthlyAverage);
+    const balance = maybeNumber(average.balance) ?? 0;
+    return `Prognose ${projectionCount} Monate, durchschnittlicher Saldo ${formatEuro(balance)}`;
+  }
+
+  return "Werkzeug ausgeführt";
+}
+
+export function buildToolTraceFromSteps(steps: unknown[]): ToolTrace[] {
+  const trace: ToolTrace[] = [];
+  for (const step of steps) {
+    const stepRecord = unknownRecord(step);
+    const toolResults = Array.isArray(stepRecord.toolResults) ? stepRecord.toolResults : [];
+    for (const result of toolResults) {
+      const resultRecord = unknownRecord(result);
+      const name = maybeString(resultRecord.toolName);
+      if (!name) continue;
+      trace.push({
+        name,
+        inputSummary: summarizeToolInput(resultRecord.input),
+        resultSummary: summarizeToolOutput(name, resultRecord.output),
+      });
+    }
+  }
+  return trace;
+}
+
+const transactionToolInputSchema = z.object({
+  from: z.string().optional().describe("Optionales Startdatum im Format YYYY-MM-DD."),
+  to: z.string().optional().describe("Optionales Enddatum im Format YYYY-MM-DD."),
+  accountName: z.string().optional().describe("Optionaler Kontoname, falls von der UI-Auswahl abweichend."),
+  categoryNames: z.array(z.string()).optional().describe("Optionale Kategorienamen wie Lebensmittel oder Miete."),
+  search: z.string().optional().describe("Optionaler Suchtext für Beschreibung, Gegenpartei, Konto oder Kategorie."),
+  type: z.enum(["income", "expense"]).optional().describe("Optional nur Einnahmen oder Ausgaben abrufen."),
+  limit: z.number().int().min(1).max(MAX_TOOL_ROW_LIMIT).optional().describe("Maximale Anzahl Umsatzzeilen."),
+});
+
+const summaryToolInputSchema = transactionToolInputSchema.omit({ limit: true });
+
+const forecastToolInputSchema = z.object({
+  from: z.string().optional().describe("Optionales Startdatum der historischen Basis im Format YYYY-MM-DD."),
+  to: z.string().optional().describe("Optionales Enddatum der historischen Basis im Format YYYY-MM-DD."),
+  accountName: z.string().optional().describe("Optionaler Kontoname, falls von der UI-Auswahl abweichend."),
+  horizonMonths: z.number().int().min(1).max(3).optional().describe("Anzahl der zu prognostizierenden Monate, 1 bis 3."),
+});
+
 export const ask = action({
   args: {
     messages: v.array(chatMessageValidator),
@@ -325,6 +831,7 @@ export const ask = action({
       expenses: v.number(),
       balance: v.number(),
     }),
+    toolTrace: v.array(toolTraceValidator),
   }),
   handler: async (ctx, args): Promise<ChatAskResult> => {
     if (args.messages.length === 0) {
@@ -338,26 +845,65 @@ export const ask = action({
     }
 
     await requireUserId(ctx);
-
-    const context: ChatPromptContext = await ctx.runQuery(internal.savingsChat.getPromptContext, {
+    const scope: AgentToolScope = {
       from: args.from,
       to: args.to,
       accountId: args.accountId,
       basis: args.basis,
+    };
+
+    const selectedSummary: {
+      totalCount: number;
+      totals: { income: number; expenses: number; balance: number; transactionCount: number };
+      accountName?: string;
+    } = await ctx.runQuery(internal.savingsChat.getTransactionsTool, {
+      scope,
+      limit: 1,
     });
 
     const lastMessages = args.messages
       .map((message): ChatMessage => ({ role: normalizeRole(message.role), content: message.content }))
       .slice(-MAX_CONVERSATION_MESSAGES);
 
-    const prompt = buildPrompt(context, lastMessages);
-    if (prompt.length > MAX_PROMPT_CHARACTERS) {
-      throw new Error(
-        "Der ausgewählte Zeitraum enthält zu viele Umsatzdetails für eine vollständige KI-Anfrage. Bitte Zeitraum oder Konto eingrenzen.",
-      );
-    }
+    const system = buildSystemPrompt({
+      from: args.from,
+      to: args.to,
+      basis: args.basis,
+      accountName: selectedSummary.accountName,
+    });
 
-    const system = buildSystemPrompt(context);
+    const savingsTools = {
+      get_transactions: tool({
+        description:
+          "Ruft passende Umsätze read-only ab. Nutze dieses Tool für Detailfragen, Suche nach Gegenparteien/Beschreibungen oder Belege einzelner Aussagen. Es liefert exakte Summen und nur begrenzte, sanitizte Zeilen.",
+        inputSchema: transactionToolInputSchema,
+        execute: async (input) =>
+          await ctx.runQuery(internal.savingsChat.getTransactionsTool, {
+            scope,
+            ...input,
+          }),
+      }),
+      summarize_spending: tool({
+        description:
+          "Berechnet read-only exakte Summen, Monatsverläufe, Kategorien sowie fixe und variable Ausgaben für den ausgewählten oder angegebenen Zeitraum.",
+        inputSchema: summaryToolInputSchema,
+        execute: async (input) =>
+          await ctx.runQuery(internal.savingsChat.summarizeSpendingTool, {
+            scope,
+            ...input,
+          }),
+      }),
+      forecast_cashflow: tool({
+        description:
+          "Erstellt eine deterministische Cashflow-Prognose für 1 bis 3 kommende Monate aus vollständigen historischen Monaten. Nutze es für Sparrate, Monatsüberschuss und kurzfristige Prognosen.",
+        inputSchema: forecastToolInputSchema,
+        execute: async (input) =>
+          await ctx.runQuery(internal.savingsChat.forecastCashflowTool, {
+            scope,
+            ...input,
+          }),
+      }),
+    };
 
     const envModel = process.env.SAVINGS_CHAT_MODEL?.trim();
     const candidates = [
@@ -373,17 +919,20 @@ export const ask = action({
         const result = await generateText({
           model: openai(modelName),
           system,
-          prompt,
+          messages: lastMessages,
+          tools: savingsTools,
+          stopWhen: stepCountIs(5),
         });
         return {
           model: modelName,
           answer: result.text,
-          usedTransactions: context.totals.transactionCount,
+          usedTransactions: selectedSummary.totals.transactionCount,
           usedBalance: {
-            income: context.totals.income,
-            expenses: context.totals.expenses,
-            balance: context.totals.balance,
+            income: selectedSummary.totals.income,
+            expenses: selectedSummary.totals.expenses,
+            balance: selectedSummary.totals.balance,
           },
+          toolTrace: buildToolTraceFromSteps(result.steps),
         };
       } catch (error) {
         lastError = error;
diff --git a/src/pages/SavingsChatPage.tsx b/src/pages/SavingsChatPage.tsx
index c495af0..4d15ff1 100644
--- a/src/pages/SavingsChatPage.tsx
+++ b/src/pages/SavingsChatPage.tsx
@@ -11,7 +11,18 @@ import { Separator } from "@/components/ui/separator";
 import { ChatHistory, type ChatHistoryItem } from "@/components/chat/ChatHistory";
 import { toast } from "sonner";
 
-type ChatMessage = { role: "user" | "assistant"; content: string };
+type ToolTrace = {
+  name: string;
+  inputSummary: string;
+  resultSummary: string;
+};
+type UserChatMessage = { role: "user"; content: string };
+type AssistantChatMessage = {
+  role: "assistant";
+  content: string;
+  toolTrace?: ToolTrace[];
+};
+type ChatMessage = UserChatMessage | AssistantChatMessage;
 type ChatSession = {
   id: string;
   title: string;
@@ -27,6 +38,77 @@ const initialAssistantMessage: ChatMessage = {
 };
 const fallbackMessages = [initialAssistantMessage];
 
+function normalizeToolTrace(value: unknown): ToolTrace[] | undefined {
+  if (!Array.isArray(value)) return undefined;
+  const trace = value.flatMap((item) => {
+    if (!item || typeof item !== "object") return [];
+    const candidate = item as Record<string, unknown>;
+    if (
+      typeof candidate.name !== "string" ||
+      typeof candidate.inputSummary !== "string" ||
+      typeof candidate.resultSummary !== "string"
+    ) {
+      return [];
+    }
+
+    return [
+      {
+        name: candidate.name,
+        inputSummary: candidate.inputSummary,
+        resultSummary: candidate.resultSummary,
+      },
+    ];
+  });
+
+  return trace.length > 0 ? trace : undefined;
+}
+
+function normalizeMessage(value: unknown): ChatMessage | null {
+  if (!value || typeof value !== "object") return null;
+  const candidate = value as Record<string, unknown>;
+  if (typeof candidate.content !== "string") return null;
+  if (candidate.role === "user") {
+    return { role: "user", content: candidate.content };
+  }
+  if (candidate.role === "assistant") {
+    const toolTrace = normalizeToolTrace(candidate.toolTrace);
+    return toolTrace
+      ? { role: "assistant", content: candidate.content, toolTrace }
+      : { role: "assistant", content: candidate.content };
+  }
+
+  return null;
+}
+
+function isChatMessage(value: ChatMessage | null): value is ChatMessage {
+  return value !== null;
+}
+
+function normalizeSession(value: unknown): ChatSession | null {
+  if (!value || typeof value !== "object") return null;
+  const candidate = value as Record<string, unknown>;
+  if (
+    typeof candidate.id !== "string" ||
+    typeof candidate.title !== "string" ||
+    typeof candidate.createdAt !== "number" ||
+    typeof candidate.updatedAt !== "number" ||
+    !Array.isArray(candidate.messages)
+  ) {
+    return null;
+  }
+
+  const messages = candidate.messages.map(normalizeMessage);
+  if (!messages.every(isChatMessage)) return null;
+
+  return {
+    id: candidate.id,
+    title: candidate.title,
+    createdAt: candidate.createdAt,
+    updatedAt: candidate.updatedAt,
+    messages,
+  };
+}
+
 function createSession(): ChatSession {
   const now = Date.now();
   const randomId =
@@ -47,9 +129,11 @@ function loadSessions(): ChatSession[] {
   try {
     const raw = localStorage.getItem(STORAGE_KEY);
     if (!raw) return [createSession()];
-    const parsed = JSON.parse(raw) as ChatSession[];
+    const parsed: unknown = JSON.parse(raw);
     if (!Array.isArray(parsed) || parsed.length === 0) return [createSession()];
-    return parsed;
+    const sessions = parsed.map(normalizeSession);
+    if (sessions.some((session) => session === null)) return [createSession()];
+    return sessions as ChatSession[];
   } catch {
     return [createSession()];
   }
@@ -156,16 +240,23 @@ export function SavingsChatPage() {
 
     try {
       const response = await ask({
-        messages: typedNextMessages,
+        messages: typedNextMessages.map((message) => ({
+          role: message.role,
+          content: message.content,
+        })),
         from,
         to,
         accountId,
         basis: monthBasis,
-      });
+      }) as { answer: string; toolTrace?: unknown };
 
       updateSession(submittedSessionId, [
         ...typedNextMessages,
-        { role: "assistant", content: response.answer },
+        {
+          role: "assistant",
+          content: response.answer,
+          toolTrace: normalizeToolTrace(response.toolTrace),
+        },
       ]);
     } catch (error) {
       console.error(error);
@@ -228,6 +319,21 @@ export function SavingsChatPage() {
                 >
                   <p className="text-xs uppercase text-muted-foreground">{message.role}</p>
                   <p className="whitespace-pre-wrap text-sm">{message.content}</p>
+                  {message.role === "assistant" && message.toolTrace && message.toolTrace.length > 0 && (
+                    <div className="mt-3 rounded-md border bg-muted/30 p-2">
+                      <p className="text-xs font-medium text-muted-foreground">
+                        Verwendete Werkzeuge
+                      </p>
+                      <div className="mt-2 space-y-2">
+                        {message.toolTrace.map((tool, toolIndex) => (
+                          <div key={`${tool.name}-${toolIndex}`} className="text-xs">
+                            <p className="font-medium">{tool.name}</p>
+                            <p className="text-muted-foreground">{tool.resultSummary}</p>
+                          </div>
+                        ))}
+                      </div>
+                    </div>
+                  )}
                 </div>
               ))}
               {isSubmitting && (