diff --git a/package-lock.json b/package-lock.json
index 7e94363..a1811ef 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -35,7 +35,8 @@
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@@ -1763,6 +1764,17 @@
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+      "resolved": "https://registry.npmjs.org/@types/chai/-/chai-5.2.3.tgz",
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+      "resolved": "https://registry.npmjs.org/@types/deep-eql/-/deep-eql-4.0.2.tgz",
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+      "license": "MIT"
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+      "license": "MIT",
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+        "@types/chai": "^5.2.2",
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+        "tinyrainbow": "^3.0.3"
+      },
+      "funding": {
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+    "node_modules/@vitest/mocker": {
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+      "resolved": "https://registry.npmjs.org/@vitest/mocker/-/mocker-4.0.18.tgz",
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+      "dev": true,
+      "license": "MIT",
+      "dependencies": {
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+        "estree-walker": "^3.0.3",
+        "magic-string": "^0.30.21"
+      },
+      "funding": {
+        "url": "https://opencollective.com/vitest"
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+        "vite": "^6.0.0 || ^7.0.0-0"
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+        "vite": {
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+        }
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+      "dev": true,
+      "license": "MIT",
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+      "resolved": "https://registry.npmjs.org/@vitest/snapshot/-/snapshot-4.0.18.tgz",
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+      "dev": true,
+      "license": "MIT",
+      "dependencies": {
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+        "magic-string": "^0.30.21",
+        "pathe": "^2.0.3"
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+        "url": "https://opencollective.com/vitest"
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+      "resolved": "https://registry.npmjs.org/@vitest/spy/-/spy-4.0.18.tgz",
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+      "dev": true,
+      "license": "MIT",
+      "funding": {
+        "url": "https://opencollective.com/vitest"
+      }
+    },
+    "node_modules/@vitest/utils": {
+      "version": "4.0.18",
+      "resolved": "https://registry.npmjs.org/@vitest/utils/-/utils-4.0.18.tgz",
+      "integrity": "sha512-msMRKLMVLWygpK3u2Hybgi4MNjcYJvwTb0Ru09+fOyCXIgT5raYP041DRRdiJiI3k/2U6SEbAETB3YtBrUkCFA==",
+      "dev": true,
+      "license": "MIT",
+      "dependencies": {
+        "@vitest/pretty-format": "4.0.18",
+        "tinyrainbow": "^3.0.3"
+      },
+      "funding": {
+        "url": "https://opencollective.com/vitest"
+      }
+    },
+    "node_modules/assertion-error": {
+      "version": "2.0.1",
+      "resolved": "https://registry.npmjs.org/assertion-error/-/assertion-error-2.0.1.tgz",
+      "integrity": "sha512-Izi8RQcffqCeNVgFigKli1ssklIbpHnCYc6AknXGYoB6grJqyeby7jv12JUQgmTAnIDnbck1uxksT4dzN3PWBA==",
+      "dev": true,
+      "license": "MIT",
+      "engines": {
+        "node": ">=12"
+      }
+    },
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       "resolved": "https://registry.npmjs.org/baseline-browser-mapping/-/baseline-browser-mapping-2.9.19.tgz",
@@ -1946,6 +2086,16 @@
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+    "node_modules/chai": {
+      "version": "6.2.2",
+      "resolved": "https://registry.npmjs.org/chai/-/chai-6.2.2.tgz",
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+      "dev": true,
+      "license": "MIT",
+      "engines": {
+        "node": ">=18"
+      }
+    },
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@@ -2138,6 +2288,13 @@
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+    "node_modules/es-module-lexer": {
+      "version": "1.7.0",
+      "resolved": "https://registry.npmjs.org/es-module-lexer/-/es-module-lexer-1.7.0.tgz",
+      "integrity": "sha512-jEQoCwk8hyb2AZziIOLhDqpm5+2ww5uIE6lkO/6jcOCusfk6LhMHpXXfBLXTZ7Ydyt0j4VoUQv6uGNYbdW+kBA==",
+      "dev": true,
+      "license": "MIT"
+    },
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@@ -2193,11 +2350,31 @@
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       }
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+    "node_modules/estree-walker": {
+      "version": "3.0.3",
+      "resolved": "https://registry.npmjs.org/estree-walker/-/estree-walker-3.0.3.tgz",
+      "integrity": "sha512-7RUKfXgSMMkzt6ZuXmqapOurLGPPfgj6l9uRZ7lRGolvk0y2yocc35LdcxKC5PQZdn2DMqioAQ2NoWcrTKmm6g==",
+      "dev": true,
+      "license": "MIT",
+      "dependencies": {
+        "@types/estree": "^1.0.0"
+      }
+    },
     "node_modules/eventemitter3": {
       "version": "5.0.4",
       "resolved": "https://registry.npmjs.org/eventemitter3/-/eventemitter3-5.0.4.tgz",
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     },
+    "node_modules/expect-type": {
+      "version": "1.3.0",
+      "resolved": "https://registry.npmjs.org/expect-type/-/expect-type-1.3.0.tgz",
+      "integrity": "sha512-knvyeauYhqjOYvQ66MznSMs83wmHrCycNEN6Ao+2AeYEfxUIkuiVxdEa1qlGEPK+We3n0THiDciYSsCcgW/DoA==",
+      "dev": true,
+      "license": "Apache-2.0",
+      "engines": {
+        "node": ">=12.0.0"
+      }
+    },
     "node_modules/fdir": {
       "version": "6.5.0",
       "resolved": "https://registry.npmjs.org/fdir/-/fdir-6.5.0.tgz",
@@ -2643,11 +2820,29 @@
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       "dev": true
     },
+    "node_modules/obug": {
+      "version": "2.1.1",
+      "resolved": "https://registry.npmjs.org/obug/-/obug-2.1.1.tgz",
+      "integrity": "sha512-uTqF9MuPraAQ+IsnPf366RG4cP9RtUi7MLO1N3KEc+wb0a6yKpeL0lmk2IB1jY5KHPAlTc6T/JRdC/YqxHNwkQ==",
+      "dev": true,
+      "funding": [
+        "https://github.com/sponsors/sxzz",
+        "https://opencollective.com/debug"
+      ],
+      "license": "MIT"
+    },
     "node_modules/papaparse": {
       "version": "5.5.3",
       "resolved": "https://registry.npmjs.org/papaparse/-/papaparse-5.5.3.tgz",
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     },
+    "node_modules/pathe": {
+      "version": "2.0.3",
+      "resolved": "https://registry.npmjs.org/pathe/-/pathe-2.0.3.tgz",
+      "integrity": "sha512-WUjGcAqP1gQacoQe+OBJsFA7Ld4DyXuUIjZ5cc75cLHvJ7dtNsTugphxIADwspS+AraAUePCKrSVtPLFj/F88w==",
+      "dev": true,
+      "license": "MIT"
+    },
     "node_modules/picocolors": {
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       "resolved": "https://registry.npmjs.org/picocolors/-/picocolors-1.1.1.tgz",
@@ -2920,6 +3115,13 @@
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     },
+    "node_modules/siginfo": {
+      "version": "2.0.0",
+      "resolved": "https://registry.npmjs.org/siginfo/-/siginfo-2.0.0.tgz",
+      "integrity": "sha512-ybx0WO1/8bSBLEWXZvEd7gMW3Sn3JFlW3TvX1nREbDLRNQNaeNN8WK0meBwPdAaOI7TtRRRJn/Es1zhrrCHu7g==",
+      "dev": true,
+      "license": "ISC"
+    },
     "node_modules/source-map-js": {
       "version": "1.2.1",
       "resolved": "https://registry.npmjs.org/source-map-js/-/source-map-js-1.2.1.tgz",
@@ -2929,6 +3131,20 @@
         "node": ">=0.10.0"
       }
     },
+    "node_modules/stackback": {
+      "version": "0.0.2",
+      "resolved": "https://registry.npmjs.org/stackback/-/stackback-0.0.2.tgz",
+      "integrity": "sha512-1XMJE5fQo1jGH6Y/7ebnwPOBEkIEnT4QF32d5R1+VXdXveM0IBMJt8zfaxX1P3QhVwrYe+576+jkANtSS2mBbw==",
+      "dev": true,
+      "license": "MIT"
+    },
+    "node_modules/std-env": {
+      "version": "3.10.0",
+      "resolved": "https://registry.npmjs.org/std-env/-/std-env-3.10.0.tgz",
+      "integrity": "sha512-5GS12FdOZNliM5mAOxFRg7Ir0pWz8MdpYm6AY6VPkGpbA7ZzmbzNcBJQ0GPvvyWgcY7QAhCgf9Uy89I03faLkg==",
+      "dev": true,
+      "license": "MIT"
+    },
     "node_modules/tailwindcss": {
       "version": "4.1.18",
       "resolved": "https://registry.npmjs.org/tailwindcss/-/tailwindcss-4.1.18.tgz",
@@ -2953,6 +3169,23 @@
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     },
+    "node_modules/tinybench": {
+      "version": "2.9.0",
+      "resolved": "https://registry.npmjs.org/tinybench/-/tinybench-2.9.0.tgz",
+      "integrity": "sha512-0+DUvqWMValLmha6lr4kD8iAMK1HzV0/aKnCtWb9v9641TnP/MFb7Pc2bxoxQjTXAErryXVgUOfv2YqNllqGeg==",
+      "dev": true,
+      "license": "MIT"
+    },
+    "node_modules/tinyexec": {
+      "version": "1.0.2",
+      "resolved": "https://registry.npmjs.org/tinyexec/-/tinyexec-1.0.2.tgz",
+      "integrity": "sha512-W/KYk+NFhkmsYpuHq5JykngiOCnxeVL8v8dFnqxSD8qEEdRfXk1SDM6JzNqcERbcGYj9tMrDQBYV9cjgnunFIg==",
+      "dev": true,
+      "license": "MIT",
+      "engines": {
+        "node": ">=18"
+      }
+    },
     "node_modules/tinyglobby": {
       "version": "0.2.15",
       "resolved": "https://registry.npmjs.org/tinyglobby/-/tinyglobby-0.2.15.tgz",
@@ -2969,6 +3202,16 @@
         "url": "https://github.com/sponsors/SuperchupuDev"
       }
     },
+    "node_modules/tinyrainbow": {
+      "version": "3.0.3",
+      "resolved": "https://registry.npmjs.org/tinyrainbow/-/tinyrainbow-3.0.3.tgz",
+      "integrity": "sha512-PSkbLUoxOFRzJYjjxHJt9xro7D+iilgMX/C9lawzVuYiIdcihh9DXmVibBe8lmcFrRi/VzlPjBxbN7rH24q8/Q==",
+      "dev": true,
+      "license": "MIT",
+      "engines": {
+        "node": ">=14.0.0"
+      }
+    },
     "node_modules/tslib": {
       "version": "2.8.1",
       "resolved": "https://registry.npmjs.org/tslib/-/tslib-2.8.1.tgz",
@@ -3126,6 +3369,84 @@
         }
       }
     },
+    "node_modules/vitest": {
+      "version": "4.0.18",
+      "resolved": "https://registry.npmjs.org/vitest/-/vitest-4.0.18.tgz",
+      "integrity": "sha512-hOQuK7h0FGKgBAas7v0mSAsnvrIgAvWmRFjmzpJ7SwFHH3g1k2u37JtYwOwmEKhK6ZO3v9ggDBBm0La1LCK4uQ==",
+      "dev": true,
+      "license": "MIT",
+      "dependencies": {
+        "@vitest/expect": "4.0.18",
+        "@vitest/mocker": "4.0.18",
+        "@vitest/pretty-format": "4.0.18",
+        "@vitest/runner": "4.0.18",
+        "@vitest/snapshot": "4.0.18",
+        "@vitest/spy": "4.0.18",
+        "@vitest/utils": "4.0.18",
+        "es-module-lexer": "^1.7.0",
+        "expect-type": "^1.2.2",
+        "magic-string": "^0.30.21",
+        "obug": "^2.1.1",
+        "pathe": "^2.0.3",
+        "picomatch": "^4.0.3",
+        "std-env": "^3.10.0",
+        "tinybench": "^2.9.0",
+        "tinyexec": "^1.0.2",
+        "tinyglobby": "^0.2.15",
+        "tinyrainbow": "^3.0.3",
+        "vite": "^6.0.0 || ^7.0.0",
+        "why-is-node-running": "^2.3.0"
+      },
+      "bin": {
+        "vitest": "vitest.mjs"
+      },
+      "engines": {
+        "node": "^20.0.0 || ^22.0.0 || >=24.0.0"
+      },
+      "funding": {
+        "url": "https://opencollective.com/vitest"
+      },
+      "peerDependencies": {
+        "@edge-runtime/vm": "*",
+        "@opentelemetry/api": "^1.9.0",
+        "@types/node": "^20.0.0 || ^22.0.0 || >=24.0.0",
+        "@vitest/browser-playwright": "4.0.18",
+        "@vitest/browser-preview": "4.0.18",
+        "@vitest/browser-webdriverio": "4.0.18",
+        "@vitest/ui": "4.0.18",
+        "happy-dom": "*",
+        "jsdom": "*"
+      },
+      "peerDependenciesMeta": {
+        "@edge-runtime/vm": {
+          "optional": true
+        },
+        "@opentelemetry/api": {
+          "optional": true
+        },
+        "@types/node": {
+          "optional": true
+        },
+        "@vitest/browser-playwright": {
+          "optional": true
+        },
+        "@vitest/browser-preview": {
+          "optional": true
+        },
+        "@vitest/browser-webdriverio": {
+          "optional": true
+        },
+        "@vitest/ui": {
+          "optional": true
+        },
+        "happy-dom": {
+          "optional": true
+        },
+        "jsdom": {
+          "optional": true
+        }
+      }
+    },
     "node_modules/void-elements": {
       "version": "3.1.0",
       "resolved": "https://registry.npmjs.org/void-elements/-/void-elements-3.1.0.tgz",
@@ -3134,6 +3455,23 @@
         "node": ">=0.10.0"
       }
     },
+    "node_modules/why-is-node-running": {
+      "version": "2.3.0",
+      "resolved": "https://registry.npmjs.org/why-is-node-running/-/why-is-node-running-2.3.0.tgz",
+      "integrity": "sha512-hUrmaWBdVDcxvYqnyh09zunKzROWjbZTiNy8dBEjkS7ehEDQibXJ7XvlmtbwuTclUiIyN+CyXQD4Vmko8fNm8w==",
+      "dev": true,
+      "license": "MIT",
+      "dependencies": {
+        "siginfo": "^2.0.0",
+        "stackback": "0.0.2"
+      },
+      "bin": {
+        "why-is-node-running": "cli.js"
+      },
+      "engines": {
+        "node": ">=8"
+      }
+    },
     "node_modules/yallist": {
       "version": "3.1.1",
       "resolved": "https://registry.npmjs.org/yallist/-/yallist-3.1.1.tgz",
diff --git a/package.json b/package.json
index f337c2d..f02b823 100644
--- a/package.json
+++ b/package.json
@@ -8,7 +8,9 @@
     "dev": "vite",
     "build": "tsc && vite build",
     "preview": "vite preview",
-    "tauri": "tauri"
+    "tauri": "tauri",
+    "test": "vitest run",
+    "test:watch": "vitest"
   },
   "dependencies": {
     "@dnd-kit/core": "^6.3.1",
@@ -37,6 +39,7 @@
     "@vitejs/plugin-react": "^4.7.0",
     "tailwindcss": "^4.1.18",
     "typescript": "~5.8.3",
-    "vite": "^6.4.1"
+    "vite": "^6.4.1",
+    "vitest": "^4.0.18"
   }
 }
diff --git a/src/utils/dateRange.test.ts b/src/utils/dateRange.test.ts
new file mode 100644
index 0000000..2c2ccfb
--- /dev/null
+++ b/src/utils/dateRange.test.ts
@@ -0,0 +1,123 @@
+import { describe, it, expect, vi, beforeEach, afterEach } from "vitest";
+import { computeDateRange, buildMonthOptions } from "./dateRange";
+
+describe("computeDateRange", () => {
+  beforeEach(() => {
+    // Fix "now" to 2025-07-15 for deterministic tests
+    vi.useFakeTimers();
+    vi.setSystemTime(new Date(2025, 6, 15)); // July 15, 2025
+  });
+
+  afterEach(() => {
+    vi.useRealTimers();
+  });
+
+  it('returns empty object for "all" period', () => {
+    expect(computeDateRange("all")).toEqual({});
+  });
+
+  it('returns custom range for "custom" period', () => {
+    expect(computeDateRange("custom", "2025-01-01", "2025-06-30")).toEqual({
+      dateFrom: "2025-01-01",
+      dateTo: "2025-06-30",
+    });
+  });
+
+  it('falls back to default when "custom" has missing dates', () => {
+    const result = computeDateRange("custom");
+    // Should fall through to default (same as "month")
+    expect(result.dateFrom).toBe("2025-07-01");
+    expect(result.dateTo).toBe("2025-07-15");
+  });
+
+  it('computes "month" period (first of current month to today)', () => {
+    const result = computeDateRange("month");
+    expect(result).toEqual({ dateFrom: "2025-07-01", dateTo: "2025-07-15" });
+  });
+
+  it('computes "3months" period (3 months back)', () => {
+    const result = computeDateRange("3months");
+    expect(result).toEqual({ dateFrom: "2025-05-01", dateTo: "2025-07-15" });
+  });
+
+  it('computes "6months" period (6 months back)', () => {
+    const result = computeDateRange("6months");
+    expect(result).toEqual({ dateFrom: "2025-02-01", dateTo: "2025-07-15" });
+  });
+
+  it('computes "year" period (Jan 1st of current year)', () => {
+    const result = computeDateRange("year");
+    expect(result).toEqual({ dateFrom: "2025-01-01", dateTo: "2025-07-15" });
+  });
+
+  it('computes "12months" period (12 months back)', () => {
+    const result = computeDateRange("12months");
+    expect(result).toEqual({ dateFrom: "2024-08-01", dateTo: "2025-07-15" });
+  });
+
+  it("handles January rollover for 3months period", () => {
+    vi.setSystemTime(new Date(2025, 1, 10)); // Feb 10, 2025
+    const result = computeDateRange("3months");
+    expect(result).toEqual({ dateFrom: "2024-12-01", dateTo: "2025-02-10" });
+  });
+
+  it("handles January rollover for 6months period", () => {
+    vi.setSystemTime(new Date(2025, 0, 20)); // Jan 20, 2025
+    const result = computeDateRange("6months");
+    expect(result).toEqual({ dateFrom: "2024-08-01", dateTo: "2025-01-20" });
+  });
+
+  it("handles January rollover for 12months period", () => {
+    vi.setSystemTime(new Date(2025, 0, 5)); // Jan 5, 2025
+    const result = computeDateRange("12months");
+    expect(result).toEqual({ dateFrom: "2024-02-01", dateTo: "2025-01-05" });
+  });
+});
+
+describe("buildMonthOptions", () => {
+  beforeEach(() => {
+    vi.useFakeTimers();
+    vi.setSystemTime(new Date(2025, 6, 15)); // July 15, 2025
+  });
+
+  afterEach(() => {
+    vi.useRealTimers();
+  });
+
+  it("returns 24 month options", () => {
+    const options = buildMonthOptions("fr");
+    expect(options).toHaveLength(24);
+  });
+
+  it("starts with the current month", () => {
+    const options = buildMonthOptions("en");
+    expect(options[0].key).toBe("2025-7");
+    expect(options[0].value).toBe("2025-7");
+  });
+
+  it("ends 23 months ago", () => {
+    const options = buildMonthOptions("en");
+    expect(options[23].key).toBe("2023-8");
+    expect(options[23].value).toBe("2023-8");
+  });
+
+  it("handles January rollover correctly", () => {
+    vi.setSystemTime(new Date(2025, 0, 15)); // Jan 15, 2025
+    const options = buildMonthOptions("en");
+    expect(options[0].key).toBe("2025-1");
+    expect(options[1].key).toBe("2024-12");
+    expect(options[12].key).toBe("2024-1");
+  });
+
+  it("capitalizes the first letter of labels", () => {
+    const options = buildMonthOptions("fr");
+    for (const opt of options) {
+      expect(opt.label[0]).toBe(opt.label[0].toUpperCase());
+    }
+  });
+
+  it("labels contain year information", () => {
+    const options = buildMonthOptions("en");
+    expect(options[0].label).toContain("2025");
+  });
+});