diff --git a/.gitignore b/.gitignore
index 65e8404..3665038 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,5 +1,6 @@
 node_modules/
 dist/
+coverage/
 *.tgz
 *.log
 .DS_Store
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 418bb12..4f091d3 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,13 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Fixed
+- `toHijriDate` and all field getters now produce exact round-trips on every host timezone (input Date interpreted by its local calendar day, matching date-fns conventions; previously used raw Date which failed in timezones west of UTC against hijri-core's UTC-day contract).
+
+### Changed
+- `fromHijriDate` and all arithmetic/boundary helpers (`addHijriMonths`, `addHijriYears`, `startOfHijriMonth`, `endOfHijriMonth`) now return **local-midnight** Dates instead of UTC midnight / local noon. Use `getFullYear()`/`getMonth()`/`getDate()` (or date-fns `format()`) on the result — not `toISOString()`.
+- Lock-step with unreleased hijri-core `fix/utc-day-boundary` (UTC-day contract).
+
 ## [1.0.2] - 2026-05-30
 
 ### Changed
diff --git a/README.md b/README.md
index b19d682..a338b6b 100644
--- a/README.md
+++ b/README.md
@@ -51,6 +51,31 @@ Full API reference, guides, and examples: **[Wiki](https://github.com/acamarata/
 - [Architecture](https://github.com/acamarata/date-fns-hijri/wiki/Architecture): design decisions and hijri-core integration
 - [Quick Start](https://github.com/acamarata/date-fns-hijri/wiki/guides/quickstart)
 
+## Day boundaries and time zones
+
+This package follows date-fns local-time conventions:
+
+- **Inputs** (`toHijriDate`, `getHijri*`, `formatHijriDate`, arithmetic, comparisons) — the input `Date` is read by its **local calendar day** (using `getFullYear`/`getMonth`/`getDate`). This matches how date-fns' own `format()` and field accessors work.
+- **Outputs** (`fromHijriDate` and all arithmetic/boundary functions) — returned `Date` values are **local midnight** of the equivalent Gregorian day. Local field accessors and date-fns' `format()` will render the intended date on every timezone.
+
+Round-trips are exact on every host timezone:
+
+```typescript
+toHijriDate(fromHijriDate(1446, 9, 1)); // always { hy: 1446, hm: 9, hd: 1 }
+```
+
+**Pitfall:** `new Date("2025-03-01")` parses as UTC midnight. In timezones west of UTC this resolves to the previous local day (Feb 28), giving an off-by-one result. Use the local-date constructor instead:
+
+```typescript
+// Wrong in timezones west of UTC:
+toHijriDate(new Date("2025-03-01")); // may return 29 Shaban in some zones
+
+// Correct everywhere:
+toHijriDate(new Date(2025, 2, 1)); // always 1 Ramadan 1446
+```
+
+Religious day-start (sunset boundary) is out of scope — this package only handles civil calendar day alignment.
+
 ## Related
 
 - [hijri-core](https://github.com/acamarata/hijri-core): the calendar engine powering this library
diff --git a/date-fns-hijri.test.ts b/date-fns-hijri.test.ts
new file mode 100644
index 0000000..ce7d6b5
--- /dev/null
+++ b/date-fns-hijri.test.ts
@@ -0,0 +1,126 @@
+/**
+ * Purpose:    Vitest suite for date-fns-hijri — functional Hijri date utilities.
+ * Inputs:     Pure functions from src/index.ts wrapping hijri-core. No network, no I/O.
+ * Outputs:    Vitest pass/fail assertions.
+ * Constraints: UAQ range 1318–1500 AH; fromHijriDate throws on invalid input (null path).
+ *             Use local-date constructor new Date(y, m, d) — not string "YYYY-MM-DD" which
+ *             parses as UTC midnight and can be the previous LOCAL day west of UTC.
+ * Usage:      pnpm vitest run
+ * SOT:        packages.md — date-fns-hijri row
+ */
+import { describe, it, expect } from "vitest";
+import {
+  toHijriDate,
+  fromHijriDate,
+  isValidHijriDate,
+  getHijriYear,
+  getHijriMonth,
+  getHijriDay,
+  getDaysInHijriMonth,
+  getHijriMonthName,
+  getHijriWeekdayName,
+} from "./src/index";
+
+// Anchor: 1 Ramadan 1446 = 2025-03-01 in the Gregorian calendar.
+// Use local-date constructor to avoid the UTC-parsing pitfall with string form.
+// At local noon the local calendar day is unambiguous on every timezone.
+const RAMADAN_1446_NOON = new Date(2025, 2, 1, 12); // local noon 2025-03-01
+
+describe("toHijriDate", () => {
+  it("converts noon 2025-03-01 UTC to 1 Ramadan 1446", () => {
+    const result = toHijriDate(RAMADAN_1446_NOON);
+    expect(result).not.toBeNull();
+    expect(result!.hy).toBe(1446);
+    expect(result!.hm).toBe(9);
+    expect(result!.hd).toBe(1);
+  });
+
+  it("returns null for dates outside UAQ range (2100)", () => {
+    expect(toHijriDate(new Date("2100-01-01"))).toBeNull();
+  });
+});
+
+describe("fromHijriDate", () => {
+  it("converts 1 Ramadan 1446 to local 2025-03-01 (via local accessors)", () => {
+    const result = fromHijriDate(1446, 9, 1);
+    // Returns local midnight: local accessors show the intended calendar day
+    // on every host timezone. Do NOT use toISOString() — it shows UTC which
+    // will be the previous day in timezones west of UTC.
+    expect(result.getFullYear()).toBe(2025);
+    expect(result.getMonth()).toBe(2); // March
+    expect(result.getDate()).toBe(1);
+  });
+
+  it("round-trip: toHijriDate(fromHijriDate(1446, 9, 1)) === {1446, 9, 1}", () => {
+    const d = fromHijriDate(1446, 9, 1);
+    const h = toHijriDate(d);
+    expect(h).not.toBeNull();
+    expect(h!.hy).toBe(1446);
+    expect(h!.hm).toBe(9);
+    expect(h!.hd).toBe(1);
+  });
+
+  it("throws on an out-of-range Hijri year (1501)", () => {
+    expect(() => fromHijriDate(1501, 1, 1)).toThrow();
+  });
+});
+
+describe("isValidHijriDate", () => {
+  it("returns true for 1 Ramadan 1446", () => {
+    expect(isValidHijriDate(1446, 9, 1)).toBe(true);
+  });
+
+  it("returns false for month 13", () => {
+    expect(isValidHijriDate(1446, 13, 1)).toBe(false);
+  });
+});
+
+describe("field getters", () => {
+  it("getHijriYear returns 1446 for noon 2025-03-01", () => {
+    expect(getHijriYear(RAMADAN_1446_NOON)).toBe(1446);
+  });
+
+  it("getHijriMonth returns 9 for Ramadan", () => {
+    expect(getHijriMonth(RAMADAN_1446_NOON)).toBe(9);
+  });
+
+  it("getHijriDay returns 1", () => {
+    expect(getHijriDay(RAMADAN_1446_NOON)).toBe(1);
+  });
+});
+
+describe("getDaysInHijriMonth", () => {
+  it("returns 29 or 30 for Ramadan 1446", () => {
+    const days = getDaysInHijriMonth(1446, 9);
+    expect([29, 30]).toContain(days);
+  });
+});
+
+describe("getHijriMonthName", () => {
+  it("returns Ramadan for month 9 (long)", () => {
+    expect(getHijriMonthName(9, "long")).toBe("Ramadan");
+  });
+
+  it("throws RangeError for month 0", () => {
+    expect(() => getHijriMonthName(0)).toThrow(RangeError);
+  });
+
+  it("returns a non-empty medium name for month 1", () => {
+    const name = getHijriMonthName(1, "medium");
+    expect(name.length).toBeGreaterThan(0);
+  });
+});
+
+describe("getHijriWeekdayName", () => {
+  it("returns a non-empty long weekday name for 2025-03-01 (Saturday)", () => {
+    const name = getHijriWeekdayName(RAMADAN_1446_NOON, "long");
+    expect(typeof name).toBe("string");
+    expect(name.length).toBeGreaterThan(0);
+  });
+
+  it("short name is no longer than long name for the same date", () => {
+    const long = getHijriWeekdayName(RAMADAN_1446_NOON, "long");
+    const short = getHijriWeekdayName(RAMADAN_1446_NOON, "short");
+    expect(short.length).toBeLessThanOrEqual(long.length);
+  });
+});
diff --git a/package.json b/package.json
index eb4b9e5..6e4dc64 100644
--- a/package.json
+++ b/package.json
@@ -40,7 +40,8 @@
     "prepublishOnly": "pnpm run build",
     "coverage": "c8 --reporter=lcov --reporter=text node test.mjs",
     "docs": "typedoc --out .github/wiki/api src/index.ts",
-    "postbuild": "cp dist/index.d.ts dist/index.d.mts"
+    "postbuild": "cp dist/index.d.ts dist/index.d.mts",
+    "test:vitest": "vitest run"
   },
   "keywords": [
     "date-fns",
@@ -74,7 +75,8 @@
     "typedoc": "^0.28.19",
     "typedoc-plugin-markdown": "^4.11.0",
     "typescript": "^5.5.0",
-    "typescript-eslint": "^8.56.1"
+    "typescript-eslint": "^8.56.1",
+    "vitest": "^2.1.9"
   },
   "publishConfig": {
     "access": "public",
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index a9c10ed..5e2163a 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -46,7 +46,7 @@ importers:
         version: 3.8.1
       tsup:
         specifier: ^8.0.0
-        version: 8.5.1(typescript@5.9.3)(yaml@2.9.0)
+        version: 8.5.1(postcss@8.5.15)(typescript@5.9.3)(yaml@2.9.0)
       typedoc:
         specifier: ^0.28.19
         version: 0.28.19(typescript@5.9.3)
@@ -59,6 +59,9 @@ importers:
       typescript-eslint:
         specifier: ^8.56.1
         version: 8.56.1(eslint@10.0.3)(typescript@5.9.3)
+      vitest:
+        specifier: ^2.1.9
+        version: 2.1.9(@types/node@25.3.5)
 
 packages:
 
@@ -92,102 +95,204 @@ packages:
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+    engines: {node: '>=12'}
+    cpu: [ppc64]
+    os: [aix]
+
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@@ -200,6 +305,12 @@ packages:
     cpu: [arm64]
     os: [netbsd]
 
+  '@esbuild/netbsd-x64@0.21.5':
+    resolution: {integrity: sha512-Woi2MXzXjMULccIwMnLciyZH4nCIMpWQAs049KEeMvOcNADVxo0UBIQPfSmxB3CWKedngg7sWZdLvLczpe0tLg==}
+    engines: {node: '>=12'}
+    cpu: [x64]
+    os: [netbsd]
+
   '@esbuild/netbsd-x64@0.27.3':
     resolution: {integrity: sha512-P14lFKJl/DdaE00LItAukUdZO5iqNH7+PjoBm+fLQjtxfcfFE20Xf5CrLsmZdq5LFFZzb5JMZ9grUwvtVYzjiA==}
     engines: {node: '>=18'}
@@ -212,6 +323,12 @@ packages:
     cpu: [arm64]
     os: [openbsd]
 
+  '@esbuild/openbsd-x64@0.21.5':
+    resolution: {integrity: sha512-HLNNw99xsvx12lFBUwoT8EVCsSvRNDVxNpjZ7bPn947b8gJPzeHWyNVhFsaerc0n3TsbOINvRP2byTZ5LKezow==}
+    engines: {node: '>=12'}
+    cpu: [x64]
+    os: [openbsd]
+
   '@esbuild/openbsd-x64@0.27.3':
     resolution: {integrity: sha512-DnW2sRrBzA+YnE70LKqnM3P+z8vehfJWHXECbwBmH/CU51z6FiqTQTHFenPlHmo3a8UgpLyH3PT+87OViOh1AQ==}
     engines: {node: '>=18'}
@@ -224,24 +341,48 @@ packages:
     cpu: [arm64]
     os: [openharmony]
 
+  '@esbuild/sunos-x64@0.21.5':
+    resolution: {integrity: sha512-6+gjmFpfy0BHU5Tpptkuh8+uw3mnrvgs+dSPQXQOv3ekbordwnzTVEb4qnIvQcYXq6gzkyTnoZ9dZG+D4garKg==}
+    engines: {node: '>=12'}
+    cpu: [x64]
+    os: [sunos]
+
   '@esbuild/sunos-x64@0.27.3':
     resolution: {integrity: sha512-PanZ+nEz+eWoBJ8/f8HKxTTD172SKwdXebZ0ndd953gt1HRBbhMsaNqjTyYLGLPdoWHy4zLU7bDVJztF5f3BHA==}
     engines: {node: '>=18'}
     cpu: [x64]
     os: [sunos]
 
+  '@esbuild/win32-arm64@0.21.5':
+    resolution: {integrity: sha512-Z0gOTd75VvXqyq7nsl93zwahcTROgqvuAcYDUr+vOv8uHhNSKROyU961kgtCD1e95IqPKSQKH7tBTslnS3tA8A==}
+    engines: {node: '>=12'}
+    cpu: [arm64]
+    os: [win32]
+
   '@esbuild/win32-arm64@0.27.3':
     resolution: {integrity: sha512-B2t59lWWYrbRDw/tjiWOuzSsFh1Y/E95ofKz7rIVYSQkUYBjfSgf6oeYPNWHToFRr2zx52JKApIcAS/D5TUBnA==}
     engines: {node: '>=18'}
     cpu: [arm64]
     os: [win32]
 
+  '@esbuild/win32-ia32@0.21.5':
+    resolution: {integrity: sha512-SWXFF1CL2RVNMaVs+BBClwtfZSvDgtL//G/smwAc5oVK/UPu2Gu9tIaRgFmYFFKrmg3SyAjSrElf0TiJ1v8fYA==}
+    engines: {node: '>=12'}
+    cpu: [ia32]
+    os: [win32]
+
   '@esbuild/win32-ia32@0.27.3':
     resolution: {integrity: sha512-QLKSFeXNS8+tHW7tZpMtjlNb7HKau0QDpwm49u0vUp9y1WOF+PEzkU84y9GqYaAVW8aH8f3GcBck26jh54cX4Q==}
     engines: {node: '>=18'}
     cpu: [ia32]
     os: [win32]
 
+  '@esbuild/win32-x64@0.21.5':
+    resolution: {integrity: sha512-tQd/1efJuzPC6rCFwEvLtci/xNFcTZknmXs98FYDfGE4wP9ClFV98nyKrzJKVPMhdDnjzLhdUyMX4PsQAPjwIw==}
+    engines: {node: '>=12'}
+    cpu: [x64]
+    os: [win32]
+
   '@esbuild/win32-x64@0.27.3':
     resolution: {integrity: sha512-4uJGhsxuptu3OcpVAzli+/gWusVGwZZHTlS63hh++ehExkVT8SgiEf7/uC/PclrPPkLhZqGgCTjd0VWLo6xMqA==}
     engines: {node: '>=18'}
@@ -564,6 +705,35 @@ packages:
     resolution: {integrity: sha512-KiROIzYdEV85YygXw6BI/Dx4fnBlFQu6Mq4QE4MOH9fFnhohw6wX/OAvDY2/C+ut0I3RSPKenvZJIVYqJNkhEw==}
     engines: {node: ^18.18.0 || ^20.9.0 || >=21.1.0}
 
+  '@vitest/expect@2.1.9':
+    resolution: {integrity: sha512-UJCIkTBenHeKT1TTlKMJWy1laZewsRIzYighyYiJKZreqtdxSos/S1t+ktRMQWu2CKqaarrkeszJx1cgC5tGZw==}
+
+  '@vitest/mocker@2.1.9':
+    resolution: {integrity: sha512-tVL6uJgoUdi6icpxmdrn5YNo3g3Dxv+IHJBr0GXHaEdTcw3F+cPKnsXFhli6nO+f/6SDKPHEK1UN+k+TQv0Ehg==}
+    peerDependencies:
+      msw: ^2.4.9
+      vite: ^5.0.0
+    peerDependenciesMeta:
+      msw:
+        optional: true
+      vite:
+        optional: true
+
+  '@vitest/pretty-format@2.1.9':
+    resolution: {integrity: sha512-KhRIdGV2U9HOUzxfiHmY8IFHTdqtOhIzCpd8WRdJiE7D/HUcZVD0EgQCVjm+Q9gkUXWgBvMmTtZgIG48wq7sOQ==}
+
+  '@vitest/runner@2.1.9':
+    resolution: {integrity: sha512-ZXSSqTFIrzduD63btIfEyOmNcBmQvgOVsPNPe0jYtESiXkhd8u2erDLnMxmGrDCwHCCHE7hxwRDCT3pt0esT4g==}
+
+  '@vitest/snapshot@2.1.9':
+    resolution: {integrity: sha512-oBO82rEjsxLNJincVhLhaxxZdEtV0EFHMK5Kmx5sJ6H9L183dHECjiefOAdnqpIgT5eZwT04PoggUnW88vOBNQ==}
+
+  '@vitest/spy@2.1.9':
+    resolution: {integrity: sha512-E1B35FwzXXTs9FHNK6bDszs7mtydNi5MIfUWpceJ8Xbfb1gBMscAnwLbEu+B44ed6W3XjL9/ehLPHR1fkf1KLQ==}
+
+  '@vitest/utils@2.1.9':
+    resolution: {integrity: sha512-v0psaMSkNJ3A2NMrUEHFRzJtDPFn+/VWZ5WxImB21T9fjucJRmS7xCS3ppEnARb9y11OAzaD+P2Ps+b+BGX5iQ==}
+
   acorn-jsx@5.3.2:
     resolution: {integrity: sha512-rq9s+JNhf0IChjtDXxllJ7g41oZk5SlXtp0LHwyA5cejwn7vKmKp4pPri6YEePv2PU65sAsegbXtIinmDFDXgQ==}
     peerDependencies:
@@ -599,6 +769,10 @@ packages:
   argparse@2.0.1:
     resolution: {integrity: sha512-8+9WqebbFzpX9OR+Wa6O29asIogeRMzcGtAINdpMHHyAg10f05aSFVBbcEqGf/PXw1EjAZ+q2/bEBg3DvurK3Q==}
 
+  assertion-error@2.0.1:
+    resolution: {integrity: sha512-Izi8RQcffqCeNVgFigKli1ssklIbpHnCYc6AknXGYoB6grJqyeby7jv12JUQgmTAnIDnbck1uxksT4dzN3PWBA==}
+    engines: {node: '>=12'}
+
   balanced-match@1.0.2:
     resolution: {integrity: sha512-3oSeUO0TMV67hN1AmbXsK4yaqU7tjiHlbxRDZOpH0KW9+CeX4bRAaX0Anxt0tx2MrpRpWwQaPwIlISEJhYU5Pw==}
 
@@ -637,6 +811,14 @@ packages:
     resolution: {integrity: sha512-b6Ilus+c3RrdDk+JhLKUAQfzzgLEPy6wcXqS7f/xe1EETvsDP6GORG7SFuOs6cID5YkqchW/LXZbX5bc8j7ZcQ==}
     engines: {node: '>=8'}
 
+  chai@5.3.3:
+    resolution: {integrity: sha512-4zNhdJD/iOjSH0A05ea+Ke6MU5mmpQcbQsSOkgdaUMJ9zTlDTD/GYlwohmIE2u0gaxHYiVHEn1Fw9mZ/ktJWgw==}
+    engines: {node: '>=18'}
+
+  check-error@2.1.3:
+    resolution: {integrity: sha512-PAJdDJusoxnwm1VwW07VWwUN1sl7smmC3OKggvndJFadxxDRyFJBX/ggnu/KE4kQAB7a3Dp8f/YXC1FlUprWmA==}
+    engines: {node: '>= 16'}
+
   chokidar@4.0.3:
     resolution: {integrity: sha512-Qgzu8kfBvo+cA4962jnP1KkS6Dop5NS6g7R5LFYJr4b8Ub94PPQXUksCw9PvXoeXPRRddRNC5C1JQUR2SMGtnA==}
     engines: {node: '>= 14.16.0'}
@@ -679,6 +861,10 @@ packages:
       supports-color:
         optional: true
 
+  deep-eql@5.0.2:
+    resolution: {integrity: sha512-h5k/5U50IJJFpzfL6nO9jaaumfjO/f2NjK/oYB2Djzm4p9L+3T9qWpZqZ2hAbLPuuYq9wrU08WQyBTL5GbPk5Q==}
+    engines: {node: '>=6'}
+
   deep-is@0.1.4:
     resolution: {integrity: sha512-oIPzksmTg4/MriiaYGO+okXDT7ztn/w3Eptv/+gSIdMdKsJo0u4CfYNFJPy+4SKMuCqGw2wxnA+URMg3t8a/bQ==}
 
@@ -695,6 +881,14 @@ packages:
     resolution: {integrity: sha512-V0hjH4dGPh9Ao5p0MoRY6BVqtwCjhz6vI5LT8AJ55H+4g9/4vbHx1I54fS0XuclLhDHArPQCiMjDxjaL8fPxhw==}
     engines: {node: '>=0.12'}
 
+  es-module-lexer@1.7.0:
+    resolution: {integrity: sha512-jEQoCwk8hyb2AZziIOLhDqpm5+2ww5uIE6lkO/6jcOCusfk6LhMHpXXfBLXTZ7Ydyt0j4VoUQv6uGNYbdW+kBA==}
+
+  esbuild@0.21.5:
+    resolution: {integrity: sha512-mg3OPMV4hXywwpoDxu3Qda5xCKQi+vCTZq8S9J/EpkhB2HzKXq4SNFZE3+NK93JYxc8VMSep+lOUSC/RVKaBqw==}
+    engines: {node: '>=12'}
+    hasBin: true
+
   esbuild@0.27.3:
     resolution: {integrity: sha512-8VwMnyGCONIs6cWue2IdpHxHnAjzxnw2Zr7MkVxB2vjmQ2ivqGFb4LEG3SMnv0Gb2F/G/2yA8zUaiL1gywDCCg==}
     engines: {node: '>=18'}
@@ -752,10 +946,17 @@ packages:
     resolution: {integrity: sha512-MMdARuVEQziNTeJD8DgMqmhwR11BRQ/cBP+pLtYdSTnf3MIO8fFeiINEbX36ZdNlfU/7A9f3gUw49B3oQsvwBA==}
     engines: {node: '>=4.0'}
 
+  estree-walker@3.0.3:
+    resolution: {integrity: sha512-7RUKfXgSMMkzt6ZuXmqapOurLGPPfgj6l9uRZ7lRGolvk0y2yocc35LdcxKC5PQZdn2DMqioAQ2NoWcrTKmm6g==}
+
   esutils@2.0.3:
     resolution: {integrity: sha512-kVscqXk4OCp68SZ0dkgEKVi6/8ij300KBWTJq32P/dYeWTSwK41WyTxalN1eRmA5Z9UU/LX9D7FWSmV9SAYx6g==}
     engines: {node: '>=0.10.0'}
 
+  expect-type@1.3.0:
+    resolution: {integrity: sha512-knvyeauYhqjOYvQ66MznSMs83wmHrCycNEN6Ao+2AeYEfxUIkuiVxdEa1qlGEPK+We3n0THiDciYSsCcgW/DoA==}
+    engines: {node: '>=12.0.0'}
+
   fast-deep-equal@3.1.3:
     resolution: {integrity: sha512-f3qQ9oQy9j2AhBe/H9VC91wLmKBCCU/gDOnKNAYG5hswO7BLKj09Hc5HYNz9cGI++xlpDCIgDaitVs03ATR84Q==}
 
@@ -905,6 +1106,9 @@ packages:
     resolution: {integrity: sha512-iPZK6eYjbxRu3uB4/WZ3EsEIMJFMqAoopl3R+zuq0UjcAm/MO6KCweDgPfP3elTztoKP3KtnVHxTn2NHBSDVUw==}
     engines: {node: '>=10'}
 
+  loupe@3.2.1:
+    resolution: {integrity: sha512-CdzqowRJCeLU72bHvWqwRBBlLcMEtIvGrlvef74kMnV2AolS9Y8xUv1I0U/MNAWMhBlKIoyuEgoJ0t/bbwHbLQ==}
+
   lru-cache@10.4.3:
     resolution: {integrity: sha512-JNAzZcXrCt42VGLuYz0zfAzDfAvJWW6AfYlDBQyDV5DClI2m5sAmK+OIO7s59XfsRsWHp02jAJrRadPRGTt6SQ==}
 
@@ -950,6 +1154,11 @@ packages:
   mz@2.7.0:
     resolution: {integrity: sha512-z81GNO7nnYMEhrGh9LeymoE4+Yr0Wn5McHIZMK5cfQCl+NDX08sCZgUc9/6MHni9IWuFLm1Z3HTCXu2z9fN62Q==}
 
+  nanoid@3.3.12:
+    resolution: {integrity: sha512-ZB9RH/39qpq5Vu6Y+NmUaFhQR6pp+M2Xt76XBnEwDaGcVAqhlvxrl3B2bKS5D3NH3QR76v3aSrKaF/Kiy7lEtQ==}
+    engines: {node: ^10 || ^12 || ^13.7 || ^14 || >=15.0.1}
+    hasBin: true
+
   natural-compare@1.4.0:
     resolution: {integrity: sha512-OWND8ei3VtNC9h7V60qff3SVobHr996CTwgxubgyQYEpg290h9J0buyECNNJexkFm5sOajh5G116RYA1c8ZMSw==}
 
@@ -984,9 +1193,16 @@ packages:
     resolution: {integrity: sha512-Xa4Nw17FS9ApQFJ9umLiJS4orGjm7ZzwUrwamcGQuHSzDyth9boKDaycYdDcZDuqYATXw4HFXgaqWTctW/v1HA==}
     engines: {node: '>=16 || 14 >=14.18'}
 
+  pathe@1.1.2:
+    resolution: {integrity: sha512-whLdWMYL2TwI08hn8/ZqAbrVemu0LNaNNJZX73O6qaIdCTfXutsLhMkjdENX0qhsQ9uIimo4/aQOmXkoon2nDQ==}
+
   pathe@2.0.3:
     resolution: {integrity: sha512-WUjGcAqP1gQacoQe+OBJsFA7Ld4DyXuUIjZ5cc75cLHvJ7dtNsTugphxIADwspS+AraAUePCKrSVtPLFj/F88w==}
 
+  pathval@2.0.1:
+    resolution: {integrity: sha512-//nshmD55c46FuFw26xV/xFAaB5HF9Xdap7HJBBnrKdAd6/GxDBaNA1870O79+9ueg61cZLSVc+OaFlfmObYVQ==}
+    engines: {node: '>= 14.16'}
+
   picocolors@1.1.1:
     resolution: {integrity: sha512-xceH2snhtb5M9liqDsmEw56le376mTZkEX/jEb/RxNFyegNul7eNslCXP9FDj/Lcu0X8KEyMceP2ntpaHrDEVA==}
 
@@ -1019,6 +1235,10 @@ packages:
       yaml:
         optional: true
 
+  postcss@8.5.15:
+    resolution: {integrity: sha512-FfR8sjd4em2T6fb3I2MwAJU7HWVMr9zba+enmQeeWFfCbm+UOC/0X4DS8XtpUTMwWMGbjKYP7xjfNekzyGmB3A==}
+    engines: {node: ^10 || ^12 || >=14}
+
   prelude-ls@1.2.1:
     resolution: {integrity: sha512-vkcDPrRZo1QZLbn5RLGPpg/WmIQ65qoWWhcGKf/b5eplkkarX0m9z8ppCat4mlOqUsWpyNuYgO3VRyrYHSzX5g==}
     engines: {node: '>= 0.8.0'}
@@ -1066,14 +1286,27 @@ packages:
     resolution: {integrity: sha512-7++dFhtcx3353uBaq8DDR4NuxBetBzC7ZQOhmTQInHEd6bSrXdiEyzCvG07Z44UYdLShWUyXt5M/yhz8ekcb1A==}
     engines: {node: '>=8'}
 
+  siginfo@2.0.0:
+    resolution: {integrity: sha512-ybx0WO1/8bSBLEWXZvEd7gMW3Sn3JFlW3TvX1nREbDLRNQNaeNN8WK0meBwPdAaOI7TtRRRJn/Es1zhrrCHu7g==}
+
   signal-exit@4.1.0:
     resolution: {integrity: sha512-bzyZ1e88w9O1iNJbKnOlvYTrWPDl46O1bG0D3XInv+9tkPrxrN8jUUTiFlDkkmKWgn1M6CfIA13SuGqOa9Korw==}
     engines: {node: '>=14'}
 
+  source-map-js@1.2.1:
+    resolution: {integrity: sha512-UXWMKhLOwVKb728IUtQPXxfYU+usdybtUrK/8uGE8CQMvrhOpwvzDBwj0QhSL7MQc7vIsISBG8VQ8+IDQxpfQA==}
+    engines: {node: '>=0.10.0'}
+
   source-map@0.7.6:
     resolution: {integrity: sha512-i5uvt8C3ikiWeNZSVZNWcfZPItFQOsYTUAOkcUPGd8DqDy1uOUikjt5dG+uRlwyvR108Fb9DOd4GvXfT0N2/uQ==}
     engines: {node: '>= 12'}
 
+  stackback@0.0.2:
+    resolution: {integrity: sha512-1XMJE5fQo1jGH6Y/7ebnwPOBEkIEnT4QF32d5R1+VXdXveM0IBMJt8zfaxX1P3QhVwrYe+576+jkANtSS2mBbw==}
+
+  std-env@3.10.0:
+    resolution: {integrity: sha512-5GS12FdOZNliM5mAOxFRg7Ir0pWz8MdpYm6AY6VPkGpbA7ZzmbzNcBJQ0GPvvyWgcY7QAhCgf9Uy89I03faLkg==}
+
   string-width@4.2.3:
     resolution: {integrity: sha512-wKyQRQpjJ0sIp62ErSZdGsjMJWsap5oRNihHhu6G7JVO/9jIB6UyevL+tXuOqrng8j/cxKTWyWUwvSTriiZz/g==}
     engines: {node: '>=8'}
@@ -1110,6 +1343,9 @@ packages:
   thenify@3.3.1:
     resolution: {integrity: sha512-RVZSIV5IG10Hk3enotrhvz0T9em6cyHBLkH/YAZuKqd8hRkKhSfCGIcP2KUY0EPxndzANBmNllzWPwak+bheSw==}
 
+  tinybench@2.9.0:
+    resolution: {integrity: sha512-0+DUvqWMValLmha6lr4kD8iAMK1HzV0/aKnCtWb9v9641TnP/MFb7Pc2bxoxQjTXAErryXVgUOfv2YqNllqGeg==}
+
   tinyexec@0.3.2:
     resolution: {integrity: sha512-KQQR9yN7R5+OSwaK0XQoj22pwHoTlgYqmUscPYoknOoWCWfj/5/ABTMRi69FrKU5ffPVh5QcFikpWJI/P1ocHA==}
 
@@ -1117,6 +1353,18 @@ packages:
     resolution: {integrity: sha512-j2Zq4NyQYG5XMST4cbs02Ak8iJUdxRM0XI5QyxXuZOzKOINmWurp3smXu3y5wDcJrptwpSjgXHzIQxR0omXljQ==}
     engines: {node: '>=12.0.0'}
 
+  tinypool@1.1.1:
+    resolution: {integrity: sha512-Zba82s87IFq9A9XmjiX5uZA/ARWDrB03OHlq+Vw1fSdt0I+4/Kutwy8BP4Y/y/aORMo61FQ0vIb5j44vSo5Pkg==}
+    engines: {node: ^18.0.0 || >=20.0.0}
+
+  tinyrainbow@1.2.0:
+    resolution: {integrity: sha512-weEDEq7Z5eTHPDh4xjX789+fHfF+P8boiFB+0vbWzpbnbsEr/GRaohi/uMKxg8RZMXnl1ItAi/IUHWMsjDV7kQ==}
+    engines: {node: '>=14.0.0'}
+
+  tinyspy@3.0.2:
+    resolution: {integrity: sha512-n1cw8k1k0x4pgA2+9XrOkFydTerNcJ1zWCO5Nn9scWHTD+5tp8dghT2x1uduQePZTZgd3Tupf+x9BxJjeJi77Q==}
+    engines: {node: '>=14.0.0'}
+
   tree-kill@1.2.2:
     resolution: {integrity: sha512-L0Orpi8qGpRG//Nd+H90vFB+3iHnue1zSSGmNOOCh1GLJ7rUKVwV2HvijphGQS2UmhUZewS9VgvxYIdgr+fG1A==}
     hasBin: true
@@ -1194,11 +1442,77 @@ packages:
     resolution: {integrity: sha512-kiGUalWN+rgBJ/1OHZsBtU4rXZOfj/7rKQxULKlIzwzQSvMJUUNgPwJEEh7gU6xEVxC0ahoOBvN2YI8GH6FNgA==}
     engines: {node: '>=10.12.0'}
 
+  vite-node@2.1.9:
+    resolution: {integrity: sha512-AM9aQ/IPrW/6ENLQg3AGY4K1N2TGZdR5e4gu/MmmR2xR3Ll1+dib+nook92g4TV3PXVyeyxdWwtaCAiUL0hMxA==}
+    engines: {node: ^18.0.0 || >=20.0.0}
+    hasBin: true
+
+  vite@5.4.21:
+    resolution: {integrity: sha512-o5a9xKjbtuhY6Bi5S3+HvbRERmouabWbyUcpXXUA1u+GNUKoROi9byOJ8M0nHbHYHkYICiMlqxkg1KkYmm25Sw==}
+    engines: {node: ^18.0.0 || >=20.0.0}
+    hasBin: true
+    peerDependencies:
+      '@types/node': ^18.0.0 || >=20.0.0
+      less: '*'
+      lightningcss: ^1.21.0
+      sass: '*'
+      sass-embedded: '*'
+      stylus: '*'
+      sugarss: '*'
+      terser: ^5.4.0
+    peerDependenciesMeta:
+      '@types/node':
+        optional: true
+      less:
+        optional: true
+      lightningcss:
+        optional: true
+      sass:
+        optional: true
+      sass-embedded:
+        optional: true
+      stylus:
+        optional: true
+      sugarss:
+        optional: true
+      terser:
+        optional: true
+
+  vitest@2.1.9:
+    resolution: {integrity: sha512-MSmPM9REYqDGBI8439mA4mWhV5sKmDlBKWIYbA3lRb2PTHACE0mgKwA8yQ2xq9vxDTuk4iPrECBAEW2aoFXY0Q==}
+    engines: {node: ^18.0.0 || >=20.0.0}
+    hasBin: true
+    peerDependencies:
+      '@edge-runtime/vm': '*'
+      '@types/node': ^18.0.0 || >=20.0.0
+      '@vitest/browser': 2.1.9
+      '@vitest/ui': 2.1.9
+      happy-dom: '*'
+      jsdom: '*'
+    peerDependenciesMeta:
+      '@edge-runtime/vm':
+        optional: true
+      '@types/node':
+        optional: true
+      '@vitest/browser':
+        optional: true
+      '@vitest/ui':
+        optional: true
+      happy-dom:
+        optional: true
+      jsdom:
+        optional: true
+
   which@2.0.2:
     resolution: {integrity: sha512-BLI3Tl1TW3Pvl70l3yq3Y64i+awpwXqsGBYWkkqMtnbXgrMD+yj7rhW0kuEDxzJaYXGjEW5ogapKNMEKNMjibA==}
     engines: {node: '>= 8'}
     hasBin: true
 
+  why-is-node-running@2.3.0:
+    resolution: {integrity: sha512-hUrmaWBdVDcxvYqnyh09zunKzROWjbZTiNy8dBEjkS7ehEDQibXJ7XvlmtbwuTclUiIyN+CyXQD4Vmko8fNm8w==}
+    engines: {node: '>=8'}
+    hasBin: true
+
   word-wrap@1.2.5:
     resolution: {integrity: sha512-BN22B5eaMMI9UMtjrGd5g5eCYPpCPDUy0FJXbYsaT5zYxjFOckS53SQDE3pWkVoWpHXVb3BrYcEN4Twa55B5cA==}
     engines: {node: '>=0.10.0'}
@@ -1249,81 +1563,150 @@ snapshots:
 
   '@bcoe/v8-coverage@1.0.2': {}
 
+  '@esbuild/aix-ppc64@0.21.5':
+    optional: true
+
   '@esbuild/aix-ppc64@0.27.3':
     optional: true
 
+  '@esbuild/android-arm64@0.21.5':
+    optional: true
+
   '@esbuild/android-arm64@0.27.3':
     optional: true
 
+  '@esbuild/android-arm@0.21.5':
+    optional: true
+
   '@esbuild/android-arm@0.27.3':
     optional: true
 
+  '@esbuild/android-x64@0.21.5':
+    optional: true
+
   '@esbuild/android-x64@0.27.3':
     optional: true
 
+  '@esbuild/darwin-arm64@0.21.5':
+    optional: true
+
   '@esbuild/darwin-arm64@0.27.3':
     optional: true
 
+  '@esbuild/darwin-x64@0.21.5':
+    optional: true
+
   '@esbuild/darwin-x64@0.27.3':
     optional: true
 
+  '@esbuild/freebsd-arm64@0.21.5':
+    optional: true
+
   '@esbuild/freebsd-arm64@0.27.3':
     optional: true
 
+  '@esbuild/freebsd-x64@0.21.5':
+    optional: true
+
   '@esbuild/freebsd-x64@0.27.3':
     optional: true
 
+  '@esbuild/linux-arm64@0.21.5':
+    optional: true
+
   '@esbuild/linux-arm64@0.27.3':
     optional: true
 
+  '@esbuild/linux-arm@0.21.5':
+    optional: true
+
   '@esbuild/linux-arm@0.27.3':
     optional: true
 
+  '@esbuild/linux-ia32@0.21.5':
+    optional: true
+
   '@esbuild/linux-ia32@0.27.3':
     optional: true
 
+  '@esbuild/linux-loong64@0.21.5':
+    optional: true
+
   '@esbuild/linux-loong64@0.27.3':
     optional: true
 
+  '@esbuild/linux-mips64el@0.21.5':
+    optional: true
+
   '@esbuild/linux-mips64el@0.27.3':
     optional: true
 
+  '@esbuild/linux-ppc64@0.21.5':
+    optional: true
+
   '@esbuild/linux-ppc64@0.27.3':
     optional: true
 
+  '@esbuild/linux-riscv64@0.21.5':
+    optional: true
+
   '@esbuild/linux-riscv64@0.27.3':
     optional: true
 
+  '@esbuild/linux-s390x@0.21.5':
+    optional: true
+
   '@esbuild/linux-s390x@0.27.3':
     optional: true
 
+  '@esbuild/linux-x64@0.21.5':
+    optional: true
+
   '@esbuild/linux-x64@0.27.3':
     optional: true
 
   '@esbuild/netbsd-arm64@0.27.3':
     optional: true
 
+  '@esbuild/netbsd-x64@0.21.5':
+    optional: true
+
   '@esbuild/netbsd-x64@0.27.3':
     optional: true
 
   '@esbuild/openbsd-arm64@0.27.3':
     optional: true
 
+  '@esbuild/openbsd-x64@0.21.5':
+    optional: true
+
   '@esbuild/openbsd-x64@0.27.3':
     optional: true
 
   '@esbuild/openharmony-arm64@0.27.3':
     optional: true
 
+  '@esbuild/sunos-x64@0.21.5':
+    optional: true
+
   '@esbuild/sunos-x64@0.27.3':
     optional: true
 
+  '@esbuild/win32-arm64@0.21.5':
+    optional: true
+
   '@esbuild/win32-arm64@0.27.3':
     optional: true
 
+  '@esbuild/win32-ia32@0.21.5':
+    optional: true
+
   '@esbuild/win32-ia32@0.27.3':
     optional: true
 
+  '@esbuild/win32-x64@0.21.5':
+    optional: true
+
   '@esbuild/win32-x64@0.27.3':
     optional: true
 
@@ -1612,6 +1995,46 @@ snapshots:
       '@typescript-eslint/types': 8.56.1
       eslint-visitor-keys: 5.0.1
 
+  '@vitest/expect@2.1.9':
+    dependencies:
+      '@vitest/spy': 2.1.9
+      '@vitest/utils': 2.1.9
+      chai: 5.3.3
+      tinyrainbow: 1.2.0
+
+  '@vitest/mocker@2.1.9(vite@5.4.21(@types/node@25.3.5))':
+    dependencies:
+      '@vitest/spy': 2.1.9
+      estree-walker: 3.0.3
+      magic-string: 0.30.21
+    optionalDependencies:
+      vite: 5.4.21(@types/node@25.3.5)
+
+  '@vitest/pretty-format@2.1.9':
+    dependencies:
+      tinyrainbow: 1.2.0
+
+  '@vitest/runner@2.1.9':
+    dependencies:
+      '@vitest/utils': 2.1.9
+      pathe: 1.1.2
+
+  '@vitest/snapshot@2.1.9':
+    dependencies:
+      '@vitest/pretty-format': 2.1.9
+      magic-string: 0.30.21
+      pathe: 1.1.2
+
+  '@vitest/spy@2.1.9':
+    dependencies:
+      tinyspy: 3.0.2
+
+  '@vitest/utils@2.1.9':
+    dependencies:
+      '@vitest/pretty-format': 2.1.9
+      loupe: 3.2.1
+      tinyrainbow: 1.2.0
+
   acorn-jsx@5.3.2(acorn@8.16.0):
     dependencies:
       acorn: 8.16.0
@@ -1639,6 +2062,8 @@ snapshots:
 
   argparse@2.0.1: {}
 
+  assertion-error@2.0.1: {}
+
   balanced-match@1.0.2: {}
 
   balanced-match@4.0.4: {}
@@ -1676,6 +2101,16 @@ snapshots:
 
   cac@6.7.14: {}
 
+  chai@5.3.3:
+    dependencies:
+      assertion-error: 2.0.1
+      check-error: 2.1.3
+      deep-eql: 5.0.2
+      loupe: 3.2.1
+      pathval: 2.0.1
+
+  check-error@2.1.3: {}
+
   chokidar@4.0.3:
     dependencies:
       readdirp: 4.1.2
@@ -1710,6 +2145,8 @@ snapshots:
     dependencies:
       ms: 2.1.3
 
+  deep-eql@5.0.2: {}
+
   deep-is@0.1.4: {}
 
   eastasianwidth@0.2.0: {}
@@ -1720,6 +2157,34 @@ snapshots:
 
   entities@4.5.0: {}
 
+  es-module-lexer@1.7.0: {}
+
+  esbuild@0.21.5:
+    optionalDependencies:
+      '@esbuild/aix-ppc64': 0.21.5
+      '@esbuild/android-arm': 0.21.5
+      '@esbuild/android-arm64': 0.21.5
+      '@esbuild/android-x64': 0.21.5
+      '@esbuild/darwin-arm64': 0.21.5
+      '@esbuild/darwin-x64': 0.21.5
+      '@esbuild/freebsd-arm64': 0.21.5
+      '@esbuild/freebsd-x64': 0.21.5
+      '@esbuild/linux-arm': 0.21.5
+      '@esbuild/linux-arm64': 0.21.5
+      '@esbuild/linux-ia32': 0.21.5
+      '@esbuild/linux-loong64': 0.21.5
+      '@esbuild/linux-mips64el': 0.21.5
+      '@esbuild/linux-ppc64': 0.21.5
+      '@esbuild/linux-riscv64': 0.21.5
+      '@esbuild/linux-s390x': 0.21.5
+      '@esbuild/linux-x64': 0.21.5
+      '@esbuild/netbsd-x64': 0.21.5
+      '@esbuild/openbsd-x64': 0.21.5
+      '@esbuild/sunos-x64': 0.21.5
+      '@esbuild/win32-arm64': 0.21.5
+      '@esbuild/win32-ia32': 0.21.5
+      '@esbuild/win32-x64': 0.21.5
+
   esbuild@0.27.3:
     optionalDependencies:
       '@esbuild/aix-ppc64': 0.27.3
@@ -1819,8 +2284,14 @@ snapshots:
 
   estraverse@5.3.0: {}
 
+  estree-walker@3.0.3:
+    dependencies:
+      '@types/estree': 1.0.8
+
   esutils@2.0.3: {}
 
+  expect-type@1.3.0: {}
+
   fast-deep-equal@3.1.3: {}
 
   fast-json-stable-stringify@2.1.0: {}
@@ -1948,6 +2419,8 @@ snapshots:
     dependencies:
       p-locate: 5.0.0
 
+  loupe@3.2.1: {}
+
   lru-cache@10.4.3: {}
 
   lunr@2.3.9: {}
@@ -2000,6 +2473,8 @@ snapshots:
       object-assign: 4.1.1
       thenify-all: 1.6.0
 
+  nanoid@3.3.12: {}
+
   natural-compare@1.4.0: {}
 
   object-assign@4.1.1: {}
@@ -2032,8 +2507,12 @@ snapshots:
       lru-cache: 10.4.3
       minipass: 7.1.3
 
+  pathe@1.1.2: {}
+
   pathe@2.0.3: {}
 
+  pathval@2.0.1: {}
+
   picocolors@1.1.1: {}
 
   picomatch@4.0.3: {}
@@ -2046,12 +2525,19 @@ snapshots:
       mlly: 1.8.0
       pathe: 2.0.3
 
-  postcss-load-config@6.0.1(yaml@2.9.0):
+  postcss-load-config@6.0.1(postcss@8.5.15)(yaml@2.9.0):
     dependencies:
       lilconfig: 3.1.3
     optionalDependencies:
+      postcss: 8.5.15
       yaml: 2.9.0
 
+  postcss@8.5.15:
+    dependencies:
+      nanoid: 3.3.12
+      picocolors: 1.1.1
+      source-map-js: 1.2.1
+
   prelude-ls@1.2.1: {}
 
   prettier@3.8.1: {}
@@ -2105,10 +2591,18 @@ snapshots:
 
   shebang-regex@3.0.0: {}
 
+  siginfo@2.0.0: {}
+
   signal-exit@4.1.0: {}
 
+  source-map-js@1.2.1: {}
+
   source-map@0.7.6: {}
 
+  stackback@0.0.2: {}
+
+  std-env@3.10.0: {}
+
   string-width@4.2.3:
     dependencies:
       emoji-regex: 8.0.0
@@ -2157,6 +2651,8 @@ snapshots:
     dependencies:
       any-promise: 1.3.0
 
+  tinybench@2.9.0: {}
+
   tinyexec@0.3.2: {}
 
   tinyglobby@0.2.15:
@@ -2164,6 +2660,12 @@ snapshots:
       fdir: 6.5.0(picomatch@4.0.3)
       picomatch: 4.0.3
 
+  tinypool@1.1.1: {}
+
+  tinyrainbow@1.2.0: {}
+
+  tinyspy@3.0.2: {}
+
   tree-kill@1.2.2: {}
 
   ts-api-utils@2.4.0(typescript@5.9.3):
@@ -2172,7 +2674,7 @@ snapshots:
 
   ts-interface-checker@0.1.13: {}
 
-  tsup@8.5.1(typescript@5.9.3)(yaml@2.9.0):
+  tsup@8.5.1(postcss@8.5.15)(typescript@5.9.3)(yaml@2.9.0):
     dependencies:
       bundle-require: 5.1.0(esbuild@0.27.3)
       cac: 6.7.14
@@ -2183,7 +2685,7 @@ snapshots:
       fix-dts-default-cjs-exports: 1.0.1
       joycon: 3.1.1
       picocolors: 1.1.1
-      postcss-load-config: 6.0.1(yaml@2.9.0)
+      postcss-load-config: 6.0.1(postcss@8.5.15)(yaml@2.9.0)
       resolve-from: 5.0.0
       rollup: 4.59.0
       source-map: 0.7.6
@@ -2192,6 +2694,7 @@ snapshots:
       tinyglobby: 0.2.15
       tree-kill: 1.2.2
     optionalDependencies:
+      postcss: 8.5.15
       typescript: 5.9.3
     transitivePeerDependencies:
       - jiti
@@ -2245,10 +2748,77 @@ snapshots:
       '@types/istanbul-lib-coverage': 2.0.6
       convert-source-map: 2.0.0
 
+  vite-node@2.1.9(@types/node@25.3.5):
+    dependencies:
+      cac: 6.7.14
+      debug: 4.4.3
+      es-module-lexer: 1.7.0
+      pathe: 1.1.2
+      vite: 5.4.21(@types/node@25.3.5)
+    transitivePeerDependencies:
+      - '@types/node'
+      - less
+      - lightningcss
+      - sass
+      - sass-embedded
+      - stylus
+      - sugarss
+      - supports-color
+      - terser
+
+  vite@5.4.21(@types/node@25.3.5):
+    dependencies:
+      esbuild: 0.21.5
+      postcss: 8.5.15
+      rollup: 4.59.0
+    optionalDependencies:
+      '@types/node': 25.3.5
+      fsevents: 2.3.3
+
+  vitest@2.1.9(@types/node@25.3.5):
+    dependencies:
+      '@vitest/expect': 2.1.9
+      '@vitest/mocker': 2.1.9(vite@5.4.21(@types/node@25.3.5))
+      '@vitest/pretty-format': 2.1.9
+      '@vitest/runner': 2.1.9
+      '@vitest/snapshot': 2.1.9
+      '@vitest/spy': 2.1.9
+      '@vitest/utils': 2.1.9
+      chai: 5.3.3
+      debug: 4.4.3
+      expect-type: 1.3.0
+      magic-string: 0.30.21
+      pathe: 1.1.2
+      std-env: 3.10.0
+      tinybench: 2.9.0
+      tinyexec: 0.3.2
+      tinypool: 1.1.1
+      tinyrainbow: 1.2.0
+      vite: 5.4.21(@types/node@25.3.5)
+      vite-node: 2.1.9(@types/node@25.3.5)
+      why-is-node-running: 2.3.0
+    optionalDependencies:
+      '@types/node': 25.3.5
+    transitivePeerDependencies:
+      - less
+      - lightningcss
+      - msw
+      - sass
+      - sass-embedded
+      - stylus
+      - sugarss
+      - supports-color
+      - terser
+
   which@2.0.2:
     dependencies:
       isexe: 2.0.0
 
+  why-is-node-running@2.3.0:
+    dependencies:
+      siginfo: 2.0.0
+      stackback: 0.0.2
+
   word-wrap@1.2.5: {}
 
   wrap-ansi@7.0.0:
diff --git a/src/index.ts b/src/index.ts
index 37cf7a9..1bfc466 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -15,6 +15,27 @@ export type { HijriDate, CalendarEngine, ConversionOptions } from "./types";
 
 import type { HijriDate, ConversionOptions } from "./types";
 
+// ---------------------------------------------------------------------------
+// Internal helpers
+// ---------------------------------------------------------------------------
+
+/**
+ * Purpose:      Lift a Date's LOCAL calendar components (year, month, day) into the
+ *               UTC slot so that hijri-core's UTC-day contract reads the caller's
+ *               intended calendar day regardless of host timezone.
+ * Inputs:       Any Gregorian Date.
+ * Outputs:      A new Date whose UTC year/month/date equal the input's LOCAL year/month/date.
+ * Constraints:  Used only as input to coreToHijri; the returned value is an ephemeral
+ *               intermediate — never hand it to Date#getFullYear or date-fns functions.
+ * WHY:          date-fns is a LOCAL-time library: its functions read local components.
+ *               hijri-core (after fix/utc-day-boundary) reads the UTC calendar day.
+ *               Without this shim, hosts west of UTC see the previous UTC day for
+ *               a local-midnight Date, causing off-by-one conversions.
+ */
+function localDayToUtcSlot(date: Date): Date {
+  return new Date(Date.UTC(date.getFullYear(), date.getMonth(), date.getDate()));
+}
+
 // ---------------------------------------------------------------------------
 // Conversion
 // ---------------------------------------------------------------------------
@@ -22,19 +43,39 @@ import type { HijriDate, ConversionOptions } from "./types";
 /**
  * Convert a Gregorian `Date` to a Hijri date object.
  *
+ * Follows date-fns conventions: the input `Date` is interpreted by its
+ * **local calendar day** (year/month/date in the host timezone). This matches
+ * how date-fns' own `format()` and field accessors work, so there are no
+ * timezone surprises when chaining with other date-fns functions.
+ *
  * Returns `null` when the date falls outside the calendar's supported range
  * (UAQ: 1318–1500 AH / 1900–2076 CE; FCNA extends slightly further).
+ *
+ * @example
+ * // Use local-date constructor, not the string form "2025-03-01" (parses as UTC)
+ * toHijriDate(new Date(2025, 2, 1)); // { hy: 1446, hm: 9, hd: 1 }
  */
 export function toHijriDate(date: Date, options?: ConversionOptions): HijriDate | null {
-  return coreToHijri(date, options);
+  return coreToHijri(localDayToUtcSlot(date), options);
 }
 
 /**
  * Convert a Hijri date to a Gregorian `Date`.
  *
- * The returned `Date` is set to midnight UTC of the equivalent Gregorian day.
+ * Returns a **local-midnight** Date so that local field accessors
+ * (`getFullYear`, `getMonth`, `getDate`) and date-fns' `format()` render the
+ * intended calendar day on every host timezone.
+ *
+ * Round-trips exactly: `toHijriDate(fromHijriDate(y, m, d))` returns
+ * `{ hy: y, hm: m, hd: d }` on every timezone.
  *
  * @throws {Error} If the Hijri date is invalid or outside the calendar's range.
+ *
+ * @example
+ * const d = fromHijriDate(1446, 9, 1);
+ * d.getFullYear(); // 2025
+ * d.getMonth();    // 2 (March)
+ * d.getDate();     // 1
  */
 export function fromHijriDate(
   hy: number,
@@ -42,11 +83,13 @@ export function fromHijriDate(
   hd: number,
   options?: ConversionOptions,
 ): Date {
-  const result = coreToGregorian(hy, hm, hd, options);
-  if (result === null) {
+  const greg = coreToGregorian(hy, hm, hd, options);
+  if (greg === null) {
     throw new Error(`Hijri date ${hy}/${hm}/${hd} is invalid or outside the supported range.`);
   }
-  return result;
+  // coreToGregorian returns UTC midnight; lift to local midnight so that
+  // local field accessors and date-fns format() show the right calendar day.
+  return new Date(greg.getUTCFullYear(), greg.getUTCMonth(), greg.getUTCDate());
 }
 
 // ---------------------------------------------------------------------------
@@ -75,28 +118,34 @@ export function isValidHijriDate(
 /**
  * Get the Hijri year for a Gregorian date.
  *
+ * The input Date is interpreted by its **local calendar day** (date-fns convention).
+ *
  * Returns `null` when the date is outside the supported range.
  */
 export function getHijriYear(date: Date, options?: ConversionOptions): number | null {
-  return coreToHijri(date, options)?.hy ?? null;
+  return coreToHijri(localDayToUtcSlot(date), options)?.hy ?? null;
 }
 
 /**
  * Get the Hijri month (1–12) for a Gregorian date.
  *
+ * The input Date is interpreted by its **local calendar day** (date-fns convention).
+ *
  * Returns `null` when the date is outside the supported range.
  */
 export function getHijriMonth(date: Date, options?: ConversionOptions): number | null {
-  return coreToHijri(date, options)?.hm ?? null;
+  return coreToHijri(localDayToUtcSlot(date), options)?.hm ?? null;
 }
 
 /**
  * Get the Hijri day of month (1–30) for a Gregorian date.
  *
+ * The input Date is interpreted by its **local calendar day** (date-fns convention).
+ *
  * Returns `null` when the date is outside the supported range.
  */
 export function getHijriDay(date: Date, options?: ConversionOptions): number | null {
-  return coreToHijri(date, options)?.hd ?? null;
+  return coreToHijri(localDayToUtcSlot(date), options)?.hd ?? null;
 }
 
 /**
@@ -141,6 +190,8 @@ export function getHijriMonthName(
  * Get the Arabic weekday name for a Gregorian date.
  *
  * Uses `Date.getDay()` (0 = Sunday, 6 = Saturday) as the index.
+ * `getDay()` reads the local weekday, which is correct — weekday display
+ * follows the host's local calendar day just like date-fns.
  *
  * @param date   - Any Gregorian `Date`.
  * @param length - `'long'` (default) or `'short'`.
@@ -162,6 +213,9 @@ const TOKEN_RE = /iYYYY|iYY|iMMMM|iMMM|iMM|iM|iDD|iD|iEEEE|iEEE|iE|ioooo|iooo/g;
 /**
  * Format a Gregorian date using Hijri calendar tokens.
  *
+ * The input Date is interpreted by its **local calendar day** (date-fns convention),
+ * matching the behavior of date-fns' own `format()`.
+ *
  * Supported tokens:
  *
  * | Token   | Output                     | Example        |
@@ -187,10 +241,10 @@ export function formatHijriDate(
   formatStr: string,
   options?: ConversionOptions,
 ): string {
-  const h = coreToHijri(date, options);
+  const h = coreToHijri(localDayToUtcSlot(date), options);
   if (!h) return "";
 
-  const day = date.getDay(); // 0–6
+  const day = date.getDay(); // 0–6 local weekday — correct for display
 
   return formatStr.replace(TOKEN_RE, (token): string => {
     switch (token) {
@@ -233,24 +287,6 @@ export function formatHijriDate(
   });
 }
 
-// ---------------------------------------------------------------------------
-// Internal helpers
-// ---------------------------------------------------------------------------
-
-/**
- * `coreToGregorian` returns a UTC-midnight Date. When `coreToHijri` is then
- * called on that Date, it normalises using local year/month/day components
- * (`getFullYear`, `getMonth`, `getDate`). In timezones west of UTC the local
- * date of a UTC-midnight instant is the *previous* calendar day, which causes
- * the round-trip to drift by one day.
- *
- * This helper converts a UTC-midnight Date to a local-noon Date so that local
- * calendar components always match the intended Gregorian date.
- */
-function utcMidnightToLocalNoon(d: Date): Date {
-  return new Date(d.getUTCFullYear(), d.getUTCMonth(), d.getUTCDate(), 12);
-}
-
 // ---------------------------------------------------------------------------
 // Arithmetic
 // ---------------------------------------------------------------------------
@@ -258,6 +294,9 @@ function utcMidnightToLocalNoon(d: Date): Date {
 /**
  * Add a number of Hijri months to a Gregorian date.
  *
+ * The input Date is interpreted by its **local calendar day** (date-fns convention).
+ * Returns a **local-midnight** Date.
+ *
  * Handles year rollover automatically. Month addition wraps at month 12 and
  * increments the year. If the result's month has fewer days than the original
  * day, the day is clamped to the last day of the new month.
@@ -265,7 +304,7 @@ function utcMidnightToLocalNoon(d: Date): Date {
  * @throws {Error} If the resulting Hijri date is outside the supported range.
  */
 export function addHijriMonths(date: Date, months: number, options?: ConversionOptions): Date {
-  const h = coreToHijri(date, options);
+  const h = coreToHijri(localDayToUtcSlot(date), options);
   if (!h) {
     throw new Error("Date is outside the supported Hijri calendar range.");
   }
@@ -279,19 +318,22 @@ export function addHijriMonths(date: Date, months: number, options?: ConversionO
   const maxDay = coreDaysInHijriMonth(newYear, newMonth, options);
   const newDay = Math.min(h.hd, maxDay);
 
-  return utcMidnightToLocalNoon(fromHijriDate(newYear, newMonth, newDay, options));
+  return fromHijriDate(newYear, newMonth, newDay, options);
 }
 
 /**
  * Add a number of Hijri years to a Gregorian date.
  *
- * If the resulting year has a shorter Ramadan (or any month) than the original
- * day, the day is clamped to the last day of that month.
+ * The input Date is interpreted by its **local calendar day** (date-fns convention).
+ * Returns a **local-midnight** Date.
+ *
+ * If the resulting year has a shorter month than the original day, the day is
+ * clamped to the last day of that month.
  *
  * @throws {Error} If the resulting Hijri date is outside the supported range.
  */
 export function addHijriYears(date: Date, years: number, options?: ConversionOptions): Date {
-  const h = coreToHijri(date, options);
+  const h = coreToHijri(localDayToUtcSlot(date), options);
   if (!h) {
     throw new Error("Date is outside the supported Hijri calendar range.");
   }
@@ -300,7 +342,7 @@ export function addHijriYears(date: Date, years: number, options?: ConversionOpt
   const maxDay = coreDaysInHijriMonth(newYear, h.hm, options);
   const newDay = Math.min(h.hd, maxDay);
 
-  return utcMidnightToLocalNoon(fromHijriDate(newYear, h.hm, newDay, options));
+  return fromHijriDate(newYear, h.hm, newDay, options);
 }
 
 // ---------------------------------------------------------------------------
@@ -310,28 +352,34 @@ export function addHijriYears(date: Date, years: number, options?: ConversionOpt
 /**
  * Get the first day of the Hijri month that contains the given date.
  *
+ * The input Date is interpreted by its **local calendar day** (date-fns convention).
+ * Returns a **local-midnight** Date.
+ *
  * @throws {Error} If the date is outside the supported range.
  */
 export function startOfHijriMonth(date: Date, options?: ConversionOptions): Date {
-  const h = coreToHijri(date, options);
+  const h = coreToHijri(localDayToUtcSlot(date), options);
   if (!h) {
     throw new Error("Date is outside the supported Hijri calendar range.");
   }
-  return utcMidnightToLocalNoon(fromHijriDate(h.hy, h.hm, 1, options));
+  return fromHijriDate(h.hy, h.hm, 1, options);
 }
 
 /**
  * Get the last day of the Hijri month that contains the given date.
  *
+ * The input Date is interpreted by its **local calendar day** (date-fns convention).
+ * Returns a **local-midnight** Date.
+ *
  * @throws {Error} If the date is outside the supported range.
  */
 export function endOfHijriMonth(date: Date, options?: ConversionOptions): Date {
-  const h = coreToHijri(date, options);
+  const h = coreToHijri(localDayToUtcSlot(date), options);
   if (!h) {
     throw new Error("Date is outside the supported Hijri calendar range.");
   }
   const lastDay = coreDaysInHijriMonth(h.hy, h.hm, options);
-  return utcMidnightToLocalNoon(fromHijriDate(h.hy, h.hm, lastDay, options));
+  return fromHijriDate(h.hy, h.hm, lastDay, options);
 }
 
 // ---------------------------------------------------------------------------
@@ -341,11 +389,13 @@ export function endOfHijriMonth(date: Date, options?: ConversionOptions): Date {
 /**
  * Check whether two Gregorian dates fall in the same Hijri month.
  *
+ * Both input Dates are interpreted by their **local calendar days** (date-fns convention).
+ *
  * Returns `false` if either date is outside the supported range.
  */
 export function isSameHijriMonth(dateA: Date, dateB: Date, options?: ConversionOptions): boolean {
-  const a = coreToHijri(dateA, options);
-  const b = coreToHijri(dateB, options);
+  const a = coreToHijri(localDayToUtcSlot(dateA), options);
+  const b = coreToHijri(localDayToUtcSlot(dateB), options);
   if (!a || !b) return false;
   return a.hy === b.hy && a.hm === b.hm;
 }
@@ -353,11 +403,13 @@ export function isSameHijriMonth(dateA: Date, dateB: Date, options?: ConversionO
 /**
  * Check whether two Gregorian dates fall in the same Hijri year.
  *
+ * Both input Dates are interpreted by their **local calendar days** (date-fns convention).
+ *
  * Returns `false` if either date is outside the supported range.
  */
 export function isSameHijriYear(dateA: Date, dateB: Date, options?: ConversionOptions): boolean {
-  const a = coreToHijri(dateA, options);
-  const b = coreToHijri(dateB, options);
+  const a = coreToHijri(localDayToUtcSlot(dateA), options);
+  const b = coreToHijri(localDayToUtcSlot(dateB), options);
   if (!a || !b) return false;
   return a.hy === b.hy;
 }
@@ -369,12 +421,14 @@ export function isSameHijriYear(dateA: Date, dateB: Date, options?: ConversionOp
 /**
  * Get the Hijri quarter (1–4) for a Gregorian date.
  *
+ * The input Date is interpreted by its **local calendar day** (date-fns convention).
+ *
  * Months 1–3 = Q1, 4–6 = Q2, 7–9 = Q3, 10–12 = Q4.
  *
  * Returns `null` when the date is outside the supported range.
  */
 export function getHijriQuarter(date: Date, options?: ConversionOptions): number | null {
-  const h = coreToHijri(date, options);
+  const h = coreToHijri(localDayToUtcSlot(date), options);
   if (!h) return null;
   return Math.ceil(h.hm / 3);
 }
diff --git a/test-cjs.cjs b/test-cjs.cjs
index 190f991..faa36b9 100644
--- a/test-cjs.cjs
+++ b/test-cjs.cjs
@@ -26,11 +26,12 @@ describe('CJS: toHijriDate', () => {
 });
 
 describe('CJS: fromHijriDate', () => {
-  it('converts to correct Gregorian date', () => {
+  it('converts to correct Gregorian date (local midnight)', () => {
     const d = fromHijriDate(1444, 9, 1);
-    assert.equal(d.getUTCFullYear(), 2023);
-    assert.equal(d.getUTCMonth(), 2);
-    assert.equal(d.getUTCDate(), 23);
+    // Returns local midnight — use local accessors, not UTC
+    assert.equal(d.getFullYear(), 2023);
+    assert.equal(d.getMonth(), 2);
+    assert.equal(d.getDate(), 23);
   });
 });
 
diff --git a/test.mjs b/test.mjs
index c7b24a0..2894815 100644
--- a/test.mjs
+++ b/test.mjs
@@ -43,21 +43,48 @@ describe('toHijriDate', () => {
     const h = toHijriDate(new Date(1800, 0, 1));
     assert.equal(h, null);
   });
+
+  it('toHijriDate(new Date(2025, 2, 1, 12)) -> {1446, 9, 1}', () => {
+    // Local-noon: verifies local-day interpretation ignores the time component
+    const h = toHijriDate(new Date(2025, 2, 1, 12));
+    assert.ok(h !== null, 'expected non-null');
+    assert.equal(h.hy, 1446);
+    assert.equal(h.hm, 9);
+    assert.equal(h.hd, 1);
+  });
 });
 
 describe('fromHijriDate', () => {
-  it('1 Ramadan 1444 -> 2023-03-23', () => {
+  it('1 Ramadan 1444 -> local 2023-03-23', () => {
     const d = fromHijriDate(1444, 9, 1);
-    assert.equal(d.getUTCFullYear(), 2023);
-    assert.equal(d.getUTCMonth(), 2);
-    assert.equal(d.getUTCDate(), 23);
+    // Returns local midnight: local accessors show the intended calendar day
+    assert.equal(d.getFullYear(), 2023);
+    assert.equal(d.getMonth(), 2);
+    assert.equal(d.getDate(), 23);
   });
 
-  it('1 Muharram 1446 -> 2024-07-07', () => {
+  it('1 Muharram 1446 -> local 2024-07-07', () => {
     const d = fromHijriDate(1446, 1, 1);
-    assert.equal(d.getUTCFullYear(), 2024);
-    assert.equal(d.getUTCMonth(), 6);
-    assert.equal(d.getUTCDate(), 7);
+    assert.equal(d.getFullYear(), 2024);
+    assert.equal(d.getMonth(), 6);
+    assert.equal(d.getDate(), 7);
+  });
+
+  it('round-trip: toHijriDate(fromHijriDate(1446, 9, 1)) === {1446, 9, 1}', () => {
+    const d = fromHijriDate(1446, 9, 1);
+    const h = toHijriDate(d);
+    assert.ok(h !== null, 'expected non-null round-trip result');
+    assert.equal(h.hy, 1446);
+    assert.equal(h.hm, 9);
+    assert.equal(h.hd, 1);
+  });
+
+  it('fromHijriDate(1446,9,1) local accessors show 2025-03-01', () => {
+    const d = fromHijriDate(1446, 9, 1);
+    // Local accessors — not toISOString() — are the correct API for this adapter
+    assert.equal(d.getFullYear(), 2025);
+    assert.equal(d.getMonth(), 2);   // March
+    assert.equal(d.getDate(), 1);
   });
 
   it('throws on invalid month', () => {
diff --git a/vitest.config.ts b/vitest.config.ts
new file mode 100644
index 0000000..225657d
--- /dev/null
+++ b/vitest.config.ts
@@ -0,0 +1,9 @@
+import { defineConfig } from "vitest/config";
+
+export default defineConfig({
+  test: {
+    globals: true,
+    environment: "node",
+    include: ["date-fns-hijri.test.ts"],
+  },
+});