diff --git a/.github/workflows/changelog.yml b/.github/workflows/changelog.yml
deleted file mode 100644
index e8f596e..0000000
--- a/.github/workflows/changelog.yml
+++ /dev/null
@@ -1,30 +0,0 @@
-name: Changelog
-
-on:
-  pull_request:
-    branches: [main]
-    paths:
-      - 'lib/**'
-      - 'tests/**'
-      - 'composer.json'
-
-jobs:
-  check:
-    runs-on: ubuntu-latest
-    name: Check CHANGELOG updated
-
-    steps:
-      - uses: actions/checkout@v6
-        with:
-          fetch-depth: 0
-
-      - name: Verify CHANGELOG.md was updated
-        run: |
-          git fetch origin ${{ github.base_ref }} --depth=1
-          if git diff --name-only origin/${{ github.base_ref }} HEAD | grep -q 'CHANGELOG.md'; then
-            echo "CHANGELOG.md was updated"
-            exit 0
-          else
-            echo "ERROR: CHANGELOG.md was not updated. Please document your changes."
-            exit 1
-          fi
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index d2c8132..903ae15 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -11,15 +11,15 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        php-version: ['8.1', '8.2', '8.3', '8.4']
+        php-version: ['8.1', '8.2', '8.3', '8.4', '8.5']
 
     name: PHP ${{ matrix.php-version }}
 
     steps:
-      - uses: actions/checkout@v6
+      - uses: actions/checkout@v7.0.1
 
       - name: Setup PHP
-        uses: shivammathur/setup-php@v2
+        uses: shivammathur/setup-php@2.37.2
         with:
           php-version: ${{ matrix.php-version }}
           coverage: none
@@ -29,7 +29,7 @@ jobs:
 
       - name: Cache Composer packages
         id: composer-cache
-        uses: actions/cache@v5
+        uses: actions/cache@v6.1.0
         with:
           path: vendor
           key: ${{ runner.os }}-php-${{ matrix.php-version }}-${{ hashFiles('**/composer.lock') }}
@@ -47,10 +47,10 @@ jobs:
     name: Static Analysis
 
     steps:
-      - uses: actions/checkout@v6
+      - uses: actions/checkout@v7.0.1
 
       - name: Setup PHP
-        uses: shivammathur/setup-php@v2
+        uses: shivammathur/setup-php@2.37.2
         with:
           php-version: '8.1'
           coverage: none
@@ -66,10 +66,10 @@ jobs:
     name: Code Style
 
     steps:
-      - uses: actions/checkout@v6
+      - uses: actions/checkout@v7.0.1
 
       - name: Setup PHP
-        uses: shivammathur/setup-php@v2
+        uses: shivammathur/setup-php@2.37.2
         with:
           php-version: '8.1'
           coverage: none
diff --git a/.github/workflows/pr-summary.yml b/.github/workflows/pr-summary.yml
deleted file mode 100644
index 930c7b2..0000000
--- a/.github/workflows/pr-summary.yml
+++ /dev/null
@@ -1,49 +0,0 @@
-name: Auto Generate PR Summary
-
-on:
-  pull_request:
-    types: [opened, synchronize]
-
-jobs:
-  generate-summary:
-    runs-on: ubuntu-latest
-    permissions:
-      contents: read
-      pull-requests: write
-
-    steps:
-      - name: Checkout code
-        uses: actions/checkout@v6
-        with:
-          fetch-depth: 0
-
-      - name: Set up Python
-        uses: actions/setup-python@v6
-        with:
-          python-version: '3.11'
-
-      - name: Install dependencies
-        run: pip install requests
-
-      - name: Get PR Diff
-        run: |
-          git diff origin/${{ github.base_ref }}...HEAD > pr_diff.txt
-
-      - name: Generate Summary with Ollama Cloud
-        id: ollama
-        env:
-          OLLAMA_API_KEY: ${{ secrets.OLLAMA_API_KEY }}
-          GH_TOKEN: ${{ github.token }}
-        run: |
-          gh pr view ${{ github.event.pull_request.number }} --json body -q .body > current_body.md || touch current_body.md
-          python scripts/generate_pr_summary.py pr_diff.txt current_body.md > summary.md
-
-          echo "SUMMARY<<EOF" >> $GITHUB_ENV
-          cat summary.md >> $GITHUB_ENV
-          echo "EOF" >> $GITHUB_ENV
-
-      - name: Update PR Description
-        env:
-          GH_TOKEN: ${{ github.token }}
-        run: |
-          gh pr edit ${{ github.event.pull_request.number }} --body "$SUMMARY"
diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
deleted file mode 100644
index 9f90fdd..0000000
--- a/.github/workflows/release.yml
+++ /dev/null
@@ -1,43 +0,0 @@
-name: Release
-
-on:
-  push:
-    tags:
-      - 'v*'
-
-permissions:
-  contents: write
-
-jobs:
-  create-release:
-    runs-on: ubuntu-latest
-    name: Create GitHub Release
-
-    steps:
-      - uses: actions/checkout@v6
-
-      - name: Extract version from tag
-        id: version
-        run: echo "VERSION=${GITHUB_REF#refs/tags/}" >> "$GITHUB_OUTPUT"
-
-      - name: Extract release notes from CHANGELOG
-        id: notes
-        run: |
-          VERSION="${GITHUB_REF#refs/tags/v}"
-          # Extract section for this version from CHANGELOG.md
-          awk "/^## \\[$VERSION\\]/ {flag=1; next} /^## \\[/ {flag=0} flag" CHANGELOG.md > release_notes.md
-          if [ ! -s release_notes.md ]; then
-            echo "No release notes found for $VERSION in CHANGELOG.md"
-            exit 1
-          fi
-          echo "notes<<EOF" >> "$GITHUB_OUTPUT"
-          cat release_notes.md >> "$GITHUB_OUTPUT"
-          echo "EOF" >> "$GITHUB_OUTPUT"
-
-      - name: Create GitHub Release
-        uses: softprops/action-gh-release@v2
-        with:
-          name: ${{ steps.version.outputs.VERSION }}
-          body_path: release_notes.md
-          draft: false
-          prerelease: false
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 74220cb..c95e963 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,22 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+## [2.1.0] - 2026-09-01
+
+### Fixed
+
+- Coerce money fields (`price`, `discount`, `total_price_override`, capture/refund `amount`, `total`, `debt`, `subtotal_override`, `total_tax_override`, `total_discount_override`, `total_override`) to integers before API calls — floating point noise from `ringgit × 100` conversions (e.g. `0.29 * 100 = 28.999999999999996`) no longer produces fractional JSON that the API rejects with 400 "A valid integer is required."
+- Values within 1e-9 of an integer are rounded to it; genuine fractional sen (e.g. `108.5`) now throws `InvalidMoneyValueException` instead of being silently truncated by the builder's implicit int cast (previously `28.999…` became `28` sen — a wrong charge amount)
+
+### Added
+
+- `Chip\Support\Money::coerce()` shared money coercion helper
+- `Chip\Exception\InvalidMoneyValueException` for money values that cannot be safely sent to the API
+
+### Removed
+
+- Remove auto PR summary workflow and script (`pr-summary.yml`, `generate_pr_summary.py`) — the Ollama endpoint returns 410 Gone and the workflow overwrote PR descriptions with its error output
+
 ## [2.0.2] - 2026-05-18
 
 ### Added
diff --git a/lib/Builder/PurchaseBuilder.php b/lib/Builder/PurchaseBuilder.php
index f8689a9..5b7101d 100644
--- a/lib/Builder/PurchaseBuilder.php
+++ b/lib/Builder/PurchaseBuilder.php
@@ -6,6 +6,7 @@
 use Chip\Model\Product;
 use Chip\Model\Purchase;
 use Chip\Model\PurchaseDetails;
+use Chip\Support\Money;
 
 class PurchaseBuilder
 {
@@ -328,21 +329,21 @@ public function clientBankCode(?string $bankCode): self
 
     public function addProduct(
         string $name,
-        int $price,
+        int|float|string $price,
         float|string $quantity = 1.0,
-        ?int $discount = null,
+        int|float|string|null $discount = null,
         ?string $taxPercent = null,
         ?string $category = null,
-        ?int $totalPriceOverride = null
+        int|float|string|null $totalPriceOverride = null
     ): self {
         $product = new Product();
         $product->name = $name;
-        $product->price = $price;
+        $product->price = Money::coerce($price);
         $product->quantity = is_string($quantity) ? $quantity : (string) $quantity;
-        $product->discount = $discount;
+        $product->discount = $discount === null ? null : Money::coerce($discount);
         $product->tax_percent = $taxPercent;
         $product->category = $category;
-        $product->total_price_override = $totalPriceOverride;
+        $product->total_price_override = $totalPriceOverride === null ? null : Money::coerce($totalPriceOverride);
 
         $this->purchase->purchase->products[] = $product;
 
@@ -356,37 +357,37 @@ public function notes(string $notes): self
         return $this;
     }
 
-    public function debt(int $debt): self
+    public function debt(int|float|string $debt): self
     {
-        $this->purchase->purchase->debt = $debt;
+        $this->purchase->purchase->debt = Money::coerce($debt);
 
         return $this;
     }
 
-    public function subtotalOverride(int $subtotalOverride): self
+    public function subtotalOverride(int|float|string $subtotalOverride): self
     {
-        $this->purchase->purchase->subtotal_override = $subtotalOverride;
+        $this->purchase->purchase->subtotal_override = Money::coerce($subtotalOverride);
 
         return $this;
     }
 
-    public function totalTaxOverride(int $totalTaxOverride): self
+    public function totalTaxOverride(int|float|string $totalTaxOverride): self
     {
-        $this->purchase->purchase->total_tax_override = $totalTaxOverride;
+        $this->purchase->purchase->total_tax_override = Money::coerce($totalTaxOverride);
 
         return $this;
     }
 
-    public function totalDiscountOverride(int $totalDiscountOverride): self
+    public function totalDiscountOverride(int|float|string $totalDiscountOverride): self
     {
-        $this->purchase->purchase->total_discount_override = $totalDiscountOverride;
+        $this->purchase->purchase->total_discount_override = Money::coerce($totalDiscountOverride);
 
         return $this;
     }
 
-    public function totalOverride(int $totalOverride): self
+    public function totalOverride(int|float|string $totalOverride): self
     {
-        $this->purchase->purchase->total_override = $totalOverride;
+        $this->purchase->purchase->total_override = Money::coerce($totalOverride);
 
         return $this;
     }
diff --git a/lib/Exception/InvalidMoneyValueException.php b/lib/Exception/InvalidMoneyValueException.php
new file mode 100644
index 0000000..51bf94d
--- /dev/null
+++ b/lib/Exception/InvalidMoneyValueException.php
@@ -0,0 +1,17 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Chip\Exception;
+
+use Exception;
+
+/**
+ * Thrown when a money field (price, discount, totals, overrides) receives a value
+ * that cannot be safely sent to the CHIP API — e.g. a float with a genuine
+ * fractional sen component (108.5) or a non-numeric type. Extends the base
+ * SDK exception so existing catch blocks keep working.
+ */
+class InvalidMoneyValueException extends Exception
+{
+}
diff --git a/lib/Model/Product.php b/lib/Model/Product.php
index 9e771e8..db82d79 100644
--- a/lib/Model/Product.php
+++ b/lib/Model/Product.php
@@ -2,6 +2,9 @@
 
 namespace Chip\Model;
 
+use Chip\Exception\InvalidMoneyValueException;
+use Chip\Support\Money;
+
 class Product implements \JsonSerializable
 {
     /**
@@ -47,11 +50,11 @@ public static function fromArray(array $data): self
         $product = new self();
         $product->name = $data['name'] ?? null;
         $product->quantity = $data['quantity'] ?? null;
-        $product->price = $data['price'] ?? null;
-        $product->discount = $data['discount'] ?? null;
+        $product->price = isset($data['price']) ? Money::coerce($data['price']) : null;
+        $product->discount = isset($data['discount']) ? Money::coerce($data['discount']) : null;
         $product->tax_percent = $data['tax_percent'] ?? null;
         $product->category = $data['category'] ?? null;
-        $product->total_price_override = $data['total_price_override'] ?? null;
+        $product->total_price_override = isset($data['total_price_override']) ? Money::coerce($data['total_price_override']) : null;
 
         return $product;
     }
@@ -59,7 +62,22 @@ public static function fromArray(array $data): self
     #[\ReturnTypeWillChange]
     public function jsonSerialize()
     {
-        return array_filter((array) $this, [$this, 'allow_non_null']);
+        // Coerce at serialization time too: public properties mean callers may
+        // assign raw values (e.g. 0.29 * 100 float noise) directly without the
+        // builder. Money fields must reach the API as integers.
+        $data = (array) $this;
+
+        foreach (['price', 'discount', 'total_price_override'] as $moneyField) {
+            if ($data[$moneyField] !== null) {
+                try {
+                    $data[$moneyField] = Money::coerce($data[$moneyField]);
+                } catch (InvalidMoneyValueException $e) {
+                    throw new InvalidMoneyValueException("Product->{$moneyField}: " . $e->getMessage(), 0, $e);
+                }
+            }
+        }
+
+        return array_filter($data, [$this, 'allow_non_null']);
     }
 
     /**
diff --git a/lib/Model/PurchaseDetails.php b/lib/Model/PurchaseDetails.php
index 1e624ba..59adcb7 100644
--- a/lib/Model/PurchaseDetails.php
+++ b/lib/Model/PurchaseDetails.php
@@ -2,6 +2,9 @@
 
 namespace Chip\Model;
 
+use Chip\Exception\InvalidMoneyValueException;
+use Chip\Support\Money;
+
 class PurchaseDetails implements \JsonSerializable
 {
     /**
@@ -131,14 +134,14 @@ public static function fromArray(array $data): self
             fn (array $p) => Product::fromArray($p),
             $data['products'] ?? []
         );
-        $details->total = $data['total'] ?? 0;
+        $details->total = Money::coerce($data['total'] ?? 0);
         $details->language = $data['language'] ?? '';
         $details->notes = $data['notes'] ?? '';
-        $details->debt = $data['debt'] ?? 0;
-        $details->subtotal_override = $data['subtotal_override'] ?? 0;
-        $details->total_tax_override = $data['total_tax_override'] ?? 0;
-        $details->total_discount_override = $data['total_discount_override'] ?? 0;
-        $details->total_override = $data['total_override'] ?? 0;
+        $details->debt = Money::coerce($data['debt'] ?? 0);
+        $details->subtotal_override = Money::coerce($data['subtotal_override'] ?? 0);
+        $details->total_tax_override = Money::coerce($data['total_tax_override'] ?? 0);
+        $details->total_discount_override = Money::coerce($data['total_discount_override'] ?? 0);
+        $details->total_override = Money::coerce($data['total_override'] ?? 0);
         $details->request_client_details = $data['request_client_details'] ?? [];
         $details->timezone = $data['timezone'] ?? '';
         $details->due_strict = $data['due_strict'] ?? false;
@@ -155,6 +158,21 @@ public static function fromArray(array $data): self
     #[\ReturnTypeWillChange]
     public function jsonSerialize()
     {
-        return array_filter((array) $this);
+        // Coerce money fields at serialization time: callers may assign raw
+        // values (e.g. ringgit * 100 float noise) directly to the public
+        // properties. Money fields must reach the API as integers.
+        $data = (array) $this;
+
+        foreach (['total', 'debt', 'subtotal_override', 'total_tax_override', 'total_discount_override', 'total_override'] as $moneyField) {
+            if ($data[$moneyField] !== null) {
+                try {
+                    $data[$moneyField] = Money::coerce($data[$moneyField]);
+                } catch (InvalidMoneyValueException $e) {
+                    throw new InvalidMoneyValueException("PurchaseDetails->{$moneyField}: " . $e->getMessage(), 0, $e);
+                }
+            }
+        }
+
+        return array_filter($data);
     }
 }
diff --git a/lib/Resource/PurchasesResource.php b/lib/Resource/PurchasesResource.php
index 6edbde9..a2911e1 100644
--- a/lib/Resource/PurchasesResource.php
+++ b/lib/Resource/PurchasesResource.php
@@ -6,6 +6,7 @@
 
 use Chip\Http\ClientInterface;
 use Chip\Model\Purchase;
+use Chip\Support\Money;
 
 final class PurchasesResource
 {
@@ -43,11 +44,11 @@ public function release(string $purchaseId): Purchase
         return Purchase::fromArray((array) $response);
     }
 
-    public function capture(string $purchaseId, ?int $amount = null): Purchase
+    public function capture(string $purchaseId, int|float|string|null $amount = null): Purchase
     {
         $options = [];
         if ($amount !== null) {
-            $options['json'] = ['amount' => $amount];
+            $options['json'] = ['amount' => Money::coerce($amount)];
         }
 
         $response = $this->client->request('POST', "purchases/$purchaseId/capture/", $options);
@@ -71,11 +72,11 @@ public function deleteRecurringToken(string $purchaseId): Purchase
         return Purchase::fromArray((array) $response);
     }
 
-    public function refund(string $purchaseId, ?int $amount = null): Purchase
+    public function refund(string $purchaseId, int|float|string|null $amount = null): Purchase
     {
         $options = [];
         if ($amount !== null) {
-            $options['json'] = ['amount' => $amount];
+            $options['json'] = ['amount' => Money::coerce($amount)];
         }
 
         $response = $this->client->request('POST', "purchases/$purchaseId/refund/", $options);
diff --git a/lib/Support/Money.php b/lib/Support/Money.php
new file mode 100644
index 0000000..169623e
--- /dev/null
+++ b/lib/Support/Money.php
@@ -0,0 +1,74 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Chip\Support;
+
+use Chip\Exception\InvalidMoneyValueException;
+
+/**
+ * Shared numeric coercion helpers for CHIP money fields.
+ *
+ * CHIP Collect requires money fields (price, discount, total_price_override,
+ * totals, overrides) to be integers in minor units (sen). Floating point math
+ * upstream (e.g. ringgit * 100) frequently produces values that *are* whole
+ * numbers but do not have an integer PHP type, such as 28.999999999999996 for
+ * 0.29 * 100. JSON-encoding such a value sends a fractional number and the API
+ * rejects it with 400 "A valid integer is required.".
+ *
+ * - A numeric value within 1e-9 of an integer is coerced to that integer
+ *   (covers float precision noise, int-valued floats and numeric strings like
+ *   "108.00").
+ * - A numeric value with a genuine fractional part (e.g. 108.5) throws
+ *   InvalidMoneyValueException instead of silently truncating (PHP's implicit
+ *   int cast would send the wrong amount).
+ *
+ * Null passes through untouched so optional fields stay omitted.
+ */
+final class Money
+{
+    private const EPSILON = 1e-9;
+
+    /**
+     * Coerce a money value to the integer the CHIP API requires.
+     *
+     * @param int|float|string|null $value
+     * @return ($value is null ? int|null : int)
+     */
+    public static function coerce(mixed $value): ?int
+    {
+        if ($value === null) {
+            return null;
+        }
+
+        if (! is_numeric($value)) {
+            throw new InvalidMoneyValueException(
+                'Money value must be numeric (int, float or numeric string), got: '
+                . get_debug_type($value)
+            );
+        }
+
+        // int-valued numerics short-circuit without float conversion.
+        if (is_int($value)) {
+            return $value;
+        }
+
+        $float = (float) $value;
+
+        if (! is_finite($float)) {
+            throw new InvalidMoneyValueException('Money value must be a finite number.');
+        }
+
+        $rounded = round($float);
+
+        if (abs($float - $rounded) < self::EPSILON) {
+            return (int) $rounded;
+        }
+
+        throw new InvalidMoneyValueException(sprintf(
+            'Money value must be a whole number of minor units; got %s. '
+            . 'Round to sen before passing it to the SDK.',
+            var_export($value, true)
+        ));
+    }
+}
diff --git a/scripts/generate_pr_summary.py b/scripts/generate_pr_summary.py
deleted file mode 100644
index 103d6dd..0000000
--- a/scripts/generate_pr_summary.py
+++ /dev/null
@@ -1,99 +0,0 @@
-import os
-import sys
-import requests
-
-
-def generate_summary(diff_text: str, current_body: str, api_key: str, model: str = "gemini-3-flash-preview:cloud") -> str:
-    url = os.getenv("OLLAMA_API_URL", "https://api.ollama.com/api/generate")
-
-    prompt = f"""You are a senior software engineer. Please review the following git diff and generate a Pull Request description.
-
-Current PR Body (if any):
-{current_body}
-
-Git Diff:
-{diff_text}
-
-Please generate a Pull Request description that follows this exact format:
-
-## What does this change?
-[Provide a detailed explanation of WHAT the problem was and HOW this change solves it. Focus on the 'why' and 'how'.]
-
-## Asana / Jira / Trello task link
-<!-- Provide Asana / Jira / Trello task link here -->
-
-## How to test
-[Provide step-by-step instructions to help others verify the change. Suggest specific tests based on the modified files.]
-
-## Potential Risks & Senior Review Items
-[Identify potential side effects, performance implications, security considerations, or architectural concerns. Highlight specific areas where a senior engineer should focus their review.]
-
-## Is this PR warrant an automatic approval?
-[Yes/No. Provide a brief justification based on the complexity and risk of the changes.]
-
-## Images
-<!-- Usually only applicable to UI changes, what did it look like before and what will it look like after? -->
-
-Important:
-- If the 'Current PR Body' already contains information (like task links or images), PRESERVE them in the new summary.
-- Fill in the 'What does this change?', 'How to test', 'Potential Risks & Senior Review Items', and 'Is this PR warrant an automatic approval?' sections based on the provided diff.
-- Keep the other sections exactly as shown (with their HTML comments/placeholders) so the user can fill them in manually if needed.
-- Return ONLY the markdown content.
-"""
-
-    headers = {
-        "Authorization": f"Bearer {api_key}",
-        "Content-Type": "application/json",
-    }
-
-    data = {
-        "model": model,
-        "prompt": prompt,
-        "stream": False,
-    }
-
-    try:
-        response = requests.post(url, headers=headers, json=data, timeout=90)
-        response.raise_for_status()
-        result = response.json()
-        return result.get("response", "Could not generate summary.")
-    except requests.exceptions.RequestException as e:
-        return f"Error calling Ollama API: {e!s}"
-
-
-def main() -> int:
-    if len(sys.argv) < 2:
-        print("Usage: python generate_pr_summary.py <diff_file> [current_body_file]")
-        return 1
-
-    diff_file = sys.argv[1]
-    current_body_file = sys.argv[2] if len(sys.argv) > 2 else None
-
-    api_key = os.getenv("OLLAMA_API_KEY")
-    if not api_key:
-        print("Error: OLLAMA_API_KEY environment variable not set.")
-        return 1
-
-    if not os.path.exists(diff_file):
-        print(f"Error: File {diff_file} not found.")
-        return 1
-
-    with open(diff_file, encoding="utf-8") as f:
-        diff_text = f.read()
-
-    current_body = ""
-    if current_body_file and os.path.exists(current_body_file):
-        with open(current_body_file, encoding="utf-8") as f:
-            current_body = f.read()
-
-    # Limit diff size to avoid token limits
-    if len(diff_text) > 50000:
-        diff_text = diff_text[:50000] + "\n\n... (diff truncated for size) ..."
-
-    summary = generate_summary(diff_text, current_body, api_key)
-    print(summary)
-    return 0
-
-
-if __name__ == "__main__":
-    sys.exit(main())
diff --git a/tests/MoneyCoercionTest.php b/tests/MoneyCoercionTest.php
new file mode 100644
index 0000000..00db0a3
--- /dev/null
+++ b/tests/MoneyCoercionTest.php
@@ -0,0 +1,180 @@
+<?php
+
+declare(strict_types=1);
+
+use Chip\Builder\PurchaseBuilder;
+use Chip\Exception\InvalidMoneyValueException;
+use Chip\Model\Product;
+use Chip\Model\PurchaseDetails;
+use Chip\Support\Money;
+use PHPUnit\Framework\TestCase;
+
+final class MoneyCoercionTest extends TestCase
+{
+    // ===== Money::coerce unit behaviour =====
+
+    public function testCoercePassesThroughInt(): void
+    {
+        $this->assertSame(108, Money::coerce(108));
+        $this->assertSame(0, Money::coerce(0));
+    }
+
+    public function testCoercePassesThroughNull(): void
+    {
+        $this->assertNull(Money::coerce(null));
+    }
+
+    public function testCoerceIntValuedFloat(): void
+    {
+        $this->assertSame(108, Money::coerce(108.0));
+        $this->assertSame(10800, Money::coerce(10800.0));
+    }
+
+    public function testCoerceFloatRoundingNoise(): void
+    {
+        // 0.29 * 100 in binary floating point is 28.999999999999996 — a whole
+        // number in intent, fractional in representation. This exact value was
+        // rejected by the API with 400 "A valid integer is required.".
+        $this->assertSame(29, Money::coerce(0.29 * 100));
+        $this->assertSame(29, Money::coerce(28.999999999999996));
+    }
+
+    public function testCoerceNumericStrings(): void
+    {
+        $this->assertSame(108, Money::coerce('108'));
+        $this->assertSame(108, Money::coerce('108.00'));
+        $this->assertSame(10800, Money::coerce('108.00' * 100));
+    }
+
+    public function testCoerceRejectsGenuineFraction(): void
+    {
+        $this->expectException(InvalidMoneyValueException::class);
+        Money::coerce(108.5);
+    }
+
+    public function testCoerceRejectsNonNumeric(): void
+    {
+        $this->expectException(InvalidMoneyValueException::class);
+        Money::coerce('12abc');
+    }
+
+    public function testCoerceRejectsNanAndInfinity(): void
+    {
+        $this->expectException(InvalidMoneyValueException::class);
+        Money::coerce(NAN);
+    }
+
+    // ===== Product serialization (covers direct model usage, v1-style apps) =====
+
+    public function testProductSerializesFloatNoiseAsInteger(): void
+    {
+        $product = new \Chip\Model\Product();
+        $product->name = 'X';
+        $product->price = 0.29 * 100; // @phpstan-ignore assign.propertyType (raw app input on purpose)
+        $product->quantity = '1';
+
+        $decoded = json_decode((string) json_encode($product), true);
+        $this->assertSame(29, $decoded['price']);
+    }
+
+    public function testProductSerializeRejectsGenuineFraction(): void
+    {
+        $product = new \Chip\Model\Product();
+        $product->name = 'X';
+        $product->price = 108.5; // @phpstan-ignore assign.propertyType (raw app input on purpose)
+
+        $this->expectException(InvalidMoneyValueException::class);
+        $this->expectExceptionMessage('price');
+        json_encode($product);
+    }
+
+    public function testProductFromArrayCoercesMoneyFields(): void
+    {
+        $product = Product::fromArray([
+            'name' => 'X',
+            'price' => '108.00',
+            'discount' => 2.0,
+            'total_price_override' => 106.0,
+        ]);
+
+        $this->assertSame(108, $product->price);
+        $this->assertSame(2, $product->discount);
+        $this->assertSame(106, $product->total_price_override);
+    }
+
+    // ===== PurchaseDetails =====
+
+    public function testPurchaseDetailsSerializesOverrideFloatsAsIntegers(): void
+    {
+        $details = new PurchaseDetails();
+        $details->total = 100.0 * 100; // @phpstan-ignore assign.propertyType (raw app input on purpose)
+        $details->total_override = '999.00'; // @phpstan-ignore assign.propertyType (raw app input on purpose)
+
+        $decoded = json_decode((string) json_encode($details), true);
+        $this->assertSame(10000, $decoded['total']);
+        $this->assertSame(999, $decoded['total_override']);
+    }
+
+    public function testPurchaseDetailsSerializeRejectsFractionalOverride(): void
+    {
+        $details = new PurchaseDetails();
+        $details->total_override = 108.25; // @phpstan-ignore assign.propertyType (raw app input on purpose)
+
+        $this->expectException(InvalidMoneyValueException::class);
+        $this->expectExceptionMessage('total_override');
+        json_encode($details);
+    }
+
+    // ===== Builder =====
+
+    public function testBuilderAcceptsFloatNoisePrice(): void
+    {
+        $purchase = PurchaseBuilder::create()
+            ->currency('MYR')
+            ->addProduct('X', 0.29 * 100)
+            ->build();
+
+        $this->assertSame(29, $purchase->purchase->products[0]->price);
+        $this->assertStringNotContainsString('28.9', (string) json_encode($purchase));
+    }
+
+    public function testBuilderAcceptsStringPrice(): void
+    {
+        $purchase = PurchaseBuilder::create()
+            ->currency('MYR')
+            ->addProduct('X', '108.00')
+            ->build();
+
+        $this->assertSame(108, $purchase->purchase->products[0]->price);
+    }
+
+    public function testBuilderRejectsFractionalPrice(): void
+    {
+        $this->expectException(InvalidMoneyValueException::class);
+        PurchaseBuilder::create()->addProduct('X', 108.999);
+    }
+
+    public function testBuilderCoercesDiscountAndOverride(): void
+    {
+        $purchase = PurchaseBuilder::create()
+            ->currency('MYR')
+            ->addProduct('X', 100, 1.0, 1.0, null, null, 99.0000000001)
+            ->build();
+
+        $product = $purchase->purchase->products[0];
+        $this->assertSame(1, $product->discount);
+        $this->assertSame(99, $product->total_price_override);
+    }
+
+    public function testBuilderCoercesTotalOverrideMoney(): void
+    {
+        $purchase = PurchaseBuilder::create()
+            ->currency('MYR')
+            ->addProduct('X', 100)
+            ->totalOverride('1000.00')
+            ->build();
+
+        $decoded = json_decode((string) json_encode($purchase), true);
+        $this->assertSame(1000, $decoded['purchase']['total_override']);
+    }
+}