diff --git a/src/ZVec.php b/src/ZVec.php
index 071c876..5db7010 100644
--- a/src/ZVec.php
+++ b/src/ZVec.php
@@ -250,7 +250,7 @@ private static function parseGroupResult(FFI\CData $result): array
         return $groups;
     }
 
-    public static function create(string $path, ZVecSchema $schema, bool $readOnly = false, bool $enableMmap = true, int $maxBufferSize = 67108864): self
+    public static function create(string $path, ZVecSchema $schema, bool $readOnly = false, bool $enableMmap = true, int $maxBufferSize = self::DEFAULT_MAX_BUFFER_SIZE): self
     {
         $path = self::validateCollectionPath($path);
         $ffi = self::ffi();
@@ -260,7 +260,7 @@ public static function create(string $path, ZVecSchema $schema, bool $readOnly =
         return new self($out, $path);
     }
 
-    public static function open(string $path, bool $readOnly = false, bool $enableMmap = true, int $maxBufferSize = 67108864): self
+    public static function open(string $path, bool $readOnly = false, bool $enableMmap = true, int $maxBufferSize = self::DEFAULT_MAX_BUFFER_SIZE): self
     {
         $path = self::validateCollectionPath($path);
         $ffi = self::ffi();
@@ -336,7 +336,7 @@ public function destroy(): void
             // Re-open via stored path so we can destroy the on-disk data
             $ffi = self::ffi();
             $newHandle = $ffi->new('zvec_collection_t');
-            $status = $ffi->zvec_collection_open($this->path, 0, 1, 67108864, FFI::addr($newHandle));
+            $status = $ffi->zvec_collection_open($this->path, 0, 1, self::DEFAULT_MAX_BUFFER_SIZE, FFI::addr($newHandle));
             self::checkStatus($status);
             try {
                 self::checkStatus($ffi->zvec_collection_destroy($newHandle));
@@ -358,7 +358,7 @@ public function schema(): string
     {
         $this->checkClosed();
         $ffi = self::ffi();
-        $bufSize = 8192;
+        $bufSize = self::SCHEMA_BUFFER_SIZE;
         while (true) {
             $buf = $ffi->new("char[$bufSize]");
             self::checkStatus($ffi->zvec_collection_schema($this->handle, $buf, $bufSize));
@@ -367,7 +367,7 @@ public function schema(): string
                 return $str;
             }
             $bufSize *= 2;
-            if ($bufSize > 1048576) {
+            if ($bufSize > self::MAX_STRING_BUFFER_SIZE) {
                 throw new ZVecException('Schema string exceeds maximum buffer size of 1 MB');
             }
         }
@@ -377,7 +377,7 @@ public function path(): string
     {
         $this->checkClosed();
         $ffi = self::ffi();
-        $bufSize = 4096;
+        $bufSize = self::PATH_BUFFER_SIZE;
         while (true) {
             $buf = $ffi->new("char[$bufSize]");
             self::checkStatus($ffi->zvec_collection_path($this->handle, $buf, $bufSize));
@@ -386,7 +386,7 @@ public function path(): string
                 return $str;
             }
             $bufSize *= 2;
-            if ($bufSize > 1048576) {
+            if ($bufSize > self::MAX_STRING_BUFFER_SIZE) {
                 throw new ZVecException('Path string exceeds maximum buffer size of 1 MB');
             }
         }
@@ -504,13 +504,13 @@ public function createInvertIndex(string $fieldName, bool $enableRange = true, b
     }
 
     /** @deprecated Use createIndex() with ZVecIndexParams::forHnsw() instead */
-    public function createHnswIndex(string $fieldName, int $metricType = ZVecSchema::METRIC_IP, int $m = 50, int $efConstruction = 500, int $quantizeType = 0, int $concurrency = 0, bool $useContiguousMemory = false): void
+    public function createHnswIndex(string $fieldName, int $metricType = ZVecSchema::METRIC_IP, int $m = self::DEFAULT_HNSW_M, int $efConstruction = self::DEFAULT_HNSW_EF_CONSTRUCTION, int $quantizeType = 0, int $concurrency = 0, bool $useContiguousMemory = false): void
     {
         $this->createIndex($fieldName, ZVecIndexParams::forHnsw($metricType, $m, $efConstruction, $quantizeType, $useContiguousMemory), $concurrency);
     }
 
     /** @deprecated Use createIndex() with ZVecIndexParams::forHnswRabitq() instead */
-    public function createHnswRabitqIndex(string $fieldName, int $metricType = ZVecSchema::METRIC_IP, int $totalBits = 7, int $numClusters = 16, int $m = 50, int $efConstruction = 500, int $sampleCount = 0, int $concurrency = 0): void
+    public function createHnswRabitqIndex(string $fieldName, int $metricType = ZVecSchema::METRIC_IP, int $totalBits = 7, int $numClusters = 16, int $m = self::DEFAULT_HNSW_M, int $efConstruction = self::DEFAULT_HNSW_EF_CONSTRUCTION, int $sampleCount = 0, int $concurrency = 0): void
     {
         $this->createIndex($fieldName, ZVecIndexParams::forHnswRabitq($metricType, $totalBits, $numClusters, $m, $efConstruction, $sampleCount), $concurrency);
     }
@@ -657,6 +657,17 @@ public function fetch(string ...$pks): array
     public const LOG_ERROR = 3;
     public const LOG_FATAL = 4;
 
+    // Default buffer sizes
+    public const DEFAULT_MAX_BUFFER_SIZE = 67108864; // 64 MB
+    public const SCHEMA_BUFFER_SIZE = 8192;
+    public const PATH_BUFFER_SIZE = 4096;
+    public const MAX_STRING_BUFFER_SIZE = 1048576; // 1 MB max for schema/stats strings
+    public const BYTES_PER_MB = 1048576;
+
+    // Default HNSW index parameters
+    public const DEFAULT_HNSW_M = 50;
+    public const DEFAULT_HNSW_EF_CONSTRUCTION = 500;
+
     // Data types for alterColumn (scalar numeric only)
     public const TYPE_INT32 = 4;
     public const TYPE_INT64 = 5;
@@ -738,7 +749,7 @@ public static function init(
             $ffi->zvec_config_data_set_brute_force_by_keys_ratio($configData, $bruteForceByKeysRatio);
         }
         if ($memoryLimitMb > 0) {
-            $ffi->zvec_config_data_set_memory_limit($configData, $memoryLimitMb * 1048576);
+            $ffi->zvec_config_data_set_memory_limit($configData, $memoryLimitMb * self::BYTES_PER_MB);
         }
 
         try {
@@ -1354,7 +1365,7 @@ public function stats(): string
     {
         $this->checkClosed();
         $ffi = self::ffi();
-        $bufSize = 4096;
+        $bufSize = self::PATH_BUFFER_SIZE;
         while (true) {
             $buf = $ffi->new("char[$bufSize]");
             self::checkStatus($ffi->zvec_collection_stats($this->handle, $buf, $bufSize));
@@ -1363,7 +1374,7 @@ public function stats(): string
                 return $str;
             }
             $bufSize *= 2;
-            if ($bufSize > 1048576) {
+            if ($bufSize > self::MAX_STRING_BUFFER_SIZE) {
                 throw new ZVecException('Stats string exceeds maximum buffer size of 1 MB');
             }
         }
diff --git a/src/ZVecIndexParams.php b/src/ZVecIndexParams.php
index 66802ed..23280fb 100644
--- a/src/ZVecIndexParams.php
+++ b/src/ZVecIndexParams.php
@@ -27,7 +27,7 @@ public function getHandle(): FFI\CData
         return $this->handle;
     }
 
-    public static function forHnsw(int $metricType, int $m = 50, int $efConstruction = 500, int $quantizeType = ZVec::QUANTIZE_UNDEFINED, bool $useContiguousMemory = false): self
+    public static function forHnsw(int $metricType, int $m = ZVec::DEFAULT_HNSW_M, int $efConstruction = ZVec::DEFAULT_HNSW_EF_CONSTRUCTION, int $quantizeType = ZVec::QUANTIZE_UNDEFINED, bool $useContiguousMemory = false): self
     {
         if ($m <= 0) {
             throw new ZVecException("m must be a positive integer, got: {$m}");
@@ -41,7 +41,7 @@ public static function forHnsw(int $metricType, int $m = 50, int $efConstruction
         return new self($handle);
     }
 
-    public static function forHnswRabitq(int $metricType, int $totalBits = 7, int $numClusters = 16, int $m = 50, int $efConstruction = 500, int $sampleCount = 0): self
+    public static function forHnswRabitq(int $metricType, int $totalBits = 7, int $numClusters = 16, int $m = ZVec::DEFAULT_HNSW_M, int $efConstruction = ZVec::DEFAULT_HNSW_EF_CONSTRUCTION, int $sampleCount = 0): self
     {
         if ($m <= 0) {
             throw new ZVecException("m must be a positive integer, got: {$m}");
diff --git a/tests/test_magic_number_constants.phpt b/tests/test_magic_number_constants.phpt
new file mode 100644
index 0000000..3402bc7
--- /dev/null
+++ b/tests/test_magic_number_constants.phpt
@@ -0,0 +1,188 @@
+--TEST--
+SMELL-007: Named constants replace magic numbers
+--SKIPIF--
+<?php if (!extension_loaded('ffi')) die('skip FFI extension not available'); ?>
+--FILE--
+<?php
+require_once __DIR__ . '/../src/ZVec.php';
+
+// Verify all new constants have expected values
+$tests = [
+    ['ZVec::DEFAULT_MAX_BUFFER_SIZE', ZVec::DEFAULT_MAX_BUFFER_SIZE, 67108864],
+    ['ZVec::SCHEMA_BUFFER_SIZE', ZVec::SCHEMA_BUFFER_SIZE, 8192],
+    ['ZVec::PATH_BUFFER_SIZE', ZVec::PATH_BUFFER_SIZE, 4096],
+    ['ZVec::MAX_STRING_BUFFER_SIZE', ZVec::MAX_STRING_BUFFER_SIZE, 1048576],
+    ['ZVec::BYTES_PER_MB', ZVec::BYTES_PER_MB, 1048576],
+    ['ZVec::DEFAULT_HNSW_M', ZVec::DEFAULT_HNSW_M, 50],
+    ['ZVec::DEFAULT_HNSW_EF_CONSTRUCTION', ZVec::DEFAULT_HNSW_EF_CONSTRUCTION, 500],
+];
+
+$failed = 0;
+foreach ($tests as [$name, $actual, $expected]) {
+    if ($actual === $expected) {
+        echo "OK: $name = $actual\n";
+    } else {
+        echo "FAIL: $name = $actual (expected $expected)\n";
+        $failed++;
+    }
+}
+
+// Verify no magic numbers remain in ZVec.php (outside constant declarations)
+$source = file_get_contents(__DIR__ . '/../src/ZVec.php');
+$lines = explode("\n", $source);
+
+// Check for 67108864 (64 MB) - should only appear in constant declaration
+$found67108864 = [];
+foreach ($lines as $i => $line) {
+    if (strpos($line, '67108864') !== false) {
+        $found67108864[] = $i + 1;
+    }
+}
+if (count($found67108864) === 1 && strpos($lines[$found67108864[0] - 1], 'DEFAULT_MAX_BUFFER_SIZE') !== false) {
+    echo "OK: 67108864 only in constant declaration\n";
+} else {
+    echo "FAIL: 67108864 found at lines: " . implode(', ', $found67108864) . "\n";
+    $failed++;
+}
+
+// Check for 8192 - should only appear in constant declaration
+$found8192 = [];
+foreach ($lines as $i => $line) {
+    if (preg_match('/\b8192\b/', $line)) {
+        $found8192[] = $i + 1;
+    }
+}
+if (count($found8192) === 1 && strpos($lines[$found8192[0] - 1], 'SCHEMA_BUFFER_SIZE') !== false) {
+    echo "OK: 8192 only in constant declaration\n";
+} else {
+    echo "FAIL: 8192 found at lines: " . implode(', ', $found8192) . "\n";
+    $failed++;
+}
+
+// Check for 4096 - should only appear in constant declaration
+$found4096 = [];
+foreach ($lines as $i => $line) {
+    if (preg_match('/\b4096\b/', $line)) {
+        $found4096[] = $i + 1;
+    }
+}
+if (count($found4096) === 1 && strpos($lines[$found4096[0] - 1], 'PATH_BUFFER_SIZE') !== false) {
+    echo "OK: 4096 only in constant declaration\n";
+} else {
+    echo "FAIL: 4096 found at lines: " . implode(', ', $found4096) . "\n";
+    $failed++;
+}
+
+// Check for 1048576 - should only appear in constant declarations
+$found1048576 = [];
+foreach ($lines as $i => $line) {
+    if (preg_match('/\b1048576\b/', $line)) {
+        $found1048576[] = $i + 1;
+    }
+}
+if (count($found1048576) === 2) {
+    $bothConstants = true;
+    foreach ($found1048576 as $lineNum) {
+        $line = $lines[$lineNum - 1];
+        if (strpos($line, 'MAX_STRING_BUFFER_SIZE') === false && strpos($line, 'BYTES_PER_MB') === false) {
+            $bothConstants = false;
+        }
+    }
+    if ($bothConstants) {
+        echo "OK: 1048576 only in constant declarations\n";
+    } else {
+        echo "FAIL: 1048576 found at non-constant lines: " . implode(', ', $found1048576) . "\n";
+        $failed++;
+    }
+} else {
+    echo "FAIL: 1048576 found at lines: " . implode(', ', $found1048576) . "\n";
+    $failed++;
+}
+
+// Check for 50 as default HNSW m - should only appear in constant declaration and deprecated methods
+$found50 = [];
+foreach ($lines as $i => $line) {
+    if (preg_match('/\b50\b/', $line) && strpos($line, 'LOG_WARN') === false) {
+        $found50[] = $i + 1;
+    }
+}
+$valid50 = true;
+foreach ($found50 as $lineNum) {
+    $line = $lines[$lineNum - 1];
+    if (strpos($line, 'DEFAULT_HNSW_M') === false && 
+        strpos($line, 'deprecated') === false &&
+        strpos($line, '@deprecated') === false) {
+        $valid50 = false;
+    }
+}
+if ($valid50 && count($found50) >= 1) {
+    echo "OK: 50 only in constant declaration and deprecated methods\n";
+} else {
+    echo "FAIL: 50 found at lines: " . implode(', ', $found50) . "\n";
+    $failed++;
+}
+
+// Check for 500 as default HNSW efConstruction - should only appear in constant declaration and deprecated methods
+$found500 = [];
+foreach ($lines as $i => $line) {
+    if (preg_match('/\b500\b/', $line)) {
+        $found500[] = $i + 1;
+    }
+}
+$valid500 = true;
+foreach ($found500 as $lineNum) {
+    $line = $lines[$lineNum - 1];
+    if (strpos($line, 'DEFAULT_HNSW_EF_CONSTRUCTION') === false && 
+        strpos($line, 'deprecated') === false &&
+        strpos($line, '@deprecated') === false) {
+        $valid500 = false;
+    }
+}
+if ($valid500 && count($found500) >= 1) {
+    echo "OK: 500 only in constant declaration and deprecated methods\n";
+} else {
+    echo "FAIL: 500 found at lines: " . implode(', ', $found500) . "\n";
+    $failed++;
+}
+
+// Verify ZVecIndexParams uses the constants
+$indexParamsSource = file_get_contents(__DIR__ . '/../src/ZVecIndexParams.php');
+if (strpos($indexParamsSource, 'ZVec::DEFAULT_HNSW_M') !== false) {
+    echo "OK: ZVecIndexParams uses ZVec::DEFAULT_HNSW_M\n";
+} else {
+    echo "FAIL: ZVecIndexParams does not use ZVec::DEFAULT_HNSW_M\n";
+    $failed++;
+}
+if (strpos($indexParamsSource, 'ZVec::DEFAULT_HNSW_EF_CONSTRUCTION') !== false) {
+    echo "OK: ZVecIndexParams uses ZVec::DEFAULT_HNSW_EF_CONSTRUCTION\n";
+} else {
+    echo "FAIL: ZVecIndexParams does not use ZVec::DEFAULT_HNSW_EF_CONSTRUCTION\n";
+    $failed++;
+}
+
+// Summary
+echo "\n";
+if ($failed === 0) {
+    echo "All tests passed!\n";
+} else {
+    echo "FAILED: $failed test(s) failed\n";
+}
+?>
+--EXPECT--
+OK: ZVec::DEFAULT_MAX_BUFFER_SIZE = 67108864
+OK: ZVec::SCHEMA_BUFFER_SIZE = 8192
+OK: ZVec::PATH_BUFFER_SIZE = 4096
+OK: ZVec::MAX_STRING_BUFFER_SIZE = 1048576
+OK: ZVec::BYTES_PER_MB = 1048576
+OK: ZVec::DEFAULT_HNSW_M = 50
+OK: ZVec::DEFAULT_HNSW_EF_CONSTRUCTION = 500
+OK: 67108864 only in constant declaration
+OK: 8192 only in constant declaration
+OK: 4096 only in constant declaration
+OK: 1048576 only in constant declarations
+OK: 50 only in constant declaration and deprecated methods
+OK: 500 only in constant declaration and deprecated methods
+OK: ZVecIndexParams uses ZVec::DEFAULT_HNSW_M
+OK: ZVecIndexParams uses ZVec::DEFAULT_HNSW_EF_CONSTRUCTION
+
+All tests passed!