diff --git a/phpunit/src/CompilerBaseApiTest.php b/phpunit/src/CompilerBaseApiTest.php
index 706b4ec5..221963e0 100644
--- a/phpunit/src/CompilerBaseApiTest.php
+++ b/phpunit/src/CompilerBaseApiTest.php
@@ -80,6 +80,7 @@ class CompilerBaseApiTest extends TestCase
 
     public function testMethodCacheKeepsPreviouslyAssignedClassLifetime(): void
     {
+        $this->setPropertyValue('compilerPhase', 'convert');
         // The two maps have independent ID spaces. This reproduces the tpc
         // bootstrap ordering where both classes occupied slot zero.
         $this->setPropertyValue('classMap', ['LateKnownClass' => 0]);
@@ -100,6 +101,7 @@ class CompilerBaseApiTest extends TestCase
 
     public function testMethodCacheRejectsMismatchedLifetimeDomains(): void
     {
+        $this->setPropertyValue('compilerPhase', 'convert');
         $this->setPropertyValue('classMap', ['LateKnownClass' => 0]);
         $this->setPropertyValue('classIndex', 1);
         $this->setPropertyValue('persistentFuncMap', ['LateKnownClass::run' => 0]);
@@ -112,6 +114,78 @@ class CompilerBaseApiTest extends TestCase
         $this->invokeMethod('getMethodPtr', 'LateKnownClass', 'run');
     }
 
+    public function testPrepareStoresDeclarationAstsWithoutAllocatingCacheIds(): void
+    {
+        $consumer = $this->testDir . '/consumer.php';
+        $declaration = $this->testDir . '/late.php';
+        file_put_contents($consumer, <<<'PHP'
+<?php
+namespace CachePhase;
+
+final class Defaults
+{
+    public const string VALUE = LateClass::VALUE;
+    public string $property = LateClass::VALUE;
+
+    public function read(string $value = LateClass::VALUE): string
+    {
+        return $value;
+    }
+}
+PHP);
+        file_put_contents($declaration, <<<'PHP'
+<?php
+namespace CachePhase;
+
+final class LateClass
+{
+    public const string VALUE = 'ready';
+}
+PHP);
+
+        // Deliberately prepare the consumer first. This was the bootstrap
+        // ordering that used to assign a request ID before LateClass became
+        // visible, then assign persistent IDs to later method lookups.
+        $this->compiler->prepareFile($consumer);
+        $this->compiler->prepareFile($declaration);
+
+        foreach (['classMap', 'persistentClassMap', 'funcMap', 'persistentFuncMap', 'persistentPropMap'] as $map) {
+            $this->assertSame([], $this->getPropertyValue($map), $map);
+        }
+        $defaults = $this->compiler->getClassDef('CachePhase\\Defaults');
+        $this->assertNotNull($defaults);
+        $this->assertInstanceOf(
+            \PhpParser\Node\Expr\ClassConstFetch::class,
+            $defaults->getConstant('VALUE')->valueExpr,
+        );
+        $this->assertSame('', $defaults->getConstant('VALUE')->value);
+        $this->assertNotNull($defaults->getProperty('property')->defaultExpr);
+        $this->assertTrue($defaults->getMethod('read')->functionDef->argInfoList[0]->hasDefaultValue());
+        $this->assertSame('', $defaults->getMethod('read')->functionDef->argInfoList[0]->default);
+
+        $this->setPropertyValue('compilerPhase', 'convert');
+        $this->compiler->finalizeDeclarationExpressions([$consumer, $declaration]);
+
+        $this->assertSame([], $this->getPropertyValue('classMap'));
+        $this->assertArrayHasKey(
+            'CachePhase\\LateClass',
+            $this->getPropertyValue('persistentClassMap'),
+        );
+        $this->assertNotSame('', $defaults->getConstant('VALUE')->value);
+        $this->assertNotNull($defaults->getProperty('property')->default);
+        $this->assertNotSame('', $defaults->getMethod('read')->functionDef->argInfoList[0]->default);
+    }
+
+    public function testCacheIdAllocationIsRejectedOutsideConvertPhase(): void
+    {
+        $this->setPropertyValue('compilerPhase', 'prepare');
+        $this->expectException(TestError::class);
+        $this->expectExceptionMessage(
+            'class cache ID allocation can only be used during convert phase, current phase is prepare',
+        );
+        $this->invokeMethod('getClassId', 'ForbiddenDuringPrepare');
+    }
+
     private function fixturePath(string $file): string
     {
         return __DIR__ . '/../code/compiler_api/' . $file;
diff --git a/phpunit/src/PreprocessorTest.php b/phpunit/src/PreprocessorTest.php
index 86984f93..377f9029 100644
--- a/phpunit/src/PreprocessorTest.php
+++ b/phpunit/src/PreprocessorTest.php
@@ -287,7 +287,7 @@ class PreprocessorTest extends TestCase
         $this->assertNotEmpty($functionDef->returnTypeCheck);
     }
 
-    public function testPrepareFileParsesInterfaceArrayConstantInitExpr(): void
+    public function testInterfaceArrayConstantIsLoweredOnlyDuringConvert(): void
     {
         $file = __DIR__ . '/../code/interface_array_constant.php';
 
@@ -298,6 +298,15 @@ class PreprocessorTest extends TestCase
         $constant = $interfaces['interfacearrayconstant']->constants['ITEMS'];
 
         $this->assertSame('php::Array', $constant->type);
+        $this->assertInstanceOf(\PhpParser\Node\Expr\Array_::class, $constant->valueExpr);
+        $this->assertSame('', $constant->value);
+        $this->assertSame([], $this->getProperty('classMap'));
+        $this->assertSame([], $this->getProperty('persistentClassMap'));
+        $this->assertSame([], $this->getProperty('funcMap'));
+        $this->assertSame([], $this->getProperty('persistentFuncMap'));
+
+        $this->setProperty('compilerPhase', 'convert');
+        $this->compiler->finalizeDeclarationExpressions([$file]);
         $this->assertStringContainsString('php::Array', $constant->value);
     }
 
diff --git a/src/Build/SourcePipelineTrait.php b/src/Build/SourcePipelineTrait.php
index 1ba70006..4fbf35e8 100644
--- a/src/Build/SourcePipelineTrait.php
+++ b/src/Build/SourcePipelineTrait.php
@@ -249,49 +249,59 @@ trait SourcePipelineTrait
 
     public function convert(array $files): array
     {
-        $sourceFiles = [];
-        $validSourceCount = 0;
-        // 生成 C++ 文件
-        foreach ($files as $k => $file) {
-            try {
-                if (FileScanner::isPhpFile($file)) {
-                    $cppFile = $this->convertFile($file);
-                } elseif (FileScanner::isNativeSourceFile($file)) {
-                    $cppFile = $file;
-                } else {
-                    continue;
-                }
-                $validSourceCount++;
-                if ($cppFile !== null) {
-                    $sourceFiles[] = $cppFile;
+        $previousPhase = $this->enterCompilerPhase(self::PHASE_CONVERT);
+        try {
+            // All declarations are now known. Lower declaration constant
+            // expressions before translating any function body so cache IDs
+            // are assigned exclusively in the convert phase.
+            $this->finalizeDeclarationExpressions($files);
+
+            $sourceFiles = [];
+            $validSourceCount = 0;
+            // 生成 C++ 文件
+            foreach ($files as $k => $file) {
+                try {
+                    if (FileScanner::isPhpFile($file)) {
+                        $cppFile = $this->convertFile($file);
+                    } elseif (FileScanner::isNativeSourceFile($file)) {
+                        $cppFile = $file;
+                    } else {
+                        continue;
+                    }
+                    $validSourceCount++;
+                    if ($cppFile !== null) {
+                        $sourceFiles[] = $cppFile;
+                    }
+                } catch (Unsupported $e) {
+                    echo ' unsupported syntax: ' . $e->getMessage() . "\n";
+                    echo ' skip: ' . $file . "\n";
+                    unset($files[$k]);
                 }
-            } catch (Unsupported $e) {
-                echo ' unsupported syntax: ' . $e->getMessage() . "\n";
-                echo ' skip: ' . $file . "\n";
-                unset($files[$k]);
             }
-        }
 
-        // A valid PHP input may intentionally emit no standalone translation
-        // unit (for example a compile-time trait or an interface). The shared
-        // extension source still carries its runtime metadata, so only reject
-        // an input set in which no supported source was converted at all.
-        if ($validSourceCount === 0) {
-            $this->stop('No valid source file found');
-        }
+            // A valid PHP input may intentionally emit no standalone translation
+            // unit (for example a compile-time trait or an interface). The shared
+            // extension source still carries its runtime metadata, so only reject
+            // an input set in which no supported source was converted at all.
+            if ($validSourceCount === 0) {
+                $this->stop('No valid source file found');
+            }
 
-        // A WASI library publishes WIT/Component exports rather than a native
-        // TypePHP shared-library ABI, so a PHP import stub would be misleading.
-        if ($this->isBuildModeLib() && !$this->isWasiTarget()) {
-            $this->genLibraryImportStub($files);
-        }
+            // A WASI library publishes WIT/Component exports rather than a native
+            // TypePHP shared-library ABI, so a PHP import stub would be misleading.
+            if ($this->isBuildModeLib() && !$this->isWasiTarget()) {
+                $this->genLibraryImportStub($files);
+            }
 
-        // 生成构建期内部头文件：函数声明、运行时数据声明
-        $this->genFunctionDeclarations($this->getIncludeDir() . "/php_{$this->targetName}_func_decl.h");
-        $this->genDataDeclarations($this->getIncludeDir() . "/php_{$this->targetName}_data_decl.h");
-        // 生成扩展模块源文件
-        $sourceFiles[] = $this->genExtension();
+            // 生成构建期内部头文件：函数声明、运行时数据声明
+            $this->genFunctionDeclarations($this->getIncludeDir() . "/php_{$this->targetName}_func_decl.h");
+            $this->genDataDeclarations($this->getIncludeDir() . "/php_{$this->targetName}_data_decl.h");
+            // 生成扩展模块源文件
+            $sourceFiles[] = $this->genExtension();
 
-        return $sourceFiles;
+            return $sourceFiles;
+        } finally {
+            $this->restoreCompilerPhase($previousPhase);
+        }
     }
 }
diff --git a/src/Build/WasmInterfaceGenerator.php b/src/Build/WasmInterfaceGenerator.php
index 1ab059be..6109e67e 100644
--- a/src/Build/WasmInterfaceGenerator.php
+++ b/src/Build/WasmInterfaceGenerator.php
@@ -55,7 +55,7 @@ final class WasmInterfaceGenerator
 
             $parameters = [];
             foreach ($function->argInfoList as $argument) {
-                if ($argument->byRef || $argument->variadic || $argument->default !== '') {
+                if ($argument->byRef || $argument->variadic || $argument->hasDefaultValue()) {
                     throw new RuntimeException(
                         "WasmExport parameter \${$argument->phpName} of {$displayName}() cannot be by-reference, variadic, or optional"
                     );
diff --git a/src/CompilerBase.php b/src/CompilerBase.php
index 0924868b..0e05a3d8 100644
--- a/src/CompilerBase.php
+++ b/src/CompilerBase.php
@@ -316,6 +316,9 @@ class CompilerBase implements PropertyAccessContext
      */
     protected array $persistentPropMap = [];
     protected int $persistentPropIndex = 0;
+    /** @var array<string, array<Node\Stmt>> Prepared declaration ASTs keyed by real path. */
+    protected array $preparedFileAsts = [];
+    protected bool $declarationExpressionsFinalized = false;
     protected const array PHP_RUNTIME_TYPE_MAP = [
         'integer' => Type::INT,
         'double' => Type::FLOAT,
@@ -1277,19 +1280,6 @@ class CompilerBase implements PropertyAccessContext
     {
         if (str_contains($funcName, '::')) {
             [$class] = explode('::', $funcName, 2);
-
-            // Class and method caches use parallel lifetime domains. Once a
-            // class has been assigned an ID, keep every subsequently resolved
-            // method in the same domain even if the class becomes visible in
-            // the symbol repository later in the prepare pass. Otherwise a
-            // request-local class ID may be used to index persistentClassMap.
-            if (isset($this->classMap[$class])) {
-                return false;
-            }
-            if (isset($this->persistentClassMap[$class])) {
-                return true;
-            }
-
             return $this->isProcessStableClass($class);
         }
         if ($this->hasFunction($funcName)) {
@@ -1301,6 +1291,7 @@ class CompilerBase implements PropertyAccessContext
 
     protected function getClassId(string $className): int
     {
+        $this->assertCompilerPhase(self::PHASE_CONVERT, 'class cache ID allocation');
         if (isset($this->classMap[$className])) {
             return $this->classMap[$className];
         }
@@ -1319,6 +1310,7 @@ class CompilerBase implements PropertyAccessContext
 
     protected function getFuncId(string $funcName): int
     {
+        $this->assertCompilerPhase(self::PHASE_CONVERT, 'function cache ID allocation');
         if (isset($this->funcMap[$funcName])) {
             return $this->funcMap[$funcName];
         }
@@ -1346,6 +1338,7 @@ class CompilerBase implements PropertyAccessContext
      */
     protected function getPropertyId(string $className, string $propName): int
     {
+        $this->assertCompilerPhase(self::PHASE_CONVERT, 'property cache ID allocation');
         $key = $className . '::' . $propName;
         if (isset($this->persistentPropMap[$key])) {
             return $this->persistentPropMap[$key];
@@ -2869,6 +2862,9 @@ class CompilerBase implements PropertyAccessContext
                 if ($interfaceConstDef->type === Type::ARRAY) {
                     return self::PREFIX . $this->getNativeName($interfaceConstDef->name, $interfaceDef->namespace, $interfaceDef->name);
                 }
+                if (!$interfaceConstDef->codegenFinalized) {
+                    return false;
+                }
                 $expr->setAttribute('nativeConst', $interfaceConstDef);
                 return $interfaceConstDef->value;
             }
@@ -2887,6 +2883,13 @@ class CompilerBase implements PropertyAccessContext
         if ($constDef->type === Type::ARRAY) {
             return self::PREFIX . $this->getNativeName($constDef->name, $classDef->namespace, $classDef->name);
         } else {
+            // Forward constant references may be encountered while the
+            // declaration-expression pass is still visiting another file.
+            // Fall back to the Zend class-constant lookup instead of emitting
+            // an incomplete value; the lookup is cached in the convert phase.
+            if (!$constDef->codegenFinalized) {
+                return false;
+            }
             $expr->setAttribute('nativeConst', $constDef);
             return $constDef->value;
         }
diff --git a/src/Entity/ArgInfo.php b/src/Entity/ArgInfo.php
index a7d9038d..b7c17f70 100644
--- a/src/Entity/ArgInfo.php
+++ b/src/Entity/ArgInfo.php
@@ -19,6 +19,8 @@ class ArgInfo
     public string $type;
     public string $default = '';
     public ?ArrayInitPlan $arrayInitPlan = null;
+    /** Original declaration AST; lowered to $default only in the convert phase. */
+    public ?Expr $defaultExpr = null;
     public ?Expr $defaultValue = null;
     public string $class = '';
 
@@ -56,4 +58,9 @@ class ArgInfo
 
     /** Original union/nullable AST node. Only set when typeCheck is non-null. */
     public ?NodeAbstract $typeNode = null;
+
+    public function hasDefaultValue(): bool
+    {
+        return $this->defaultExpr !== null;
+    }
 }
diff --git a/src/Entity/ConstantDef.php b/src/Entity/ConstantDef.php
index ed587ee9..c4c62cde 100644
--- a/src/Entity/ConstantDef.php
+++ b/src/Entity/ConstantDef.php
@@ -19,6 +19,8 @@ class ConstantDef
     public string $arrayExpr = '';
     public string $class = '';
     public ?NodeAbstract $valueExpr = null;
+    /** True after the declaration AST has been lowered to C++ in convert. */
+    public bool $codegenFinalized = false;
     /** Explicit declared type (e.g. `const int FOO`); null for inferred/untyped constants. */
     public ?string $declaredType = null;
 
diff --git a/src/Entity/PropertyDef.php b/src/Entity/PropertyDef.php
index c36891fa..cd3a0b01 100644
--- a/src/Entity/PropertyDef.php
+++ b/src/Entity/PropertyDef.php
@@ -19,6 +19,8 @@ class PropertyDef
     public int $flags;
     public ?string $default = null;
     public ?ArrayInitPlan $arrayInitPlan = null;
+    /** Original declaration AST; lowered to $default only in the convert phase. */
+    public ?NodeAbstract $defaultExpr = null;
     public ?ArrayDefinition $arrayDef = null;
     public bool $nullable = false;
     /** The declared type is TypePHP's unconstrained, reference-capable `any` type. */
diff --git a/src/Generator/CallArgumentGenerator.php b/src/Generator/CallArgumentGenerator.php
index f60d35b5..2e27a97a 100644
--- a/src/Generator/CallArgumentGenerator.php
+++ b/src/Generator/CallArgumentGenerator.php
@@ -99,7 +99,7 @@ trait CallArgumentGenerator
                             'Named calls to Native virtual methods cannot skip an earlier optional parameter',
                         );
                     }
-                    if ($argInfo->default === '') {
+                    if (!$argInfo->hasDefaultValue()) {
                         $errorNode = null;
                         foreach ($callArgs as $a) {
                             if ($a instanceof Node\Arg && $a->name) {
diff --git a/src/Generator/DefaultArgumentGenerator.php b/src/Generator/DefaultArgumentGenerator.php
index ef41305a..2242f3b7 100644
--- a/src/Generator/DefaultArgumentGenerator.php
+++ b/src/Generator/DefaultArgumentGenerator.php
@@ -127,6 +127,6 @@ trait DefaultArgumentGenerator
             return true;
         }
 
-        return $argInfo->default !== '';
+        return $argInfo->hasDefaultValue();
     }
 }
diff --git a/src/Preprocessor.php b/src/Preprocessor.php
index a663b15e..1926cd62 100644
--- a/src/Preprocessor.php
+++ b/src/Preprocessor.php
@@ -303,6 +303,11 @@ class Preprocessor extends CompilerBase
             $traverser->addVisitor(new ConstantExpressionValidationVisitor($this->phpVersion));
             $traverser->addVisitor(new RuntimeAttributeFactoryLowering($this->file));
             $stmts = $traverser->traverse($ast);
+            // Keep the resolved declaration AST until convert. Defaults and
+            // constants are validated here, but their C++ expressions are not
+            // generated until the complete symbol table is available.
+            $this->preparedFileAsts[$this->file] = $stmts;
+            $this->declarationExpressionsFinalized = false;
             // CompilerTest and embedding users may invoke prepareFile()
             // directly instead of the project pipeline. Preserve same-file
             // forward Native references for that public entry path as well.
@@ -350,6 +355,218 @@ class Preprocessor extends CompilerBase
         }
     }
 
+    /**
+     * Lower declaration-only constant expressions after every symbol is known.
+     *
+     * @param list<string> $files
+     */
+    public function finalizeDeclarationExpressions(array $files): void
+    {
+        $this->assertCompilerPhase(self::PHASE_CONVERT, 'declaration expression finalization');
+        if ($this->declarationExpressionsFinalized) {
+            return;
+        }
+        foreach ($files as $file) {
+            $path = realpath($file);
+            if ($path === false || !isset($this->preparedFileAsts[$path])) {
+                continue;
+            }
+            $this->loadFile($path);
+            $this->resetFile();
+            $this->resetFunction();
+            $this->resetMethod();
+            $this->resetClass();
+            $this->resetNamespace();
+            $this->finalizeDeclarationStatementList($this->preparedFileAsts[$path]);
+        }
+        $this->declarationExpressionsFinalized = true;
+    }
+
+    /** @param array<Node\Stmt> $statements */
+    private function finalizeDeclarationStatementList(array $statements): void
+    {
+        foreach ($statements as $statement) {
+            if ($statement instanceof Node\Stmt\Namespace_) {
+                $this->resetClass();
+                $this->resetMethod();
+                $this->resetFunction();
+                $this->resetNamespace();
+                $this->namespace = $statement->name ? $this->parseIdentifier($statement->name) : '';
+                $this->finalizeDeclarationStatementList($statement->stmts);
+                continue;
+            }
+            if ($statement instanceof Node\Stmt\Use_) {
+                $this->parseUse($statement);
+                continue;
+            }
+            if ($statement instanceof Node\Stmt\GroupUse) {
+                $this->parseGroupUse($statement);
+                continue;
+            }
+            if ($statement instanceof Node\Stmt\Class_
+                || $statement instanceof Node\Stmt\Trait_
+                || $statement instanceof Node\Stmt\Enum_
+            ) {
+                $this->finalizeClassDeclarationExpressions($statement);
+                continue;
+            }
+            if ($statement instanceof Node\Stmt\Interface_) {
+                $this->finalizeInterfaceDeclarationExpressions($statement);
+                continue;
+            }
+            if ($statement instanceof Node\Stmt\Function_) {
+                $this->resetClass();
+                $this->resetMethod();
+                $this->finalizePreparedFunctionDefaults(
+                    $statement,
+                    $this->getFunction($this->getFunctionName($statement)),
+                );
+                continue;
+            }
+            if ($statement instanceof Node\Stmt\Const_) {
+                $this->finalizeGlobalConstantExpressions($statement);
+            }
+        }
+    }
+
+    private function finalizeClassDeclarationExpressions(
+        Node\Stmt\Class_|Node\Stmt\Trait_|Node\Stmt\Enum_ $class,
+    ): void {
+        $this->resetClass();
+        $this->class = $this->parseIdentifier($class->name);
+        $this->classDef = $this->getClass($this->getFullClassName());
+        foreach ($class->stmts as $statement) {
+            if ($statement instanceof Node\Stmt\ClassConst) {
+                foreach ($statement->consts as $constant) {
+                    $name = $this->parseIdentifier($constant->name);
+                    $this->finalizePreparedConstant(
+                        $this->classDef->getConstant($name),
+                        $constant->value,
+                    );
+                }
+                continue;
+            }
+            if ($statement instanceof Node\Stmt\Property) {
+                foreach ($statement->props as $property) {
+                    $name = $this->parseIdentifier($property->name);
+                    if ($property->default !== null && $this->classDef->hasProperty($name)) {
+                        $this->finalizePreparedProperty(
+                            $this->classDef->getProperty($name),
+                            $property->default,
+                        );
+                    }
+                }
+                continue;
+            }
+            if (!$statement instanceof Node\Stmt\ClassMethod) {
+                continue;
+            }
+            $name = $this->getMethodName($statement);
+            $this->resetMethod();
+            $this->method = $name;
+            $this->methodDef = $this->classDef->hasMethod($name)
+                ? $this->classDef->getMethod($name)
+                : ($this->classDef->hasAbstractMethod($name)
+                    ? $this->classDef->getAbstractMethod($name)
+                    : null);
+            if ($this->methodDef !== null && $this->methodDef->functionDef !== null) {
+                $this->finalizePreparedFunctionDefaults($statement, $this->methodDef->functionDef);
+            }
+        }
+    }
+
+    private function finalizeInterfaceDeclarationExpressions(Node\Stmt\Interface_ $interface): void
+    {
+        $this->resetClass();
+        $this->interface = $this->parseIdentifier($interface->name);
+        $this->interfaceDef = $this->getInterface($this->getFullClassLikeName());
+        foreach ($interface->stmts as $statement) {
+            if ($statement instanceof Node\Stmt\ClassConst) {
+                foreach ($statement->consts as $constant) {
+                    $name = $this->parseIdentifier($constant->name);
+                    $this->finalizePreparedConstant(
+                        $this->interfaceDef->constants[$name],
+                        $constant->value,
+                    );
+                }
+                continue;
+            }
+            if (!$statement instanceof Node\Stmt\ClassMethod) {
+                continue;
+            }
+            $name = $this->getMethodName($statement);
+            $this->resetMethod();
+            $this->method = $name;
+            $this->methodDef = $this->interfaceDef->methods[strtolower($name)] ?? null;
+            if ($this->methodDef !== null && $this->methodDef->functionDef !== null) {
+                $this->finalizePreparedFunctionDefaults($statement, $this->methodDef->functionDef);
+            }
+        }
+        $this->interface = '';
+        $this->interfaceDef = null;
+    }
+
+    private function finalizePreparedFunctionDefaults(
+        Node\Stmt\Function_|Node\Stmt\ClassMethod $function,
+        FunctionDef $functionDef,
+    ): void {
+        $this->resetFunction();
+        $this->function = $this->parseIdentifier($function->name);
+        $this->functionDef = $functionDef;
+        foreach ($function->params as $index => $parameter) {
+            if ($parameter->default === null || !isset($functionDef->argInfoList[$index])) {
+                continue;
+            }
+            $argument = $functionDef->argInfoList[$index];
+            $argument->default = '';
+            $argument->arrayInitPlan = null;
+            $this->lowerArgumentDefault($parameter, $argument);
+        }
+    }
+
+    private function finalizePreparedProperty(PropertyDef $property, Node\Expr $expression): void
+    {
+        $this->resetFunction();
+        $property->arrayInitPlan = null;
+        if ($expression instanceof Node\Expr\Array_) {
+            $property->arrayInitPlan = $this->buildLiteralArrayInitPlan($expression);
+            $property->default = $property->arrayInitPlan->expr;
+        } else {
+            $property->default = $this->parseIdentifier($expression);
+        }
+    }
+
+    private function finalizePreparedConstant(ConstantDef $constant, Node\Expr $expression): void
+    {
+        $this->resetFunction();
+        $constant->arrayExpr = '';
+        $constant->value = $this->parseIdentifier($expression);
+        if ($this->context->beforeStmtLines) {
+            if ($this->context->localVars) {
+                $constant->arrayExpr .= $this->genScopeVarDecl();
+            }
+            $constant->arrayExpr .= $this->parseBeforeStmtLines();
+        }
+        $constant->codegenFinalized = true;
+    }
+
+    private function finalizeGlobalConstantExpressions(Node\Stmt\Const_ $statement): void
+    {
+        foreach ($statement->consts as $constant) {
+            $name = $this->parseIdentifier($constant->name);
+            if ($this->namespace !== '') {
+                $name = $this->namespace . '\\' . $name;
+            }
+            $key = $this->escapeConstVar($name);
+            if (!isset($this->constants[$key])) {
+                continue;
+            }
+            $this->resetFunction();
+            $this->constants[$key]->value = $this->parseIdentifier($constant->value);
+            $this->constants[$key]->codegenFinalized = true;
+        }
+    }
+
     /** @param array<Node> $stmts */
     private function hasLibraryImportAnnotation(array $stmts): bool
     {
@@ -679,28 +896,10 @@ class Preprocessor extends CompilerBase
                 $list[] = $this->genArgumentDeclaration($argInfo);
             }
             if ($param->default) {
-                $arrayInitPlan = $param->default instanceof Node\Expr\Array_
-                    ? $this->withoutLocalClassEntryHoisting(
-                        fn (): ArrayInitPlan => $this->buildLiteralArrayInitPlan($param->default),
-                    )
-                    : null;
-                if ($param->byRef) {
-                    if ($this->isEmptyArray($param->default)) {
-                        $argInfo->default = 'php::getEmptyArrayRef()';
-                        $argInfo->defaultValue = null;
-                    } elseif ($this->isNull($param->default)) {
-                        $argInfo->default = 'nullptr';
-                        $argInfo->defaultValue = null;
-                    } elseif ($arrayInitPlan) {
-                        $argInfo->default = 'php::newReference(' . $arrayInitPlan->expr . ')';
-                        $argInfo->arrayInitPlan = $arrayInitPlan;
-                    } else {
-                        $argInfo->default = 'php::newReference(' . $this->parseParamDefaultValue($param->default) . ')';
-                    }
-                } else {
-                    $argInfo->default = $arrayInitPlan ? $arrayInitPlan->expr : $this->parseParamDefaultValue($param->default);
-                    $argInfo->arrayInitPlan = $arrayInitPlan;
-                    $argInfo->defaultValue = $param->default;
+                $argInfo->defaultExpr = $param->default;
+                $argInfo->defaultValue = $param->default;
+                if ($this->compilerPhase === self::PHASE_CONVERT) {
+                    $this->lowerArgumentDefault($param, $argInfo);
                 }
             } elseif ($param->variadic) {
                 // 变长参数可以视为空数组默认值
@@ -713,6 +912,33 @@ class Preprocessor extends CompilerBase
         $functionDef->argCountRequired = $lastRequiredIndex + 1;
     }
 
+    protected function lowerArgumentDefault(Node\Param $param, ArgInfo $argInfo): void
+    {
+        if ($param->default === null) {
+            return;
+        }
+        $arrayInitPlan = $param->default instanceof Node\Expr\Array_
+            ? $this->withoutLocalClassEntryHoisting(
+                fn (): ArrayInitPlan => $this->buildLiteralArrayInitPlan($param->default),
+            )
+            : null;
+        $argInfo->arrayInitPlan = $arrayInitPlan;
+        if ($param->byRef) {
+            if ($this->isEmptyArray($param->default)) {
+                $argInfo->default = 'php::getEmptyArrayRef()';
+                return;
+            }
+            if ($this->isNull($param->default)) {
+                $argInfo->default = 'nullptr';
+                return;
+            }
+            $value = $arrayInitPlan?->expr ?? $this->parseParamDefaultValue($param->default);
+            $argInfo->default = 'php::newReference(' . $value . ')';
+            return;
+        }
+        $argInfo->default = $arrayInitPlan?->expr ?? $this->parseParamDefaultValue($param->default);
+    }
+
     protected function getFunctionDisplayName(FunctionDef $functionDef): string
     {
         if ($this->class) {
@@ -1398,13 +1624,16 @@ class Preprocessor extends CompilerBase
     private function parseClassLikeConstant(Node\Const_ $const, int $flags, string $type, string $class = '', ?string $declaredType = null): ConstantDef
     {
         $constName = $this->parseIdentifier($const->name);
-        $constValue = $this->parseIdentifier($const->value);
+        $constValue = $this->compilerPhase === self::PHASE_CONVERT
+            ? $this->parseIdentifier($const->value)
+            : '';
 
         $constInfo = new ConstantDef($constName, $flags, $type, $constValue);
         $constInfo->valueExpr = $const->value;
         $constInfo->declaredType = $declaredType;
+        $constInfo->codegenFinalized = $this->compilerPhase === self::PHASE_CONVERT;
 
-        if ($this->context->beforeStmtLines) {
+        if ($constInfo->codegenFinalized && $this->context->beforeStmtLines) {
             $arrayExpr = '';
             if ($this->context->localVars) {
                 $arrayExpr .= $this->genScopeVarDecl();
@@ -1455,8 +1684,10 @@ class Preprocessor extends CompilerBase
         if ($defaultNode !== null) {
             $this->checkPropertyDefaultType($name, $typeNode, $defaultNode, $errorNode);
             if ($defaultNode instanceof Node\Expr\Array_) {
-                $arrayInitPlan = $this->buildLiteralArrayInitPlan($defaultNode);
-                $default = $arrayInitPlan->expr;
+                if ($this->compilerPhase === self::PHASE_CONVERT) {
+                    $arrayInitPlan = $this->buildLiteralArrayInitPlan($defaultNode);
+                    $default = $arrayInitPlan->expr;
+                }
                 // Only narrow the property type to `array` when the declared type
                 // cannot already hold an array. `mixed`/`iterable`/union/nullable
                 // types are represented as php::Var and can legally store an array,
@@ -1465,7 +1696,7 @@ class Preprocessor extends CompilerBase
                 if ($type !== Type::VAR) {
                     $type = Type::ARRAY;
                 }
-            } else {
+            } elseif ($this->compilerPhase === self::PHASE_CONVERT) {
                 $default = $this->parseIdentifier($defaultNode);
             }
         }
@@ -1489,6 +1720,7 @@ class Preprocessor extends CompilerBase
         }
         $propDef->readonly = (bool) (($flags | $this->classDef->flags) & Modifiers::READONLY);
         $propDef->class = $class;
+        $propDef->defaultExpr = $defaultNode;
         $propDef->arrayInitPlan = $arrayInitPlan;
         $propDef->requiresRuntimeDefaultInit = $this->propertyDefaultRequiresRuntimeInit($defaultNode);
         $propDef->promoted = $promoted;
diff --git a/src/Resolver/DeclarationSymbolTrait.php b/src/Resolver/DeclarationSymbolTrait.php
index cc2949bb..ea3aa2e6 100644
--- a/src/Resolver/DeclarationSymbolTrait.php
+++ b/src/Resolver/DeclarationSymbolTrait.php
@@ -17,7 +17,9 @@ trait DeclarationSymbolTrait
     {
         foreach ($v2->consts as $const) {
             $name  = $this->parseIdentifier($const->name);
-            $value = $this->parseIdentifier($const->value);
+            $value = $this->compilerPhase === self::PHASE_CONVERT
+                ? $this->parseIdentifier($const->value)
+                : '';
             if ($this->namespace) {
                 $name = $this->namespace . '\\' . $name;
             }
@@ -30,7 +32,10 @@ trait DeclarationSymbolTrait
         $constInfo                    = new \stdClass();
         $constInfo->value             = $value;
         $constInfo->valueExpr         = $valueExpr;
-        $constInfo->type              = $this->detectStrValueType($value);
+        $constInfo->type = $this->compilerPhase === self::PHASE_CONVERT
+            ? $this->detectStrValueType($value)
+            : Type::VAR;
+        $constInfo->codegenFinalized = $this->compilerPhase === self::PHASE_CONVERT;
         $constInfo->namespace = $this->namespace;
         $constInfo->name = $name;
         $this->constants[$this->escapeConstVar($name)] = $constInfo;
diff --git a/src/Translator.php b/src/Translator.php
index dcfe3a19..8a7b170b 100644
--- a/src/Translator.php
+++ b/src/Translator.php
@@ -537,6 +537,9 @@ class Translator extends Preprocessor
     {
         $previousPhase = $this->enterCompilerPhase(self::PHASE_CONVERT);
         try {
+            if (!$this->declarationExpressionsFinalized) {
+                $this->finalizeDeclarationExpressions(array_keys($this->preparedFileAsts));
+            }
             $file = realpath($file);
             $phpCode = $this->loadFile($file);
             $this->localHeaders = [];
@@ -808,6 +811,16 @@ class Translator extends Preprocessor
     }
 
     public function genExtension(): string
+    {
+        $previousPhase = $this->enterCompilerPhase(self::PHASE_CONVERT);
+        try {
+            return $this->doGenExtension();
+        } finally {
+            $this->restoreCompilerPhase($previousPhase);
+        }
+    }
+
+    private function doGenExtension(): string
     {
         if ($this->isBuildModeBin()) {
             if (!$this->hasFunction(self::ENTRY_FUNCTION)) {
@@ -1860,7 +1873,7 @@ CODE;
                             . ' = ' . $this->genDefaultArgumentExpr($name, $argumentIndex);
                     } else {
                         $arg = $this->genArgumentDeclaration($argInfo);
-                        if ($argInfo->default !== '' && !$this->isConstructorNativeFunction($func)) {
+                        if ($argInfo->hasDefaultValue() && !$this->isConstructorNativeFunction($func)) {
                             $arg .= ' = ' . $this->genDefaultArgumentExpr($name, $argumentIndex);
                         }
                     }
@@ -3722,7 +3735,7 @@ CODE;
                 $cppCode .= $this->getIndent() . '}' . PHP_EOL;
                 $cppCode .= $this->genExtraNamedVariadicArgs($var);
             } else {
-                if ($argInfo->default !== '') {
+                if ($argInfo->hasDefaultValue()) {
                     $nativeName = str_starts_with($fn, self::PREFIX)
                         ? substr($fn, strlen(self::PREFIX))
                         : $fn;