diff --git a/.github/workflows/windows-ci.yml b/.github/workflows/windows-ci.yml
index f733c0beda7..ab61f84ea31 100644
--- a/.github/workflows/windows-ci.yml
+++ b/.github/workflows/windows-ci.yml
@@ -56,7 +56,7 @@ jobs:
         with:
           php-version: '8.5'
           #ini-values: zend.assertions=1, assert.exception=1, opcache.enable_cli=1, opcache.jit=function, opcache.jit_buffer_size=512M
-          ini-values: zend.assertions=1, assert.exception=1, opcache.enable_cli=1, opcache.jit=off
+          ini-values: zend.assertions=1, assert.exception=1
           tools: composer:v2
           coverage: none
           #extensions: none, curl, dom, filter, intl, json, libxml, mbstring, openssl, opcache, pcre, phar, reflection, simplexml, spl, tokenizer, xml, xmlwriter
diff --git a/src/Psalm/Internal/Analyzer/Statements/Expression/Call/NewAnalyzer.php b/src/Psalm/Internal/Analyzer/Statements/Expression/Call/NewAnalyzer.php
index 3d70bc56bba..94531fa4d34 100644
--- a/src/Psalm/Internal/Analyzer/Statements/Expression/Call/NewAnalyzer.php
+++ b/src/Psalm/Internal/Analyzer/Statements/Expression/Call/NewAnalyzer.php
@@ -1110,6 +1110,8 @@ private static function getNewType(
      * Whether the constructor binds the given template through a `class-string<T>`
      * (`T::class`) parameter position, which names the template's type exactly
      * rather than providing a value of it.
+     *
+     * @psalm-mutation-free
      */
     private static function templateBoundThroughClassString(
         MethodStorage $method_storage,
@@ -1139,6 +1141,7 @@ private static function templateBoundThroughClassString(
      * only have been fixed at the construction site.
      *
      * @return array<string, true>
+     * @psalm-mutation-free
      */
     private static function getUnconstrainableTemplates(ClassLikeStorage $storage): array
     {
diff --git a/src/Psalm/Internal/Analyzer/StatementsAnalyzer.php b/src/Psalm/Internal/Analyzer/StatementsAnalyzer.php
index 1bbf23c481e..a5aad70ea0e 100644
--- a/src/Psalm/Internal/Analyzer/StatementsAnalyzer.php
+++ b/src/Psalm/Internal/Analyzer/StatementsAnalyzer.php
@@ -168,8 +168,16 @@ final class StatementsAnalyzer extends SourceAnalyzer
      */
     public readonly bool $owns_type_variable_tracker;
 
-    public function __construct(protected SourceAnalyzer $source, public NodeDataProvider $node_data)
-    {
+    private int $depth = 0;
+
+    /**
+     * @psalm-mutation-free
+     */
+    public function __construct(
+        protected SourceAnalyzer $source,
+        public NodeDataProvider $node_data,
+        private readonly bool $root_scope,
+    ) {
         $this->file_analyzer = $source->getFileAnalyzer();
         $this->codebase = $source->getCodebase();
 
@@ -185,10 +193,17 @@ public function __construct(protected SourceAnalyzer $source, public NodeDataPro
             $this->owns_type_variable_tracker = true;
         }
 
-        if ($this->codebase->taint_flow_graph) {
-            $this->data_flow_graph = new TaintFlowGraph();
-        } elseif ($this->codebase->find_unused_variables) {
-            $this->data_flow_graph = new VariableUseGraph();
+        if ($this->codebase->taint_flow_graph
+            && $root_scope
+            && $this->codebase->config->trackTaintsInPath($this->getFilePath())
+        ) {
+            $this->data_flow_graph = $this->taint_flow_graph = $this->codebase->taint_flow_graph;
+        }
+        if ($this->codebase->find_unused_variables) {
+            $this->data_flow_graph = $this->variable_use_graph = new VariableUseGraph();
+        }
+        if ($this->taint_flow_graph && $this->variable_use_graph) {
+            $this->data_flow_graph = new CombinedFlowGraph($this->variable_use_graph, $this->taint_flow_graph);
         }
     }
 
diff --git a/src/Psalm/Internal/Provider/ReturnTypeProvider/FilterUtils.php b/src/Psalm/Internal/Provider/ReturnTypeProvider/FilterUtils.php
index 6331724668a..0d395b965fd 100644
--- a/src/Psalm/Internal/Provider/ReturnTypeProvider/FilterUtils.php
+++ b/src/Psalm/Internal/Provider/ReturnTypeProvider/FilterUtils.php
@@ -20,7 +20,6 @@
 use Psalm\Type\Atomic\TArray;
 use Psalm\Type\Atomic\TArrayKey;
 use Psalm\Type\Atomic\TBool;
-use Psalm\Type\Atomic\TClosure;
 use Psalm\Type\Atomic\TFalse;
 use Psalm\Type\Atomic\TFloat;
 use Psalm\Type\Atomic\TInt;
diff --git a/src/Psalm/Internal/Type/TypeVariableBounds.php b/src/Psalm/Internal/Type/TypeVariableBounds.php
index 65597cb2d11..be941e8f795 100644
--- a/src/Psalm/Internal/Type/TypeVariableBounds.php
+++ b/src/Psalm/Internal/Type/TypeVariableBounds.php
@@ -12,6 +12,10 @@
  * when the surrounding function-like has been analyzed.
  *
  * @internal
+ * @psalm-suppress MissingImmutableAnnotation TypeVariableTracker::addBounds()
+ *     appends to lower_bounds/upper_bounds in place, on purpose: every
+ *     TTypeVariable holding a reference to this object needs to see later
+ *     constraints as they're recorded during analysis.
  */
 final class TypeVariableBounds
 {
@@ -24,6 +28,7 @@ final class TypeVariableBounds
     /**
      * @param list<TemplateBound> $lower_bounds
      * @param list<TemplateBound> $upper_bounds
+     * @psalm-mutation-free
      */
     public function __construct(
         public array $lower_bounds = [],
diff --git a/src/Psalm/Internal/Type/TypeVariableTracker.php b/src/Psalm/Internal/Type/TypeVariableTracker.php
index dbe5d429258..b4433c0b8ce 100644
--- a/src/Psalm/Internal/Type/TypeVariableTracker.php
+++ b/src/Psalm/Internal/Type/TypeVariableTracker.php
@@ -40,6 +40,8 @@ final class TypeVariableTracker
 
     /**
      * Mints a fresh type variable name, registering its bound storage.
+     *
+     * @psalm-external-mutation-free
      */
     public function addVariable(TypeVariableBounds $bounds): string
     {
@@ -80,6 +82,8 @@ public function addBounds(array $lower, array $upper, ?CodeLocation $pos): void
      * below. Used where a concrete shape is required (property reads, method
      * call returns); the variable itself stays in the object's type params,
      * so later uses still constrain it.
+     *
+     * @psalm-external-mutation-free
      */
     public static function resolveTypeVariables(Union $type, ?Codebase $codebase): Union
     {
@@ -327,6 +331,7 @@ private static function reconcileLowerBoundsWithUpperBounds(
      *
      * @param list<TemplateBound> $lower_bounds
      * @return list<TemplateBound>
+     * @psalm-mutation-free
      */
     private static function getRelevantBounds(array $lower_bounds): array
     {
diff --git a/src/Psalm/Internal/TypeVisitor/TypeVariableResolver.php b/src/Psalm/Internal/TypeVisitor/TypeVariableResolver.php
index 67446826ada..4dd48ce21a8 100644
--- a/src/Psalm/Internal/TypeVisitor/TypeVariableResolver.php
+++ b/src/Psalm/Internal/TypeVisitor/TypeVariableResolver.php
@@ -29,6 +29,9 @@ final class TypeVariableResolver extends MutableTypeVisitor
 {
     public bool $resolved_a_variable = false;
 
+    /**
+     * @psalm-mutation-free
+     */
     public function __construct(
         private readonly ?Codebase $codebase,
     ) {
diff --git a/src/Psalm/Issue/IncompatibleTypeParameters.php b/src/Psalm/Issue/IncompatibleTypeParameters.php
index c8636c03b1b..7689a3f2cd7 100644
--- a/src/Psalm/Issue/IncompatibleTypeParameters.php
+++ b/src/Psalm/Issue/IncompatibleTypeParameters.php
@@ -7,5 +7,5 @@
 final class IncompatibleTypeParameters extends CodeIssue
 {
     public const ERROR_LEVEL = 1;
-    public const SHORTCODE = 362;
+    public const SHORTCODE = 368;
 }
diff --git a/src/Psalm/Type/Atomic/TTypeVariable.php b/src/Psalm/Type/Atomic/TTypeVariable.php
index 06c5f733c58..2cbd1b14b96 100644
--- a/src/Psalm/Type/Atomic/TTypeVariable.php
+++ b/src/Psalm/Type/Atomic/TTypeVariable.php
@@ -66,7 +66,8 @@ public function getId(bool $exact = true, bool $nested = false): string
     }
 
     /**
-     * @param  array<lowercase-string, string> $aliased_classes
+     * @param array<lowercase-string, string> $aliased_classes
+     * @psalm-pure
      */
     #[Override]
     public function toPhpString(
@@ -78,6 +79,9 @@ public function toPhpString(
         return null;
     }
 
+    /**
+     * @psalm-pure
+     */
     #[Override]
     public function canBeFullyExpressedInPhp(int $analysis_php_version_id): bool
     {
diff --git a/tests/Template/TypeVariableTest.php b/tests/Template/TypeVariableTest.php
index c7561e96c17..70d1deda0bb 100644
--- a/tests/Template/TypeVariableTest.php
+++ b/tests/Template/TypeVariableTest.php
@@ -16,6 +16,9 @@ final class TypeVariableTest extends TestCase
     use InvalidCodeAnalysisTestTrait;
     use ValidCodeAnalysisTestTrait;
 
+    /**
+     * @psalm-pure
+     */
     #[Override]
     public function providerValidCodeParse(): iterable
     {
@@ -84,6 +87,9 @@ function probe(): void {
         ];
     }
 
+    /**
+     * @psalm-pure
+     */
     #[Override]
     public function providerInvalidCodeParse(): iterable
     {