1 files changed, 153 insertions, 0 deletions
diff --git a/scripts/plugin-class-classifier/src/NativeFixedPoint.php b/scripts/plugin-class-classifier/src/NativeFixedPoint.php
new file mode 100644
index 00000000..7b0ecc65
--- /dev/null
+++ b/scripts/plugin-class-classifier/src/NativeFixedPoint.php
@@ -0,0 +1,153 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Shirabe\PluginClassifier;
+
+/**
+ * Decides php-native vs unsupported for classes the closure never reached,
+ * per "Mechanical rules" step 6: leaf-first fixed point over body
+ * references.
+ *
+ * What a reference may legally target from real PHP running in the child
+ * process:
+ *
+ *   - `new X` works when X exists there as executable-or-local code: a
+ *     php-native class, a two-world class (real console code), a vendor
+ *     class (real package code), a rust-snapshot value object (values are
+ *     built locally), or a PHP builtin. Constructing a rust-proxy service
+ *     is the unresolved dual-instantiation case and demotes.
+ *   - `X::method()` / `X::$prop` additionally works when X is any stubbed
+ *     reachable class (proxy stubs carry static methods as RPC), so only
+ *     unsupported peers and unknown types demote.
+ */
+final class NativeFixedPoint
+{
+    /** @var array<string, string> unreachable FQCN => 'php-native' | 'unsupported' */
+    public array $categories = [];
+
+    /** @var array<string, list<string>> FQCN => reasons for demotion */
+    public array $reasons = [];
+
+    /** @var list<string> classes writing static props with no filed disposition */
+    public array $unfiledStaticState = [];
+
+    public function __construct(
+        private readonly SourceParser $sources,
+        private readonly ReachabilityClosure $closure,
+        private readonly Lists $lists,
+        /** @var array<string, string> reachable FQCN => preliminary category */
+        private readonly array $reachableCategories,
+    ) {
+    }
+
+    public function run(): void
+    {
+        $universe = [];
+        foreach ($this->sources->classes as $fqcn => $info) {
+            if (isset($this->closure->reachable[$fqcn]) || $this->lists->isTwoWorld($fqcn)) {
+                continue;
+            }
+            if (isset($this->lists->overrides[$fqcn])) {
+                // The override fixes this class's category; it does not
+                // participate in the fixed point.
+                continue;
+            }
+            $universe[$fqcn] = $info;
+        }
+
+        foreach ($universe as $fqcn => $info) {
+            $this->categories[$fqcn] = 'php-native';
+            if ($info->writesOwnStaticProps) {
+                $disposition = $this->lists->staticDispositions[$fqcn] ?? null;
+                if ($disposition === null) {
+                    $this->unfiledStaticState[] = $fqcn;
+                    $this->demote($fqcn, 'mutable static state with no filed disposition');
+                } elseif ($disposition === 'needs-sync') {
+                    $this->demote($fqcn, 'mutable static state shared with the Rust side (needs-sync)');
+                }
+            }
+        }
+
+        do {
+            $changed = false;
+            foreach ($universe as $fqcn => $info) {
+                if ($this->categories[$fqcn] === 'unsupported') {
+                    continue;
+                }
+                $bad = $this->firstBadRef($info);
+                if ($bad !== null) {
+                    $this->demote($fqcn, $bad);
+                    $changed = true;
+                }
+            }
+        } while ($changed);
+    }
+
+    private function firstBadRef(ClassInfo $info): ?string
+    {
+        foreach (array_unique($info->newRefs) as $ref) {
+            $problem = $this->checkTarget($info, $ref, true);
+            if ($problem !== null) {
+                return $problem;
+            }
+        }
+        foreach (array_unique($info->staticRefs) as $ref) {
+            $problem = $this->checkTarget($info, $ref, false);
+            if ($problem !== null) {
+                return $problem;
+            }
+        }
+
+        return null;
+    }
+
+    private function checkTarget(ClassInfo $info, string $ref, bool $isNew): ?string
+    {
+        if ($ref === $info->fqcn) {
+            return null;
+        }
+
+        $category = $this->lists->overrides[$ref]['category']
+            ?? $this->reachableCategories[$ref]
+            ?? null;
+        if ($category !== null) {
+            if ($isNew && $category === 'rust-proxy') {
+                return "constructs proxied service $ref (dual instantiation unresolved)";
+            }
+
+            return null;
+        }
+
+        if ($this->lists->isTwoWorld($ref)) {
+            return null;
+        }
+
+        if (isset($this->sources->classes[$ref])) {
+            if (($this->categories[$ref] ?? 'unsupported') === 'unsupported') {
+                return ($isNew ? 'constructs' : 'statically references') . " unsupported type $ref";
+            }
+
+            return null;
+        }
+
+        if (VendorPackages::lookup($ref) !== null) {
+            // Vendor packages ship as real PHP in the child process
+            // regardless of their bridging category.
+            return null;
+        }
+
+        if (!str_contains($ref, '\\')) {
+            // Global namespace: PHP builtin.
+            return null;
+        }
+
+        return ($isNew ? 'constructs' : 'statically references') . " unknown type $ref";
+    }
+
+    private function demote(string $fqcn, string $reason): void
+    {
+        $this->categories[$fqcn] = 'unsupported';
+        $this->reasons[$fqcn][] = $reason;
+    }
+}