[SwiftExtract] Invoke ExtractDecider for typealiases

Sources/SwiftExtract/SwiftAnalysisVisitor.swift

@@ -527,6 +527,10 @@ final class SwiftAnalysisVisitor {
     in typeContext: ExtractedNominalType?,
     sourceFilePath: String,
   ) {
+    guard node.shouldExtract(config: config, in: typeContext, decider: analyzer.extractDecider) else {
+      return
+    }
+
     let outputName = node.name.text
     let rhsType = node.initializer.value
 

Tests/SwiftExtractTests/AnalysisResultTests.swift

@@ -13,6 +13,7 @@
 //===----------------------------------------------------------------------===//
 
 import SwiftExtract
+import SwiftSyntax
 import Testing
 
 /// End-to-end tests that drive the analysis pipeline (Swift source →
@@ -553,6 +554,35 @@ struct AnalysisResultSuite {
     #expect(fishTank.isSpecialization)
   }
 
+  @Test func typealiasTriggersDecider() throws {
+    final class RecordingDecider: ExtractDecider, @unchecked Sendable {
+      var typealiasNames: [String] = []
+      func shouldExtract(decl: DeclSyntax, in parent: ExtractedNominalType?) -> Bool {
+        if let ta = decl.as(TypeAliasDeclSyntax.self) {
+          typealiasNames.append(ta.name.text)
+        }
+        return true
+      }
+    }
+    let decider = RecordingDecider()
+    _ = try SwiftAnalyzer.analyze(
+      sources: [
+        (
+          "/fake/Source.swift",
+          """
+          public struct Tank<Element> { public init() {} }
+          public struct Fish {}
+          public typealias FishTank = Tank<Fish>
+          """
+        )
+      ],
+      moduleName: "Aquarium",
+      extractDecider: decider,
+      config: DefaultSwiftExtractConfiguration(swiftModule: "Aquarium")
+    )
+    #expect(decider.typealiasNames == ["FishTank"])
+  }
+
   // ==== -----------------------------------------------------------------------
   // MARK: Empty input