fix: address verification findings from audit remediation

- CLAUDE.md: Update TypeChecker partial file count from 10 to 11, add
  .Statements.Patterns.cs to the list
- FileCompilationPipeline: Make CodeGenResult.HasErrors derive from
  Diagnostics.HasErrors consistently with all other result structs
- ImportResolver: Remove inconsistent `\!= default` guard on
  cancellationToken in ResolveImport/ResolveFromImport, assign
  unconditionally like ResolveAllImports does
- TypeChecker.Statements.Patterns.cs: Fix doc comment (remove "tuple
  unpacking" which isn't in this file)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: antonsynd

CLAUDE.md

@@ -67,7 +67,7 @@ The semantic phase runs multiple ordered passes. Understanding this is critical
 
 **Pass 2 — Type Resolution** (`TypeResolver.cs`): Resolves type annotations on declarations to concrete types. Type inference provided by `TypeInferenceService` and `GenericTypeInferenceService`.
 
-**Pass 3 — Type Checking** (`TypeChecker.cs`, split into 10 partial files: `.cs`, `.Definitions.cs`, `.Expressions.cs`, `.Expressions.Access.cs`, `.Expressions.Access.Calls.cs`, `.Expressions.Access.Lambdas.cs`, `.Expressions.Literals.cs`, `.Expressions.Operators.cs`, `.Statements.cs`, `.Utilities.cs`): Traverses AST, infers types, records them in `SemanticInfo`. Then runs `ValidationPipeline`. Type narrowing (e.g., `if x is not None:` narrows `T?` → `T`) is tracked via `_narrowingContext` (`TypeNarrowingContext`).
+**Pass 3 — Type Checking** (`TypeChecker.cs`, split into 11 partial files: `.cs`, `.Definitions.cs`, `.Expressions.cs`, `.Expressions.Access.cs`, `.Expressions.Access.Calls.cs`, `.Expressions.Access.Lambdas.cs`, `.Expressions.Literals.cs`, `.Expressions.Operators.cs`, `.Statements.cs`, `.Statements.Patterns.cs`, `.Utilities.cs`): Traverses AST, infers types, records them in `SemanticInfo`. Then runs `ValidationPipeline`. Type narrowing (e.g., `if x is not None:` narrows `T?` → `T`) is tracked via `_narrowingContext` (`TypeNarrowingContext`).
 
 **Key registries**: `OperatorRegistry`, `ProtocolRegistry`, `BuiltinRegistry`, `ModuleRegistry`, `PrimitiveCatalog` (source of truth for primitive types and CLR mappings).
 

src/Sharpy.Compiler/FileCompilationPipeline.cs

@@ -300,7 +300,7 @@ public CodeGenResult GenerateCode(
         if (codeGenContext.HasErrors)
         {
             diagnostics.Merge(codeGenContext.Diagnostics);
-            return new CodeGenResult(csharpCode, new Dictionary<string, string>(), diagnostics, true);
+            return new CodeGenResult(csharpCode, new Dictionary<string, string>(), diagnostics);
         }
 
         // Generate C# for all imported .spy modules
@@ -324,7 +324,7 @@ public CodeGenResult GenerateCode(
             // Errors are silently skipped — matching ProjectCompiler behavior.
         }
 
-        return new CodeGenResult(csharpCode, allGeneratedFiles, diagnostics, false);
+        return new CodeGenResult(csharpCode, allGeneratedFiles, diagnostics);
     }
 
     /// <summary>
@@ -450,19 +450,17 @@ internal readonly struct CodeGenResult
     public CodeGenResult(
         string csharpCode,
         Dictionary<string, string> allGeneratedFiles,
-        DiagnosticBag diagnostics,
-        bool hasErrors)
+        DiagnosticBag diagnostics)
     {
         CSharpCode = csharpCode;
         AllGeneratedFiles = allGeneratedFiles;
         Diagnostics = diagnostics;
-        HasErrors = hasErrors;
     }
 
     public string CSharpCode { get; }
     public Dictionary<string, string> AllGeneratedFiles { get; }
     public DiagnosticBag Diagnostics { get; }
-    public bool HasErrors { get; }
+    public bool HasErrors => Diagnostics.HasErrors;
 }
 
 /// <summary>

src/Sharpy.Compiler/Semantic/ImportResolver.cs

@@ -250,8 +250,7 @@ public void ResolveAllImports(Module module, SymbolTable symbolTable, string? cu
     {
         if (currentModulePath != null)
             UpdateCurrentModule(currentModulePath);
-        if (cancellationToken != default)
-            _cancellationToken = cancellationToken;
+        _cancellationToken = cancellationToken;
         _logger.LogDebug($"Resolving import: {string.Join(", ", importStmt.Names.Select(n => n.Name))}");
 
         var result = new List<ModuleInfo?>();
@@ -320,8 +319,7 @@ public void ResolveAllImports(Module module, SymbolTable symbolTable, string? cu
     {
         if (currentModulePath != null)
             UpdateCurrentModule(currentModulePath);
-        if (cancellationToken != default)
-            _cancellationToken = cancellationToken;
+        _cancellationToken = cancellationToken;
         var importedNames = fromImport.ImportAll ? "*" : string.Join(", ", fromImport.Names.Select(n => n.AsName != null ? $"{n.Name} as {n.AsName}" : n.Name));
         _logger.LogDebug($"[ImportResolver] Resolving from-import: from {fromImport.Module} import {importedNames}");
         if (_currentModulePath != null)

src/Sharpy.Compiler/Semantic/TypeChecker.Statements.Patterns.cs

@@ -7,7 +7,7 @@
 namespace Sharpy.Compiler.Semantic;
 
 /// <summary>
-/// TypeChecker partial class: Pattern matching, tuple unpacking, and related helpers
+/// TypeChecker partial class: Pattern matching and related helpers
 /// </summary>
 internal partial class TypeChecker
 {