Make chunk validation a framework contract

internal/framework/contracts/composition_test.go

@@ -17,6 +17,7 @@ var _ contracts.Extractor = compositionExtractor{}
 var _ contracts.Merger = compositionMerger{}
 var _ contracts.Normalizer = compositionNormalizer{}
 var _ contracts.Validator = compositionValidator{}
+var _ contracts.StructuredLLMClient = compositionLLMClient{}
 var _ contracts.OutputEncoder = compositionOutputEncoder{}
 
 func TestContractsComposeAcrossPackages(t *testing.T) {
@@ -38,8 +39,9 @@ func TestContractsComposeAcrossPackages(t *testing.T) {
 	}
 
 	chunking, err := chunker.Chunk(ctx, contracts.ChunkRequest{
-		Source:   doc,
-		Metadata: map[string]any{"max_units": 2},
+		Source:    doc,
+		LLMClient: compositionLLMClient{},
+		Metadata:  map[string]any{"max_units": 2},
 	})
 	if err != nil {
 		t.Fatalf("Chunk() error = %v, want nil", err)
@@ -164,6 +166,9 @@ func (chunker compositionChunker) Chunk(ctx context.Context, req contracts.Chunk
 	if req.Source == nil {
 		return contracts.ChunkResult{}, errors.New("source document is required")
 	}
+	if req.LLMClient == nil {
+		return contracts.ChunkResult{}, errors.New("structured llm client is required")
+	}
 
 	return contracts.ChunkResult{
 		Chunks: []contracts.SourceChunk{
@@ -178,6 +183,12 @@ func (chunker compositionChunker) Chunk(ctx context.Context, req contracts.Chunk
 	}, nil
 }
 
+type compositionLLMClient struct{}
+
+func (client compositionLLMClient) CompleteStructured(ctx context.Context, req contracts.StructuredCompletionRequest, out any) (contracts.StructuredCompletionResponse, error) {
+	return contracts.StructuredCompletionResponse{}, nil
+}
+
 type compositionExtractor struct{}
 
 func (extractor compositionExtractor) Key() string {