diff --git a/internal/framework/contracts/composition_test.go b/internal/framework/contracts/composition_test.go
new file mode 100644
index 0000000..49842c3
--- /dev/null
+++ b/internal/framework/contracts/composition_test.go
@@ -0,0 +1,150 @@
+package contracts_test
+
+import (
+	"context"
+	"encoding/json"
+	"errors"
+	"testing"
+
+	"gitea.maximumdirect.net/eric/notarius/internal/core/artifacts"
+	"gitea.maximumdirect.net/eric/notarius/internal/core/source"
+	"gitea.maximumdirect.net/eric/notarius/internal/framework/contracts"
+)
+
+var _ contracts.InputAdapter = compositionAdapter{}
+var _ contracts.Extractor = compositionExtractor{}
+var _ contracts.Validator = compositionValidator{}
+
+func TestContractsComposeAcrossPackages(t *testing.T) {
+	ctx := context.Background()
+	adapter := compositionAdapter{}
+	extractor := compositionExtractor{}
+	validator := compositionValidator{}
+
+	doc, err := adapter.Parse(ctx, contracts.ParseRequest{SourceID: "source-1"})
+	if err != nil {
+		t.Fatalf("Parse() error = %v, want nil", err)
+	}
+	if err := source.ValidateDocument(doc); err != nil {
+		t.Fatalf("ValidateDocument() error = %v, want nil", err)
+	}
+
+	extraction, err := extractor.Extract(ctx, contracts.ExtractionRequest{Source: doc})
+	if err != nil {
+		t.Fatalf("Extract() error = %v, want nil", err)
+	}
+	if len(extraction.Candidates) != 1 {
+		t.Fatalf("len(Candidates) = %d, want 1", len(extraction.Candidates))
+	}
+
+	candidate := extraction.Candidates[0]
+	for _, ref := range candidate.SourceRefs {
+		if err := source.ValidateRef(doc, ref); err != nil {
+			t.Fatalf("ValidateRef() error = %v, want nil", err)
+		}
+	}
+
+	validation, err := validator.Validate(ctx, contracts.ValidationRequest{
+		Source:     doc,
+		Candidates: extraction.Candidates,
+	})
+	if err != nil {
+		t.Fatalf("Validate() error = %v, want nil", err)
+	}
+	if len(validation.Decisions) != 1 {
+		t.Fatalf("len(Decisions) = %d, want 1", len(validation.Decisions))
+	}
+
+	decision := validation.Decisions[0]
+	if !decision.Approved {
+		t.Fatal("Approved = false, want true")
+	}
+	if decision.CandidateIndex != candidate.Index {
+		t.Fatalf("CandidateIndex = %d, want %d", decision.CandidateIndex, candidate.Index)
+	}
+}
+
+type compositionAdapter struct{}
+
+func (adapter compositionAdapter) Key() string {
+	return "generic-input"
+}
+
+func (adapter compositionAdapter) Parse(ctx context.Context, req contracts.ParseRequest) (*source.SourceDocument, error) {
+	return &source.SourceDocument{
+		ID:     req.SourceID,
+		Kind:   "document",
+		Format: "text/plain",
+		Digest: "sha256:abc123",
+		Units: []source.SourceUnit{
+			{ID: "u1", Kind: "unit", Text: "First source unit."},
+			{ID: "u2", Kind: "unit", Text: "Second source unit."},
+		},
+	}, nil
+}
+
+type compositionExtractor struct{}
+
+func (extractor compositionExtractor) Key() string {
+	return "generic-extractor"
+}
+
+func (extractor compositionExtractor) ArtifactType() string {
+	return "generic-artifact"
+}
+
+func (extractor compositionExtractor) SchemaVersion() string {
+	return "v1"
+}
+
+func (extractor compositionExtractor) Validators() []contracts.Validator {
+	return []contracts.Validator{compositionValidator{}}
+}
+
+func (extractor compositionExtractor) Extract(ctx context.Context, req contracts.ExtractionRequest) (contracts.ExtractionResult, error) {
+	if req.Source == nil {
+		return contracts.ExtractionResult{}, errors.New("source document is required")
+	}
+
+	return contracts.ExtractionResult{
+		Candidates: []artifacts.Candidate{
+			{
+				Index:         0,
+				ExtractorKey:  extractor.Key(),
+				ArtifactType:  extractor.ArtifactType(),
+				SchemaVersion: extractor.SchemaVersion(),
+				Payload:       json.RawMessage(`{"value":"example"}`),
+				SourceRefs: []source.SourceRef{
+					{
+						SourceID:    req.Source.ID,
+						StartUnitID: req.Source.Units[0].ID,
+						EndUnitID:   req.Source.Units[1].ID,
+					},
+				},
+			},
+		},
+	}, nil
+}
+
+type compositionValidator struct{}
+
+func (validator compositionValidator) Name() string {
+	return "generic-validator"
+}
+
+func (validator compositionValidator) Validate(ctx context.Context, req contracts.ValidationRequest) (contracts.ValidationResult, error) {
+	decisions := make([]contracts.ValidationDecision, 0, len(req.Candidates))
+	for _, candidate := range req.Candidates {
+		decisions = append(decisions, contracts.ValidationDecision{
+			CandidateIndex: candidate.Index,
+			Approved:       true,
+			ReasonCode:     "accepted",
+			Message:        "candidate accepted",
+		})
+	}
+
+	return contracts.ValidationResult{
+		ValidatorName: validator.Name(),
+		Decisions:     decisions,
+	}, nil
+}