Add artifact provenance and stage skip outcomes

internal/artifactmodel/metadata.go

@@ -0,0 +1,17 @@
+package artifactmodel
+
+// ContractMetadata identifies the data contract implemented by an artifact.
+type ContractMetadata struct {
+	MediaType     string `json:"media_type"`
+	SchemaID      string `json:"schema_id"`
+	SchemaVersion string `json:"schema_version"`
+	ModuleKey     string `json:"module_key,omitempty"`
+}
+
+// ExternalProvenance identifies an artifact produced by an external system.
+type ExternalProvenance struct {
+	System     string `json:"system"`
+	RunID      string `json:"run_id"`
+	PipelineID string `json:"pipeline_id"`
+	ArtifactID string `json:"artifact_id"`
+}

internal/artifactmodel/metadata_test.go

@@ -0,0 +1,56 @@
+package artifactmodel
+
+import (
+	"encoding/json"
+	"strings"
+	"testing"
+)
+
+func TestArtifactMetadataJSON(t *testing.T) {
+	type envelope struct {
+		Contract           *ContractMetadata   `json:"contract,omitempty"`
+		ExternalProvenance *ExternalProvenance `json:"external_provenance,omitempty"`
+	}
+
+	complete, err := json.Marshal(envelope{
+		Contract: &ContractMetadata{
+			MediaType:     "application/json",
+			SchemaID:      "notarius.dnd.npc_registry",
+			SchemaVersion: "v1",
+			ModuleKey:     "dnd/npc-registry",
+		},
+		ExternalProvenance: &ExternalProvenance{
+			System:     "notarius",
+			RunID:      "run-123",
+			PipelineID: "dnd-session",
+			ArtifactID: "npc-registry",
+		},
+	})
+	if err != nil {
+		t.Fatalf("Marshal() complete metadata error = %v", err)
+	}
+	wantComplete := `{"contract":{"media_type":"application/json","schema_id":"notarius.dnd.npc_registry","schema_version":"v1","module_key":"dnd/npc-registry"},"external_provenance":{"system":"notarius","run_id":"run-123","pipeline_id":"dnd-session","artifact_id":"npc-registry"}}`
+	if string(complete) != wantComplete {
+		t.Fatalf("complete metadata JSON = %s, want %s", complete, wantComplete)
+	}
+
+	omitted, err := json.Marshal(envelope{})
+	if err != nil {
+		t.Fatalf("Marshal() omitted metadata error = %v", err)
+	}
+	if string(omitted) != `{}` {
+		t.Fatalf("omitted metadata JSON = %s, want {}", omitted)
+	}
+
+	withoutModule, err := json.Marshal(envelope{Contract: &ContractMetadata{
+		MediaType:     "application/json",
+		SchemaID:      "notarius.dnd.npc_registry",
+		SchemaVersion: "v1",
+	}})
+	if err != nil {
+		t.Fatalf("Marshal() contract without module key error = %v", err)
+	}
+	if strings.Contains(string(withoutModule), "module_key") {
+		t.Fatalf("contract JSON unexpectedly contains omitted module_key: %s", withoutModule)
+	}
+}