Add run manifest and logical output file contracts

internal/framework/contracts/composition_test.go

@@ -124,10 +124,13 @@ func TestContractsComposeAcrossPackages(t *testing.T) {
 	if err != nil {
 		t.Fatalf("Encode() error = %v, want nil", err)
 	}
-	if output.ContentType != "application/json" {
-		t.Fatalf("ContentType = %q, want application/json", output.ContentType)
+	if len(output.Files) != 1 {
+		t.Fatalf("len(Files) = %d, want 1", len(output.Files))
 	}
-	if len(output.Bytes) == 0 {
+	if output.Files[0].ContentType != "application/json" {
+		t.Fatalf("ContentType = %q, want application/json", output.Files[0].ContentType)
+	}
+	if len(output.Files[0].Bytes) == 0 {
 		t.Fatal("len(Bytes) = 0, want encoded bytes")
 	}
 }
@@ -293,7 +296,12 @@ func (encoder compositionOutputEncoder) Encode(ctx context.Context, req contract
 	}
 
 	return contracts.OutputResult{
-		Bytes:       encoded,
-		ContentType: "application/json",
+		Files: []contracts.OutputFile{
+			{
+				Name:        "artifacts/generic.json",
+				ContentType: "application/json",
+				Bytes:       encoded,
+			},
+		},
 	}, nil
 }

internal/framework/contracts/contracts.go

@@ -182,8 +182,17 @@ type OutputRequest struct {
 	Metadata   map[string]any               `json:"metadata,omitempty"`
 }
 
+type OutputFile struct {
+	Name        string `json:"name"`
+	ContentType string `json:"content_type,omitempty"`
+	Bytes       []byte `json:"-"`
+}
+
 type OutputResult struct {
-	Bytes       []byte    `json:"-"`
+	Files []OutputFile `json:"files,omitempty"`
+	// Bytes is the legacy single-output payload. New encoders should return Files.
+	Bytes []byte `json:"-"`
+	// ContentType is the legacy single-output content type. New encoders should return Files.
 	ContentType string    `json:"content_type,omitempty"`
 	Warnings    []Warning `json:"warnings,omitempty"`
 }
@@ -192,3 +201,7 @@ type OutputEncoder interface {
 	Key() string
 	Encode(ctx context.Context, req OutputRequest) (OutputResult, error)
 }
+
+type ManifestMetadataProvider interface {
+	ManifestMetadata() map[string]any
+}

internal/framework/contracts/contracts_test.go

@@ -230,11 +230,44 @@ func TestFakeMergeNormalizeAndOutputContracts(t *testing.T) {
 	if encoder.Key() != "generic-output" {
 		t.Fatalf("OutputEncoder.Key() = %q, want generic-output", encoder.Key())
 	}
-	if encoded.ContentType != "application/json" {
-		t.Fatalf("ContentType = %q, want application/json", encoded.ContentType)
+	if len(encoded.Files) != 1 {
+		t.Fatalf("len(Files) = %d, want 1", len(encoded.Files))
 	}
-	if string(encoded.Bytes) != `{"run_id":"run-1","approved_count":1}` {
-		t.Fatalf("Bytes = %s, want encoded output", encoded.Bytes)
+	if encoded.Files[0].ContentType != "application/json" {
+		t.Fatalf("ContentType = %q, want application/json", encoded.Files[0].ContentType)
+	}
+	if string(encoded.Files[0].Bytes) != `{"run_id":"run-1","approved_count":1}` {
+		t.Fatalf("Bytes = %s, want encoded output", encoded.Files[0].Bytes)
+	}
+}
+
+func TestOutputFileJSONShapeOmitsBytes(t *testing.T) {
+	file := OutputFile{
+		Name:        "artifacts/events.json",
+		ContentType: "application/json",
+		Bytes:       []byte(`{"ignored":true}`),
+	}
+
+	encoded, err := json.Marshal(file)
+	if err != nil {
+		t.Fatalf("json.Marshal() error = %v, want nil", err)
+	}
+
+	var got map[string]any
+	if err := json.Unmarshal(encoded, &got); err != nil {
+		t.Fatalf("json.Unmarshal() error = %v, want nil", err)
+	}
+	if got["name"] != "artifacts/events.json" {
+		t.Fatalf("name = %#v, want logical file name", got["name"])
+	}
+	if got["content_type"] != "application/json" {
+		t.Fatalf("content_type = %#v, want application/json", got["content_type"])
+	}
+	if _, ok := got["Bytes"]; ok {
+		t.Fatalf("encoded output file leaked Bytes: %s", encoded)
+	}
+	if _, ok := got["bytes"]; ok {
+		t.Fatalf("encoded output file leaked bytes: %s", encoded)
 	}
 }
 
@@ -397,7 +430,12 @@ func (encoder fakeOutputEncoder) Key() string {
 
 func (encoder fakeOutputEncoder) Encode(ctx context.Context, req OutputRequest) (OutputResult, error) {
 	return OutputResult{
-		Bytes:       []byte(`{"run_id":"` + req.Manifest.RunID + `","approved_count":1}`),
-		ContentType: "application/json",
+		Files: []OutputFile{
+			{
+				Name:        "artifacts/generic.json",
+				ContentType: "application/json",
+				Bytes:       []byte(`{"run_id":"` + req.Manifest.RunID + `","approved_count":1}`),
+			},
+		},
 	}, nil
 }