Adopt ConfigKit overlays for pipeline selection

internal/manifest/manifest.go

@@ -1,6 +1,7 @@
 package manifest
 
 import (
+	"encoding/json"
 	"strings"
 	"time"
 
@@ -71,13 +72,25 @@ type StageRecord struct {
 // EffectiveConfigProvenance records bounded non-secret configuration identity
 // for one resolved invocation.
 type EffectiveConfigProvenance struct {
-	SelectedProfile       *SelectedProfileProvenance `json:"selected_profile,omitempty"`
+	SelectedOverlay       *SelectedOverlayProvenance `json:"selected_overlay,omitempty"`
 	EffectiveConfigDigest string                     `json:"effective_config_digest,omitempty"`
 }
 
-// SelectedProfileProvenance identifies an explicitly or default-selected
-// pipeline profile without recording profile content.
-type SelectedProfileProvenance struct {
+// UnmarshalJSON accepts unknown informational provenance from older manifests.
+// The enclosing manifest and its execution state remain strictly decoded.
+func (p *EffectiveConfigProvenance) UnmarshalJSON(data []byte) error {
+	type provenance EffectiveConfigProvenance
+	var decoded provenance
+	if err := json.Unmarshal(data, &decoded); err != nil {
+		return err
+	}
+	*p = EffectiveConfigProvenance(decoded)
+	return nil
+}
+
+// SelectedOverlayProvenance identifies an explicitly or default-selected
+// pipeline overlay without recording overlay content.
+type SelectedOverlayProvenance struct {
 	Name   string `json:"name"`
 	Source string `json:"source"`
 }