Centralize Scriptorium input source policy across config, analyze, and previous-cache

internal/artifacts/previous_requirements.go

@@ -5,6 +5,7 @@ import (
 	"sort"
 	"strings"
 
+	"gitea.maximumdirect.net/eric/narratio/internal/artifactpolicy"
 	"gitea.maximumdirect.net/eric/narratio/internal/config"
 )
 
@@ -36,10 +37,11 @@ func CollectPreviousArtifactRequirements(
 		inputNames := sortedScriptoriumInputKeys(artifactCfg.Inputs)
 		for _, inputName := range inputNames {
 			inputCfg := artifactCfg.Inputs[inputName]
-			previousName, ok := PreviousSessionArtifactName(inputCfg.Source)
-			if !ok {
+			descriptor, err := artifactpolicy.DescribeScriptoriumInputSource(inputCfg.Source)
+			if err != nil || descriptor.PreviousSession == nil {
 				continue
 			}
+			previousName := descriptor.PreviousSession.ConfiguredKey
 
 			location := fmt.Sprintf(
 				"pipeline.scriptorium.artifacts.%s.inputs.%s.source",