Implemented new campaign/session stable inputs and corresponding input source references

internal/stage/analyze.go

@@ -632,6 +632,16 @@ func resolveScriptoriumInput(
 	if describeErr != nil {
 		return "", false, nil, describeErr
 	}
+	if descriptor.Source.Kind == artifactpolicy.SourceKindStableInput {
+		resolvedPath, ok, err := resolvePreparedStableInput(descriptor.Source.ID, paths)
+		if err != nil {
+			if inputCfg.Required {
+				return "", false, nil, err
+			}
+			return "", false, nil, nil
+		}
+		return resolvedPath, ok, nil, nil
+	}
 	if descriptor.Source.Kind == artifactpolicy.SourceKindPreviousArtifact {
 		resolved, err := artifacts.ResolvePreviousSessionArtifactWithCatalog(paths, m, source, runtimeCatalog)
 		if err == nil {
@@ -684,6 +694,36 @@ func resolveScriptoriumInput(
 	}
 }
 
+func resolvePreparedStableInput(sourceID string, paths artifacts.SessionPaths) (string, bool, error) {
+	filename, ok := preparedStableInputFilename(sourceID)
+	if !ok {
+		return "", false, fmt.Errorf("unsupported prepared input source %q", sourceID)
+	}
+	path := filepath.Join(paths.InputsDir, filename)
+	if err := requireNonEmptyFile(path, "prepared input "+sourceID); err != nil {
+		return "", false, fmt.Errorf(
+			"prepared input source %q is unavailable; run narratio run-stage prepare %s --force: %w",
+			sourceID,
+			paths.SessionID,
+			err,
+		)
+	}
+	return path, true, nil
+}
+
+func preparedStableInputFilename(sourceID string) (string, bool) {
+	switch strings.TrimSpace(sourceID) {
+	case artifactpolicy.SourceInputPlayers:
+		return "players.yml", true
+	case artifactpolicy.SourceInputParty:
+		return "party.yml", true
+	case artifactpolicy.SourceInputGlossary:
+		return "glossary.yml", true
+	default:
+		return "", false
+	}
+}
+
 func buildAnalyzeRuntimeArtifactCatalog(
 	paths artifacts.SessionPaths,
 	scriptoriumCfg *config.ScriptoriumConfig,