Cut configuration and CLI over to output cache and debug surfaces

internal/core/config/cache.go

@@ -8,6 +8,14 @@ import (
 
 // DefaultChunkPlanRoot resolves the existing per-user chunk-plan cache root.
 func DefaultChunkPlanRoot(userCacheDir func() (string, error)) (string, error) {
+	return defaultCacheFamilyRoot(userCacheDir, "chunk-plans")
+}
+
+func DefaultCheckpointRoot(userCacheDir func() (string, error)) (string, error) {
+	return defaultCacheFamilyRoot(userCacheDir, "checkpoints")
+}
+
+func defaultCacheFamilyRoot(userCacheDir func() (string, error), family string) (string, error) {
 	if userCacheDir == nil {
 		return "", fmt.Errorf("user cache directory resolver must not be nil")
 	}
@@ -19,5 +27,5 @@ func DefaultChunkPlanRoot(userCacheDir func() (string, error)) (string, error) {
 	if root == "" {
 		return "", fmt.Errorf("user cache directory must not be empty")
 	}
-	return filepath.Join(filepath.Clean(root), "notarius", "chunk-plans"), nil
+	return filepath.Join(filepath.Clean(root), "notarius", family), nil
 }