Implement selective checkpoint recomputation

internal/framework/checkpoint/manifest.go

@@ -3,9 +3,8 @@ package checkpoint
 import "time"
 
 const (
-	// These names and values are frozen checkpoint wire-compatibility
-	// identifiers. They intentionally retain the former terminology.
-	WorkspaceSchemaVersion   = "notarius.workspace.v2"
+	WorkspaceSchemaVersion   = "notarius.workspace.v3"
+	WorkspaceSchemaVersionV2 = "notarius.workspace.v2"
 	WorkspaceSchemaVersionV1 = "notarius.workspace.v1"
 )
 
@@ -32,6 +31,7 @@ const (
 type StageManifest struct {
 	WorkspaceSchemaVersion string             `json:"workspace_schema_version"`
 	Stage                  StageName          `json:"stage"`
+	StepID                 string             `json:"step_id,omitempty"`
 	LaneID                 string             `json:"lane_id,omitempty"`
 	ModuleKey              string             `json:"module_key,omitempty"`
 	DependencyFingerprints []Fingerprint      `json:"dependency_fingerprints,omitempty"`