fix: finalize durable Pi lifecycle

tools/thothctl/internal/pi/state.go

@@ -15,7 +15,7 @@ import (
 	"github.com/gofrs/flock"
 )
 
-const stateFileVersion = 3
+const stateFileVersion = 4
 
 // Phase describes the durable point reached by a Pi update.
 type Phase string
@@ -24,6 +24,7 @@ const (
 	PhasePreflight  Phase = "preflight"
 	PhaseBuilding   Phase = "building"
 	PhaseRecreated  Phase = "recreated"
+	PhasePromoting  Phase = "promoting"
 	PhaseVerified   Phase = "verified"
 	PhaseRolledBack Phase = "rolled_back"
 	PhaseFailed     Phase = "failed"
@@ -59,14 +60,15 @@ type Target struct {
 // State is recovery metadata stored below the installation project. It never stores environment
 // values, secret paths, credentials, or command output.
 type State struct {
-	Version     int       `json:"version"`
-	Transaction string    `json:"transaction"`
-	Phase       Phase     `json:"phase"`
-	UpdatedAt   time.Time `json:"updated_at"`
-	Target      Target    `json:"target,omitempty"`
-	Previous    Image     `json:"previous"`
-	Candidate   Image     `json:"candidate,omitempty"`
-	Error       string    `json:"error,omitempty"`
+	Version         int       `json:"version"`
+	Transaction     string    `json:"transaction"`
+	Phase           Phase     `json:"phase"`
+	UpdatedAt       time.Time `json:"updated_at"`
+	Target          Target    `json:"target,omitempty"`
+	Previous        Image     `json:"previous"`
+	Candidate       Image     `json:"candidate,omitempty"`
+	MutationStarted bool      `json:"mutation_started,omitempty"`
+	Error           string    `json:"error,omitempty"`
 }
 
 func readState(path string) (State, error) {