Implement minimal downstream invalidation after forced upstream reruns

internal/app/run_control.go

@@ -1,6 +1,8 @@
 package app
 
 import (
+	"time"
+
 	"gitea.maximumdirect.net/eric/narratio/internal/manifest"
 	"gitea.maximumdirect.net/eric/narratio/internal/stage"
 )
@@ -49,3 +51,43 @@ func firstNonSucceededIndex(stages []stage.Stage, m *manifest.Manifest) int {
 	}
 	return len(stages)
 }
+
+func canonicalStageNames() []string {
+	all := stage.All()
+	out := make([]string, 0, len(all))
+	for _, s := range all {
+		if s == nil {
+			continue
+		}
+		out = append(out, s.Name())
+	}
+	return out
+}
+
+func downstreamStageNames(stageName string) []string {
+	names := canonicalStageNames()
+	for i, name := range names {
+		if name != stageName {
+			continue
+		}
+		return append([]string(nil), names[i+1:]...)
+	}
+	return nil
+}
+
+func invalidateDownstreamSucceededStages(m *manifest.Manifest, upstreamStage string, at time.Time) []string {
+	if m == nil || m.Stages == nil {
+		return nil
+	}
+
+	invalidated := make([]string, 0)
+	for _, downstream := range downstreamStageNames(upstreamStage) {
+		sr := m.Stages[downstream]
+		if sr == nil || sr.Status != manifest.StatusSucceeded {
+			continue
+		}
+		m.MarkStageStale(downstream, at, "upstream stage rerun with force")
+		invalidated = append(invalidated, downstream)
+	}
+	return invalidated
+}