Reuse valid workspace checkpoints on request

internal/core/diagnostics/artifacts.go

@@ -5,6 +5,7 @@ const (
 	ArtifactEffectiveConfig    = "effective-config.json"
 	ArtifactResolvedPipeline   = "resolved-pipeline.json"
 	ArtifactResolvedReferences = "resolved-references.json"
+	ArtifactCheckpointEvents   = "checkpoint-events.json"
 	ArtifactSourceDocument     = "source-document.json"
 	ArtifactRunManifest        = "run-manifest.json"
 	ArtifactRunReport          = "run-report.json"

internal/core/diagnostics/run_dir.go

@@ -51,6 +51,7 @@ type InvocationMetadata struct {
 	Operation      string    `json:"operation"`
 	PipelineID     string    `json:"pipeline_id,omitempty"`
 	PipelineDigest string    `json:"pipeline_digest,omitempty"`
+	Resume         bool      `json:"resume,omitempty"`
 	InputPath      string    `json:"input_path,omitempty"`
 	ConfigPath     string    `json:"config_path,omitempty"`
 	ConfigSource   string    `json:"config_source,omitempty"`
@@ -153,6 +154,10 @@ func (r *RunDirectory) WriteResolvedReferences(payload any) error {
 	return r.WriteJSONArtifact(ArtifactResolvedReferences, payload)
 }
 
+func (r *RunDirectory) WriteCheckpointEvents(payload any) error {
+	return r.WriteJSONArtifact(ArtifactCheckpointEvents, payload)
+}
+
 func (r *RunDirectory) WriteSourceDocument(payload any) error {
 	return r.WriteJSONArtifact(ArtifactSourceDocument, payload)
 }