Include conversation ancestry in execution observations

internal/observation/recorder.go

@@ -16,6 +16,7 @@ import (
 // calls methods in execution order; it has no shared history or background work.
 type Recorder struct {
 	runID                string
+	parentRunID          string
 	startedAt            time.Time
 	now                  func() time.Time
 	observer             domain.ExecutionObserver
@@ -95,6 +96,9 @@ func NewRunID() (string, error) {
 // RunID returns this invocation's identity.
 func (r *Recorder) RunID() string { return r.runID }
 
+// SetParentRunID records the immediate source identity before start delivery.
+func (r *Recorder) SetParentRunID(id string) { r.parentRunID = id }
+
 // Start delivers the opening event with only identities already resolved.
 func (r *Recorder) Start() {
 	event := r.event(domain.ExecutionStarted)
@@ -177,7 +181,7 @@ func (r *Recorder) Finish(data FinishData) {
 
 func (r *Recorder) event(kind domain.ExecutionEventKind) domain.ExecutionEvent {
 	return domain.ExecutionEvent{
-		Kind: kind, RunID: r.runID, Time: r.now(), PromptID: r.selection.PromptID,
+		Kind: kind, RunID: r.runID, ParentRunID: r.parentRunID, Time: r.now(), PromptID: r.selection.PromptID,
 		ProfileID: r.selection.ProfileID,
 		BackendID: r.selection.BackendID, Model: r.selection.Model,
 	}