Derive stable prompt sessions for CLI runs

internal/framework/pipeline/runner.go

@@ -191,7 +191,7 @@ func (r *Runner) Run(ctx context.Context, input RunInput) (output RunOutput, err
 		return failOutput(output), fmt.Errorf("write source debug artifact: %w", err)
 	}
 	sourceInput := sourceInputMaterial(input.Path, input.RawInput)
-	sessionID := resolvedSessionID(input.SessionID, doc.ID)
+	sessionID := strings.TrimSpace(input.SessionID)
 	output.Manifest.Metadata, err = manifestMetadataWithSessionID(output.Manifest.Metadata, sessionID)
 	if err != nil {
 		return failOutput(output), err
@@ -896,13 +896,6 @@ func sourceInputOriginURI(inputPath string) string {
 	return fileURI(inputPath)
 }
 
-func resolvedSessionID(explicit string, sourceDocumentID string) string {
-	if trimmed := strings.TrimSpace(explicit); trimmed != "" {
-		return trimmed
-	}
-	return strings.TrimSpace(sourceDocumentID)
-}
-
 func manifestMetadataWithSessionID(metadata map[string]any, sessionID string) (map[string]any, error) {
 	out, err := cloneMetadata(metadata)
 	if err != nil {