Q167: the model in effect and what a default change reaches are shown

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/shared/domain.ts

@@ -211,6 +211,8 @@ export interface TaskRunRecord {
   contextJson: string | null;
   /** Capabilities the run could not load, one per line, so the user sees what it worked without. */
   capabilityWarnings: string | null;
+  /** The model the session pinned when it started; null until then. */
+  runModel: string | null;
 }
 
 export interface ApprovalRecord {