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/agent-model.ts

@@ -0,0 +1,17 @@
+/** Where an agent's model comes from: its own setting, else its provider's default. */
+export type ModelSource = "agent" | "provider_default" | "none";
+
+/** The model a new session of the agent starts with; a running session keeps the one it pinned. */
+export function agentModel(agentModelId: string | null, providerModel: string | null): { model: string | null; source: ModelSource } {
+  const own = agentModelId?.trim();
+  if (own) return { model: own, source: "agent" };
+  if (providerModel) return { model: providerModel, source: "provider_default" };
+  return { model: null, source: "none" };
+}
+
+/** Agents a change to this provider's default model reaches, and those that keep their own model. */
+export function defaultModelReach(agents: Array<{ modelProviderId: string | null; modelId: string | null }>, providerId: string): { following: number; ownModel: number } {
+  const bound = agents.filter((agent) => agent.modelProviderId === providerId);
+  const ownModel = bound.filter((agent) => agent.modelId?.trim()).length;
+  return { following: bound.length - ownModel, ownModel };
+}

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 {