fix: normalize model override auth handling

src/sessions/model-overrides.ts

@@ -0,0 +1,72 @@
+import type { SessionEntry } from "../config/sessions.js";
+
+export type ModelOverrideSelection = {
+  provider: string;
+  model: string;
+  isDefault?: boolean;
+};
+
+export function applyModelOverrideToSessionEntry(params: {
+  entry: SessionEntry;
+  selection: ModelOverrideSelection;
+  profileOverride?: string;
+  profileOverrideSource?: "auto" | "user";
+}): { updated: boolean } {
+  const { entry, selection, profileOverride } = params;
+  const profileOverrideSource = params.profileOverrideSource ?? "user";
+  let updated = false;
+
+  if (selection.isDefault) {
+    if (entry.providerOverride) {
+      delete entry.providerOverride;
+      updated = true;
+    }
+    if (entry.modelOverride) {
+      delete entry.modelOverride;
+      updated = true;
+    }
+  } else {
+    if (entry.providerOverride !== selection.provider) {
+      entry.providerOverride = selection.provider;
+      updated = true;
+    }
+    if (entry.modelOverride !== selection.model) {
+      entry.modelOverride = selection.model;
+      updated = true;
+    }
+  }
+
+  if (profileOverride) {
+    if (entry.authProfileOverride !== profileOverride) {
+      entry.authProfileOverride = profileOverride;
+      updated = true;
+    }
+    if (entry.authProfileOverrideSource !== profileOverrideSource) {
+      entry.authProfileOverrideSource = profileOverrideSource;
+      updated = true;
+    }
+    if (entry.authProfileOverrideCompactionCount !== undefined) {
+      delete entry.authProfileOverrideCompactionCount;
+      updated = true;
+    }
+  } else {
+    if (entry.authProfileOverride) {
+      delete entry.authProfileOverride;
+      updated = true;
+    }
+    if (entry.authProfileOverrideSource) {
+      delete entry.authProfileOverrideSource;
+      updated = true;
+    }
+    if (entry.authProfileOverrideCompactionCount !== undefined) {
+      delete entry.authProfileOverrideCompactionCount;
+      updated = true;
+    }
+  }
+
+  if (updated) {
+    entry.updatedAt = Date.now();
+  }
+
+  return { updated };
+}