diff --git a/src/sessions/model-overrides.test.ts b/src/sessions/model-overrides.test.ts
index 4029788f8940..faa7e503aa84 100644
--- a/src/sessions/model-overrides.test.ts
+++ b/src/sessions/model-overrides.test.ts
@@ -180,6 +180,39 @@ describe("applyModelOverrideToSessionEntry", () => {
     expect((entry.updatedAt ?? 0) > before).toBe(true);
   });
 
+  it("sets liveModelSwitchPending when switching to default with runtime-only fields", () => {
+    const entry: SessionEntry = {
+      sessionId: "sess-96269",
+      updatedAt: Date.now() - 5_000,
+      modelProvider: "anthropic",
+      model: "claude-sonnet-4-6",
+      contextTokens: 200_000,
+      contextBudgetStatus: contextBudgetStatus({
+        updatedAt: Date.now() - 5_000,
+        provider: "anthropic",
+        model: "claude-sonnet-4-6",
+        contextTokenBudget: 200_000,
+      }),
+    };
+
+    const result = applyModelOverrideToSessionEntry({
+      entry,
+      selection: {
+        provider: "openai",
+        model: "gpt-5.4",
+        isDefault: true,
+      },
+      markLiveSwitchPending: true,
+    });
+
+    expect(result.updated).toBe(true);
+    expect(entry.modelProvider).toBeUndefined();
+    expect(entry.model).toBeUndefined();
+    expect(entry.contextTokens).toBeUndefined();
+    expect(entry.contextBudgetStatus).toBeUndefined();
+    expect(entry.liveModelSwitchPending).toBe(true);
+  });
+
   it("marks non-default overrides with the provided source", () => {
     const entry: SessionEntry = {
       sessionId: "sess-5a",
diff --git a/src/sessions/model-overrides.ts b/src/sessions/model-overrides.ts
index 1da6b657232a..24f427d26e8d 100644
--- a/src/sessions/model-overrides.ts
+++ b/src/sessions/model-overrides.ts
@@ -93,6 +93,14 @@ export function applyModelOverrideToSessionEntry(params: {
     }
   }
 
+  // When switching back to the default model without override fields to delete
+  // (e.g. model comes from steering/fallback runtime fields), the isDefault
+  // branch at line 42 won't set selectionUpdated. Mark it here so that
+  // liveModelSwitchPending can still be set below when runtime is misaligned.
+  if (selection.isDefault && runtimePresent && !runtimeAligned) {
+    selectionUpdated = true;
+  }
+
   // contextTokens are derived from the active session model. When the selected
   // model changes (or runtime model is already stale), the cached window can
   // pin the session to an older/smaller limit until another run refreshes it.