diff --git a/packages/cli/src/config/persistence_regression.test.ts b/packages/cli/src/config/persistence_regression.test.ts
index 3c8fb8aed6..1738970133 100644
--- a/packages/cli/src/config/persistence_regression.test.ts
+++ b/packages/cli/src/config/persistence_regression.test.ts
@@ -104,8 +104,16 @@ describe('Issue 25428 Regression', () => {
     const settings = loadSettings('/mock/workspace-' + Math.random());
 
     expect(settings.user.settings.general?.plan?.enabled).toBe(true);
-    expect(settings.user.settings.experimental?.plan).toBeUndefined();
-    expect(settings.user.settings.experimental?.keepMe).toBe('important');
+    expect(
+      (settings.user.settings.experimental as Record<string, unknown>)?.[
+        'plan'
+      ],
+    ).toBeUndefined();
+    expect(
+      (settings.user.settings.experimental as Record<string, unknown>)?.[
+        'keepMe'
+      ],
+    ).toBe('important');
 
     expect(updateSettingsFilePreservingFormat).toHaveBeenCalled();
     const lastCall = vi
diff --git a/packages/core/src/config/config.ts b/packages/core/src/config/config.ts
index 69d1b59c92..76f9741760 100644
--- a/packages/core/src/config/config.ts
+++ b/packages/core/src/config/config.ts
@@ -3542,7 +3542,7 @@ export class Config implements McpContext, AgentLoopContext {
         if (s.model) this.setModel(s.model);
         if (s.compressionThreshold !== undefined) {
           // eslint-disable-next-line @typescript-eslint/no-unsafe-type-assertion
-          (this as unknown as Record<string, unknown>).compressionThreshold =
+          (this as unknown as Record<string, unknown>)['compressionThreshold'] =
             s.compressionThreshold;
         }
         if (s.ideMode !== undefined) this.ideMode = s.ideMode;
@@ -3551,17 +3551,18 @@ export class Config implements McpContext, AgentLoopContext {
         }
         if (s.topicUpdateNarration !== undefined) {
           // eslint-disable-next-line @typescript-eslint/no-unsafe-type-assertion
-          (this as unknown as Record<string, unknown>).topicUpdateNarration =
+          (this as unknown as Record<string, unknown>)['topicUpdateNarration'] =
             s.topicUpdateNarration;
         }
         if (s.experimentalAutoMemory !== undefined) {
           // eslint-disable-next-line @typescript-eslint/no-unsafe-type-assertion
-          (this as unknown as Record<string, unknown>).experimentalAutoMemory =
-            s.experimentalAutoMemory;
+          (this as unknown as Record<string, unknown>)[
+            'experimentalAutoMemory'
+          ] = s.experimentalAutoMemory;
         }
         if (s.experimentalMemoryV2 !== undefined) {
           // eslint-disable-next-line @typescript-eslint/no-unsafe-type-assertion
-          (this as unknown as Record<string, unknown>).experimentalMemoryV2 =
+          (this as unknown as Record<string, unknown>)['experimentalMemoryV2'] =
             s.experimentalMemoryV2;
         }
       }
@@ -3573,7 +3574,7 @@ export class Config implements McpContext, AgentLoopContext {
       }
       if (refreshed.adminSkillsEnabled !== undefined) {
         // eslint-disable-next-line @typescript-eslint/no-unsafe-type-assertion
-        (this as unknown as Record<string, unknown>).adminSkillsEnabled =
+        (this as unknown as Record<string, unknown>)['adminSkillsEnabled'] =
           refreshed.adminSkillsEnabled;
       }
     }