Ensure agent experiment defaults to not disabled (#239625)

* Safer fix for 239274 (#239511)

* Revert "fix config-context-key handling when config isn't known yet (#239294)"

This reverts commit d231e6c.

* Ensure agentModeDisallowed key always changes when setting is registered

* Ensure defaults to not disabled

Author: roblourens

src/vs/workbench/contrib/chat/browser/chat.contribution.ts

@@ -234,10 +234,11 @@ class ChatAgentSettingContribution implements IWorkbenchContribution {
 		}
 
 		const expDisabledKey = ChatContextKeys.Editing.agentModeDisallowed.bindTo(contextKeyService);
-		experimentService.getTreatment<boolean>('chatAgentEnabled').then(value => {
-			if (value) {
+		experimentService.getTreatment<boolean>('chatAgentEnabled').then(enabled => {
+			if (enabled) {
 				this.registerSetting();
-			} else if (value === false) {
+				expDisabledKey.set(false);
+			} else if (enabled === false) {
 				this.deregisterSetting();
 				expDisabledKey.set(true);
 			}

src/vs/workbench/contrib/chat/common/chatContextKeys.ts

@@ -83,6 +83,6 @@ export namespace ChatContextKeys {
 	export const Editing = {
 		hasToolsAgent: new RawContextKey<boolean>('chatHasToolsAgent', false, { type: 'boolean', description: localize('chatEditingHasToolsAgent', "True when a tools agent is registered.") }),
 		agentMode: new RawContextKey<boolean>('chatAgentMode', false, { type: 'boolean', description: localize('chatEditingAgentMode', "True when edits is in agent mode.") }),
-		agentModeDisallowed: new RawContextKey<boolean>('chatAgentModeDisallowed', false, { type: 'boolean', description: localize('chatAgentModeDisallowed', "True when agent mode is not allowed.") }), // experiment-driven disablement
+		agentModeDisallowed: new RawContextKey<boolean>('chatAgentModeDisallowed', undefined, { type: 'boolean', description: localize('chatAgentModeDisallowed', "True when agent mode is not allowed.") }), // experiment-driven disablement
 	};
 }