feat: add general subagent model override (#24610)

Adds a deployment-wide admin override for general delegated subagents.

## What changed
- store the general override in `site_configs` and expose it through the
shared `agent-model-override/{context}` API
- apply the general override when spawning delegated general subagents,
while preserving the existing Explore override behavior
- reuse a shared Agents settings form for the general and Explore
override sections

## Validation
- `make gen`
- `go test ./coderd -run 'TestChatModelOverrides'`
- `go test ./coderd/x/chatd -run
'TestSpawnAgent_(GeneralUsesConfiguredModelOverride|GeneralOverrideLogsAndFallsBackWhenCredentialsUnavailable|GeneralOverrideLogsAndFallsBackWhenProviderDisabled)'`
- `pnpm -C site lint:types`
- `pnpm -C site test:storybook --
AgentSettingsAgentsPageView.stories.tsx`
- `make lint`
- `make pre-commit`

> Mux is acting on Mike's behalf.

site/src/api/api.ts

@@ -3257,20 +3257,22 @@ class ExperimentalApiMethods {
 		);
 	};
 
-	getChatExploreModelOverride =
-		async (): Promise<TypesGen.ChatExploreModelOverrideResponse> => {
-			const response =
-				await this.axios.get<TypesGen.ChatExploreModelOverrideResponse>(
-					"/api/experimental/chats/config/explore-model-override",
-				);
-			return response.data;
-		};
+	getChatAgentModelOverride = async (
+		context: TypesGen.ChatAgentModelOverrideContext,
+	): Promise<TypesGen.ChatAgentModelOverrideResponse> => {
+		const response =
+			await this.axios.get<TypesGen.ChatAgentModelOverrideResponse>(
+				`/api/experimental/chats/config/agent-model-override/${encodeURIComponent(context)}`,
+			);
+		return response.data;
+	};
 
-	updateChatExploreModelOverride = async (
-		req: TypesGen.UpdateChatExploreModelOverrideRequest,
+	updateChatAgentModelOverride = async (
+		context: TypesGen.ChatAgentModelOverrideContext,
+		req: TypesGen.UpdateChatAgentModelOverrideRequest,
 	): Promise<void> => {
 		await this.axios.put(
-			"/api/experimental/chats/config/explore-model-override",
+			`/api/experimental/chats/config/agent-model-override/${encodeURIComponent(context)}`,
 			req,
 		);
 	};

site/src/api/queries/chats.ts

@@ -1127,23 +1127,6 @@ export const updateChatPlanModeInstructions = (queryClient: QueryClient) => ({
 	},
 });
 
-const chatExploreModelOverrideKey = ["chat-explore-model-override"] as const;
-
-export const chatExploreModelOverride = () => ({
-	queryKey: chatExploreModelOverrideKey,
-	queryFn: () => API.experimental.getChatExploreModelOverride(),
-});
-
-export const updateChatExploreModelOverride = (queryClient: QueryClient) => ({
-	mutationFn: (req: TypesGen.UpdateChatExploreModelOverrideRequest) =>
-		API.experimental.updateChatExploreModelOverride(req),
-	onSuccess: async () => {
-		await queryClient.invalidateQueries({
-			queryKey: chatExploreModelOverrideKey,
-		});
-	},
-});
-
 const chatDesktopEnabledKey = ["chat-desktop-enabled"] as const;
 
 export const chatDesktopEnabled = () => ({

site/src/api/typesGenerated.ts

@@ -1272,6 +1272,25 @@ export interface Chat {
 	readonly children: readonly Chat[];
 }
 
+// From codersdk/chats.go
+export type ChatAgentModelOverrideContext = "explore" | "general";
+
+export const ChatAgentModelOverrideContexts: ChatAgentModelOverrideContext[] = [
+	"explore",
+	"general",
+];
+
+// From codersdk/chats.go
+/**
+ * ChatAgentModelOverrideResponse is the response body for the chat agent
+ * model override configuration endpoint.
+ */
+export interface ChatAgentModelOverrideResponse {
+	readonly context: ChatAgentModelOverrideContext;
+	readonly model_config_id: string;
+	readonly is_malformed: boolean;
+}
+
 // From codersdk/chats.go
 export type ChatBusyBehavior = "interrupt" | "queue";
 
@@ -1590,20 +1609,6 @@ export interface ChatDiffStatus {
 	readonly stale_at?: string;
 }
 
-// From codersdk/chats.go
-/**
- * ChatExploreModelOverrideResponse is the response body for the Explore
- * subagent model override configuration endpoint.
- */
-export interface ChatExploreModelOverrideResponse {
-	readonly model_config_id?: string;
-	/**
-	 * HasMalformedOverride reports whether the saved override is malformed and
-	 * is currently being treated as unset.
-	 */
-	readonly has_malformed_override: boolean;
-}
-
 // From codersdk/chats.go
 /**
  * ChatFileMetadata contains lightweight metadata about a file
@@ -7657,6 +7662,15 @@ export interface UpdateAppearanceConfig {
 	readonly announcement_banners: readonly BannerConfig[];
 }
 
+// From codersdk/chats.go
+/**
+ * UpdateChatAgentModelOverrideRequest is the request body for updating the
+ * chat agent model override configuration endpoint.
+ */
+export interface UpdateChatAgentModelOverrideRequest {
+	readonly model_config_id: string;
+}
+
 // From codersdk/chats.go
 /**
  * UpdateChatDebugLoggingAllowUsersRequest is the admin request to
@@ -7674,15 +7688,6 @@ export interface UpdateChatDesktopEnabledRequest {
 	readonly enable_desktop: boolean;
 }
 
-// From codersdk/chats.go
-/**
- * UpdateChatExploreModelOverrideRequest is the request body for updating the
- * Explore subagent model override configuration endpoint.
- */
-export interface UpdateChatExploreModelOverrideRequest {
-	readonly model_config_id?: string;
-}
-
 // From codersdk/chats.go
 /**
  * UpdateChatModelConfigRequest updates a chat model config.