perf(control-ui): coalesce chat metadata startup

Add a coalesced chat.metadata Gateway method so the Control UI can fetch model and command metadata without blocking a clean first message path. Reuses existing models/commands builders, keeps compatibility fallback for older gateways, updates protocol artifacts, and adds focused gateway/UI/e2e coverage.

packages/gateway-protocol/src/index.test.ts

@@ -5,6 +5,7 @@ import {
   formatValidationErrors,
   validateChatAbortParams,
   validateChatHistoryParams,
+  validateChatMetadataParams,
   validateChatSendParams,
   validateChatEvent,
   validateCommandsListParams,
@@ -104,6 +105,13 @@ describe("lazy protocol validators", () => {
     ).toBe(true);
   });
 
+  it("accepts selected-agent scope on chat metadata params", () => {
+    expect(validateChatMetadataParams({})).toBe(true);
+    expect(validateChatMetadataParams({ agentId: "work" })).toBe(true);
+    expect(validateChatMetadataParams({ agentId: "" })).toBe(false);
+    expect(validateChatMetadataParams({ agentId: "work", view: "configured" })).toBe(false);
+  });
+
   it("can still compile every exported protocol validator", () => {
     const failures: string[] = [];
     const validators: Array<[string, ProtocolValidator]> = [];

packages/gateway-protocol/src/index.ts

@@ -126,6 +126,8 @@ import {
   type ChatEvent,
   ChatEventSchema,
   ChatHistoryParamsSchema,
+  type ChatMetadataParams,
+  ChatMetadataParamsSchema,
   ChatMessageGetResultSchema,
   ChatMessageGetParamsSchema,
   type ChatInjectParams,
@@ -846,6 +848,7 @@ export const validateExecApprovalsNodeSetParams = lazyCompile<ExecApprovalsNodeS
 );
 export const validateLogsTailParams = lazyCompile<LogsTailParams>(LogsTailParamsSchema);
 export const validateChatHistoryParams = lazyCompile(ChatHistoryParamsSchema);
+export const validateChatMetadataParams = lazyCompile<ChatMetadataParams>(ChatMetadataParamsSchema);
 export const validateChatMessageGetParams = lazyCompile(ChatMessageGetParamsSchema);
 export const validateChatSendParams = lazyCompile(ChatSendParamsSchema);
 export const validateChatAbortParams = lazyCompile<ChatAbortParams>(ChatAbortParamsSchema);
@@ -1115,6 +1118,7 @@ export {
   ExecApprovalRequestParamsSchema,
   ExecApprovalResolveParamsSchema,
   ChatHistoryParamsSchema,
+  ChatMetadataParamsSchema,
   ChatSendParamsSchema,
   ChatInjectParamsSchema,
   UpdateRunParamsSchema,
@@ -1223,6 +1227,7 @@ export type {
   ArtifactsDownloadResult,
   AgentsListParams,
   AgentsListResult,
+  ChatMetadataParams,
   CommandsListParams,
   CommandsListResult,
   CommandEntry,

packages/gateway-protocol/src/schema/logs-chat.ts

@@ -34,6 +34,13 @@ export const ChatHistoryParamsSchema = Type.Object(
   { additionalProperties: false },
 );
 
+export const ChatMetadataParamsSchema = Type.Object(
+  {
+    agentId: Type.Optional(NonEmptyString),
+  },
+  { additionalProperties: false },
+);
+
 export const ChatMessageGetParamsSchema = Type.Object(
   {
     sessionKey: NonEmptyString,

packages/gateway-protocol/src/schema/protocol-schemas.ts

@@ -191,6 +191,7 @@ import {
   ChatEventSchema,
   ChatFinalEventSchema,
   ChatHistoryParamsSchema,
+  ChatMetadataParamsSchema,
   ChatMessageGetParamsSchema,
   ChatMessageGetResultSchema,
   ChatInjectParamsSchema,
@@ -534,6 +535,7 @@ export const ProtocolSchemas = {
   DevicePairRequestedEvent: DevicePairRequestedEventSchema,
   DevicePairResolvedEvent: DevicePairResolvedEventSchema,
   ChatHistoryParams: ChatHistoryParamsSchema,
+  ChatMetadataParams: ChatMetadataParamsSchema,
   ChatMessageGetParams: ChatMessageGetParamsSchema,
   ChatMessageGetResult: ChatMessageGetResultSchema,
   ChatSendParams: ChatSendParamsSchema,

packages/gateway-protocol/src/schema/types.ts

@@ -160,6 +160,7 @@ export type AgentsListResult = SchemaType<"AgentsListResult">;
 export type ModelChoice = SchemaType<"ModelChoice">;
 export type ModelsListParams = SchemaType<"ModelsListParams">;
 export type ModelsListResult = SchemaType<"ModelsListResult">;
+export type ChatMetadataParams = SchemaType<"ChatMetadataParams">;
 export type CommandEntry = SchemaType<"CommandEntry">;
 export type CommandsListParams = SchemaType<"CommandsListParams">;
 export type CommandsListResult = SchemaType<"CommandsListResult">;