refactor: polish trigger and manifest seams

ui/src/ui/app-chat.ts

@@ -305,13 +305,9 @@ async function dispatchSlashCommand(
   }
 
   const targetSessionKey = host.sessionKey;
-  const result = await executeSlashCommand(
-    host.client,
-    targetSessionKey,
-    name,
-    args,
-    host.chatModelCatalog,
-  );
+  const result = await executeSlashCommand(host.client, targetSessionKey, name, args, {
+    chatModelCatalog: host.chatModelCatalog,
+  });
 
   if (result.content) {
     injectCommandResult(host, result.content);

ui/src/ui/chat/slash-command-executor.node.test.ts

@@ -285,7 +285,9 @@ describe("executeSlashCommand directives", () => {
       "main",
       "model",
       "gpt-5-mini",
-      [{ id: "gpt-5-mini", name: "gpt-5-mini", provider: "openai" }],
+      {
+        chatModelCatalog: [{ id: "gpt-5-mini", name: "gpt-5-mini", provider: "openai" }],
+      },
     );
 
     expect(request).toHaveBeenCalledWith("sessions.patch", {
@@ -317,7 +319,9 @@ describe("executeSlashCommand directives", () => {
       "main",
       "model",
       "gpt-5-mini",
-      [{ id: "gpt-5-mini", name: "GPT-5 Mini", provider: "openai" }],
+      {
+        chatModelCatalog: [{ id: "gpt-5-mini", name: "GPT-5 Mini", provider: "openai" }],
+      },
     );
 
     expect(result.sessionPatch?.modelOverride).toEqual({

ui/src/ui/chat/slash-command-executor.ts

@@ -50,12 +50,16 @@ export type SlashCommandResult = {
   };
 };
 
+export type SlashCommandContext = {
+  chatModelCatalog?: ModelCatalogEntry[];
+};
+
 export async function executeSlashCommand(
   client: GatewayBrowserClient,
   sessionKey: string,
   commandName: string,
   args: string,
-  chatModelCatalog: ModelCatalogEntry[] = [],
+  context: SlashCommandContext = {},
 ): Promise<SlashCommandResult> {
   switch (commandName) {
     case "help":
@@ -73,7 +77,7 @@ export async function executeSlashCommand(
     case "compact":
       return await executeCompact(client, sessionKey);
     case "model":
-      return await executeModel(client, sessionKey, args, chatModelCatalog);
+      return await executeModel(client, sessionKey, args, context);
     case "think":
       return await executeThink(client, sessionKey, args);
     case "fast":
@@ -130,7 +134,7 @@ async function executeModel(
   client: GatewayBrowserClient,
   sessionKey: string,
   args: string,
-  chatModelCatalog: ModelCatalogEntry[],
+  context: SlashCommandContext,
 ): Promise<SlashCommandResult> {
   if (!args) {
     try {
@@ -163,6 +167,7 @@ async function executeModel(
     });
     const patchedModel = patched.resolved?.model ?? args.trim();
     const rawOverride = createChatModelOverride(patchedModel.trim());
+    const chatModelCatalog = context.chatModelCatalog ?? [];
     const resolvedValue = rawOverride
       ? normalizeChatModelOverrideValue(rawOverride, chatModelCatalog) ||
         resolveServerChatModelValue(patchedModel, patched.resolved?.modelProvider)