fix(webapp): let the dashboard agent target a different Trigger instance

The agent session-start, token mint, head-start, in-proxy and the client
transport all used the webapp's own origin (API_ORIGIN ?? APP_ORIGIN) as the
agent instance. That only holds when the agent project runs on the same instance
as the webapp. When it doesn't — e.g. a test-cloud webapp using the shared agent
project on prod cloud — DASHBOARD_AGENT_SECRET_KEY is a prod-cloud key sent to
test-cloud's API, which rejects it ("Invalid API key") and the chat can't start.

Add an optional DASHBOARD_AGENT_BASE_URL. dashboardAgentApiOrigin() now returns
it, or the SDK default (https://api.trigger.dev) when unset — never the webapp's
own origin, and independent of TRIGGER_API_URL (which the webapp may point at an
internal host). All server call sites already funnel through that function; the
client transport gets the value via the root loader and a useDashboardAgentBaseUrl
hook, replacing the general useApiOrigin in the panel.

Unset (prod cloud) resolves to the SDK default, matching today's behavior. Test
cloud sets DASHBOARD_AGENT_BASE_URL=https://api.trigger.dev.

Author: ericallam

apps/webapp/app/components/dashboard-agent/DashboardAgentPanel.tsx

@@ -5,7 +5,7 @@ import { useCallback, useEffect, useMemo, useReducer, useRef, useState } from "r
 import { AgentSpinner } from "~/components/primitives/Spinner";
 import { useToast } from "~/components/primitives/Toast";
 import { useAgentPageContext } from "~/hooks/useAgentPageContext";
-import { useApiOrigin } from "~/hooks/useApiOrigin";
+import { useDashboardAgentBaseUrl } from "~/hooks/useDashboardAgentBaseUrl";
 import { useEnvironment } from "~/hooks/useEnvironment";
 import { useOrganization } from "~/hooks/useOrganizations";
 import { useProject } from "~/hooks/useProject";
@@ -104,7 +104,7 @@ export function DashboardAgentPanel({
   const project = useProject();
   const environment = useEnvironment();
   const user = useUser();
-  const apiOrigin = useApiOrigin();
+  const apiOrigin = useDashboardAgentBaseUrl();
   const location = useLocation();
   const pageContext = useAgentPageContext();
   const toast = useToast();

apps/webapp/app/env.server.ts

@@ -192,6 +192,7 @@ const EnvironmentSchema = z
     // standard chat.agent SDK flow. When unset, the live agent is disabled — the
     // conversation store / History still work, no chat can start.
     DASHBOARD_AGENT_SECRET_KEY: z.string().optional(),
+    DASHBOARD_AGENT_BASE_URL: z.string().optional(),
     // Pins agent sessions to a specific deployed version (paired with
     // --skip-promotion deploys); unset => the project env's current version.
     DASHBOARD_AGENT_VERSION: z.string().optional(),

apps/webapp/app/hooks/useDashboardAgentBaseUrl.ts

@@ -0,0 +1,8 @@
+import { useTypedRouteLoaderData } from "remix-typedjson";
+import type { loader } from "../root";
+
+export function useDashboardAgentBaseUrl() {
+  const routeMatch = useTypedRouteLoaderData<typeof loader>("root");
+
+  return routeMatch!.dashboardAgentBaseUrl;
+}

apps/webapp/app/root.tsx

@@ -120,6 +120,7 @@ export const loader = async ({ request }: LoaderFunctionArgs) => {
       appEnv: env.APP_ENV,
       appOrigin: env.APP_ORIGIN,
       apiOrigin: env.API_ORIGIN ?? env.APP_ORIGIN,
+      dashboardAgentBaseUrl: env.DASHBOARD_AGENT_BASE_URL ?? "https://api.trigger.dev",
       triggerCliTag: env.TRIGGER_CLI_TAG,
       kapa,
       timezone,

apps/webapp/app/services/dashboardAgent.server.ts

@@ -49,7 +49,7 @@ const DASHBOARD_AGENT_UAT_TTL_SECONDS = 10 * 60;
 // The Trigger instance this webapp runs against — the same origin the agent
 // task calls back to (as the user) for its read tools.
 export function dashboardAgentApiOrigin(): string {
-  return env.API_ORIGIN ?? env.APP_ORIGIN;
+  return env.DASHBOARD_AGENT_BASE_URL ?? "https://api.trigger.dev";
 }
 
 // Mint a short-lived, read-only delegated token for the signed-in user. Self