fix(cursor): HTTP/2 AgentService support + version bump to 3.12.17

Real Cursor IDE now uses AgentService at agent.api5.cursor.sh (HTTP/2-only)
while 9router still spoke the retired ChatService at api2.cursor.sh with
outdated headers, producing HTTP 429 "Update Required". Add an executeAgent
path that builds an agent.v1.RunRequest Connect RPC over a raw http2 stream
and fetches the account-specific usable model catalog via GetUsableModels.

Also implement MCP tool calling over AgentService: encode OpenAI tools as
AgentRunRequest.mcp_tools (McpToolDefinition with google.protobuf.Value
input_schema), decode McpArgs tool calls, and forward them to the client as
OpenAI tool_calls so the client runs the tool and resumes in the next turn.
Reply to request_context_args with a non-empty RequestContext, to server
heartbeats with client_heartbeat, and to KV blob get/set with empty results,
so action queries no longer stall the stream. Fold the client system prompt
into the user message (custom_system_prompt makes the server return an empty
turn). Bump clientVersion to 3.12.17 and add the x-cursor-client-commit
header so the gateway identifies as a current Cursor IDE release.

src/app/(dashboard)/dashboard/providers/[id]/page.js

@@ -67,6 +67,7 @@ export default function ProviderDetailPage() {
   const [thinkingMode, setThinkingMode] = useState("auto");
   const [autoPing, setAutoPing] = useState({ enabled: false, connections: {} });
   const [suggestedModels, setSuggestedModels] = useState([]);
+  const [liveModels, setLiveModels] = useState([]);
   const [kiloFreeModels, setKiloFreeModels] = useState([]);
   const [disabledModelIds, setDisabledModelIds] = useState([]);
   const [confirmState, setConfirmState] = useState(null);
@@ -142,7 +143,10 @@ export default function ProviderDetailPage() {
   const isOAuth = !!OAUTH_PROVIDERS[providerId] || !!FREE_PROVIDERS[providerId] || authModes.includes("oauth");
   const supportsApiKeyAuth = !!APIKEY_PROVIDERS[providerId] || authModes.includes("apikey");
   const isFreeNoAuth = !!FREE_PROVIDERS[providerId]?.noAuth;
-  const models = getModelsByProviderId(providerId);
+  const staticModels = getModelsByProviderId(providerId);
+  const models = providerId === "cursor" && liveModels.length > 0
+    ? liveModels
+    : staticModels;
   const providerAlias = getProviderAlias(providerId);
   
   const isOpenAICompatible = isOpenAICompatibleProvider(providerId);
@@ -453,6 +457,34 @@ export default function ProviderDetailPage() {
     fetchDisabledModels();
   }, [fetchConnections, fetchAliases, fetchCustomModels, fetchDisabledModels]);
 
+  // Cursor's model availability is account-specific and changes frequently.
+  // Load the active account's live catalog for the dashboard; the static
+  // registry remains the fallback while the request is pending or unavailable.
+  useEffect(() => {
+    if (providerId !== "cursor") {
+      setLiveModels([]);
+      return;
+    }
+
+    const connection = connections.find((item) => item.isActive !== false);
+    if (!connection?.id) {
+      setLiveModels([]);
+      return;
+    }
+
+    let cancelled = false;
+    fetch(`/api/providers/${connection.id}/models`, { cache: "no-store" })
+      .then(async (res) => ({ ok: res.ok, data: await res.json() }))
+      .then(({ ok, data }) => {
+        if (!cancelled && ok && Array.isArray(data.models) && data.models.length > 0) {
+          setLiveModels(data.models);
+        }
+      })
+      .catch(() => {});
+
+    return () => { cancelled = true; };
+  }, [providerId, connections]);
+
   // Fetch suggested models from provider's public API (if configured)
   useEffect(() => {
     const fetcher = (OAUTH_PROVIDERS[providerId] || APIKEY_PROVIDERS[providerId] || FREE_PROVIDERS[providerId] || FREE_TIER_PROVIDERS[providerId])?.modelsFetcher;