feat(github): resolve Copilot model catalog from upstream

Fetch the live model list from the Copilot /models endpoint and surface
it through /v1/models, replacing the hardcoded github entry so newly
shipped models appear without a code change. Catalog is cached per
credential and the Copilot token is refreshed on 401/403 before retry.

Also raise the connectivity-test budget to max_tokens:16, since Claude on
Copilot emits no choices at max_tokens:1 and produced a false negative.

Co-authored-by: Cursor <cursoragent@cursor.com>

src/app/api/models/test/ping.js

@@ -135,7 +135,9 @@ export async function pingModelByKind(model, kind, baseUrl = `http://127.0.0.1:$
     headers,
     body: JSON.stringify({
       model,
-      max_tokens: 1,
+      // Claude-on-Copilot returns empty choices at max_tokens:1 (budget is spent
+      // before a content token emits), so a 1-token probe yields a false negative.
+      max_tokens: 16,
       stream: false,
       messages: [{ role: "user", content: "hi" }],
     }),

src/app/api/v1/models/route.js

@@ -9,6 +9,8 @@ import { getProviderConnections, getCombos, getCustomModels, getModelAliases } f
 import { getDisabledModels } from "@/lib/disabledModelsDb";
 import { resolveKiroModels } from "open-sse/services/kiroModels.js";
 import { resolveQoderModels } from "open-sse/services/qoderModels.js";
+import { resolveCopilotModels } from "open-sse/services/copilotModels.js";
+import { updateProviderCredentials } from "@/sse/services/tokenRefresh";
 import { capabilitiesFromServiceKind } from "open-sse/providers/capabilities.js";
 
 // Per-provider live model resolvers. Each receives a connection record and
@@ -35,6 +37,23 @@ const LIVE_MODEL_RESOLVERS = {
     return {
       models: result.models.map((m) => ({ id: m.id, name: m.name })),
     };
+  },
+  github: async (conn) => {
+    const result = await resolveCopilotModels({
+      accessToken: conn.accessToken,
+      refreshToken: conn.refreshToken,
+      providerSpecificData: conn.providerSpecificData || {}
+    }, {
+      log: console,
+      onCredentialsRefreshed: async (refreshed) => {
+        await updateProviderCredentials(conn.id, {
+          copilotToken: refreshed.copilotToken,
+          copilotTokenExpiresAt: refreshed.copilotTokenExpiresAt,
+          existingProviderSpecificData: conn.providerSpecificData || {},
+        });
+      },
+    });
+    return result?.models?.length ? { models: result.models } : null;
   }
 };