fix: resolve bare model names to connection defaultModel before upstream calls

src/sse/handlers/chat.js

@@ -166,6 +166,13 @@ async function handleSingleModelChat(body, modelStr, clientRawRequest = null, re
   while (true) {
     const credentials = await getProviderCredentials(provider, excludeConnectionIds, model);
 
+    // If the model is a bare name (no "/" — e.g. "auto" resolved from a connection alias),
+    // and the connection has a defaultModel, use that so the upstream receives a real model ID
+    let effectiveModel = model;
+    if (!modelStr.includes("/") && credentials?.defaultModel) {
+      effectiveModel = credentials.defaultModel;
+    }
+
     // All accounts unavailable
     if (!credentials || credentials.allRateLimited) {
       if (credentials?.allRateLimited) {
@@ -201,8 +208,8 @@ async function handleSingleModelChat(body, modelStr, clientRawRequest = null, re
     const chatSettings = await getSettings();
     const providerThinking = (chatSettings.providerThinking || {})[provider] || null;
     const result = await handleChatCore({
-      body: { ...body, model: `${provider}/${model}` },
-      modelInfo: { provider, model },
+      body: { ...body, model: `${provider}/${effectiveModel}` },
+      modelInfo: { provider, model: effectiveModel },
       credentials: refreshedCredentials,
       log,
       clientRawRequest,

src/sse/handlers/embeddings.js

@@ -87,6 +87,12 @@ export async function handleEmbeddings(request) {
   while (true) {
     const credentials = await getProviderCredentials(provider, excludeConnectionIds, model);
 
+    // If the model is a bare name and the connection has a defaultModel, use that
+    let effectiveModel = model;
+    if (!modelStr.includes("/") && credentials?.defaultModel) {
+      effectiveModel = credentials.defaultModel;
+    }
+
     // All accounts unavailable
     if (!credentials || credentials.allRateLimited) {
       if (credentials?.allRateLimited) {
@@ -108,8 +114,8 @@ export async function handleEmbeddings(request) {
     const refreshedCredentials = await checkAndRefreshToken(provider, credentials);
 
     const result = await handleEmbeddingsCore({
-      body: { ...body, model: `${provider}/${model}` },
-      modelInfo: { provider, model },
+      body: { ...body, model: `${provider}/${effectiveModel}` },
+      modelInfo: { provider, model: effectiveModel },
       credentials: refreshedCredentials,
       log,
       onCredentialsRefreshed: async (newCreds) => {

src/sse/services/auth.js

@@ -165,6 +165,7 @@ export async function getProviderCredentials(provider, excludeConnectionIds = nu
       projectId: connection.projectId,
       connectionName: connection.displayName || connection.name || connection.email || connection.id,
       copilotToken: connection.providerSpecificData?.copilotToken,
+      defaultModel: connection.defaultModel || null,
       providerSpecificData: {
         ...(connection.providerSpecificData || {}),
         connectionProxyEnabled: resolvedProxy.connectionProxyEnabled,