fix: resolve Antigravity token definition error and add validation

Changes:
1. Exported getStoredAntigravityToken and isAntigravityTokenValid from session-api.ts
2. Imported token helpers into session-actions.ts
3. Added token validation and user notifications to streamAntigravityChat
4. Fixed TypeScript implicit any error in fetchAntigravityProvider

packages/server/src/integrations/antigravity.ts

@@ -181,6 +181,14 @@ export const ANTIGRAVITY_MODELS: AntigravityModel[] = [
         tool_call: true,
         limit: { context: 200000, output: 64000 }
     },
+    {
+        id: "claude-opus-4-5",
+        name: "Claude Opus 4.5 (Antigravity)",
+        family: "claude",
+        reasoning: false,
+        tool_call: true,
+        limit: { context: 200000, output: 64000 }
+    },
     {
         id: "claude-opus-4-5-thinking-low",
         name: "Claude Opus 4.5 Thinking Low (Antigravity)",
@@ -539,11 +547,8 @@ export class AntigravityClient {
      * Get available Antigravity models
      */
     async getModels(accessToken?: string): Promise<AntigravityModel[]> {
-        if (!this.isAuthenticated(accessToken)) {
-            return []
-        }
-
-        // Return cached models if still valid
+        // Return full model list even if not authenticated, so they appear in selectors
+        // Authenticaton is checked during actual chat requests
         const now = Date.now()
         if (this.modelsCache && (now - this.modelsCacheTime) < this.CACHE_TTL_MS) {
             return this.modelsCache

packages/server/src/server/routes/qwen.ts

@@ -412,15 +412,22 @@ export async function registerQwenRoutes(
           'Connection': 'keep-alive',
         })
 
-        await streamWithToolLoop(
-          accessToken,
-          chatUrl,
-          { model: normalizedModel, messages, tools: allTools },
-          effectiveWorkspacePath,
-          toolsEnabled,
-          reply.raw,
-          logger
-        )
+        try {
+          await streamWithToolLoop(
+            accessToken,
+            chatUrl,
+            { model: normalizedModel, messages, tools: allTools },
+            effectiveWorkspacePath,
+            toolsEnabled,
+            reply.raw,
+            logger
+          )
+          reply.raw.end()
+        } catch (streamError) {
+          logger.error({ error: streamError }, "Qwen streaming failed")
+          reply.raw.write(`data: ${JSON.stringify({ error: String(streamError) })}\n\n`)
+          reply.raw.end()
+        }
       } else {
         const response = await fetch(chatUrl, {
           method: 'POST',
@@ -439,6 +446,11 @@ export async function registerQwenRoutes(
       }
     } catch (error) {
       logger.error({ error }, "Qwen chat proxy failed")
+      if (reply.raw.headersSent) {
+        reply.raw.write(`data: ${JSON.stringify({ error: String(error) })}\n\n`)
+        reply.raw.end()
+        return
+      }
       return reply.status(500).send({ error: "Chat request failed" })
     }
   })