Improve AI filtering error handling and visibility

- Add listAvailableModels() and validateModel() to openai.ts
- Improve testOpenAIConnection() to test configured model
- Add checkAIStatus endpoint to filtering router
- Add pre-execution AI config check in executeRules
- Improve error messages in AI filtering service (rate limit, quota, etc.)
- Add AI status warning banner on round detail page for filtering rounds

Now admins get clear errors when AI is misconfigured instead of silent flags.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/server/routers/filtering.ts

@@ -4,8 +4,48 @@ import { Prisma } from '@prisma/client'
 import { router, adminProcedure, protectedProcedure } from '../trpc'
 import { executeFilteringRules } from '../services/ai-filtering'
 import { logAudit } from '../utils/audit'
+import { isOpenAIConfigured, testOpenAIConnection } from '@/lib/openai'
 
 export const filteringRouter = router({
+  /**
+   * Check if AI is configured and ready for filtering
+   */
+  checkAIStatus: protectedProcedure
+    .input(z.object({ roundId: z.string() }))
+    .query(async ({ ctx, input }) => {
+      // Check if round has AI rules
+      const aiRules = await ctx.prisma.filteringRule.count({
+        where: {
+          roundId: input.roundId,
+          ruleType: 'AI_SCREENING',
+          isActive: true,
+        },
+      })
+
+      if (aiRules === 0) {
+        return { hasAIRules: false, configured: true, error: null }
+      }
+
+      // Check if OpenAI is configured
+      const configured = await isOpenAIConfigured()
+      if (!configured) {
+        return {
+          hasAIRules: true,
+          configured: false,
+          error: 'OpenAI API key not configured',
+        }
+      }
+
+      // Test the connection
+      const testResult = await testOpenAIConnection()
+      return {
+        hasAIRules: true,
+        configured: testResult.success,
+        error: testResult.error || null,
+        model: testResult.modelTested,
+      }
+    }),
+
   /**
    * Get filtering rules for a round
    */
@@ -146,6 +186,30 @@ export const filteringRouter = router({
         })
       }
 
+      // Check if any AI_SCREENING rules exist
+      const hasAIRules = rules.some((r) => r.ruleType === 'AI_SCREENING' && r.isActive)
+
+      if (hasAIRules) {
+        // Verify OpenAI is configured before proceeding
+        const aiConfigured = await isOpenAIConfigured()
+        if (!aiConfigured) {
+          throw new TRPCError({
+            code: 'PRECONDITION_FAILED',
+            message:
+              'AI screening rules require OpenAI to be configured. Go to Settings → AI to configure your API key.',
+          })
+        }
+
+        // Also verify the model works
+        const testResult = await testOpenAIConnection()
+        if (!testResult.success) {
+          throw new TRPCError({
+            code: 'PRECONDITION_FAILED',
+            message: `AI configuration error: ${testResult.error}. Go to Settings → AI to fix.`,
+          })
+        }
+      }
+
       // Get projects in this round
       const roundProjectEntries = await ctx.prisma.roundProject.findMany({
         where: { roundId: input.roundId },