Use admin-configured AI model and add GPT-5/o-series options

- Add getConfiguredModel() that reads ai_model from SystemSettings
- AI assignment and mentor matching now use the admin-selected model
- Remove duplicate OpenAI client in mentor-matching (use shared singleton)
- Add GPT-5, GPT-5 Mini, o3, o3 Mini, o4 Mini to model dropdown

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

src/components/settings/ai-settings-form.tsx

@@ -162,6 +162,11 @@ export function AISettingsForm({ settings }: AISettingsFormProps) {
                 <SelectContent>
                   <SelectItem value="gpt-4o">GPT-4o (Recommended)</SelectItem>
                   <SelectItem value="gpt-4o-mini">GPT-4o Mini</SelectItem>
+                  <SelectItem value="gpt-5">GPT-5</SelectItem>
+                  <SelectItem value="gpt-5-mini">GPT-5 Mini</SelectItem>
+                  <SelectItem value="o3">o3</SelectItem>
+                  <SelectItem value="o3-mini">o3 Mini</SelectItem>
+                  <SelectItem value="o4-mini">o4 Mini</SelectItem>
                   <SelectItem value="gpt-4-turbo">GPT-4 Turbo</SelectItem>
                   <SelectItem value="gpt-4">GPT-4</SelectItem>
                 </SelectContent>

src/lib/openai.ts

@@ -107,3 +107,18 @@ export const AI_MODELS = {
   ASSIGNMENT: 'gpt-4o', // Best for complex reasoning
   QUICK: 'gpt-4o-mini', // Faster, cheaper for simple tasks
 } as const
+
+/**
+ * Get the admin-configured AI model from SystemSettings.
+ * Falls back to the provided default if not configured.
+ */
+export async function getConfiguredModel(fallback: string = AI_MODELS.ASSIGNMENT): Promise<string> {
+  try {
+    const setting = await prisma.systemSettings.findUnique({
+      where: { key: 'ai_model' },
+    })
+    return setting?.value || process.env.OPENAI_MODEL || fallback
+  } catch {
+    return process.env.OPENAI_MODEL || fallback
+  }
+}

src/server/services/ai-assignment.ts

@@ -5,7 +5,7 @@
  * to generate optimal assignment suggestions.
  */
 
-import { getOpenAI, AI_MODELS } from '@/lib/openai'
+import { getOpenAI, getConfiguredModel } from '@/lib/openai'
 import {
   anonymizeForAI,
   deanonymizeResults,
@@ -153,8 +153,10 @@ async function callAIForAssignments(
   // Build the user prompt
   const userPrompt = buildAssignmentPrompt(anonymizedData, constraints)
 
+  const model = await getConfiguredModel()
+
   const response = await openai.chat.completions.create({
-    model: AI_MODELS.ASSIGNMENT,
+    model,
     messages: [
       { role: 'system', content: ASSIGNMENT_SYSTEM_PROMPT },
       { role: 'user', content: userPrompt },

src/server/services/mentor-matching.ts

@@ -1,20 +1,5 @@
 import { PrismaClient, OceanIssue, CompetitionCategory } from '@prisma/client'
-import OpenAI from 'openai'
-
-// Lazy initialization to avoid errors when API key is not set
-let openaiClient: OpenAI | null = null
-
-function getOpenAIClient(): OpenAI | null {
-  if (!process.env.OPENAI_API_KEY) {
-    return null
-  }
-  if (!openaiClient) {
-    openaiClient = new OpenAI({
-      apiKey: process.env.OPENAI_API_KEY,
-    })
-  }
-  return openaiClient
-}
+import { getOpenAI, getConfiguredModel } from '@/lib/openai'
 
 interface ProjectInfo {
   id: string
@@ -170,13 +155,15 @@ Respond in JSON format:
   ]
 }`
 
-  const openai = getOpenAIClient()
+  const openai = await getOpenAI()
   if (!openai) {
     throw new Error('OpenAI client not available')
   }
 
+  const model = await getConfiguredModel()
+
   const response = await openai.chat.completions.create({
-    model: 'gpt-4o-mini',
+    model,
     messages: [
       {
         role: 'system',