feat: add mini model

backend/utils/constants.py

@@ -84,7 +84,7 @@ MODELS = {
         },
         "tier_availability": ["paid"]
     },
-      "openai/gpt-5": {
+    "openai/gpt-5": {
         "aliases": ["gpt-5"],
         "pricing": {
             "input_cost_per_million_tokens": 1.25,
@@ -92,6 +92,14 @@ MODELS = {
         },
         "tier_availability": ["paid"]
     },
+    "openai/gpt-5-mini": {
+        "aliases": ["gpt-5-mini"],
+        "pricing": {
+            "input_cost_per_million_tokens": 0.25,
+            "output_cost_per_million_tokens": 2.00
+        },
+        "tier_availability": ["paid"]
+    },
     "openai/gpt-4.1-mini": {
         "aliases": ["gpt-4.1-mini"],
         "pricing": {

frontend/src/components/thread/chat-input/_use-model-selection.ts

@@ -100,6 +100,12 @@ export const MODELS = {
     recommended: false,
     lowQuality: false
   },
+  'gpt-5-mini': { 
+    tier: 'premium', 
+    priority: 88,
+    recommended: false,
+    lowQuality: false
+  },
   'gemini-2.5-flash:thinking': { 
     tier: 'premium', 
     priority: 84,