chore: switch small models to gpt-5.4-mini

oh-my-opencode.jsonc

@@ -4,8 +4,8 @@
     "sisyphus": { "model": "openai/gpt-5.4", "variant": "medium" },
     "hephaestus": { "model": "openai/gpt-5.4", "variant": "medium" },
     "oracle": { "model": "openai/gpt-5.4", "variant": "high" },
-    "librarian": { "model": "ai-gateway/minimax-m2.5" },
-    "explore": { "model": "ai-gateway/minimax-m2.5" },
+    "librarian": { "model": "openai/gpt-5.4-mini" },
+    "explore": { "model": "openai/gpt-5.4-mini" },
     "multimodal-looker": { "model": "openai/gpt-5.4", "variant": "medium" },
     "prometheus": { "model": "openai/gpt-5.4", "variant": "high" },
     "metis": { "model": "openai/gpt-5.4", "variant": "high" },
@@ -18,12 +18,13 @@
     "ultrabrain": { "model": "openai/gpt-5.4", "variant": "xhigh" },
     "deep": { "model": "openai/gpt-5.3-codex", "variant": "medium" },
     "artistry": { "model": "openai/gpt-5.4", "variant": "medium" },
-    "quick": { "model": "ai-gateway/minimax-m2.5" },
+    "quick": { "model": "openai/gpt-5.4-mini" },
     "unspecified-low": { "model": "openai/gpt-5.4", "variant": "medium" },
     "unspecified-high": { "model": "openai/gpt-5.4", "variant": "high" },
     "writing": { "model": "openai/gpt-5.4", "variant": "medium" }
   },
   "experimental": {
+    "disable_omo_env": true,
     "dynamic_context_pruning": {
       "enabled": true
     }

opencode.jsonc

@@ -3,7 +3,7 @@
   "plugin": ["oh-my-opencode@latest"],
   "autoupdate": false,
   "model": "openai/gpt-5.4",
-  "small_model": "ai-gateway/minimax-m2.5",
+  "small_model": "openai/gpt-5.4-mini",
   "provider": {
     "openai": {
       "npm": "@ai-sdk/openai",
@@ -31,22 +31,6 @@
           "limit": { "context": 400000, "input": 272000, "output": 128000 }
         }
       }
-    },
-    "ai-gateway": {
-      "name": "AI Gateway",
-      "npm": "@ai-sdk/openai-compatible",
-      "options": {
-        "baseURL": "{env:AI_GATEWAY_BASE_URL}/v1",
-        "apiKey": "{env:AI_GATEWAY_API_KEY}"
-      },
-      "models": {
-        "minimax-m2.5": {
-          "name": "MiniMax M2.5",
-          "reasoning": true,
-          "modalities": { "input": ["text"], "output": ["text"] },
-          "limit": { "context": 204800, "output": 131072 }
-        }
-      }
     }
   },
   "permission": {