Use anthropic model (the default) if the api key is present in env

aider

@@ -2,5 +2,11 @@
 # TODO adjust for other OS
 # This is need for Mac as the default clang is too old
 export CC=/opt/homebrew/opt/llvm/bin/clang CXX=/opt/homebrew/opt/llvm/bin/clang++ CPATH=/opt/homebrew/opt/llvm/include LIBRARY_PATH=/opt/homebrew/opt/llvm/lib
+
+export MODEL='openai/xai:grok-beta'
+
+if [ -n "$ANTHROPIC_API_KEY" ]; then
+  export MODEL=""
+fi
 # This runs aider in a virtual environment with the specified model, configs etc.
-uvx --python 3.11 --from 'aider-chat[help,playwright]' aider --no-show-model-warnings --model 'openai/xai:grok-beta' --max-chat-history-tokens 8000 --dark-mode --subtree-only "$@"
+uvx --python 3.11 --from 'aider-chat[help,playwright]' aider --no-show-model-warnings --model "$MODEL" --max-chat-history-tokens 8000 --dark-mode --subtree-only "$@"