Apply patch
openrouter:apply_patch
Lets coding agents edit files with structured patches. The model emits a V4A diff, OpenRouter validates it and returns a structured apply_patch call, and your application applies the change to its own files.
How it works
The building block for coding agents that edit files.
Your model writes a V4A diff that creates, updates, or deletes a file.
OpenRouter validates the diff, and returns invalid patches to the model to fix.
Your app applies the patch to its own files and reports the result on the next turn.
Providers and pricing
OpenRouter validator
Free
OpenRouter validates the V4A diff and returns a structured apply_patch call.
Standard model token costs apply to every request.
Using this tool
OpenRouter validates the diff and returns it as an apply_patch_call output item. Your application applies the patch to its own files and sends the result back as apply_patch_call_output on the next turn.
Available through the API. Patches are applied by your application, so there is no file system to edit in the chatroom.
Supported APIs: Responses.
curl https://openrouter.ai/api/v1/responses \
-H "Authorization: Bearer $OPENROUTER_API_KEY" \
-H "Content-Type: application/json" \
-d '{
"model": "openai/gpt-5.2",
"tools": [
{
"type": "openrouter:apply_patch"
}
],
"input": "Rename the function greet to sayHello in src/index.ts."
}'Setup, parameters, and examples in the docs.
Read the integration guide