# Candidate compilation (llmcpp)

**Candidate compilation** checks a proposed body in its surrounding translation unit before accepting it. The tool-server fixture deliberately tries to modify a private field from outside its class:

```json
{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/call",
  "params": {
    "name": "try_compile",
    "arguments": {
      "body": "account.cents = 1;"
    }
  }
}
```

In this request, the active target is the free function `peek(Account& account)`. `Account::cents` is private, so compilation detects the invalid access. The agent can inspect members and use the public `balance()` method instead.

`try_compile` receives statements, not a complete function declaration. It returns diagnostics without accepting the candidate or executing it. Failed checks consume tool calls but not rejected-submission attempts. [[llmcpp-body-submission|`submit`]] separately checks and accepts the final body.