ractogateway.truncation._models

Data models and defaults for the token-truncation subsystem.

class ractogateway.truncation._models.TruncationConfig(**data)[source]

Bases: BaseModel

Configuration for TokenTruncator.

Parameters:

max_context_tokens (int | None) – Hard cap on total prompt tokens before calling the API. When None, the truncator looks up the model in MODEL_CONTEXT_LIMITS (falling back to 8 192).
keep_first_n (int) – Number of history messages to always preserve from the start of the conversation (anchors context). Defaults to 2.
keep_last_n (int) – Number of history messages to always preserve from the most recent end of the conversation. Defaults to 6.
token_counter (Callable[[str], int]) –
Callable (text: str) -> int. Defaults to the built-in approximate counter (len // 4). Swap for tiktoken for exact OpenAI token counts:
```
import tiktoken
enc = tiktoken.encoding_for_model("gpt-4o")
config = TruncationConfig(token_counter=lambda t: len(enc.encode(t)))
```
safety_margin (int) – Extra token budget reserved beyond the system prompt and user message. Defaults to 512.

Create a new model by parsing and validating input data from keyword arguments.

Raises [ValidationError][pydantic_core.ValidationError] if the input data cannot be validated to form a valid model.

self is explicitly positional-only to allow self as a field name.

max_context_tokens: int | None

keep_first_n: int

keep_last_n: int

token_counter: Callable[[str], int]

safety_margin: int

model_config: ClassVar[ConfigDict] = {'arbitrary_types_allowed': True}: Configuration for the model, should be a dictionary conforming to [ConfigDict][pydantic.config.ConfigDict].

resolve_limit(model)[source]

Return the effective token limit for model.

Priority: max_context_tokens → MODEL_CONTEXT_LIMITS lookup → _DEFAULT_CONTEXT.

Return type:: int

model_post_init(_TruncationConfig__context)[source]

Override this method to perform additional initialization after __init__ and model_construct. This is useful if you want to do some validation that requires the entire model to be initialized.

Return type:: None