Jolt-2B / src /jolt /predictor.py
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"""Candidate selection, truth estimates, and ordered scores over shared inputs."""
import json
import math
from collections.abc import Mapping
from pathlib import Path
from typing import Any
import torch
from huggingface_hub import snapshot_download
from PIL import Image
from jolt.adapters import Qwen35Adapter
from jolt.execution import plan_prefix
from jolt.model import DecisionModel, marker_positions
from jolt.recipe import IMAGE_PIXELS
QTYPES = {"choice": 0, "score": 1, "noul": 2}
def render(value):
return value if isinstance(value, str) else json.dumps(value, ensure_ascii=False)
def options_for(question):
kind = question.get("type")
criteria = question.get("criteria")
if kind == "noul":
criteria = criteria or {}
if not isinstance(criteria, Mapping):
raise ValueError("noul criteria must map false/true to descriptions")
labels = ["false", "true"]
options = [
"false: " + render(criteria.get("false", "no, the statement does not hold")),
"true: " + render(criteria.get("true", "yes, the statement holds")),
]
elif kind == "choice":
if isinstance(criteria, list):
labels = [str(value) for value in criteria]
options = [render(value) for value in criteria]
elif isinstance(criteria, Mapping):
labels = list(criteria)
options = [
str(key) if value is None or value == "" else f"{key}: {render(value)}"
for key, value in criteria.items()
]
else:
raise ValueError("choice requires a candidate list or mapping")
if len(set(labels)) != len(labels):
raise ValueError("Candidate labels must be unique")
elif kind == "score":
if not isinstance(criteria, list):
raise ValueError("score requires an ordered list of level descriptions")
labels = [str(i) for i in range(len(criteria))]
options = [f"level {i}: {render(value)}" for i, value in enumerate(criteria)]
else:
raise ValueError(f"Unsupported decision type: {kind}")
if not 2 <= len(options) <= 128:
raise ValueError("Each question requires 2–128 candidates")
return labels, options
def render_question(state_text, question, *, has_image=False, adapter=None, layout="inline"):
"""One prompt template shared by training, evaluation, and serving."""
adapter = adapter or Qwen35Adapter()
marker = adapter.marker
labels, options = options_for(question)
if layout not in {"inline", "readout-list"}:
raise ValueError(f"Unsupported prompt layout: {layout}")
content = (
f"State: {state_text}\n{question['type']} question: "
f"{question.get('instructions', '')}\nOptions:\n"
)
if marker in content or any(marker in option for option in options):
raise ValueError("Input contains the reserved candidate marker")
if layout == "inline":
content += "".join(f"- {option}{marker}" for option in options)
else:
content += "".join(f"[{index}] {option}\n" for index, option in enumerate(options))
content += "Readout:\n"
content += "".join(f"[{index}]{marker}\n" for index in range(len(options)))
if has_image:
content = adapter.image_prefix + content
return content, labels
class Predictor:
metadata: dict[str, Any]
def __init__(self, model: DecisionModel, *, prompt_layout="inline"):
self.model = model
self.prompt_layout = prompt_layout
self.image_pixels = IMAGE_PIXELS
self.max_length = model.adapter.max_input_tokens
self.temperatures = [1.0, 1.0, 1.0]
@classmethod
def from_checkpoint(cls, directory, *, revision=None, base_model=None, adapter=None):
"""Load a local export or Hub repository and merge its calibrated decision model."""
source = directory
directory = Path(source).expanduser()
if not directory.is_dir():
if isinstance(source, Path) or str(source).startswith(("/", ".", "~")):
raise FileNotFoundError(f"Checkpoint directory does not exist: {directory}")
directory = Path(
snapshot_download(
str(source),
revision=revision,
allow_patterns=["dohnuts.json", "adapter.safetensors", "LICENSE"],
)
)
config = json.loads((directory / "dohnuts.json").read_text())
if base_model is None:
# Resolve the exact public backbone revision recorded in the model card.
# Checkpoints must not depend on the exporting machine's local path.
base_model = snapshot_download(
config["base_model"], revision=config["base_revision"]
)
base_model = Path(base_model).expanduser()
model = DecisionModel(
base_model, adapter=adapter, architecture=config.get("architecture")
)
model.enable_lora(
checkpointing=False,
rank=config["lora_rank"],
alpha=config.get("lora_alpha", 16),
dropout=config.get("lora_dropout", 0.0),
)
config = model.load_adapter(directory)
model.merge()
predictor = cls(model, prompt_layout=config.get("prompt_layout", "inline"))
predictor.metadata = config
predictor.temperatures = [config["temperatures"][kind] for kind in QTYPES]
return predictor
def prepare(self, state, questions):
if not isinstance(questions, Mapping) or not questions:
raise ValueError("questions must be a nonempty mapping")
image = None
if isinstance(state, Mapping):
image = state.get("image")
if "images" in state:
raise ValueError("Pass one decoded PIL image via state['image']")
state_text = render({key: value for key, value in state.items() if key != "image"})
else:
state_text = render(state)
if image is not None and not isinstance(image, Image.Image):
raise ValueError("Decode the image as a PIL image before passing it in state['image']")
texts, metadata = [], []
for qid, question in questions.items():
content, labels = render_question(
state_text,
question,
has_image=image is not None,
adapter=self.model.adapter,
layout=self.prompt_layout,
)
texts.append(content)
metadata.append((qid, question["type"], labels))
if image is not None:
inputs = self.model.adapter.shared_image_inputs(self.model.processor, texts, image)
else:
inputs = self.model.adapter.batch_inputs(self.model.processor, texts, [])
if inputs["input_ids"].shape[1] > self.max_length:
raise ValueError(
"Input exceeds the token budget; no question or candidate was truncated"
)
maximum = max(len(labels) for _, _, labels in metadata)
positions = torch.zeros(len(texts), maximum, dtype=torch.long)
mask = torch.zeros_like(positions, dtype=torch.bool)
for row, (_, _, labels) in enumerate(metadata):
positions[row, : len(labels)] = marker_positions(
inputs["input_ids"][row : row + 1],
self.model.marker_id,
len(labels),
)[0]
mask[row, : len(labels)] = True
plan_prefix(inputs, positions)
return inputs, positions, mask, metadata
@torch.inference_mode()
def predict(self, state, questions):
self.model.eval()
inputs, positions, mask, metadata = self.prepare(state, questions)
token_count = int(inputs["attention_mask"].sum())
has_image = "pixel_values" in inputs
inputs = {
key: value.to("cuda") if isinstance(value, torch.Tensor) else value
for key, value in inputs.items()
}
positions = positions.to("cuda")
logits = self.model(
inputs, positions, candidate_mask=mask.to("cuda")
).cpu().masked_fill(~mask, -torch.inf)
answers = {}
for row, (qid, kind, labels) in enumerate(metadata):
temperature = self.temperatures[QTYPES[kind]]
if not math.isfinite(temperature) or temperature <= 0:
raise ValueError("Calibration temperatures must be positive and finite")
probabilities = (logits[row, : len(labels)] / temperature).softmax(-1)
if not torch.isfinite(probabilities).all():
raise RuntimeError("Model produced a non-finite distribution")
values = probabilities.tolist()
entropy = -sum(p * math.log(max(p, 1e-12)) for p in values)
answer = {
"type": kind,
"confidence": max(0.0, min(1.0, 1 - entropy / math.log(len(labels)))),
}
if kind == "noul":
answer["noul"] = values[1]
answer["confidence"] = max(values)
else:
answer["probabilities"] = dict(zip(labels, values, strict=True))
if kind == "choice":
answer["choice"] = labels[int(probabilities.argmax())]
else:
answer["score"] = sum(i * p for i, p in enumerate(values))
answers[qid] = answer
return {
"model": getattr(self, "metadata", {}).get("model_id", "jolt"),
"answers": answers,
"usage": {"input_tokens": token_count, "images": int(has_image)},
}