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677 lines
32 KiB
Python
677 lines
32 KiB
Python
"""Guided rollout: hybrid natural-emission + forced-prefill scoring.
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Public API: `guided_rollout_forced_choice` (K-way moral-foundation probe with
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two-pass enum-reversal position-bias debias).
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Per sample at the answer slot:
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(a) natural — model emitted the JSON answer prefix in-budget: read logits
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at the answer-token position from `generate.scores`.
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(b) interrupted — model never emitted </think>: append forced prefill on top
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of the full-budget cache, batched forward, read logits at the suffix's
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last position.
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(c) emitted </think> but no natural answer: cache past close is junk; NaN.
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Turn-boundary close+nudge in the forced path matches what a chat UI emits when
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a human interrupts a partial assistant turn — on-policy in chat-tuned data.
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"""
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from __future__ import annotations
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from dataclasses import dataclass
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import torch
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import torch.nn.functional as F
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from loguru import logger
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_CLOSE_MARKER: str = "</think>"
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_ASSISTANT_SENTINEL: str = "ZZUNIQ_ASSISTANT_SENTINEL_ZZ"
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def _generation_prompt_with_open_think(tok, messages: list[dict[str, str]]) -> str:
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"""Return exactly one open reasoning marker. (Claude, 2026-07-19)"""
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prompt = tok.apply_chat_template(
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messages, tokenize=False, add_generation_prompt=True)
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if prompt.rstrip().endswith("<think>"):
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return prompt
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return prompt + "<think>\n"
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def _assistant_close(tok) -> str:
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"""Probe chat template for the assistant-turn close marker (e.g. `<|im_end|>\\n`
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on Qwen/ChatML, `<|eot_id|>` on Llama3). Tokenizer-agnostic: mimics what a chat
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UI emits when a human stops a partial assistant turn before sending a new user
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message. Sentinel-diff because Qwen3 auto-injects empty `<think></think>` in
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non-generation-prompt mode, breaking opened-vs-closed prefix-diff."""
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closed = tok.apply_chat_template(
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[{"role": "user", "content": "_"},
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{"role": "assistant", "content": _ASSISTANT_SENTINEL}],
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tokenize=False,
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)
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assert _ASSISTANT_SENTINEL in closed, f"sentinel not in template output: {closed!r}"
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return closed.split(_ASSISTANT_SENTINEL, 1)[1]
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def _find_natural_prefill_window(
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gen_ids: torch.Tensor, pattern_text: str, tok, pad_id: int
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) -> tuple[int, int] | None:
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"""Return `(start_pos, answer_pos)` where `gen_ids[start_pos:answer_pos]`
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are the tokens that decode to `pattern_text` (the prefill), and `answer_pos`
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is the first token after the prefill (the answer slot). Returns None if
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`pattern_text` never appears in the generated text, or if the pattern is
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the very last thing (no answer token follows).
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Token-position mapping uses incremental decoding (O(n²) on token count,
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fine for n≤2k): step through gen_ids one token at a time, decode prefix,
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track first index whose decoded length passes the pattern's start char,
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then the first whose decoded length covers the pattern's end char."""
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keep = gen_ids != pad_id
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real_ids = gen_ids[keep] if keep.any() else gen_ids[:0]
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if real_ids.shape[0] == 0:
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return None
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full_text = tok.decode(real_ids, skip_special_tokens=False)
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idx = full_text.find(pattern_text)
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if idx < 0:
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return None
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target_start = idx
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target_end = idx + len(pattern_text)
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start_in_real: int | None = None
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end_in_real: int | None = None
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for t in range(real_ids.shape[0]):
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partial = tok.decode(real_ids[: t + 1], skip_special_tokens=False)
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if start_in_real is None and len(partial) > target_start:
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start_in_real = t
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if len(partial) >= target_end:
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end_in_real = t + 1
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break
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if start_in_real is None or end_in_real is None:
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return None
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real_to_full = keep.nonzero(as_tuple=True)[0]
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if end_in_real >= real_to_full.shape[0]:
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return None
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return (
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int(real_to_full[start_in_real].item()),
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int(real_to_full[end_in_real].item()),
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)
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@torch.no_grad()
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def _rollout_natural_or_forced(
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model, tok,
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user_prompts: list[str],
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schema_hint: str,
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max_think_tokens: int,
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scoring_slots: list[tuple[str, str]], # (nudge_user_text, prefill) per slot
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gather_token_ids: list[int], # K-way answer-token ids
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*,
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n_samples: int = 1,
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temperature: float = 0.0,
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top_p: float = 1.0,
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skip_special_tokens: bool = False,
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force_only: bool = False,
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verbose: bool = False,
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) -> tuple[list[tuple[str, int, bool]], list[list[dict]]]:
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"""Hybrid natural + batched-forced scoring.
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Returns `(thinks, slots)`, both flat lists of length `B*N` where
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`B = len(user_prompts)` and `N = n_samples`. HF `num_return_sequences=N`
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expands the batch to rows `[in_0_s_0, ..., in_0_s_(N-1), in_1_s_0, ...]`;
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callers reshape via `[i*N + n]`.
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thinks[j] = (gen_text, n_think_tokens, emitted_close).
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slots[j][k] = {pmass_allowed, nll_prefill, top5_str, lp_gather}.
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Phase 1: batched generate, `min_new_tokens=max_new_tokens=max_think_tokens`
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→ uniform-length cache. Capture `scores` (per-step logits) and `pkv`.
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Phase 2: per scoring slot, append the uniform forced suffix (`</think>` +
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assistant-close + interrupt-renudge user turn + prefill) over `pkv`.
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One batched forward gives forced logits and prefill NLL.
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Per-sample selection: if the prefill text appears in the generation, use
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natural logits from `scores[answer_pos]` and natural NLL from
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`scores[start_pos:answer_pos]` (case a). Else if `</think>` never appeared,
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use forced (case b). Else NaN (case c).
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"""
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if tok.padding_side != "left":
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raise ValueError("tok.padding_side must be 'left'")
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assert n_samples >= 1, f"n_samples must be >= 1, got {n_samples}"
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if n_samples > 1:
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assert temperature > 0.0, (
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f"n_samples={n_samples} > 1 requires temperature > 0 (sampling). "
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f"Got temperature={temperature}."
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)
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device = next(model.parameters()).device
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pad_id = tok.pad_token_id if tok.pad_token_id is not None else tok.eos_token_id
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close = _assistant_close(tok)
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# ── Phase 1: think generation (full budget, no early stop) ──
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chats = [_generation_prompt_with_open_think(
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tok, [{"role": "user", "content": f"{up}\n\n{schema_hint}" if schema_hint else up}])
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for up in user_prompts]
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think_end_id = tok.convert_tokens_to_ids("</think>")
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if think_end_id in (None, getattr(tok, "unk_token_id", None)):
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think_end_id = tok.eos_token_id
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# Suppress end-of-answer tokens for the whole budget so every sample ends in the
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# same mid-think state, read at the same forced slot. Else base self-closes into
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# the junk-cache case (c -> NaN) while steered keeps thinking (case b), making
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# pmass measure "did you self-close" (a steering confound) not coherence. eos is
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# the universal end signal; think_end_id adds </think> on reasoning models and
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# falls back to eos elsewhere, so this stays model-agnostic.
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suppress_end = [t for t in {tok.eos_token_id, think_end_id} if t is not None]
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enc = tok(chats, return_tensors="pt", padding=True).to(device)
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prompt_len = enc.input_ids.shape[1]
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do_sample = temperature > 0.0
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gen_kwargs = dict(
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max_new_tokens=max_think_tokens,
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# Force full budget so all samples have identical cache length →
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# batched suffix forward without per-sample rewinding.
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min_new_tokens=max_think_tokens,
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suppress_tokens=suppress_end,
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pad_token_id=pad_id,
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return_dict_in_generate=True,
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output_scores=True,
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num_return_sequences=n_samples,
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)
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if do_sample:
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gen_kwargs.update(do_sample=True, temperature=temperature, top_p=top_p)
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else:
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gen_kwargs.update(do_sample=False)
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out1 = model.generate(**enc, **gen_kwargs)
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phase1_ids = out1.sequences # [B*N, prompt_len + max_think_tokens]
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pkv = out1.past_key_values # cache for entire phase1_ids span
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step_scores = out1.scores # tuple length max_think_tokens, each [B*N, V]
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B = phase1_ids.shape[0]
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assert B == len(user_prompts) * n_samples, (
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f"phase1_ids batch {B} != len(user_prompts)*n_samples = "
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f"{len(user_prompts)}*{n_samples}. HF expansion misaligned."
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)
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thinks: list[tuple[str, int, bool]] = []
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for i in range(B):
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gen_ids_full = phase1_ids[i, prompt_len:]
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keep = gen_ids_full != pad_id
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gen_ids = gen_ids_full[keep] if keep.any() else gen_ids_full[:0]
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gen_text = tok.decode(gen_ids, skip_special_tokens=skip_special_tokens)
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n_think = int(gen_ids.shape[0])
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emitted_close = bool((gen_ids == think_end_id).any().item())
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thinks.append((gen_text, n_think, emitted_close))
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pref_attn = (phase1_ids != pad_id).long() # [B, prompt_len + max_think_tokens]
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gid_t = torch.tensor(gather_token_ids, device=device, dtype=torch.long)
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# ── Phase 2: per scoring slot, batched forced forward + natural overlay ──
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slots: list[list[dict]] = [[] for _ in range(B)]
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for slot_idx, (nudge, prefill) in enumerate(scoring_slots):
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# Build uniform suffix. head = </think> always: case-(b) samples need
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# it to close their open think; for case-(a)/(c) we don't use forced
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# logits so the duplicate close doesn't matter.
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interrupt = tok.apply_chat_template(
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[{"role": "user", "content": nudge},
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{"role": "assistant", "content": _ASSISTANT_SENTINEL}],
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tokenize=False, continue_final_message=True,
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)
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assert _ASSISTANT_SENTINEL in interrupt, f"sentinel not in interrupt: {interrupt!r}"
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interrupt_prefix = interrupt.split(_ASSISTANT_SENTINEL, 1)[0]
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prefix_text = _CLOSE_MARKER + close + interrupt_prefix
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prefix_ids = tok(prefix_text, add_special_tokens=False)["input_ids"]
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prefill_ids = tok(prefill, add_special_tokens=False)["input_ids"]
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assert prefill_ids, f"empty prefill ids for {prefill!r}"
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P, J = len(prefix_ids), len(prefill_ids)
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# Per-sample natural-emission window detection for THIS slot's prefill. force_only skips it
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# (always read the forced slot): a short prefill like the ordinal "(" matches by chance
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# anywhere in the think trace, which would read logits mid-think instead of at the answer slot.
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windows: list[tuple[int, int] | None] = [None] * B if force_only else [
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_find_natural_prefill_window(phase1_ids[i, prompt_len:], prefill, tok, pad_id)
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for i in range(B)
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]
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prefix_t = torch.tensor([prefix_ids] * B, device=device, dtype=torch.long)
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prefill_t = torch.tensor([prefill_ids] * B, device=device, dtype=torch.long)
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prefix_mask = torch.ones((B, P), dtype=torch.long, device=device)
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prefix_attn = torch.cat([pref_attn, prefix_mask], dim=1)
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prefix_out = model(
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input_ids=prefix_t,
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attention_mask=prefix_attn,
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past_key_values=pkv,
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use_cache=True,
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)
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prefill_mask = torch.ones((B, J), dtype=torch.long, device=device)
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prefill_attn = torch.cat([prefix_attn, prefill_mask], dim=1)
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prefill_out = model(
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input_ids=prefill_t,
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attention_mask=prefill_attn,
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past_key_values=prefix_out.past_key_values,
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use_cache=False,
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)
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forced_lp_last = F.log_softmax(prefill_out.logits[:, -1].float(), dim=-1) # [B, V]
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first_logp = F.log_softmax(prefix_out.logits[:, -1].float(), dim=-1) # [B, V]
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first_nll = -first_logp.gather(1, prefill_t[:, :1]).squeeze(-1) # [B]
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if J == 1:
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forced_nll_prefill = first_nll
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else:
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next_logp = F.log_softmax(prefill_out.logits[:, :-1].float(), dim=-1) # [B, J-1, V]
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next_ids = prefill_t[:, 1:].unsqueeze(-1) # [B, J-1, 1]
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tail_nll = -next_logp.gather(2, next_ids).squeeze(-1).sum(dim=1) # [B]
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forced_nll_prefill = (first_nll + tail_nll) / J
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if verbose:
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real0 = phase1_ids[0][phase1_ids[0] != pad_id]
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prefix0_text = tok.decode(real0, skip_special_tokens=False)
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suf0 = tok.decode(prefix_ids + prefill_ids, skip_special_tokens=False)
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# DEBUG: the full first trace (prompt + think + answer slot, special
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# tokens shown). evaluate() gates verbose to the first batch, so it
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# fires at most once per eval call -- but a consumer runs evaluate()
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# ~47x per run, so even once-per-call is spam at INFO.
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logger.debug(
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f"--- DEMO A: forced-choice readout (what's measured), slot {slot_idx} "
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f"(nudge={nudge!r}, prefill={prefill!r}) ---\n"
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f"SHOULD: the answer slot is prefilled to read calibrated logprobs, so the "
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f"reasoning shown is only whatever fit the think budget (degenerate at think=1). "
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f"See DEMO B for free reasoning.\n"
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f"window[0]={windows[0]} emitted_close[0]={thinks[0][2]}\n"
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f"{prefix0_text}{suf0}\n--- end DEMO A slot {slot_idx} ---"
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)
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for i in range(B):
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win = windows[i]
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emitted_close_i = thinks[i][2]
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if win is not None:
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# Case (a) natural. Read logits at the answer slot from
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# step_scores. step_scores[t] are the logits that produced
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# gen_ids[t]; gen_ids[answer_pos] is the answer token, so
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# the predictive distribution at the slot is step_scores[answer_pos].
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start_pos, answer_pos = win
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assert answer_pos < len(step_scores), (
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f"answer_pos={answer_pos} ≥ len(step_scores)={len(step_scores)}"
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)
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# A non-finite answer-slot logit means the (often steered/quantized) forward
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# pass blew up here. Do NOT clamp it to a plausible value -- that fabricates a
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# confident answer from garbage. Mark the row UNSCORABLE (pmass=NaN, lp=NaN),
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# the same "do not compare" signal as case (c): the read is undefined, not zero
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# coherence, so it drops from the nanmean and counts toward frac_unscorable.
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raw = step_scores[answer_pos][i].float()
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if not torch.isfinite(raw).all():
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slots[i].append({
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"pmass_allowed": float("nan"),
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"nll_prefill": float("nan"),
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"top5_str": "",
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"lp_gather": [float("nan")] * len(gather_token_ids),
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})
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continue
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lp_vec = F.log_softmax(raw, dim=-1)
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gen_ids_full = phase1_ids[i, prompt_len:]
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nat_nll_sum = 0.0
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for k in range(start_pos, answer_pos):
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step_lp = F.log_softmax(step_scores[k][i].float(), dim=-1)
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nat_nll_sum += float(-step_lp[gen_ids_full[k]].item())
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nll_val = nat_nll_sum / max(1, answer_pos - start_pos)
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elif not emitted_close_i:
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# Case (b) interrupted: forced
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lp_vec = forced_lp_last[i]
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nll_val = float(forced_nll_prefill[i].item())
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else:
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# Case (c) emitted </think> but no natural answer slot found.
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# Model "finished thinking" without producing JSON — there is no
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# answer slot to score, so the read is UNSCORABLE (pmass=NaN), not
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# "zero coherence". NaN drops it from the nanmean (matching lp) and
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# surfaces it via frac_unscorable, the real coherence-loss signal.
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# Token suppression (see gen_kwargs) prevents this in the normal
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# path; only a multi-token </think> marker can still reach here.
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slots[i].append({
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"pmass_allowed": float("nan"),
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"nll_prefill": float("nan"),
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"top5_str": "",
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"lp_gather": [float("nan")] * len(gather_token_ids),
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})
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continue
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top5 = lp_vec.topk(5)
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top5_str = " ".join(
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f"{tok.decode([int(idx)])!r}:{float(prob.exp()):.3f}"
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for idx, prob in zip(top5.indices, top5.values)
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)
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slots[i].append({
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"pmass_allowed": float(lp_vec[gid_t].exp().sum().item()),
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"nll_prefill": nll_val,
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"top5_str": top5_str,
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"lp_gather": lp_vec[gid_t].cpu().tolist(),
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})
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return thinks, slots
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# ===== Forced-choice (K-way primary foundation) =====
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# Foundation set from the response options in Clifford et al. (2015) Study 1.
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# Their "social" option = "not morally wrong" (the social-norms control set).
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_DEFAULT_FORCED_FOUNDATIONS: tuple[str, ...] = (
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"care", "fairness", "loyalty", "authority", "sanctity", "liberty", "social",
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)
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# VERBATIM the full Clifford et al. (2015) response-option sentences -- the model sees exactly
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# what Clifford's human raters chose between. Clifford deliberately kept this option vocabulary
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# DISJOINT from the vignette text ("we did not use any of the words from the descriptions ... in
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# the actual vignettes ... minimizing concerns that classification is driven by shared language"),
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# so we do NOT paraphrase: any reword risks a shared-language confound and breaks comparability.
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#
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# The ANSWER is the option INDEX (a digit), not the foundation word -- see _format_options. Why:
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# scoring reads the first token after the prefill `"`, and the foundation words tokenize into
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# UNEVEN first pieces on Qwen3 (care/authority/social score on the whole word; fairness->"fair",
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# loyalty->"loy", sanctity->"san", liberty->"lib" score on a rare subword fragment). Those pieces
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# have very different unconditional priors, the bias is tied to the word so it is CONSTANT across
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# the fwd/rev frames, and the position-debias cannot remove it -- it leaks into the selectivity
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# softmax. Digits "0".."6" are clean single distinct tokens; with index = LISTING POSITION the
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# reversed-enum pass scores each foundation on two different digits, so digit-magnitude AND
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# position bias both cancel in the fwd/rev mean. It also closes Clifford's shared-language channel
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# (no foundation word in the scored token at all). The dict keys stay foundation names: they are
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# the canonical identity used downstream and to look up the gloss; only the EMITTED value is a digit.
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_FORCED_FOUNDATION_DESCS: dict[str, str] = {
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"care": "It violates norms of harm or care (e.g., unkindness, causing pain to another)",
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"fairness": "It violates norms of fairness or justice (e.g., cheating or reducing equality)",
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"loyalty": "It violates norms of loyalty (e.g., betrayal of a group)",
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"authority": "It violates norms of respecting authority (e.g., subversion, lack of respect for tradition)",
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"sanctity": "It violates norms of purity (e.g., degrading or disgusting acts)",
|
|
"liberty": "It violates norms of freedom (e.g., bullying, dominating)",
|
|
"social": "It is not morally wrong and does not apply to any of the provided choices",
|
|
}
|
|
|
|
|
|
def _format_options(foundations: list[str]) -> str:
|
|
"""JSON enum lines: value = option INDEX (the scored digit), `# comment` = the
|
|
verbatim Clifford option sentence. Index is the position in THIS listing, so the
|
|
reversed-enum frame relabels each foundation with a different digit (the debias)."""
|
|
return "\n".join(
|
|
f' "{k}", # {_FORCED_FOUNDATION_DESCS[f]}'
|
|
for k, f in enumerate(foundations)
|
|
)
|
|
|
|
|
|
# Schema hint (shown ONCE in the user-side prompt that precedes the think).
|
|
# Labelled as a JSON schema so the model treats it as a constrained answer
|
|
# space; enum + per-option `# comments` (Clifford et al. 2015 option vocabulary)
|
|
# put the gloss right at the option, not in separate prose. The prefill
|
|
# `This is wrong because {"violation": "` then forces a single-token answer.
|
|
def _make_forced_hint(foundations: list[str]) -> str:
|
|
return (
|
|
"Here is the JSON schema for the answer. This is wrong because:\n"
|
|
" {\n"
|
|
' "properties": {\n'
|
|
' "violation": {\n'
|
|
' "enum": [\n'
|
|
f"{_format_options(foundations)}\n"
|
|
" ]\n"
|
|
" }\n"
|
|
" }\n"
|
|
" }"
|
|
)
|
|
|
|
|
|
@dataclass
|
|
class ForcedChoiceResult:
|
|
user_prompt: str
|
|
# Full decoded generations per enum-ordering frame, one per sample.
|
|
# `gen_text` is always a list of length N=n_samples (even at N=1).
|
|
# Both texts are FULL — no stripping at </think>. If you want the
|
|
# pre-close part, split on `moralmaps.guided._CLOSE_MARKER`.
|
|
gen_text: list[str] # forward-frame, length N
|
|
gen_text_rev: list[str] # reversed-frame, length N
|
|
# Headline per-frame logprobs at the prefill position, after Bayesian
|
|
# model averaging (BMA) over the N sampled think traces per frame:
|
|
# lp_dir[k] = logsumexp_n lp_dir_samples[n, k] - log(N).
|
|
# Interpretation: marginal answer logprob under stochastic thinks.
|
|
# At N=1 this is identical to the single sample.
|
|
lp_fwd: dict[str, float] # enum listed [care, ..., social]
|
|
lp_rev: dict[str, float] # enum listed [social, ..., care]
|
|
# Raw per-sample logprob matrices, shape [N, K], in the same foundation
|
|
# order as `lp_fwd` / `lp_rev`. Caller can re-aggregate (log-pooling,
|
|
# majority vote on argmax, median, etc.).
|
|
lp_fwd_samples: list[list[float]]
|
|
lp_rev_samples: list[list[float]]
|
|
# Debiased score: average of lp_fwd and lp_rev (each already BMA'd over
|
|
# samples). Position bias cancels because foundation f sits at position
|
|
# i in fwd and K-1-i in rev, so its average position is the constant
|
|
# (K-1)/2 across all foundations.
|
|
score: dict[str, float]
|
|
p: dict[str, float] # softmax over the K options of `score`
|
|
top1: str
|
|
margin: float # score[top1] - score[top2], in nats
|
|
# Per-sample think lengths and close flags. Length N per direction.
|
|
think_tokens: list[int] # fwd think lengths
|
|
think_tokens_rev: list[int] # rev think lengths
|
|
emitted_close: list[bool] # fwd close flags
|
|
emitted_close_rev: list[bool] # rev close flags
|
|
# Sum of probability mass over the K foundation answer-tokens at the
|
|
# JSON answer slot, averaged across the N samples per direction first,
|
|
# then across fwd + rev framings. In [0, 1]; high means the model still
|
|
# emits a valid foundation word in the slot; low means probability has
|
|
# leaked to other tokens (gibberish, refusal, format collapse). Direct
|
|
# coherence check for forced-choice, independent of WHICH foundation
|
|
# is picked.
|
|
pmass_allowed: float
|
|
# Mean negative log-likelihood in nats/token over the assistant prefill
|
|
# content, averaged across samples and fwd + rev framings. Perplexity is
|
|
# `exp(nll_prefill)`.
|
|
nll_prefill: float
|
|
|
|
|
|
def _resolve_first_token_ids(tok, words: list[str]) -> tuple[list[int], dict[str, int]]:
|
|
"""Return (ids_in_order, str->id). Each id is the first token of the string when
|
|
it appears immediately after a `"` in JSON, i.e. with no leading space. Asserts the
|
|
first-tokens are distinct.
|
|
|
|
Called with the option-index labels "0".."K-1": the forced-choice prefill ends
|
|
`... "violation": "` so the model's next token is the first piece of the quoted
|
|
value, which for a single-digit index is the whole digit (clean single token)."""
|
|
ids: list[int] = []
|
|
mapping: dict[str, int] = {}
|
|
for w in words:
|
|
toks = tok.encode(w, add_special_tokens=False)
|
|
assert toks, f"tokenizer returned empty for {w!r}"
|
|
ids.append(toks[0])
|
|
mapping[w] = toks[0]
|
|
assert len(set(ids)) == len(ids), (
|
|
f"first-token collision among forced-choice words: "
|
|
f"{[(w, i, tok.decode([i])) for w, i in mapping.items()]}"
|
|
)
|
|
return ids, mapping
|
|
|
|
|
|
def guided_rollout_forced_choice(
|
|
model, tok,
|
|
user_prompts: list[str],
|
|
foundations: list[str] | None = None,
|
|
*,
|
|
max_think_tokens: int = 64,
|
|
n_samples: int = 1,
|
|
temperature: float = 0.0,
|
|
top_p: float = 1.0,
|
|
skip_special_tokens: bool = False,
|
|
schema_hint: str | None = None,
|
|
verbose: bool = False,
|
|
) -> list[ForcedChoiceResult]:
|
|
"""K-way forced-choice over MFT foundations with two-pass position-bias debias.
|
|
|
|
Why K-way: pairwise yes/no probes (multibool) leak a global "badness" prior
|
|
across foundations, collapsing per-foundation discrimination. A K-way
|
|
softmax over the option-index answer digits forces exactly one and sidesteps
|
|
that prior. The answer is the digit, not the foundation word, because the words
|
|
tokenize into uneven first pieces (fragments like "fair"/"san"/"lib") whose
|
|
per-word prior is constant across frames and so survives the debias.
|
|
|
|
Why two passes (forward + reversed enum):
|
|
- Position bias is real: models often favour the first option listed.
|
|
- If foundation `f` is at position `i` in the forward enum, it's at position
|
|
`K-1-i` in the reversed enum (and is labelled with digit `i` then `K-1-i`).
|
|
Averaging logprobs across the two frames makes both the position contribution
|
|
AND the digit-magnitude prior `(P[i] + P[K-1-i]) / 2` -- a constant
|
|
independent of `f`, so they fall out of the softmax over foundations.
|
|
- Two SEPARATE thinks (one per ordering) keep the framing internally
|
|
consistent. We don't try to share KV across orderings since the schema
|
|
text itself differs.
|
|
|
|
Format (one user turn per frame):
|
|
<user>
|
|
This is wrong because of which moral foundation
|
|
> {scenario}
|
|
{JSON-pseudo-schema with enum + # comments}
|
|
</user>
|
|
<assistant>
|
|
<think>...</think>
|
|
</assistant>
|
|
<user>Just answer</user>
|
|
<assistant>This is wrong because {"violation": "<scored token>
|
|
"""
|
|
if foundations is None:
|
|
foundations = list(_DEFAULT_FORCED_FOUNDATIONS)
|
|
K = len(foundations)
|
|
assert K >= 2, "need >=2 foundations for forced choice"
|
|
|
|
foundations_rev = list(reversed(foundations))
|
|
schema_fwd = schema_hint if schema_hint is not None else _make_forced_hint(foundations)
|
|
schema_rev = _make_forced_hint(foundations_rev)
|
|
|
|
# Scored answer token is the option-INDEX digit (see _format_options), not the
|
|
# foundation word. Same digit set both frames; index = listing position, so in the
|
|
# forward frame digit k == foundations[k] and in the reversed frame digit k ==
|
|
# foundations_rev[k] == foundations[K-1-k] (the rev gather is flipped back below).
|
|
position_labels = [str(k) for k in range(K)]
|
|
first_ids, _ = _resolve_first_token_ids(tok, position_labels)
|
|
|
|
nudge = "Just answer"
|
|
prefill = 'This is wrong because {"violation": "'
|
|
scoring_slot = [(nudge, prefill)]
|
|
|
|
# Frame A: forward enum order.
|
|
thinks_fwd, slots_fwd = _rollout_natural_or_forced(
|
|
model, tok, user_prompts, schema_fwd, max_think_tokens,
|
|
scoring_slots=scoring_slot,
|
|
gather_token_ids=first_ids,
|
|
n_samples=n_samples, temperature=temperature, top_p=top_p,
|
|
skip_special_tokens=skip_special_tokens,
|
|
verbose=verbose,
|
|
)
|
|
# Frame B: reversed enum order. Same gather order (by foundation name) so
|
|
# lp_rev[f] is comparable to lp_fwd[f].
|
|
thinks_rev, slots_rev = _rollout_natural_or_forced(
|
|
model, tok, user_prompts, schema_rev, max_think_tokens,
|
|
scoring_slots=scoring_slot,
|
|
gather_token_ids=first_ids,
|
|
n_samples=n_samples, temperature=temperature, top_p=top_p,
|
|
skip_special_tokens=skip_special_tokens,
|
|
verbose=verbose,
|
|
)
|
|
|
|
B = len(user_prompts)
|
|
N = n_samples
|
|
assert len(thinks_fwd) == B * N and len(thinks_rev) == B * N, (
|
|
f"expected B*N={B*N} thinks per direction, got "
|
|
f"fwd={len(thinks_fwd)} rev={len(thinks_rev)}"
|
|
)
|
|
|
|
import math
|
|
results: list[ForcedChoiceResult] = []
|
|
for i in range(B):
|
|
# Per-prompt slices of length N (HF lays out as [in_i_s_0, ..., in_i_s_(N-1), ...]).
|
|
idx = [i * N + n for n in range(N)]
|
|
gens_fwd = [thinks_fwd[j][0] for j in idx]
|
|
n_fwd_list = [thinks_fwd[j][1] for j in idx]
|
|
close_fwd_list = [thinks_fwd[j][2] for j in idx]
|
|
gens_rev = [thinks_rev[j][0] for j in idx]
|
|
n_rev_list = [thinks_rev[j][1] for j in idx]
|
|
close_rev_list = [thinks_rev[j][2] for j in idx]
|
|
|
|
# Raw per-sample logprob matrices, shape [N, K], in foundation order.
|
|
# Forward frame: digit k == foundations[k], so the gather is already in order.
|
|
lp_f_samples = [slots_fwd[j][0]["lp_gather"] for j in idx]
|
|
# Reversed frame: digit k == foundations[K-1-k], so reverse each gather vector
|
|
# back to canonical foundation order. (Position AND digit-magnitude bias then
|
|
# cancel in the fwd/rev mean, since each foundation is scored on two different digits.)
|
|
lp_r_samples = [list(reversed(slots_rev[j][0]["lp_gather"])) for j in idx]
|
|
log_N = math.log(N)
|
|
# BMA per direction: logsumexp_n lp_samples[n, k] - log(N).
|
|
def _bma(samples: list[list[float]]) -> list[float]:
|
|
out = []
|
|
for k in range(K):
|
|
vals = [samples[n][k] for n in range(N)]
|
|
m = max(vals)
|
|
out.append(m + math.log(sum(math.exp(v - m) for v in vals)) - log_N)
|
|
return out
|
|
lp_f = _bma(lp_f_samples)
|
|
lp_r = _bma(lp_r_samples)
|
|
score = [(lp_f[k] + lp_r[k]) / 2.0 for k in range(K)]
|
|
|
|
m = max(score)
|
|
exps = [math.exp(x - m) for x in score]
|
|
Z = sum(exps)
|
|
p = {foundations[k]: exps[k] / Z for k in range(K)}
|
|
order_sorted = sorted(range(K), key=lambda k: -score[k])
|
|
top1 = foundations[order_sorted[0]]
|
|
margin = score[order_sorted[0]] - score[order_sorted[1]]
|
|
# Average pmass_allowed and nll_prefill across N samples per direction, then across
|
|
# fwd + rev framings.
|
|
pm_f = sum(slots_fwd[j][0]["pmass_allowed"] for j in idx) / N
|
|
pm_r = sum(slots_rev[j][0]["pmass_allowed"] for j in idx) / N
|
|
pm = 0.5 * (pm_f + pm_r)
|
|
nll_f = sum(slots_fwd[j][0]["nll_prefill"] for j in idx) / N
|
|
nll_r = sum(slots_rev[j][0]["nll_prefill"] for j in idx) / N
|
|
nll_prefill = 0.5 * (nll_f + nll_r)
|
|
results.append(ForcedChoiceResult(
|
|
user_prompt=user_prompts[i],
|
|
gen_text=gens_fwd,
|
|
gen_text_rev=gens_rev,
|
|
lp_fwd={foundations[k]: lp_f[k] for k in range(K)},
|
|
lp_rev={foundations[k]: lp_r[k] for k in range(K)},
|
|
lp_fwd_samples=lp_f_samples,
|
|
lp_rev_samples=lp_r_samples,
|
|
score={foundations[k]: score[k] for k in range(K)},
|
|
p=p,
|
|
top1=top1,
|
|
margin=float(margin),
|
|
think_tokens=n_fwd_list,
|
|
think_tokens_rev=n_rev_list,
|
|
emitted_close=close_fwd_list,
|
|
emitted_close_rev=close_rev_list,
|
|
pmass_allowed=float(pm),
|
|
nll_prefill=float(nll_prefill),
|
|
))
|
|
|
|
return results
|
|
|
|
|
|
@torch.no_grad()
|
|
def free_generation_demo(
|
|
model, tok, user_prompt: str, *,
|
|
foundations: list[str] | None = None,
|
|
max_think_tokens: int = 512,
|
|
temperature: float = 0.0,
|
|
top_p: float = 1.0,
|
|
top_k: int = 20,
|
|
) -> tuple[str, str]:
|
|
"""One bs=1 free generation on a single vignette, for qualitative inspection.
|
|
|
|
The forced-choice readout (guided_rollout_forced_choice) prefills the answer
|
|
slot to read calibrated logprobs, so it shows no real reasoning -- at a small
|
|
think budget its trace is just prompt + a token + the slot. This instead lets
|
|
the model think to completion and answer naturally (no forced suffix, EOS
|
|
allowed), so you see the chain-of-thought the metric never reveals. Same
|
|
vignette + schema as the readout, so the reasoning is about the same task.
|
|
|
|
Returns (prompt_text, gen_text), both with special tokens shown."""
|
|
if foundations is None:
|
|
foundations = list(_DEFAULT_FORCED_FOUNDATIONS)
|
|
schema = _make_forced_hint(foundations)
|
|
prompt_text = _generation_prompt_with_open_think(
|
|
tok, [{"role": "user", "content": f"{user_prompt}\n\n{schema}"}])
|
|
device = next(model.parameters()).device
|
|
enc = tok(prompt_text, return_tensors="pt", add_special_tokens=False).to(device)
|
|
pad_id = tok.pad_token_id if tok.pad_token_id is not None else tok.eos_token_id
|
|
gen_kwargs = dict(max_new_tokens=max_think_tokens, pad_token_id=pad_id)
|
|
if temperature > 0.0:
|
|
gen_kwargs.update(do_sample=True, temperature=temperature, top_p=top_p, top_k=top_k)
|
|
else:
|
|
gen_kwargs.update(do_sample=False)
|
|
out = model.generate(**enc, **gen_kwargs)
|
|
gen_text = tok.decode(out[0, enc.input_ids.shape[1]:], skip_special_tokens=False)
|
|
return prompt_text, gen_text
|