| --- |
| pretty_name: Mistral-7B TPU hidden-state extractor verification (CoQA references) |
| language: |
| - en |
| task_categories: |
| - feature-extraction |
| tags: |
| - mistral |
| - hidden-states |
| - tpu |
| - pytorch-xla |
| - coqa |
| --- |
| |
| # Mistral-7B TPU hidden-state extractor verification |
|
|
| > **Verification-only artifact — not a reproduction of the paper's AUROC.** |
|
|
| This dataset contains last-token embeddings and hidden states extracted from |
| 1,000 flattened CoQA validation question/reference-answer pairs with |
| `mistralai/Mistral-7B-Instruct-v0.3`. It verifies that the memory-bounded TPU |
| v5e-1 extraction path runs successfully. It does **not** contain the Mistral |
| `best_answer` generations or hallucination labels required to reproduce Table |
| 2 of *Automatic Layer Selection for Hallucination Detection*. |
|
|
| The paper authors' public repository does not contain its `prepared_data` |
| records. Do not treat this artifact as evidence for or against the paper's |
| FEPoID or hidden-state-probing AUROC claims. |
|
|
| ## Tensor layout |
|
|
| Each `states/validation/shard-*.safetensors` file contains BF16 tensors: |
|
|
| | Key | Shape | Meaning | |
| | --- | --- | --- | |
| | `embedding` | `[N, 4096]` | Last-position input-token embedding | |
| | `hidden_states` | `[N, 32, 4096]` | Last-position state for every Mistral layer | |
|
|
| Layers 0–30 are post-transformer-block states. Layer 31 is post-final-RMSNorm, |
| matching the tensors selected as `outputs.hidden_states[1:]` by the released |
| CUDA code. `metadata-validation.jsonl` maps each source index to a shard and |
| offset. `inputs-validation.jsonl` contains the exact prompt-answer text and its |
| SHA-256 digest. |
|
|
| ## Memory-bounded TPU method |
|
|
| - Loads `MistralModel`, omitting the unused language-model head. |
| - Uses BF16, `use_cache=False`, `XLA_NO_SPECIAL_SCALARS=1`, and PyTorch/XLA JIT. |
| - Never enables `output_hidden_states=True`. |
| - Hooks only `[:, -1, :]` after each layer and performs one host transfer per batch. |
| - Uses static sequence buckets of 128, 256, 512, 1,024, and 2,048 tokens. |
| - Saves resumable SafeTensors shards rather than accumulating the dataset in RAM. |
|
|
| The 1,000-record extraction completed in 215.8 seconds after model placement, |
| using the 256-, 512-, and 1,024-token buckets without truncating any record. |
|
|
| ## Loading |
|
|
| ```python |
| import json |
| from huggingface_hub import hf_hub_download |
| from safetensors import safe_open |
| |
| repo_id = "GwendalTsang/mistral-7b-hidden-states-tpu-verification" |
| metadata_path = hf_hub_download( |
| repo_id, "metadata-validation.jsonl", repo_type="dataset" |
| ) |
| row = json.loads(open(metadata_path, encoding="utf-8").readline()) |
| shard_path = hf_hub_download(repo_id, row["shard"], repo_type="dataset") |
| with safe_open(shard_path, framework="pt", device="cpu") as shard: |
| embedding = shard.get_tensor("embedding")[row["offset"]] |
| hidden_states = shard.get_tensor("hidden_states")[row["offset"]] |
| ``` |
|
|
| See [`scripts/extract_mistral_hidden_states_tpu.py`](scripts/extract_mistral_hidden_states_tpu.py) |
| for reproduction and for processing paper-compatible JSONL records containing |
| `context`, `question`, `best_answer`, and `label`. The extractor supports both |
| `--answer-view full` and the authors' rule-based |
| `--answer-view first_sentence`. |
|
|
| ## Provenance |
|
|
| - Model revision: `c170c708c41dac9275d15a8fff4eca08d52bab71` |
| - CoQA revision: `0d9e9952f1ef6e5415492d3d84b5873259137e3c` |
| - Paper code revision: `def3cb6d262c11d252e6c5a6b7e04375b94b54db` |
| - Paper: https://arxiv.org/abs/2605.26366 |
| - Released code: https://github.com/DesoloYw/Automatic-Layer-Selection-for-Hallucination-Detection |
|
|
