stage-3c: working QLoRA training + eval — pytorch base, Qwen3.5 slug, SFTConfig

Training and eval now run clean on the unsloth 2026.5.2 / transformers v5 /
torch 2.10 stack. Fixes: pytorch/pytorch base image (sidesteps the nvidia/cuda
apt-signature failure and the torch download), correct base-model slug
unsloth/Qwen3.5-4B, TRL SFTConfig API. Adds scripts/eval_adapter.py — runs
dataset rows through base+adapter with structured (transformers-v5) message
content and Qwen3.5 thinking-mode stripping.

First v1 adapter: loss 2.10 -> 0.32 over 3 epochs. Eval surfaced an ill-posed
ioc_extraction dataset (output URL not present in input) — to be fixed in the
ExampleBuilder before the next training run.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Dockerfile.train

@@ -12,36 +12,19 @@
 #       --dataset /data/datasets/routing_decision-v1.jsonl \
 #       --dataset /data/datasets/tlp_assignment-v1.jsonl \
 #       --output /data/adapters/psyc-v1
+#
+# Base image already ships Python 3.11 + torch 2.6 + CUDA 12.4 + cuDNN9, so
+# there is no apt step and no torch download. Qwen3.5 needs transformers v5 —
+# unsloth pulls it automatically.
 
-FROM nvidia/cuda:12.4.1-cudnn-devel-ubuntu22.04
+FROM pytorch/pytorch:2.6.0-cuda12.4-cudnn9-devel
 
-ENV DEBIAN_FRONTEND=noninteractive \
+ENV PYTHONUNBUFFERED=1 \
-    PYTHONUNBUFFERED=1 \
     PIP_NO_CACHE_DIR=1 \
     HF_HOME=/data/.hf-cache
 
-RUN apt-get update && apt-get install -y --no-install-recommends \
+RUN pip install --upgrade pip && \
-        python3.11 python3.11-venv python3-pip \
+    pip install unsloth unsloth_zoo trl datasets
-        git curl ca-certificates \
-    && rm -rf /var/lib/apt/lists/* \
-    && ln -sf /usr/bin/python3.11 /usr/local/bin/python \
-    && ln -sf /usr/bin/python3.11 /usr/local/bin/python3
-
-RUN python -m pip install --upgrade pip wheel setuptools && \
-    python -m pip install \
-        torch==2.5.1 \
-        --index-url https://download.pytorch.org/whl/cu124
-
-RUN python -m pip install \
-        "unsloth @ git+https://github.com/unslothai/unsloth.git" \
-        transformers>=4.46 \
-        datasets>=3.0 \
-        peft>=0.13 \
-        trl>=0.12 \
-        accelerate>=1.1 \
-        bitsandbytes>=0.44 \
-        sentencepiece \
-        protobuf
 
 WORKDIR /workspace
 COPY scripts/train_qlora.py /workspace/train_qlora.py

README.md

@@ -121,7 +121,7 @@ To fine-tune Qwen3.5-4B with QLoRA in an NVIDIA Docker container:
 # 1. build datasets (one-off; re-run after ingestion changes)
 .venv/bin/psyc train-build-all
 
-# 2. build the training image (CUDA 12.4 + unsloth + Qwen3.5)
+# 2. build the training image (pytorch 2.6/CUDA 12.4 base + unsloth + Qwen3.5)
 docker build -t psyc-trainer -f Dockerfile.train .
 
 # 3. fine-tune (mount host data/ so adapters land there)
@@ -135,14 +135,25 @@ docker run --gpus all --rm \
     --output /data/adapters/psyc-v1
 ```
 
-Defaults target a 24 GB consumer GPU (3090/4090): Qwen3.5-4B-Instruct at 4-bit,
+Defaults target a 24 GB consumer GPU (3090/4090): `unsloth/Qwen3.5-4B` at 4-bit,
 LoRA `r=16`/`alpha=16`, bf16, 3 epochs, effective batch size 8. For A100-40/80
-bump `--base-model unsloth/Qwen3.5-9B-Instruct-bnb-4bit` and raise
+bump `--base-model unsloth/Qwen3.5-9B` and raise `--batch-size` +
-`--batch-size` + `--max-seq-length`.
+`--max-seq-length`.
 
 Output: `data/adapters/psyc-v1/final/` (adapter weights) + `training_meta.json`
 (base model, hyperparameters, dataset list).
 
+Evaluate the adapter against held-out dataset rows:
+
+```bash
+docker run --gpus all --rm \
+    --entrypoint python \
+    -v $(pwd)/data:/data -v $(pwd)/scripts:/scripts \
+    psyc-trainer /scripts/eval_adapter.py \
+    --adapter /data/adapters/psyc-v1/final \
+    --dataset /data/datasets/ioc_extraction-v1.jsonl --n 5
+```
+
 ## Status
 
 Day 2 of a 48h build. Shipped: Scoutline (URLhaus) → Classifyline → Mapline

scripts/eval_adapter.py

@@ -0,0 +1,93 @@
+"""Evaluate a psyc QLoRA adapter — run held-out dataset rows through the model.
+
+Run inside the psyc training container (override the entrypoint):
+    docker run --gpus all --rm --entrypoint python \
+        -v $(pwd)/data:/data -v $(pwd)/scripts:/scripts \
+        psyc-trainer /scripts/eval_adapter.py \
+        --adapter /data/adapters/psyc-v1/final \
+        --dataset /data/datasets/ioc_extraction-v1.jsonl --n 5
+
+Sanity check, not a benchmark: for `--n` rows it prints the prompt, the model's
+generation, and the dataset's reference output side by side. With a tiny
+dataset the model has seen these rows, so this verifies the adapter learned the
+output FORMAT and task shape — not generalization.
+"""
+
+from __future__ import annotations
+
+# unsloth must be imported BEFORE transformers.
+from unsloth import FastLanguageModel  # noqa: I001
+
+import argparse
+import json
+import re
+from pathlib import Path
+from typing import Dict, List
+
+
+def strip_think(text: str) -> str:
+    """Drop Qwen3.5 thinking-mode blocks so exact-match compares the answer only."""
+    return re.sub(r"<think>.*?</think>\s*", "", text, flags=re.DOTALL).strip()
+
+
+def load_examples(path: Path, n: int) -> List[Dict[str, str]]:
+    out: List[Dict[str, str]] = []
+    with path.open("r", encoding="utf-8") as fh:
+        for line in fh:
+            line = line.strip()
+            if not line:
+                continue
+            out.append(json.loads(line))
+            if len(out) >= n:
+                break
+    return out
+
+
+def main() -> None:
+    parser = argparse.ArgumentParser(description=__doc__)
+    parser.add_argument("--adapter", required=True, help="path to adapter final/ dir")
+    parser.add_argument("--base-model", default="unsloth/Qwen3.5-4B")
+    parser.add_argument("--dataset", required=True, help="JSONL to sample test rows from")
+    parser.add_argument("--n", type=int, default=5)
+    parser.add_argument("--max-seq-length", type=int, default=4096)
+    parser.add_argument("--max-new-tokens", type=int, default=256)
+    args = parser.parse_args()
+
+    examples = load_examples(Path(args.dataset), args.n)
+    if not examples:
+        raise SystemExit("no examples loaded")
+
+    model, tokenizer = FastLanguageModel.from_pretrained(
+        model_name=args.adapter,
+        max_seq_length=args.max_seq_length,
+        dtype=None,
+        load_in_4bit=True,
+    )
+    FastLanguageModel.for_inference(model)
+
+    correct = 0
+    for i, ex in enumerate(examples, 1):
+        prompt = f"{ex['instruction']}\n\n{ex['input']}"
+        messages = [{"role": "user", "content": [{"type": "text", "text": prompt}]}]
+        inputs = tokenizer.apply_chat_template(
+            messages,
+            tokenize=True,
+            add_generation_prompt=True,
+            return_tensors="pt",
+            enable_thinking=False,
+        ).to(model.device)
+        out = model.generate(input_ids=inputs, max_new_tokens=args.max_new_tokens, do_sample=False)
+        generated = strip_think(tokenizer.decode(out[0][inputs.shape[1]:], skip_special_tokens=True))
+        expected = ex["output"].strip()
+        match = generated == expected
+        correct += int(match)
+        print(f"\n===== example {i}/{len(examples)}  [{ex.get('task', '?')}]  {'MATCH' if match else 'DIFF'} =====")
+        print(f"-- prompt --\n{prompt[:600]}")
+        print(f"-- expected --\n{expected[:600]}")
+        print(f"-- generated --\n{generated[:600]}")
+
+    print(f"\n[psyc-eval] exact-match {correct}/{len(examples)}")
+
+
+if __name__ == "__main__":
+    main()

scripts/train_qlora.py

@@ -22,8 +22,7 @@ from pathlib import Path
 from typing import Dict, List
 
 from datasets import Dataset
-from transformers import TrainingArguments
+from trl import SFTConfig, SFTTrainer
-from trl import SFTTrainer
 
 
 def load_examples(paths: List[Path]) -> List[Dict[str, str]]:
@@ -44,7 +43,7 @@ def load_examples(paths: List[Path]) -> List[Dict[str, str]]:
 def main() -> None:
     parser = argparse.ArgumentParser(description=__doc__)
     parser.add_argument("--dataset", action="append", required=True, help="JSONL path (repeatable)")
-    parser.add_argument("--base-model", default="unsloth/Qwen3.5-4B-Instruct-bnb-4bit")
+    parser.add_argument("--base-model", default="unsloth/Qwen3.5-4B")
     parser.add_argument("--output", default="/data/adapters/psyc-v1")
     parser.add_argument("--epochs", type=int, default=3)
     parser.add_argument("--lr", type=float, default=2e-4)
@@ -96,9 +95,9 @@ def main() -> None:
         model=model,
         tokenizer=tokenizer,
         train_dataset=dataset,
-        dataset_text_field="text",
+        args=SFTConfig(
-        max_seq_length=args.max_seq_length,
+            dataset_text_field="text",
-        args=TrainingArguments(
+            max_seq_length=args.max_seq_length,
             per_device_train_batch_size=args.batch_size,
             gradient_accumulation_steps=args.grad_accum,
             warmup_steps=5,