training: rewrite trainer for readout pipeline + story corpus

The old script was written for the AmygdalaConnector's expected
format ([n_emotions, n_target_layers, hidden_dim] in a single
tensor, plus a JSONL input format from extract_training_pairs.py).
Neither matches our current state: the runtime side is now
ReadoutManager loading per-layer safetensors keyed layer_<idx>.vectors,
and the data side is hand-written prose stories under
amygdala_stories/{stories,paired}/.

Changes:

* Input loader reads stories/<emotion>.txt and
  paired/<scenario>/<emotion>.txt directly. Each emotion's positive
  set is {its unpaired story} union {its within-scenario framings};
  its negative set is {all other emotions' positives} union {all
  scenario baselines}.
* Paired scenarios' baseline.txt files become shared negatives
  (scenario-neutral prose that doesn't frame any particular
  emotion), providing anchor points for within-scenario contrasts.
* Output writes readout.safetensors with per-layer tensors keyed
  layer_<idx>.vectors shape (n_concepts, hidden_size), plus a
  sidecar readout.json manifest with {concepts, layers, hidden_size,
  dtype} that ReadoutManager.from_file consumes directly.
* Dedup: activations are computed once per unique text (an emotion's
  own positive is another emotion's negative — we'd otherwise do N×
  the forwards needed).

Preserved:
* _pool_last (last non-pad residual) — matches how readout is read
  at decode time from the sampler's query-last position.
* register_forward_hook on target layer modules — correct approach
  for transformer blocks.
* _find_layers_module traversal — mirrors ReadoutManager's.
* bf16 + low_cpu_mem_usage model load — sensible for 27B on B200.

Verified locally (CPU, fake activations):
* Loader finds 89 emotions from the current corpus (80 unpaired +
  9 emotions that appear only in paired scenarios) and 6 baselines.
* Per-(layer, concept) vectors are unit-normalized.
* Output reloads cleanly through ReadoutManager.from_file with
  matching concepts / layers / shapes.

Co-Authored-By: Proof of Concept <poc@bcachefs.org>
This commit is contained in:
Kent Overstreet 2026-04-18 00:32:50 -04:00
parent 34bd122590
commit 15737dfd92

View file

@ -1,30 +1,48 @@
# SPDX-License-Identifier: Apache-2.0
# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
"""Train amygdala steering vectors via Contrastive Activation Addition.
"""Train concept-readout vectors via Contrastive Activation Addition.
Reads the per-emotion JSONL files produced by extract_training_pairs.py,
runs the target model over each example, captures the residual-stream
hidden state at the configured target layers, and computes
`mean(positive) - mean(negative)` as the steering direction per layer
per emotion.
Reads the hand-written story corpus at
``amygdala_stories/{stories,paired}/`` and produces the per-layer
safetensors file + sidecar JSON manifest that vLLM's ReadoutManager
loads at startup (``VLLM_READOUT_VECTORS`` / ``VLLM_READOUT_MANIFEST``).
Output: a safetensors file matching the format AmygdalaConnector
expects:
Training data (cross-concept contrast):
vectors: [n_emotions, n_target_layers, hidden_dim] fp16
emotion_names: [n_emotions] uint8
positive for emotion E:
stories/E.txt
paired/<scenario>/E.txt (for each scenario that covers E)
Pooling: last-token residual-stream per example (CAA convention
the final token has seen the whole context and is where the model's
"decision" lives). Alternative: mean across all tokens. The LAST
convention is more common for steering vector work.
negative for emotion E:
stories/<all other emotions>.txt
paired/<scenario>/baseline.txt (for each scenario)
Within-scenario paired stories are the highest-signal pairs (same
content, different concept framing); unpaired stories provide bulk
contrast across the 80 emotions we have written so far.
Pooling: last non-pad token. Matches how readout is consumed at decode
time (residual read at the sampler's query position).
Output:
readout.safetensors
layer_<idx>.vectors : fp16 (n_concepts, hidden_size) one per layer
readout.json
{
"concepts": [...],
"layers": [...],
"hidden_size": int,
"dtype": "float16"
}
"""
from __future__ import annotations
import argparse
import gc
import json
import os
from collections import defaultdict
from pathlib import Path
import safetensors.torch
@ -39,81 +57,11 @@ def _pool_last(hidden: torch.Tensor, attention_mask: torch.Tensor) -> torch.Tens
attention_mask: [batch, seq]
returns: [batch, hidden_dim]
"""
# last non-pad token index per row
last_idx = attention_mask.sum(dim=1) - 1
batch_idx = torch.arange(hidden.size(0), device=hidden.device)
return hidden[batch_idx, last_idx]
def _collect_activations(
model,
tokenizer,
texts: list[str],
target_layers: list[int],
device: torch.device,
batch_size: int,
max_length: int,
) -> torch.Tensor:
"""Run texts through the model, capture residual stream at target
layers, return [n_texts, n_target_layers, hidden_dim] fp32 on CPU.
"""
# Register hooks on the target layers' outputs. We want the
# residual stream AFTER each layer, which is the output of the
# transformer block (hidden_states[layer_idx+1] in HF land).
captures: dict[int, torch.Tensor] = {}
def make_hook(idx):
def hook(_mod, _inp, output):
# output is typically (hidden_states, ...) — take the first
hs = output[0] if isinstance(output, tuple) else output
captures[idx] = hs.detach()
return hook
handles = []
# Transformers' LlamaModel.layers is a ModuleList; Qwen3.5's
# language_model.model.layers follows the same convention.
# Resolve the layer list by walking common paths.
layers_module = _find_layers_module(model)
for idx in target_layers:
handles.append(
layers_module[idx].register_forward_hook(make_hook(idx))
)
out_rows: list[torch.Tensor] = []
try:
model.eval()
with torch.no_grad():
for i in range(0, len(texts), batch_size):
batch = texts[i : i + batch_size]
tok = tokenizer(
batch,
return_tensors="pt",
padding=True,
truncation=True,
max_length=max_length,
).to(device)
captures.clear()
model(**tok)
per_layer = []
for idx in target_layers:
hs = captures[idx] # [batch, seq, hidden]
pooled = _pool_last(hs, tok["attention_mask"])
per_layer.append(pooled.to(torch.float32).cpu())
# Stack to [batch, n_layers, hidden_dim]
batched = torch.stack(per_layer, dim=1)
out_rows.append(batched)
del tok, captures
if (i // batch_size) % 10 == 0:
torch.cuda.empty_cache()
finally:
for h in handles:
h.remove()
return torch.cat(out_rows, dim=0) # [n_texts, n_layers, hidden]
def _find_layers_module(model) -> torch.nn.ModuleList:
"""Walk a few likely paths to find the transformer-block list."""
candidates = [
@ -139,25 +87,143 @@ def _find_layers_module(model) -> torch.nn.ModuleList:
)
def _collect_activations(
model,
tokenizer,
texts: list[str],
target_layers: list[int],
device: torch.device,
batch_size: int,
max_length: int,
) -> torch.Tensor:
"""Run texts through the model, capture residual stream at target
layers, return ``[n_texts, n_target_layers, hidden_dim]`` fp32 on CPU.
"""
captures: dict[int, torch.Tensor] = {}
def make_hook(idx: int):
def hook(_mod, _inp, output):
hs = output[0] if isinstance(output, tuple) else output
captures[idx] = hs.detach()
return hook
layers_module = _find_layers_module(model)
handles = [
layers_module[idx].register_forward_hook(make_hook(idx))
for idx in target_layers
]
out_rows: list[torch.Tensor] = []
try:
model.eval()
with torch.no_grad():
for i in range(0, len(texts), batch_size):
batch = texts[i : i + batch_size]
tok = tokenizer(
batch,
return_tensors="pt",
padding=True,
truncation=True,
max_length=max_length,
).to(device)
captures.clear()
model(**tok)
per_layer = [
_pool_last(captures[idx], tok["attention_mask"])
.to(torch.float32)
.cpu()
for idx in target_layers
]
out_rows.append(torch.stack(per_layer, dim=1))
del tok, captures
if (i // batch_size) % 10 == 0:
torch.cuda.empty_cache()
captures = {}
finally:
for h in handles:
h.remove()
return torch.cat(out_rows, dim=0)
def _load_corpus(stories_dir: Path, paired_dir: Path | None) -> tuple[
dict[str, list[str]], # emotion -> positive texts (unpaired + within-scenario framings)
list[str], # all baseline texts (one per scenario), as scenario-agnostic negatives
]:
"""Return ``(positives_by_emotion, baselines)``.
Cross-concept negatives are computed at training time from
``positives_by_emotion`` each emotion's negative set is the
union of all other emotions' positives plus the baseline texts.
"""
positives: dict[str, list[str]] = {}
for story_path in sorted(stories_dir.glob("*.txt")):
emotion = story_path.stem
positives.setdefault(emotion, []).append(
story_path.read_text().strip()
)
baselines: list[str] = []
if paired_dir is not None and paired_dir.exists():
for scenario_dir in sorted(paired_dir.iterdir()):
if not scenario_dir.is_dir():
continue
baseline_path = scenario_dir / "baseline.txt"
if baseline_path.exists():
baselines.append(baseline_path.read_text().strip())
for framing_path in sorted(scenario_dir.glob("*.txt")):
if framing_path.stem == "baseline":
continue
emotion = framing_path.stem
positives.setdefault(emotion, []).append(
framing_path.read_text().strip()
)
return positives, baselines
def main() -> None:
ap = argparse.ArgumentParser(description=__doc__)
ap.add_argument("--model", required=True, help="HF model id or path")
ap.add_argument("--training-data-dir", required=True)
ap.add_argument(
"--target-layers", required=True,
help="Comma-separated layer indices, e.g. 3,18,33,36",
"--stories-dir",
required=True,
help="Path to amygdala_stories/stories/",
)
ap.add_argument(
"--paired-dir",
default=None,
help="Path to amygdala_stories/paired/ (optional)",
)
ap.add_argument(
"--target-layers",
required=True,
help="Comma-separated layer indices, e.g. 40,50,60,70",
)
ap.add_argument(
"--output-dir",
required=True,
help="Directory to write readout.safetensors + readout.json",
)
ap.add_argument("--output", required=True)
ap.add_argument("--dtype", default="bf16", choices=["bf16", "fp16", "fp32"])
ap.add_argument("--batch-size", type=int, default=4)
ap.add_argument("--batch-size", type=int, default=2)
ap.add_argument("--max-length", type=int, default=512)
ap.add_argument("--device", default="cuda:0")
ap.add_argument(
"--min-positives",
type=int,
default=1,
help="Skip emotions with fewer positive examples than this",
)
args = ap.parse_args()
target_layers = [int(x) for x in args.target_layers.split(",")]
dtype = {"bf16": torch.bfloat16, "fp16": torch.float16, "fp32": torch.float32}[
args.dtype
]
dtype = {
"bf16": torch.bfloat16,
"fp16": torch.float16,
"fp32": torch.float32,
}[args.dtype]
print(f"Loading {args.model} ({args.dtype}) on {args.device}...")
tokenizer = AutoTokenizer.from_pretrained(args.model)
@ -170,78 +236,137 @@ def main() -> None:
low_cpu_mem_usage=True,
)
hidden_dim = model.config.hidden_size
print(f"Model loaded. hidden_dim={hidden_dim}, "
f"n_layers={model.config.num_hidden_layers}")
manifest_path = Path(args.training_data_dir) / "_manifest.json"
manifest = json.loads(manifest_path.read_text())
emotions = sorted(manifest["emotions"].keys())
print(f"Training {len(emotions)} emotions: {emotions}")
n_emotions = len(emotions)
n_layers = len(target_layers)
vectors = torch.zeros(
(n_emotions, n_layers, hidden_dim), dtype=torch.float32
n_model_layers = model.config.num_hidden_layers
print(
f"Model loaded. hidden_dim={hidden_dim}, "
f"n_model_layers={n_model_layers}"
)
for layer_idx in target_layers:
if layer_idx < 0 or layer_idx >= n_model_layers:
raise ValueError(
f"target layer {layer_idx} out of range "
f"[0, {n_model_layers})"
)
positives_by_emotion, baselines = _load_corpus(
Path(args.stories_dir),
Path(args.paired_dir) if args.paired_dir else None,
)
emotions = sorted(
e for e, ps in positives_by_emotion.items()
if len(ps) >= args.min_positives
)
if not emotions:
raise RuntimeError(
f"No emotions with >= {args.min_positives} positive examples"
)
print(
f"Training {len(emotions)} emotions; "
f"{len(baselines)} baseline scenarios"
)
# Cache all positive-text activations once so we can reuse them as
# negatives for other emotions. Keyed by the text itself to dedup
# across emotion lists.
device = torch.device(args.device)
text_to_emotion: dict[str, str] = {}
for emotion, texts in positives_by_emotion.items():
for t in texts:
text_to_emotion[t] = emotion
unique_positive_texts = list(text_to_emotion.keys())
print(
f"Collecting activations for {len(unique_positive_texts)} unique "
f"positive texts + {len(baselines)} baselines..."
)
positive_acts = _collect_activations(
model, tokenizer, unique_positive_texts, target_layers, device,
args.batch_size, args.max_length,
)
# positive_acts[i] corresponds to unique_positive_texts[i]
text_to_row = {t: i for i, t in enumerate(unique_positive_texts)}
baseline_acts = (
_collect_activations(
model, tokenizer, baselines, target_layers, device,
args.batch_size, args.max_length,
)
if baselines
else torch.zeros(0, len(target_layers), hidden_dim)
)
n_concepts = len(emotions)
n_layers = len(target_layers)
# Per-layer output matrices. Shape (n_concepts, hidden_size) each.
per_layer_vectors = torch.zeros(
(n_layers, n_concepts, hidden_dim), dtype=torch.float32
)
for e_idx, emotion in enumerate(emotions):
path = Path(args.training_data_dir) / f"{emotion}.jsonl"
pos_texts, neg_texts = [], []
with open(path) as f:
for line in f:
ex = json.loads(line)
if ex["polarity"] == "positive":
pos_texts.append(ex["text"])
else:
neg_texts.append(ex["text"])
print(f"[{e_idx+1}/{n_emotions}] {emotion}: "
f"{len(pos_texts)} pos / {len(neg_texts)} neg")
pos_rows = [text_to_row[t] for t in positives_by_emotion[emotion]]
# Negatives: every OTHER emotion's positives + baselines.
neg_rows = [
i
for i, t in enumerate(unique_positive_texts)
if text_to_emotion[t] != emotion
]
pos_acts = _collect_activations(
model, tokenizer, pos_texts, target_layers, device,
args.batch_size, args.max_length,
)
neg_acts = _collect_activations(
model, tokenizer, neg_texts, target_layers, device,
args.batch_size, args.max_length,
)
pos = positive_acts[pos_rows] # [n_pos, n_layers, hidden]
neg = positive_acts[neg_rows] # [n_neg, n_layers, hidden]
if baseline_acts.shape[0] > 0:
neg = torch.cat([neg, baseline_acts], dim=0)
# Difference of means per layer
pos_mean = pos_acts.mean(dim=0) # [n_layers, hidden]
neg_mean = neg_acts.mean(dim=0)
pos_mean = pos.mean(dim=0) # [n_layers, hidden]
neg_mean = neg.mean(dim=0)
diff = pos_mean - neg_mean
# Normalize per layer so projections are scale-comparable
norms = diff.norm(dim=-1, keepdim=True).clamp_min(1e-6)
diff = diff / norms
vectors[e_idx] = diff
del pos_acts, neg_acts
gc.collect()
torch.cuda.empty_cache()
# diff[layer] -> per_layer_vectors[layer, e_idx]
for l_idx in range(n_layers):
per_layer_vectors[l_idx, e_idx] = diff[l_idx]
# Save in AmygdalaConnector format.
# emotion_names as padded uint8 tensor
names_bytes = [e.encode("utf-8") for e in emotions]
max_len = max(len(b) for b in names_bytes)
padded = torch.tensor(
[list(b.ljust(max_len, b"\x00")) for b in names_bytes],
dtype=torch.uint8,
)
if e_idx < 5 or e_idx == len(emotions) - 1:
print(
f" [{e_idx + 1}/{len(emotions)}] {emotion}: "
f"pos={len(pos_rows)} neg={len(neg_rows) + baseline_acts.shape[0]}"
)
os.makedirs(os.path.dirname(os.path.abspath(args.output)), exist_ok=True)
output_dir = Path(args.output_dir)
output_dir.mkdir(parents=True, exist_ok=True)
tensors = {
f"layer_{target_layers[l_idx]}.vectors": (
per_layer_vectors[l_idx].to(torch.float16)
)
for l_idx in range(n_layers)
}
safetensors.torch.save_file(
{
"vectors": vectors.to(torch.float16),
"emotion_names": padded,
"target_layers": torch.tensor(target_layers, dtype=torch.int32),
},
args.output,
tensors,
str(output_dir / "readout.safetensors"),
)
print(f"\nWrote steering vectors to {args.output}: "
f"{n_emotions} emotions x {n_layers} layers x {hidden_dim} dim (fp16)")
manifest = {
"concepts": emotions,
"layers": target_layers,
"hidden_size": hidden_dim,
"dtype": "float16",
}
(output_dir / "readout.json").write_text(
json.dumps(manifest, indent=2) + "\n"
)
total_mb = sum(t.numel() * 2 for t in tensors.values()) / (1024 * 1024)
print(
f"\nWrote readout.safetensors + readout.json to {output_dir}\n"
f" {n_concepts} concepts x {n_layers} layers x "
f"{hidden_dim} dim (fp16), total {total_mb:.1f} MiB"
)
del model
gc.collect()
torch.cuda.empty_cache()
if __name__ == "__main__":