* Cap ARA's neighbor count at the number of prompts
The nearest neighbors are selected from the outputs for the good and
bad prompts, which have one row per prompt. With fewer than 15 prompts
in either dataset, the optimizer could pick a neighbor count larger
than that, and torch.topk would crash with "selected index k out of
range". Bounding the search range instead of clamping the value keeps
the optimizer from wasting trials on counts that would all behave the
same.
* Render chat templates with a fixed date
Some chat templates, including gpt-oss's, put the current date in the
system prompt. That makes the residuals, and with them the modified
model, depend on the day Heretic runs, so a model could not be
reproduced on a different day. It also made the gpt-oss test's hash
change daily once ARA started modifying the model.
Prompts used for computing residuals and for evaluation are now
rendered with a fixed date. Interactive chat keeps the real one.
* Prevent ARA from sampling an empty layer range
The start index was sampled from [0, L//2] and the exclusive end index
from [L//2, L], so both could land on L//2 and leave no layers to
modify, wasting the trial. Starting the end range at L//2 + 1 rules
this out while keeping the bounds fixed, as multivariate TPE requires.
On the 2-layer test models, every ARA trial had picked this empty
range, so the seed-oss and gpt-oss tests never ran the optimization.
They now modify layer 1, which changes their expected hashes. The
seed-oss output also differs between the CPUs of GitHub's runners,
because L-BFGS amplifies small floating-point differences, so it gets
CI hashes as well.
* feat: add modifier base class
* feat: re-implement abliteration as a modifier plugin
* fix: adjust good/bad prompts hack to match tests
* feat: support dataset specifications containing multiple individual datasets
* feat: re-implement ARA as a modifier plugin
Arbitrary-Rank Ablation (ARA) (Weidmann 2026) was originally introduced by @p-e-w in #211
Co-authored-by: kabachuha <artemkhrapov2001@yandex.ru>
Co-authored-by: joninco <joninco@bullpoint.org>
Co-authored-by: Ashar <coder3101@users.noreply.github.com>
* feat: add tests for ARA
* feat: reduce default number of trials
* ci: remove broken "semantic-pull-request" workflow
* ci: add yet another alternative model hash
---------
Co-authored-by: kabachuha <artemkhrapov2001@yandex.ru>
Co-authored-by: joninco <joninco@bullpoint.org>
Co-authored-by: Ashar <coder3101@users.noreply.github.com>
benthecarman
Philipp Emanuel Weidmann
