_grammar_bias returned a shared module-level singleton that the loop
mutated in place (EOS block + repetition penalty). The penalty thus
accumulated across positions within a call and persisted across calls,
collapsing output to HOLD/NC until process restart. Clone the bias each
step so edits stay local. Add regression tests guarding the invariant.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Tracks ROOT-level bigrams (prev_root → curr_root) across chord-change events.
At each FREE position, subtracts penalty * count(prev→root) from ROOT logits,
capped at 3.0 to prevent NC/HOLD flooding at extreme values.
Practical range: 0.5 (mild, breaks loops after 2 occurrences) to 1.0
(aggressive). Default 0.0 keeps backward compatibility.
Added --repetition-penalty flag to scripts/generate.py.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Previously the model could emit EOS before reaching n_bars because the
EOS-suppression was only applied via the n_bars break, not the grammar
bias. Fixed by masking EOS to -inf in the logit bias while
bars_completed < n_bars.
Added _EosHungryModel fixture and test_generate_bars_overrides_early_eos
to catch this regression class.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
generate_period() now accepts n_bars=N to stop after exactly N complete
bars. bars_completed is seeded from the prefix length so --bars counts
the full output, not just the generated tail.
scripts/generate.py exposes this as --bars (default: None = model decides).
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
_encode_prefix now handles hold ('.') and no-chord ('NC') tokens
alongside chord symbols, and returns (ids, n_positions) so that
pos_in_bar is tracked correctly regardless of token type.
Fixes ChordParseError when dots were passed in --prefix.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
src/generate.py: autoregressive generation with top-p sampling, grammar
masking (ROOT→QUAL→EXT→BASS; EOS only at bar boundary), key transposition,
and optional chord prefix. Partial bars on context truncation are padded
with HOLDs rather than discarded.
scripts/generate.py: CLI wrapping generate_period — accepts mode, key,
time, subdivision, style, function, prefix, temperature, top-p, seed,
tempo; writes .chord and optional MIDI.
src/tokenizer.py: fix docstring vocab size (81→84); normalize redundant
BASS_<note>==root to no slash in _tokens_to_symbol.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
H1K0