SirStone
40ba96f649
Adds an smCounted storage mode alongside the default smBitset. Each (i,j,class) cell becomes a saturating uint8 counter; learn increments it and a global fractional decay (c -= c shr decayShift every decayEvery learns) makes forgetting possible. infer sums raw counters; new inferProb sums the per-cell posterior P(class|cell) (scale-free, recommended readout). Bitset path is the default and byte-for-byte unchanged: test_bitbrain 56/56 (was 32), and test_bitbrain_mnist reproduces 97.210% corrected / 96.540% bug-compatible exactly. Counted mode configurable at runtime (TR_BITBRAIN_MODE / TR_BITBRAIN_DECAY_*) and compile time (-d:bitbrainDecay*). Measured: forgetting (86.2% vs 48.9% on a permuted-label stream), probabilities (rare-class balanced 0.998 vs 0.500), and the stationary cost (counted hurts MNIST; see docs/bitbrain_counted_sbc.md). Harness: common_libs/tests/measure_counted_sbc.nim