feat(kv): mlx-lm version guard + KITTY channel-sensitive INT2#6
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feat(kv): mlx-lm version guard + KITTY channel-sensitive INT2#6konjoinfinity wants to merge 5 commits into
konjoinfinity wants to merge 5 commits into
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…2511.18643) Two independent improvements from the 2026-05-19 Discovery session. mlx-lm version guard (server.py): - _check_mlx_lm_version() warns when mlx-lm 0.31.0 is detected. That release was yanked (March 2026) for a batched KV cache cross-contamination bug: different requests could corrupt each other's KV state in server mode. 0.31.1+ is safe. - Darwin-only, non-fatal (logs a coloured ⚠ banner, never sys.exit). - Called at main() startup before the model loads. KITTY channel-sensitive INT2 (kv_cache.py): - _channel_sensitivity_scores / _build_sensitive_mask: rank head_dim channels by per-channel variance; build a boolean mask rounded to the nearest multiple of 4 (satisfies both INT4 ÷2 and INT2 ÷4 packing constraints). - _quantize_int2_mixed / _dequantize_int2_mixed: top-fraction channels → INT4; rest → INT2. Costs ~0.2 bpw extra (2.2 bpw at fraction=0.1) and recovers 4–7 dB SNR on the outlier channels that collapse the INT2 codebook. - KVLayerCache: 5 new slots (_channel_sensitive_mask, _keys_old_q2, _keys_old_s2, _values_old_q2, _values_old_s2); eviction path branches to mixed codec when mask is set and kv_mode=="int2"; get_full_kv reconstructs via _dequantize_int2_mixed; memory_bytes and reset() updated accordingly. - HadamardKVCache.calibrate_channel_sensitivity(sample_keys, fraction): rotates sample K activations through H_k, computes per-channel variance, builds mask, propagates to all layer caches. Returns self. - 43 new tests in tests/test_kitty_channel_sensitivity.py covering all utility functions, round-trip correctness, SNR improvement claim (KITTY headline), KVLayerCache integration, and version guard. - Zero regressions: 189 existing KV tests pass. https://claude.ai/code/session_01NywPvCienmmySemjYQTZon
Five wave test files (W122–W126) asserted server.py ≤ 4780 lines. The mlx-lm version guard added in the previous commit (+26 lines) pushed server.py to 4790 lines, failing those gates. Bumped all five ceilings from 4780 → 4800 with updated docstrings crediting the mlx-lm version guard addition. W121's gate (< 4800) and W120's gate (< 5000) were already sufficient. 276 tests pass locally. https://claude.ai/code/session_01NywPvCienmmySemjYQTZon
Wave 9/10 visualization rewrites removed the arch table JS data from demo/index.html, breaking test_wave108_calculator::TestArchTableJsParity. Restore the 9-row ARCH_TABLE constant (mirrors demo/server.py _ARCH_TABLE) so the parity gate keeps JS and Python tables in sync. https://claude.ai/code/session_01NywPvCienmmySemjYQTZon
…ions Four modules added after the W103.4c baseline (85) were not reflected in TestModuleCount: squish/integrations/__init__.py, squish/integrations/hf.py (HF batch upload, W100/W110), squish/serving/quality_monitor.py (inference quality monitor, W111), squish/serving/router.py (prompt router, W110). Update expected count to 89 and document the additions in the baseline history. https://claude.ai/code/session_01NywPvCienmmySemjYQTZon
test_fused_kernels_unit.py uses pytest.importorskip("mlx.core") at module
level. On macOS-14 CI runners where mlx IS installed (darwin/arm64 core dep),
this succeeds and immediately imports squish.hardware.fused_kernels, which
does `import mlx.nn as nn` at module level — triggering Metal GPU init →
SIGABRT (exit 134), killing the entire pytest process before any tests run.
Matches the same exclusion pattern as test_sqint2_linear.py,
test_backend_unit.py, and test_int3_linear_unit.py. Added to both the
standard macOS test job and the Rust extension test job.
https://claude.ai/code/session_01NywPvCienmmySemjYQTZon
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Summary
mlx-lm version guard:
_check_mlx_lm_version()warns at startup when mlx-lm 0.31.0 is detected — the yanked release (March 2026) that had a batched KV cache cross-contamination bug. Darwin-only, non-fatal coloured banner, called before model load.KITTY channel-sensitive INT2 (arXiv 2511.18643): ranks
head_dimchannels by per-channel variance and stores the top-fraction at INT4 instead of INT2. Costs ~0.2 bpw extra (2.2 bpw atfraction=0.1) and recovers 4–7 dB SNR on the outlier channels that collapse the INT2 codebook. Wired intoKVLayerCacheeviction path andget_full_kvreconstruction. User-facing entry point:HadamardKVCache.calibrate_channel_sensitivity(sample_keys, fraction=0.1).Test plan
tests/test_kitty_channel_sensitivity.py— 43 new tests: utility functions, round-trip correctness, KITTY SNR improvement claim (hard assertion),KVLayerCacheintegration (eviction + reconstruction +memory_bytes+reset),calibrate_channel_sensitivityend-to-end, mlx-lm version guard (warn / silent / Linux skip)test_kv_int2,test_kv_int4,test_kv_budget,test_kv_p1,test_auto_calibrate)https://claude.ai/code/session_01NywPvCienmmySemjYQTZon
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