Fidelity measurement: KL(reference || this quant) on frozen tokens, receipt-backed

#1
by malaiwah - opened

What this is. A third-party fidelity measurement of Inferact/GLM-5.3-NVFP4 @ ce67b36f3669192b5bb233819f0fda6c8a9837f8 (nvfp4, 4 bits per weight as declared) against its unquantized reference, made with quant-fidelity-suite. Measured by malaiwah, not by the model's author. Every number below is read from a sealed receipt named at the bottom.

KL(reference ‖ candidate), mean tokenwise, nats 0.07542936216471374
top-1 agreement 0.9239472398632145
KL median / p95 / p99 / max 0.004894225019666099 / 0.35061047642682547 / 1.249190350210349 / 8.380735342841277
reference root dataset malaiwah/glm53-fidelity-root-v1 @ 9c4a29ee10f393ed2fdbdb9262c1192ddb1507b4 (capture 9eba97dddb4ff2e2…)
panel panel--glm53.malaiwah.corpus5x5-v1, 25 contexts, 51175 scored positions
direction / vocabulary / accumulation KL(reference
method dequantize-and-run, weights only: nvfp4-modelopt-dequant-to-bf16 -- the ModelOpt NVFP4 dialect (quant_algo NVFP4, producer undeclared): each routed-expert projection's packed e2m1 nibbles (group 16 along the input axis) are decoded to exact fp32 as e2m1 x weight_scale.f32 x weight_scale_2 on the capture device and cast once to bf16 under the official tensor name, bitwise the compressed-tensors reference on real fetched rows; routed experts only -- every non-routed tensor is carried as shipped (plain bf16 under the official names); the per-tensor input_scale is an activation quantity and is NOT applied (static-nvfp4-not-applied), so the measurement is weights-only; same engine, schedule and device as the reference capture
determinism two fresh processes captured the candidate; both sealed captures carry content digest 83d9cd978e771583… (self-comparison 0.0)
comparability class advisory

Scope (scope_digest): attn.o=native:bf16@16|attn.other=native:bf16@16|attn.qkv=native:bf16@16|embed_tokens=native:bf16@16|lm_head=native:bf16@16|mlp.down=native:bf16@16|mlp.gate=native:bf16@16|mlp.up=native:bf16@16|moe.experts=quantized:nvfp4@4|moe.router=native:bf16@16|moe.shared_expert=native:bf16@16|mtp=native:mixed|norm=native:bf16@16|head=native|kv=bf16

Disclosures on the comparison receipt:

  • native_head_replay (info): HEAD-1d: each side replayed through its own sealed head (reference 864f488a0074, candidate 864f488a0074); head error is inside the measurement, as under HEAD-2, and nothing is substituted. The heads are content-identical.
  • activation_quantization_not_captured (caveat): candidate was captured from a bf16 materialisation of its weights (nvfp4-modelopt-dequant-to-bf16); the checkpoint declares activation quantization (static-nvfp4-not-applied) that a weights-only capture does not apply, so a served deployment also quantizes activations at runtime. That term is not in this number, which is expected to understate the served divergence; it is not a mathematical bound. The comparison is advisory.

What this number does not do. It is a same-lane distance from one reference capture on one panel. It does not rank this artifact against numbers measured on another panel, lane or reference, and a same-lane root does not retroactively upgrade rows measured against another teacher. Per-window scatter exceeds the gap between adjacent bit-widths; compare only within a group whose comparability keys match.

Receipts.

  • comparison receipt receipt_sha256 186fa1df288d25f7f097dd9aa0b7830df840f1656e54732d460b2e9c71bf4fc0
  • root-qualification receipt receipt_sha256 91a0abe2cab52e4968f95b21481df99c2480ebbb9b4499c1620f16ea67bc003a (canonical dataset_sha256 f5f8fe3dcc721e28aa00d02b428258c2121fca7c6fa659b1f51d444777e10e8e, repeat 392c7690ad52bed3a3db3484910301aa6f2a8421324c0471d510e55b3726a73d)
  • job job_id_full b46b546acb7224fa2a0435752b57898854b2cbc7bc6d73a3d264e38c908acda1
  • candidate capture dataset published: malaiwah/glm53-fidelity-nvfp4-inferact-v1 @ 25a1865187fc727989bb2c32dde49c63292370c2

Reproduce: fetch the two datasets named above and run fidelity-dataset compare --reference <root> --candidate <this> --own-heads; the receipt's estimator block is the exact recipe. Questions and corrections are welcome here; the registry files this as a third-party row (measured_by enumerated, never conflated with author-reported numbers).

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