feat(megatron): select MXFP4 forward precision - #986
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Allow late-stage recovery runs to raise only forward GEMM precision while retaining the validated MXFP4 backward path.
Exercise FP8 and BF16 forward paths through PrimusUT-compatible subtests and align the precision census assertion with logger output.
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Verdict: forward-only MXFP4 routing approvedNo blocking findings in the full base-to-head diff through
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## Summary Closes the post-merge review gap from PR #986. Adds regression coverage for FP8/BF16 forward with MXFP4 backward through `torch.compile`, including exact eager/compiled output and gradient comparisons. It also covers YAML-to-`FluxConfig` precision propagation and runtime mode-census emission. ## Test plan - [x] 35 config and audit tests passed - [x] Compiled-backward checks passed for FP8 and BF16 forward modes - [x] Flux 535M forward-only integration test passed - [x] `black` formatting verified - [x] GPU memory returned to idle Co-authored-by: Guangpu Huang <guangphu@crs-m2m-cpu-spur-012.us-east2-a.compute.internal>
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Summary
Tracks Issue 220.
Add independent MXFP4 forward precision selection so late recovery runs can use FP8 or BF16 forward GEMMs while keeping MXFP4 data- and weight-gradient GEMMs.
mxfp4_forward_precisionconfig plumbing and runtime mode census.Test plan
git diff --check