Implement reproducible event generation - #51
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Introduce a `seed` field in the mg7 run_card that makes CPU event generation reproducible: the same (seed, thread-pool sizes) reproduces bit-identically and distinct seeds are statistically independent. Seed 0 (the default) keeps the previous non-deterministic behaviour. madspace previously seeded every RNG from std::random_device with no seed input and drew randomness from thread-local generators dispatched to the pool in non-deterministic order, so runs were never reproducible. Plumbing: - run_card `[run] seed` + RunCardMG7 default; per-context seed derivation (splitmix64) in madevent.py and gridpack.py (--seed); Context(seed=) exposed through the Python bindings. - seeded_rng()/mix_seed() helpers in util.hpp; the driver-level random_device sites reseeded from the context seed. Determinism (gated on seed != 0, so the default path is unchanged): - Per-job RNG keyed by logical job identity (channel, sequence, phase) via Runtime::begin/end_job_rng, so a job's randomness no longer depends on which worker thread runs it. - Deterministic commit ordering: survey/generate harvest jobs in job-id order with unweighting folded in synchronously, making cross-section sums, max-weight snapshots, event order and stopping deterministic. Validated end-to-end through the mg7 driver with a dummy matrix element: same seed gives byte-identical events.npy at 4 and 8 threads, a different seed differs, and seed 0 differs run-to-run. Adds a portable unit test (madspace/tests/test_determinism.py) covering the seeding plumbing. For output_format = lhe, bit-identical output also needs combine_thread_pool_size = 1 (the parallel LHE combine is not yet deterministic); compact_npy and lhe_npy are reproducible at any size. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Conflict in madgraph/iolibs/template_files/mg7/gridpack.py: main added a resolve_verbosity() helper at the same spot this branch added derive_seed(); kept both. The other overlapping files (madevent.py, run_card.toml, banner.py, context.hpp) merged automatically. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
The --seed argument was parsed but never passed to ms.Context, so reproducible gridpack runs had no effect. Derive a per-context seed from it and update the help text to match the run_card (reproducible at any cpu_thread_pool_size). Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
…l fractions in rounds
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Features
events.lheandinfo.jsonfile so the run can be reproduced later.Limitations
atomicAddleads to differences in the channel weight.Benchmarks
Check if there is any degradation in performance from reproducibility
TBA