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State.robustlyCalcPosterior calls store() as a side effect #1211

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@alexeid

State.robustlyCalcPosterior() calls store(-1) internally before recalculating the posterior:

public double robustlyCalcPosterior(final Distribution posterior) {
    store(-1);
    setEverythingDirty(true);
    checkCalculationNodesDirtiness();
    final double logLikelihood = posterior.calculateLogP();
    setEverythingDirty(false);
    acceptCalculationNodes();
    return logLikelihood;
}

This means any caller that subsequently calls state.store(sampleNr) (e.g. at the start of propagateState) is doing a redundant store. In the standard MCMC.doLoop() this happens after initialization and in the debug/correction paths, so it's not a performance issue in practice.

However, the implicit store(-1) is a surprising side effect for a method that looks like a pure calculation. It makes it harder to reason about state management when subclassing MCMC (e.g. for data tempering or other custom loops that need to call robustlyCalcPosterior mid-run).

Possible fix: document the side effect clearly, or restructure so the store is the caller's responsibility.

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