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Dashboard Core — System Limits

Real, per-machine qubit limits — detects actual available RAM instead of a number picked to fit whatever machine this was developed on, so Composer refuses an allocation that would actually exhaust memory rather than crashing partway through.

system_limits

Real, per-machine qubit limits -- detects actual available RAM instead of a number picked to fit whatever machine this was developed on. A modest 8 GB dev laptop and a 128 GB workstation get genuinely different limits.

Reuses dense_evolution.chunk.get_dynamic_chunk, the same real, already-tested RAM-based sizing function the Chunk engine itself uses (confirmed in feature/streamlit-dashboard's older simulation_runner.py: "Decided by de.Chunk's own dynamic, available-RAM-based sizing... not a hardcoded qubit-count constant, so it adapts to the machine it's running on") -- rather than a second, slightly different hand-rolled formula. The actual safety enforcement (rejecting a request that would genuinely overflow RAM) is separate: dashboard_core.engine.run_circuit_from_qasm calls dense_evolution.chunk.SafeMemoryGuard.check_allocation directly, which has no floor -- this module is only the UI's suggested/default cap.

max_safe_dense_qubits 

max_safe_dense_qubits() -> dict

Suggested max qubit count for the Composer's Qubits field, from dense_evolution.chunk.get_dynamic_chunk(complex128) -- floor 16, ceiling 27 by that function's own design (a chunk always has some minimum useful size, and 27 qubits/2 GB is its own practical ceiling for a single dense block). MPS's contract_to_statevector has a separate, RAM-independent hard ceiling of 24 qubits; picking 25-27 with the MPS backend surfaces that function's own real error rather than being silently blocked here.

Source code in tools/dashboard_core/system_limits.py 
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def max_safe_dense_qubits() -> dict:
    """Suggested max qubit count for the Composer's Qubits field, from
    dense_evolution.chunk.get_dynamic_chunk(complex128) -- floor 16,
    ceiling 27 by that function's own design (a chunk always has *some*
    minimum useful size, and 27 qubits/2 GB is its own practical ceiling
    for a single dense block). MPS's contract_to_statevector has a
    separate, RAM-independent hard ceiling of 24 qubits; picking 25-27
    with the MPS backend surfaces that function's own real error rather
    than being silently blocked here."""
    guard = de.chunk.SafeMemoryGuard()
    status = guard.status()
    max_qubits = de.chunk.get_dynamic_chunk(de.chunk.jnp.complex128 if de.chunk.HAS_JAX else de.chunk.np.complex128)

    return {
        "total_mb": status["total_mb"],
        "available_mb": status["available_mb"],
        "threshold_pct": guard.threshold_pct,
        "max_qubits_dense": max_qubits,
    }