[Autoplectic]

Summary

build_mixed_state_presentation finds a known belief equal to a new one by bisecting a sorted index of numeric beliefs keyed by their first coordinate. When many beliefs share that coordinate (often exactly 0), every lookup scans most of the states, which is quadratic. On some 4-state survey processes the reverse inference then ran for many minutes before reaching its state cap. Those cases hit the survey's 1500 s hard timeout before the (budgeted) pipeline even started.

The index now uses the projection onto fixed positive weights that sum to 1. Beliefs equal coordinatewise to within the matching tolerance (rtol=1e-9, atol=1e-12) project to within the same 1e-9 window, so no match is missed, but ties become rare. The symbolic/numeric split now checks every coordinate rather than only the first.

• Regression process (4 states): reverse inference reaches a 5,000-state cap in 2.5 s instead of 135 s.
• Reverse ε-machines (state counts and statistical complexities) of all 100 finite 3-state survey processes are identical to main.

Test plan

• New test_infinite_reverse_presentation_reaches_its_cap_quickly (fails on main at 135 s, passes in 2.5 s).
• Mixed-state, ε-machine, bidirectional and properties suites: 209 passed.
• ruff, ty.

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