Δ_3: m=4 outcomes, chirality weights w=[1, -1, 1/2, 0], β_reduced=[7/8, -9/8, 3/8]

[0a] static Fisher–Rao baseline
  R = 1/4 (g∧g) (constant curvature 1/4, symbolic): True
  ⇒ ∇R ≡ 0 (constant-curvature ⇒ locally symmetric): True
  ⇒ signature (m−1, 0) positive-definite, holonomy SO(m−1)

[0b] drift-flipped metric g' = g − 2 β♭⊗β♭ / g(β,β)
  centroid: signature (2, 1), g'(β,β) = -35/4 (<0 ⇒ β time-like)
  offcenter1: signature (2, 1), g'(β,β) = -8389/208 (<0 ⇒ β time-like)
  offcenter2: signature (2, 1), g'(β,β) = -14801/640 (<0 ⇒ β time-like)

[0c] discriminator on g'
  ∇R' at centroid: 108 nonzero components ⇒ NOT locally symmetric
    e.g. (∇R')_(0, 0, 1, 0, 1) = 1987584/1500625
  L candidates at centroid: {1271/16100, -15059/9100, -19/140, 3569/11900, 2221/9100}
  L candidates at offcenter1: {-8590214568267575/3241881668558884, 16772053384459/155461617600556, 75435268381579/218698066038316, 774808063467871/5447322057141628, 269928732683725/1252646089142068, 4602893418717781/9220566956885332}

[verdict] baseline: LOCALLY SYMMETRIC (∇R=0). drift-perturbed: ∇R ≠ 0; PROPER (neither semi- nor pseudo-symmetric at sample points) — R·R ≠ L·Q(g,R)

[0d] obstruction vs drift direction (centroid)
  Σ (β^a ∇_a R')² at centroid = 69439107209066496/2251875390625 (drift direction carries obstruction)
