experiment: E2_grounding_phase_boundary
seed: 20260704
n_replicates: 100
generations: 500   # long enough that the g=0 arm slides toward 0 while g>0 arms plateau

# Headline experiment (blueprint 2.5-E2): sweep the grounding fraction g = m/(n+m);
# single teacher; proportional grounding (Multinomial(m, p*), the immigration model the
# exact H_eq of 2.4-3 is derived for); no selection. R=1 so the sweep tracks the closed
# form. Expect a critical g* << 1 above which stationary H and tail mass stabilise at a
# positive value tracking H_eq = H* * m(2n+m-1)/(n+2nm+m^2), below which they collapse.
truth:
  K: 1000
  R: 1
  tail: zipf
  zipf_s: 1.1
  tail_frac: 0.5
  tail_threshold: 1.0e-3
  init: truth

dynamics:
  n: 200
  teachers: {K_T: 1, rho: 0.0, q: 1.0}
  grounding: {m: 0, policy: proportional}   # m is overwritten per g by the sweep
  selection: {mode: none, novelty_alpha: 0.0}
  remint: {enabled: false, period: null, H_gate: null}

metrics:
  kl_floor: 1.0e-9
  support_eps: 1.0e-9

sweep:
  - param: g
    values: [0.0, 0.005, 0.01, 0.02, 0.05, 0.1, 0.2, 0.4]

output:
  dir: results/E2