A typed API for a hot mill

from steelira import Mill, Envelope

mill = Mill("tcm-2", site="kalyon-iskenderun")

# Fused, coil-length-aligned state at 50 Hz
state = mill.coil_state(coil_id="84-2213-A")
print(state.exit_gauge_mm)     # 1.982
print(state.flatness_iu)       # 3.1
print(state.chatter_margin)    # 0.24
print(state.surface.defects)   # []

# Ask the twin for the best next pass under your objective
plan = mill.plan_pass(
    coil_id="84-2213-A",
    objective={"prime_yield": 0.5, "energy": 0.3, "rate": 0.2},
    envelope=Envelope(gap_delta_mm=(-0.05, 0.05), tension_mpa=(4.0, 12.0)),
)
for move in plan.moves:
    print(move.stand, move.setpoint, move.delta, move.reason)

# Apply — signed, clamped, rate-limited, audited
ack = mill.apply(plan, mode="assist", approver="a.kohler")
print(ack.audit_id, ack.applied_at, ack.level2_ack)

{
  "request": {
    "coil_id":   "84-2213-A",
    "mill":      "tcm-2",
    "setpoint":  "stand.5.roll_gap_mm",
    "delta":     -0.011,
    "signer":    "agent:roll-gauge@2.4.1",
    "evidence":  ["twin:run/9f21", "coil:81-9944-C", "spec:DX54D"]
  },
  "guards": {
    "envelope":       [-0.05, 0.05],   // per setpoint, grade, line
    "rate_limit":     "6 writes / 10s",
    "approval_above": 0.03,           // human confirms beyond this
    "watchdog_ms":    250,            // then release to Level-2
    "grade_policy":   "DX54D/strict"
  },
  "audit": {
    "id": "7f31c", "chain": "sha256:8a1f…", "immutable": true
  }
}