{
 "tm": "1RB0LD_1RC0RF_0LD0LE_1RF1LC_0LB1LE_0RA---",
 "label": "W7-4",
 "status": "CHECKPOINT_A",
 "stage": "observe",
 "updated": "2026-10-14",
 "confidence": "high",
 "holdout_line_740": 82,
 "reason": "Observe at table level done. The machine is an exact base-4 counter: W = 100 sea, digits D(m,p) = X(10)^mY (m even, phase = 2 bits at the region's ends), one sweep = one increment with shifts at 1->2 and 3->0, +1 W at the right end per sweep (R1/R2 700/700, exact step formula R3). A mod-3 field invariant J keeps every merge clean (1,456/1,456 real fields, 1,986/1,986 glued sweeps). Overflows alternate the wall [10100]<->[] and give births at the right end (300/300); the wall then eats the top digit through a finite remnant family (80/80 small cases return clean, none halts). The three starts enter the same language by step 20,600 and differ only in the far-left field. Exact sweep simulator = C core at 1e11 on all three (configuration and step count); no halt to 1e14 on 82, 464, 722 (82 to 1e15). Not a cryptid. Stage-1 GO signal; open: complete wall case table + closure check.",
 "siblings": [
  "1RB0RD_0LC0LF_1RD1LB_0RE---_1RA0LC_0LA1LF",
  "1RB1LE_0RC---_1RD0LA_1RE0RB_0LA0LF_0LD1LF"
 ],
 "sibling_note": "Same table from B (464) and D (722); starts C, E, F reduce to D, B, A after one step. Same counter and invariant; only the far-left field differs at entry (82: [] W^1, 464: [10100] W^9, 722: [10100] W^11), so one closed-language proof plus three entry lemmas covers all three lines.",
 "upstream": "No upstream proof of any start (solved_index: no; Astra equivalence sweeps negative). Nearest framework: verify/Sk1Machines.v (mxdys, Sk1 Class 1): same digit-counter shape, but its TM17 endgame is a glider check, which does not apply here.",
 "next_goal": "Stage 1 completion (2 h): write the wall/remnant case table as affine rules and run an exhaustive closure check of the candidate language L on small parameters."
}