diff --git a/library/packet/scripts/check-circular-layout.mjs b/library/packet/scripts/check-circular-layout.mjs
index 7a28761af..f7f88f63f 100644
--- a/library/packet/scripts/check-circular-layout.mjs
+++ b/library/packet/scripts/check-circular-layout.mjs
@@ -128,15 +128,27 @@ if (four.stats.placed < 800) fails.push(`fourSides: only ${four.stats.placed} pi
     for (const n of nums) if (n <= lo) seqOk = false;
     if (nums.length) lo = Math.max(lo, ...nums);
   }
-  // monotone WITHIN a side = numbers increase in LABEL EMISSION order (ring order),
-  // which is the real placement order (four.pins is input order, so it cannot test this).
-  let monoOk = true;
+  // monotone WITHIN a side = tested against GEOMETRY, not the emission arrays (which
+  // numbering walks, so an emission-order check cannot fail — studio P2). Per classic4:
+  // L cy DESC (num↑ ⇒ screen y DOWN), R cy ASC (y UP), T cx ASC (x UP), B cx DESC (x DOWN).
+  // Pins are post-spread, so allow a drift tolerance = 60% of the side's mean step; a
+  // reversed sort (studio's poison) still fails, normal de-overlap drift does not.
+  const AXIS = { L: ['y', -1], R: ['y', +1], T: ['x', +1], B: ['x', -1] };
+  let monoOk = true, monoWhy = '';
   for (const sd of SEQ) {
-    const seq = four.labels.filter((l) => l.side === sd).map((l) => l.num);
-    for (let i = 1; i < seq.length; i++) if (seq[i] <= seq[i - 1]) { monoOk = false; break; }
+    const ps = four.pins.filter((p) => p.side === sd).sort((a, b) => a.num - b.num);
+    if (ps.length < 3) continue;
+    const [axis, dir] = AXIS[sd];
+    const coords = ps.map((p) => p[axis] * dir);          // expected non-decreasing
+    const span = coords[coords.length - 1] - coords[0];
+    const tol = 0.6 * Math.abs(span) / (coords.length - 1); // 60% of mean step
+    let inversions = 0;
+    for (let i = 1; i < coords.length; i++) if (coords[i] < coords[i - 1] - tol) inversions++;
+    // a correct side has only small local drift inversions; a reversed sort inverts ~everything
+    if (inversions > coords.length * 0.2) { monoOk = false; monoWhy = `${sd}:${inversions}/${coords.length}`; }
   }
   if (!seqOk) fails.push('fourSides: numbers not in side sequence L<T<R<B');
-  if (!monoOk) fails.push('fourSides: numbers not monotone within a side');
+  if (!monoOk) fails.push(`fourSides: numbering not geometrically monotone within a side (${monoWhy})`);
   // (4) RECOUNT outside-state from the OUTPUT (pins vs state rings), not from stats.
   const outFx = recountOutside(four.pins, feats);
   if (outFx !== 0) fails.push(`fourSides: recount found ${outFx} pins outside their state (stats said ${four.stats.pinsOutsideState})`);
@@ -163,7 +175,10 @@ if (paired.stats.placed < 800) fails.push(`pairedRows: only ${paired.stats.place
   if (xr !== 0) fails.push(`pairedRows: recount found ${xr} crossings (stats said ${paired.stats.crossings})`);
   const outPr = recountOutside(paired.pins, feats);
   if (outPr !== 0) fails.push(`pairedRows: recount found ${outPr} pins outside their state`);
-  note.push(`pairedRows check: crossings(recount) ${xr}, outside(recount) ${outPr}`);
+  // (P3) every leader must actually carry its two polylines — a dropped polys passed before.
+  const badPolys = paired.leaders.filter((l) => !Array.isArray(l.polys) || l.polys.length !== 2).length;
+  if (badPolys !== 0) fails.push(`pairedRows: ${badPolys} leaders missing polys.length===2`);
+  note.push(`pairedRows check: crossings(recount) ${xr}, outside(recount) ${outPr}, leaders-with-2-polys ${paired.leaders.length - badPolys}/${paired.leaders.length}`);
 }
 
 // ── 3. sideLanes ──────────────────────────────────────────────────────────────