diff --git a/app/patternfront.html b/app/patternfront.html
index 9f64774..96d45ba 100644
--- a/app/patternfront.html
+++ b/app/patternfront.html
@@ -446,6 +446,7 @@
           <button class="b" id="pvMap" title="Show it on a territory, at map scale · drag to move it">Map</button>
           <button class="b" id="pvFit" title="Fit to the panel">Fit</button>
           <span class="num" id="pvZ" style="min-width:3rem">fit</span>
+          <span class="note" id="pvSeam" title="Does this show a seam once the game tiles it?"></span>
           <div class="sp"></div>
           <button class="b sq" id="pvPlay" title="Play">▶</button>
         </div>
@@ -576,6 +577,11 @@
       <button class="b" id="ofJson">Copy JSON</button>
     </div>
     <span class="note" id="ofStat"></span>
+    <div class="r"><input id="ofName" placeholder="pattern name" class="wide"
+      style="background:var(--well);color:var(--text);border:0.1rem solid var(--edge-dim);
+      font:inherit;padding:0 0.4rem">
+      <button class="b" id="ofEntry" style="flex:0 0 auto">cosmetics.json entry</button></div>
+    <div class="data" id="ofEntryOut" hidden></div>
     <div class="r" style="margin-top:0.4rem">
       <input type="text" id="ofIn" spellcheck="false" style="flex:1;min-width:0"
         placeholder="paste patternData to edit it">
@@ -1207,7 +1213,21 @@
   zoom=Math.max(1,Math.min(48,z||1));
   $('zoom').value=zoom;$('zoomO').textContent=zoom;
   layout();}
-function commit(){paint();overlay();drawThumbs();syncStatus();saveSoon();markDirty();}
+function commit(){paint();overlay();drawThumbs();syncStatus();saveSoon();markDirty();seamSoon();}
+/* Scoring walks the bitmap several times looking for its intrinsic period, which
+   is far too much to redo on every pointermove. It settles after the stroke. */
+let seamTimer=null;
+function seamSoon(){clearTimeout(seamTimer);seamTimer=setTimeout(updateSeam,250);}
+function updateSeam(){
+  const el=$('pvSeam'); if(!el) return;
+  if(doc.w>OF_MAXW||doc.h>OF_MAXH){el.textContent='';return;}
+  const [sh,sv]=seamScores(doc.w,doc.h,to1bit()),label=seamLabel(sh,sv);
+  el.textContent=label;
+  el.style.color=label==='Seamless'?'var(--ok)'
+    :label==='Slight seam'?'var(--accent)':'var(--danger)';
+  el.title=label+' — wrap discontinuity '+Math.max(sh,sv).toFixed(2)
+    +'× the pattern\'s own interior transitions';
+}
 function fullSync(){alloc();layout();drawLayers();drawFrames();drawPalette();
   drawPairs();drawStamps();syncColour();syncStatus();syncMode();syncHist();setTool(tool);}
 
@@ -1782,6 +1802,17 @@
   a.href=u;a.download=n;document.body.appendChild(a);a.click();a.remove();
   setTimeout(()=>URL.revokeObjectURL(u),5000);}
 $('expBtn').onclick=()=>{openOv('ovExp');refreshOF();};
+/* A pasteable cosmetics.json entry. The file keys patterns by their encoded
+   data, so the entry is exactly that key and a name; role_group is entitlement
+   metadata the game assigns, not something a new pattern claims for itself. */
+$('ofEntry').onclick=()=>{
+  const data=refreshOF();
+  const out=$('ofEntryOut');
+  if(!data){out.hidden=false;out.textContent='Canvas is outside the format limits.';return;}
+  const name=($('ofName').value.trim()||'my_pattern')
+    .toLowerCase().replace(/[^a-z0-9_]+/g,'_').replace(/^_+|_+$/g,'')||'my_pattern';
+  out.hidden=false;
+  out.textContent=JSON.stringify({[data]:{name}},null,2).slice(1,-1).trim();};
 $('expX').onclick=()=>closeOv('ovExp');
 $('ovExp').addEventListener('pointerdown',e=>{if(e.target===$('ovExp'))closeOv('ovExp');});
 $('exScale').oninput=e=>$('exO').textContent=e.target.value+'×';
@@ -2124,6 +2155,85 @@
   return [fit(px,wantW,DSL_MIN_W,DSL_MAX_W),fit(py,wantH,DSL_MIN_H,DSL_MAX_H)];
 }
 
+/* ═══════ seam scoring ═══════
+   Does this pattern show a seam when the game tiles it?
+
+   A correctly-tiling periodic pattern legitimately has a hard transition at the
+   wrap — period-8 stripes on a 32-wide canvas put a stripe boundary exactly
+   there. What makes a seam *visible* is the wrap being an OUTLIER: more
+   discontinuous than the pattern's own interior ever gets. So the wrap is ranked
+   against the 90th percentile of interior transitions, not against their mean —
+   the mean is dragged down by the many identical column pairs inside a periodic
+   pattern, which makes every legitimate boundary look like a defect.
+
+   An earlier version of this metric flagged 17 of 28 correctly-tiling patterns
+   and had to be rewritten. This is the rewritten one, ported from
+   tools/dsl_prototype.py rather than re-derived.
+*/
+const PERIODIC_EPS=0.02,RHYTHM_PENALTY=3.0;
+function percentile(values,q){
+  if(!values.length) return 0;
+  const s=[...values].sort((a,b)=>a-b);
+  if(s.length===1) return s[0];
+  const pos=q*(s.length-1),lo=Math.floor(pos),hi=Math.min(lo+1,s.length-1);
+  return s[lo]+(s[hi]-s[lo])*(pos-lo);
+}
+/* Smallest shift under which the bitmap best repeats. Measured on the interior
+   only, so an edge defect cannot corrupt the measurement meant to expose it. */
+function dominantPeriod(w,h,buf,axis,limit){
+  const span=axis==='x'?w:h,scan=Math.min(span,limit||span);
+  let bestP=span,bestErr=1;
+  for(let p=2;p<=Math.floor(span/2);p++){
+    let bad=0,tot=0;
+    if(axis==='x'){
+      for(let x=0;x<scan-p;x++)for(let y=0;y<h;y++){tot++;if(buf[y*w+x]!==buf[y*w+x+p])bad++;}
+    }else{
+      for(let y=0;y<scan-p;y++)for(let x=0;x<w;x++){tot++;if(buf[y*w+x]!==buf[(y+p)*w+x])bad++;}}
+    if(!tot) continue;
+    const err=bad/tot;
+    if(err<bestErr-1e-9){bestErr=err;bestP=p;}}
+  return [bestP,bestErr];
+}
+/** How badly period `p` breaks once the pattern is tiled (wrapped). */
+function toroidalError(w,h,buf,axis,p){
+  let bad=0,tot=0;
+  if(axis==='x'){
+    for(let x=0;x<w;x++)for(let y=0;y<h;y++){tot++;if(buf[y*w+x]!==buf[y*w+(x+p)%w])bad++;}
+  }else{
+    for(let y=0;y<h;y++)for(let x=0;x<w;x++){tot++;if(buf[y*w+x]!==buf[((y+p)%h)*w+x])bad++;}}
+  return tot?bad/tot:0;
+}
+/* Local adjacency at the wrap cannot see a broken cadence: period-7 stripes on a
+   32-wide canvas make a perfectly ordinary-looking edge, and a duplicated final
+   column puts the defect one pixel INSIDE the wrap. Recover the intrinsic period
+   from the interior, then ask whether tiling still honours it. */
+function rhythmPenalty(w,h,buf,axis){
+  const span=axis==='x'?w:h;
+  if(span<6) return 0;
+  const [p,errInterior]=dominantPeriod(w,h,buf,axis,Math.max(4,Math.floor(span*3/4)));
+  if(errInterior>=PERIODIC_EPS) return 0;      // not periodic enough to have a rhythm
+  if(span%p!==0) return RHYTHM_PENALTY;        // cadence cannot survive tiling
+  return toroidalError(w,h,buf,axis,p)>errInterior+PERIODIC_EPS?RHYTHM_PENALTY:0;
+}
+function seamScores(w,h,buf){
+  const px=(x,y)=>buf[y*w+x];
+  const colDiffs=[];
+  for(let x=0;x<w-1;x++){let d=0;for(let y=0;y<h;y++)if(px(x,y)!==px(x+1,y))d++;colDiffs.push(d);}
+  let wrapH=0;for(let y=0;y<h;y++)if(px(w-1,y)!==px(0,y))wrapH++;
+  let sh=wrapH===0?0:wrapH/Math.max(percentile(colDiffs,0.90),1);
+  const rowDiffs=[];
+  for(let y=0;y<h-1;y++){let d=0;for(let x=0;x<w;x++)if(px(x,y)!==px(x,y+1))d++;rowDiffs.push(d);}
+  let wrapV=0;for(let x=0;x<w;x++)if(px(x,h-1)!==px(x,0))wrapV++;
+  let sv=wrapV===0?0:wrapV/Math.max(percentile(rowDiffs,0.90),1);
+  sh=Math.max(sh,rhythmPenalty(w,h,buf,'x'));
+  sv=Math.max(sv,rhythmPenalty(w,h,buf,'y'));
+  return [sh,sv];
+}
+function seamLabel(sh,sv){
+  const worst=Math.max(sh,sv);
+  return worst<=1.3?'Seamless':(worst<=2.0?'Slight seam':'Visible seam');
+}
+
 /** Run a program. Returns {w,h,scale,bits} in the same shape decodeOF gives. */
 function dslRender(raw){
   const program=dslValidate(raw);
@@ -2640,6 +2750,8 @@
     a.addEventListener('click',e=>{
       e.preventDefault();window.pfNative.openExternal(a.href);});});
 }
+// The badge is normally driven by commit(); boot never commits, so ask once.
+seamSoon();
 // Exposed for the smoke test and for anything driving the editor from outside.
 window.__pf={commands:COMMANDS,isNative:native};
 })();
diff --git a/tests/fixtures/dsl.json b/tests/fixtures/dsl.json
index 83abd24..bbd48e7 100644
--- a/tests/fixtures/dsl.json
+++ b/tests/fixtures/dsl.json
@@ -610,7 +610,12 @@
    "height": 32,
    "scale": 1,
    "ink": 512,
-   "patternData": "APF4Dw8PDw8PDw8PDw8PDw8PDw8PDw8PDw8PDw8PDw8PDw8PDw8PDw8PDw8PDw8PDw8PDw8PDw8PDw8PDw8PDw8PDw8PDw8PDw8PDw8PDw8PDw8PDw8PDw8PDw8PDw8PDw8PDw8PDw8PDw8PDw8PDw8PDw8PDw8PDw8PDw8PDw8PDw8"
+   "patternData": "APF4Dw8PDw8PDw8PDw8PDw8PDw8PDw8PDw8PDw8PDw8PDw8PDw8PDw8PDw8PDw8PDw8PDw8PDw8PDw8PDw8PDw8PDw8PDw8PDw8PDw8PDw8PDw8PDw8PDw8PDw8PDw8PDw8PDw8PDw8PDw8PDw8PDw8PDw8PDw8PDw8PDw8PDw8PDw8",
+   "seam": [
+    1.0,
+    0.0
+   ],
+   "seamLabel": "Seamless"
   },
   {
    "name": "gallery:stripes_h",
@@ -638,7 +643,12 @@
    "height": 30,
    "scale": 1,
    "ink": 480,
-   "patternData": "APFw________________AAAAAAAAAAAAAAAA________________AAAAAAAAAAAAAAAA________________AAAAAAAAAAAAAAAA________________AAAAAAAAAAAAAAAA________________AAAAAAAAAAAAAAAA"
+   "patternData": "APFw________________AAAAAAAAAAAAAAAA________________AAAAAAAAAAAAAAAA________________AAAAAAAAAAAAAAAA________________AAAAAAAAAAAAAAAA________________AAAAAAAAAAAAAAAA",
+   "seam": [
+    0.0,
+    1.0
+   ],
+   "seamLabel": "Seamless"
   },
   {
    "name": "gallery:diagonal",
@@ -667,7 +677,12 @@
    "height": 32,
    "scale": 1,
    "ink": 640,
-   "patternData": "APF4Hx8fHz4-Pj58fHx8-Pj4-PHx8fHj4-Pjx8fHx4-Pj48fHx8fPj4-Pnx8fHz4-Pj48fHx8ePj4-PHx8fHj4-Pjx8fHx8-Pj4-fHx8fPj4-Pjx8fHx4-Pj48fHx8ePj4-PHx8fHz4-Pj58fHx8-Pj4-PHx8fHj4-Pjx8fHx4-Pj48"
+   "patternData": "APF4Hx8fHz4-Pj58fHx8-Pj4-PHx8fHj4-Pjx8fHx4-Pj48fHx8fPj4-Pnx8fHz4-Pj48fHx8ePj4-PHx8fHj4-Pjx8fHx8-Pj4-fHx8fPj4-Pjx8fHx4-Pj48fHx8ePj4-PHx8fHz4-Pj58fHx8-Pj4-PHx8fHj4-Pjx8fHx4-Pj48",
+   "seam": [
+    1.0,
+    1.0
+   ],
+   "seamLabel": "Seamless"
   },
   {
    "name": "gallery:diagonal_steep",
@@ -696,7 +711,12 @@
    "height": 32,
    "scale": 1,
    "ink": 384,
-   "patternData": "APF4BwcHBxwcHBxwcHBwwcHBwQcHBwccHBwccHBwcMHBwcEHBwcHHBwcHHBwcHDBwcHBBwcHBxwcHBxwcHBwwcHBwQcHBwccHBwccHBwcMHBwcEHBwcHHBwcHHBwcHDBwcHBBwcHBxwcHBxwcHBwwcHBwQcHBwccHBwccHBwcMHBwcE"
+   "patternData": "APF4BwcHBxwcHBxwcHBwwcHBwQcHBwccHBwccHBwcMHBwcEHBwcHHBwcHHBwcHDBwcHBBwcHBxwcHBxwcHBwwcHBwQcHBwccHBwccHBwcMHBwcEHBwcHHBwcHHBwcHDBwcHBBwcHBxwcHBxwcHBwwcHBwQcHBwccHBwccHBwcMHBwcE",
+   "seam": [
+    1.0,
+    1.0
+   ],
+   "seamLabel": "Seamless"
   },
   {
    "name": "gallery:checker",
@@ -723,7 +743,12 @@
    "height": 32,
    "scale": 1,
    "ink": 512,
-   "patternData": "APF48PDw8PDw8PDw8PDw8PDw8A8PDw8PDw8PDw8PDw8PDw_w8PDw8PDw8PDw8PDw8PDwDw8PDw8PDw8PDw8PDw8PD_Dw8PDw8PDw8PDw8PDw8PAPDw8PDw8PDw8PDw8PDw8P8PDw8PDw8PDw8PDw8PDw8A8PDw8PDw8PDw8PDw8PDw8"
+   "patternData": "APF48PDw8PDw8PDw8PDw8PDw8A8PDw8PDw8PDw8PDw8PDw_w8PDw8PDw8PDw8PDw8PDwDw8PDw8PDw8PDw8PDw8PD_Dw8PDw8PDw8PDw8PDw8PAPDw8PDw8PDw8PDw8PDw8P8PDw8PDw8PDw8PDw8PDw8A8PDw8PDw8PDw8PDw8PDw8",
+   "seam": [
+    1.0,
+    1.0
+   ],
+   "seamLabel": "Seamless"
   },
   {
    "name": "gallery:checker_tall",
@@ -750,7 +775,12 @@
    "height": 30,
    "scale": 1,
    "ink": 450,
-   "patternData": "AOFwOI7jOI7jOI7jOI7jOI7jOI7j-HEcx3Ecx3Ecx3Ecx3Ecx3Ecx4HjOI7jOI7jOI7jOI7jOI7jOI4fx3Ecx3Ecx3Ecx3Ecx3Ecx3EcOI7jOI7jOI7jOI7jOI7jOI7j-HEcx3Ecx3Ecx3Ecx3Ecx3EcxwE"
+   "patternData": "AOFwOI7jOI7jOI7jOI7jOI7jOI7j-HEcx3Ecx3Ecx3Ecx3Ecx3Ecx4HjOI7jOI7jOI7jOI7jOI7jOI4fx3Ecx3Ecx3Ecx3Ecx3Ecx3EcOI7jOI7jOI7jOI7jOI7jOI7j-HEcx3Ecx3Ecx3Ecx3Ecx3EcxwE",
+   "seam": [
+    1.0,
+    1.0
+   ],
+   "seamLabel": "Seamless"
   },
   {
    "name": "gallery:grid",
@@ -779,7 +809,12 @@
    "height": 32,
    "scale": 1,
    "ink": 240,
-   "patternData": "APF4_____wEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQH_____AQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAf____8BAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEB_____wEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQE"
+   "patternData": "APF4_____wEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQH_____AQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAf____8BAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEB_____wEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQE",
+   "seam": [
+    1.0,
+    1.0
+   ],
+   "seamLabel": "Seamless"
   },
   {
    "name": "gallery:dots",
@@ -807,7 +842,12 @@
    "height": 32,
    "scale": 1,
    "ink": 208,
-   "patternData": "APF4AAAAAAAAAAAQEBAQODg4OHx8fHw4ODg4EBAQEAAAAAAAAAAAAAAAABAQEBA4ODg4fHx8fDg4ODgQEBAQAAAAAAAAAAAAAAAAEBAQEDg4ODh8fHx8ODg4OBAQEBAAAAAAAAAAAAAAAAAQEBAQODg4OHx8fHw4ODg4EBAQEAAAAAA"
+   "patternData": "APF4AAAAAAAAAAAQEBAQODg4OHx8fHw4ODg4EBAQEAAAAAAAAAAAAAAAABAQEBA4ODg4fHx8fDg4ODgQEBAQAAAAAAAAAAAAAAAAEBAQEDg4ODh8fHx8ODg4OBAQEBAAAAAAAAAAAAAAAAAQEBAQODg4OHx8fHw4ODg4EBAQEAAAAAA",
+   "seam": [
+    0.0,
+    0.0
+   ],
+   "seamLabel": "Seamless"
   },
   {
    "name": "gallery:dots_brick",
@@ -836,7 +876,12 @@
    "height": 32,
    "scale": 1,
    "ink": 208,
-   "patternData": "APF4AAAAAAAAAAAQEBAQODg4OHx8fHw4ODg4EBAQEAAAAAAAAAAAAAAAAAEBAQGDg4ODx8fHx4ODg4MBAQEBAAAAAAAAAAAAAAAAEBAQEDg4ODh8fHx8ODg4OBAQEBAAAAAAAAAAAAAAAAABAQEBg4ODg8fHx8eDg4ODAQEBAQAAAAA"
+   "patternData": "APF4AAAAAAAAAAAQEBAQODg4OHx8fHw4ODg4EBAQEAAAAAAAAAAAAAAAAAEBAQGDg4ODx8fHx4ODg4MBAQEBAAAAAAAAAAAAAAAAEBAQEDg4ODh8fHx8ODg4OBAQEBAAAAAAAAAAAAAAAAABAQEBg4ODg8fHx8eDg4ODAQEBAQAAAAA",
+   "seam": [
+    0.6666666666666666,
+    0.0
+   ],
+   "seamLabel": "Seamless"
   },
   {
    "name": "gallery:dots_sparse",
@@ -866,7 +911,12 @@
    "height": 24,
    "scale": 1,
    "ink": 78,
-   "patternData": "ABFZAAAAAAAAAAAAAAAAAAAAAAAAQAAEQAAO4AAO8AEf8AEO4AAOQAAEQAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAARAAATCAAziAB3zABzyAAziAARAAAQAAAAAAAAAAAAAAAAAA"
+   "patternData": "ABFZAAAAAAAAAAAAAAAAAAAAAAAAQAAEQAAO4AAO8AEf8AEO4AAOQAAEQAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAARAAATCAAziAB3zABzyAAziAARAAAQAAAAAAAAAAAAAAAAAA",
+   "seam": [
+    1.0,
+    0.0
+   ],
+   "seamLabel": "Seamless"
   },
   {
    "name": "gallery:brick",
@@ -895,7 +945,12 @@
    "height": 32,
    "scale": 1,
    "ink": 352,
-   "patternData": "APF4_____wEBAQEBAQEBAQEBAf____8QEBAQEBAQEBAQEBD_____AQEBAQEBAQEBAQEB_____xAQEBAQEBAQEBAQEP____8BAQEBAQEBAQEBAQH_____EBAQEBAQEBAQEBAQ_____wEBAQEBAQEBAQEBAf____8QEBAQEBAQEBAQEBA"
+   "patternData": "APF4_____wEBAQEBAQEBAQEBAf____8QEBAQEBAQEBAQEBD_____AQEBAQEBAQEBAQEB_____xAQEBAQEBAQEBAQEP____8BAQEBAQEBAQEBAQH_____EBAQEBAQEBAQEBAQ_____wEBAQEBAQEBAQEBAf____8QEBAQEBAQEBAQEBA",
+   "seam": [
+    1.0,
+    1.0
+   ],
+   "seamLabel": "Seamless"
   },
   {
    "name": "gallery:wave",
@@ -924,7 +979,12 @@
    "height": 30,
    "scale": 1,
    "ink": 320,
-   "patternData": "APFwAYMBg4MBgwHGAMYAfDh8ODh8OHwAxgDGAYMBg4MBgwHGAMYAfDh8ODh8OHwAxgDGAYMBg4MBgwHGAMYAfDh8ODh8OHwAxgDGAYMBg4MBgwHGAMYAfDh8ODh8OHwAxgDGAYMBg4MBgwHGAMYAfDh8ODh8OHwAxgDG"
+   "patternData": "APFwAYMBg4MBgwHGAMYAfDh8ODh8OHwAxgDGAYMBg4MBgwHGAMYAfDh8ODh8OHwAxgDGAYMBg4MBgwHGAMYAfDh8ODh8OHwAxgDGAYMBg4MBgwHGAMYAfDh8ODh8OHwAxgDGAYMBg4MBgwHGAMYAfDh8ODh8OHwAxgDG",
+   "seam": [
+    1.0,
+    0.5
+   ],
+   "seamLabel": "Seamless"
   },
   {
    "name": "gallery:zigzag",
@@ -953,7 +1013,12 @@
    "height": 30,
    "scale": 1,
    "ink": 320,
-   "patternData": "APFwRERERERERESCgoKCk5OTkzk5OTkoKCgoRERERERERESCgoKCk5OTkzk5OTkoKCgoRERERERERESCgoKCk5OTkzk5OTkoKCgoRERERERERESCgoKCk5OTkzk5OTkoKCgoRERERERERESCgoKCk5OTkzk5OTkoKCgo"
+   "patternData": "APFwRERERERERESCgoKCk5OTkzk5OTkoKCgoRERERERERESCgoKCk5OTkzk5OTkoKCgoRERERERERESCgoKCk5OTkzk5OTkoKCgoRERERERERESCgoKCk5OTkzk5OTkoKCgoRERERERERESCgoKCk5OTkzk5OTkoKCgo",
+   "seam": [
+    0.5,
+    1.0
+   ],
+   "seamLabel": "Seamless"
   },
   {
    "name": "gallery:triangles",
@@ -979,7 +1044,12 @@
    "height": 32,
    "scale": 1,
    "ink": 576,
-   "patternData": "APF4gAGAAcADwAPgB-AH8A_wD_gf-B_8P_w__n_-f_____-AAYABwAPAA-AH4AfwD_AP-B_4H_w__D_-f_5______4ABgAHAA8AD4AfgB_AP8A_4H_gf_D_8P_5__n______gAGAAcADwAPgB-AH8A_wD_gf-B_8P_w__n_-f_____8"
+   "patternData": "APF4gAGAAcADwAPgB-AH8A_wD_gf-B_8P_w__n_-f_____-AAYABwAPAA-AH4AfwD_AP-B_4H_w__D_-f_5______4ABgAHAA8AD4AfgB_AP8A_4H_gf_D_8P_5__n______gAGAAcADwAPgB-AH8A_wD_gf-B_8P_w__n_-f_____8",
+   "seam": [
+    0.0,
+    7.0
+   ],
+   "seamLabel": "Visible seam"
   },
   {
    "name": "gallery:rings",
@@ -1006,7 +1076,12 @@
    "height": 32,
    "scale": 1,
    "ink": 508,
-   "patternData": "APF4-D_4Px7wHvAGwAbA44_jj_Of8585ODk4GTAZMJkzmTOZM5kzmTOZMxkwGTA5ODk485_zn-OP448GwAbAHvAe8Pg_-D8e8B7wBsAGwOOP44_zn_OfOTg5OBkwGTCZM5kzmTOZM5kzmTMZMBkwOTg5OPOf85_jj-OPBsAGwB7wHvA"
+   "patternData": "APF4-D_4Px7wHvAGwAbA44_jj_Of8585ODk4GTAZMJkzmTOZM5kzmTOZMxkwGTA5ODk485_zn-OP448GwAbAHvAe8Pg_-D8e8B7wBsAGwOOP44_zn_OfOTg5OBkwGTCZM5kzmTOZM5kzmTMZMBkwOTg5OPOf85_jj-OPBsAGwB7wHvA",
+   "seam": [
+    1.1,
+    1.1
+   ],
+   "seamLabel": "Seamless"
   },
   {
    "name": "gallery:halftone",
@@ -1033,7 +1108,12 @@
    "height": 32,
    "scale": 1,
    "ink": 592,
-   "patternData": "APF4AAAAADg4ODh8fHx8_v7-_v7-_v7-_v7-fHx8fDg4ODgAAAAAODg4OHx8fHz-_v7-_v7-_v7-_v58fHx8ODg4OAAAAAA4ODg4fHx8fP7-_v7-_v7-_v7-_nx8fHw4ODg4AAAAADg4ODh8fHx8_v7-_v7-_v7-_v7-fHx8fDg4ODg"
+   "patternData": "APF4AAAAADg4ODh8fHx8_v7-_v7-_v7-_v7-fHx8fDg4ODgAAAAAODg4OHx8fHz-_v7-_v7-_v7-_v58fHx8ODg4OAAAAAA4ODg4fHx8fP7-_v7-_v7-_v7-_nx8fHw4ODg4AAAAADg4ODh8fHx8_v7-_v7-_v7-_v7-fHx8fDg4ODg",
+   "seam": [
+    1.0,
+    1.0
+   ],
+   "seamLabel": "Seamless"
   },
   {
    "name": "gallery:halftone_45",
@@ -1061,7 +1141,12 @@
    "height": 32,
    "scale": 1,
    "ink": 400,
-   "patternData": "APF4AAAAAAAAAAB8fHx8fHx8fHx8fHx8fHx8fHx8fAAAAAAAAAAAAAAAAMfHx8fHx8fHx8fHx8fHx8fHx8fHAAAAAAAAAAAAAAAAfHx8fHx8fHx8fHx8fHx8fHx8fHwAAAAAAAAAAAAAAADHx8fHx8fHx8fHx8fHx8fHx8fHxwAAAAA"
+   "patternData": "APF4AAAAAAAAAAB8fHx8fHx8fHx8fHx8fHx8fHx8fAAAAAAAAAAAAAAAAMfHx8fHx8fHx8fHx8fHx8fHx8fHAAAAAAAAAAAAAAAAfHx8fHx8fHx8fHx8fHx8fHx8fHwAAAAAAAAAAAAAAADHx8fHx8fHx8fHx8fHx8fHx8fHxwAAAAA",
+   "seam": [
+    0.0,
+    0.0
+   ],
+   "seamLabel": "Seamless"
   },
   {
    "name": "gallery:noise",
@@ -1088,7 +1173,12 @@
    "height": 16,
    "scale": 1,
    "ink": 80,
-   "patternData": "AHE4BIDCscBiYAAUQcwgBRCoSuCoNBBJCBiHcDAwNmBplro"
+   "patternData": "AHE4BIDCscBiYAAUQcwgBRCoSuCoNBBJCBiHcDAwNmBplro",
+   "seam": [
+    0.813953488372093,
+    0.7777777777777778
+   ],
+   "seamLabel": "Seamless"
   },
   {
    "name": "gallery:noise_blue",
@@ -1116,7 +1206,12 @@
    "height": 16,
    "scale": 1,
    "ink": 80,
-   "patternData": "AHE4ooJIVZEKQlCRIApJlRRKSKUQEqShUlKFhCpJEBKERSg"
+   "patternData": "AHE4ooJIVZEKQlCRIApJlRRKSKUQEqShUlKFhCpJEBKERSg",
+   "seam": [
+    0.9016393442622951,
+    0.9090909090909091
+   ],
+   "seamLabel": "Seamless"
   },
   {
    "name": "gallery:text",
@@ -1144,7 +1239,12 @@
    "height": 36,
    "scale": 1,
    "ink": 400,
-   "patternData": "ABGJ0fNEz5NEURJFRRQVUTREzxA9RVQUUZFESRIl0RNFTwQAAAAAAAAAABA9T_Q8SRQlUVREURFFQ_QM0VNERREVSZQkURI9UfREAAAAAAAAAAAA0fNEz5NEURJFRRQVUTREzxA9RVQUUZFESRIl0RNFTwQAAAAAAAAAABA9T_Q8SRQlUVREURFFQ_QM0VNERREVSZQkURI9UfREAAAAAAAAAAAA"
+   "patternData": "ABGJ0fNEz5NEURJFRRQVUTREzxA9RVQUUZFESRIl0RNFTwQAAAAAAAAAABA9T_Q8SRQlUVREURFFQ_QM0VNERREVSZQkURI9UfREAAAAAAAAAAAA0fNEz5NEURJFRRQVUTREzxA9RVQUUZFESRIl0RNFTwQAAAAAAAAAABA9T_Q8SRQlUVREURFFQ_QM0VNERREVSZQkURI9UfREAAAAAAAAAAAA",
+   "seam": [
+    1.0,
+    1.0
+   ],
+   "seamLabel": "Seamless"
   },
   {
    "name": "gallery:text_small",
@@ -1172,7 +1272,12 @@
    "height": 35,
    "scale": 1,
    "ink": 320,
-   "patternData": "APGEcnJychUVFRU1NTU1FRUVFRISEhIAAAAAAAAAAHJycnIVFRUVNTU1NRUVFRUSEhISAAAAAAAAAABycnJyFRUVFTU1NTUVFRUVEhISEgAAAAAAAAAAcnJychUVFRU1NTU1FRUVFRISEhIAAAAAAAAAAHJycnIVFRUVNTU1NRUVFRUSEhISAAAAAAAAAAA"
+   "patternData": "APGEcnJychUVFRU1NTU1FRUVFRISEhIAAAAAAAAAAHJycnIVFRUVNTU1NRUVFRUSEhISAAAAAAAAAABycnJyFRUVFTU1NTUVFRUVEhISEgAAAAAAAAAAcnJychUVFRU1NTU1FRUVFRISEhIAAAAAAAAAAHJycnIVFRUVNTU1NRUVFRUSEhISAAAAAAAAAAA",
+   "seam": [
+    0.6,
+    0.8
+   ],
+   "seamLabel": "Seamless"
   },
   {
    "name": "gallery:border",
@@ -1199,7 +1304,12 @@
    "height": 16,
    "scale": 1,
    "ink": 44,
-   "patternData": "AHE4AAAAAPw_BCAEIAQgBCAEIAQgBCAEIAQgBCD8PwAAAAA"
+   "patternData": "AHE4AAAAAPw_BCAEIAQgBCAEIAQgBCAEIAQgBCD8PwAAAAA",
+   "seam": [
+    0.0,
+    0.0
+   ],
+   "seamLabel": "Seamless"
   },
   {
    "name": "gallery:solid",
@@ -1224,7 +1334,12 @@
    "height": 8,
    "scale": 3,
    "ink": 64,
-   "patternData": "ADMY__________8"
+   "patternData": "ADMY__________8",
+   "seam": [
+    0.0,
+    0.0
+   ],
+   "seamLabel": "Seamless"
   },
   {
    "name": "gallery:chainlink",
@@ -1263,7 +1378,12 @@
    "height": 32,
    "scale": 1,
    "ink": 256,
-   "patternData": "APF4AwMDAwYGBgYMDAwMGBgYGDAwMDBgYGBgwMDAwIGBgYEDAwMDBgYGBgwMDAwYGBgYMDAwMGBgYGDAwMDAgYGBgQMDAwMGBgYGDAwMDBgYGBgwMDAwYGBgYMDAwMCBgYGBAwMDAwYGBgYMDAwMGBgYGDAwMDBgYGBgwMDAwIGBgYE"
+   "patternData": "APF4AwMDAwYGBgYMDAwMGBgYGDAwMDBgYGBgwMDAwIGBgYEDAwMDBgYGBgwMDAwYGBgYMDAwMGBgYGDAwMDAgYGBgQMDAwMGBgYGDAwMDBgYGBgwMDAwYGBgYMDAwMCBgYGBAwMDAwYGBgYMDAwMGBgYGDAwMDBgYGBgwMDAwIGBgYE",
+   "seam": [
+    1.0,
+    1.0
+   ],
+   "seamLabel": "Seamless"
   },
   {
    "name": "gallery:plaid",
@@ -1300,7 +1420,12 @@
    "height": 30,
    "scale": 1,
    "ink": 440,
-   "patternData": "APFw-Pj4-Pj4-PgHBwcHBwcHBwcHBwcHBwcH-Pj4-Pj4-PgHBwcHBwcHBwcHBwcHBwcH-Pj4-Pj4-PgHBwcHBwcHBwcHBwcHBwcH-Pj4-Pj4-PgHBwcHBwcHBwcHBwcHBwcH-Pj4-Pj4-PgHBwcHBwcHBwcHBwcHBwcH"
+   "patternData": "APFw-Pj4-Pj4-PgHBwcHBwcHBwcHBwcHBwcH-Pj4-Pj4-PgHBwcHBwcHBwcHBwcHBwcH-Pj4-Pj4-PgHBwcHBwcHBwcHBwcHBwcH-Pj4-Pj4-PgHBwcHBwcHBwcHBwcHBwcH-Pj4-Pj4-PgHBwcHBwcHBwcHBwcHBwcH",
+   "seam": [
+    1.0,
+    1.0
+   ],
+   "seamLabel": "Seamless"
   },
   {
    "name": "gallery:dotted_grid",
@@ -1338,7 +1463,12 @@
    "height": 32,
    "scale": 1,
    "ink": 448,
-   "patternData": "APF4__________8DAwMDAwMDAwMDAwMDAwMDAwMDAwMDAwP__________wMDAwMDAwMDAwMDAwMDAwMDAwMDAwMDA___________AwMDAwMDAwMDAwMDAwMDAwMDAwMDAwMD__________8DAwMDAwMDAwMDAwMDAwMDAwMDAwMDAwM"
+   "patternData": "APF4__________8DAwMDAwMDAwMDAwMDAwMDAwMDAwMDAwP__________wMDAwMDAwMDAwMDAwMDAwMDAwMDAwMDA___________AwMDAwMDAwMDAwMDAwMDAwMDAwMDAwMD__________8DAwMDAwMDAwMDAwMDAwMDAwMDAwMDAwM",
+   "seam": [
+    1.0,
+    1.0
+   ],
+   "seamLabel": "Seamless"
   },
   {
    "name": "gallery:houndstooth",
@@ -1375,7 +1505,12 @@
    "height": 32,
    "scale": 1,
    "ink": 640,
-   "patternData": "APF4_____-7u7u7MzMzMiIiIiP_____u7u7uzMzMzIiIiIj_____7u7u7szMzMyIiIiI_____-7u7u7MzMzMiIiIiP_____u7u7uzMzMzIiIiIj_____7u7u7szMzMyIiIiI_____-7u7u7MzMzMiIiIiP_____u7u7uzMzMzIiIiIg"
+   "patternData": "APF4_____-7u7u7MzMzMiIiIiP_____u7u7uzMzMzIiIiIj_____7u7u7szMzMyIiIiI_____-7u7u7MzMzMiIiIiP_____u7u7uzMzMzIiIiIj_____7u7u7szMzMyIiIiI_____-7u7u7MzMzMiIiIiP_____u7u7uzMzMzIiIiIg",
+   "seam": [
+    1.0,
+    1.0
+   ],
+   "seamLabel": "Seamless"
   },
   {
    "name": "gallery:inverted_waves",
@@ -1406,7 +1541,12 @@
    "height": 36,
    "scale": 1,
    "ink": 288,
-   "patternData": "APGIiIiIiBEREREiIiIiIiIiIiIiIiIRERERiIiIiEREREQiIiIiIiIiIiIiIiJEREREiIiIiBEREREiIiIiIiIiIiIiIiIRERERiIiIiEREREQiIiIiIiIiIiIiIiJEREREiIiIiBEREREiIiIiIiIiIiIiIiIRERERiIiIiEREREQiIiIiIiIiIiIiIiJERERE"
+   "patternData": "APGIiIiIiBEREREiIiIiIiIiIiIiIiIRERERiIiIiEREREQiIiIiIiIiIiIiIiJEREREiIiIiBEREREiIiIiIiIiIiIiIiIRERERiIiIiEREREQiIiIiIiIiIiIiIiJEREREiIiIiBEREREiIiIiIiIiIiIiIiIRERERiIiIiEREREQiIiIiIiIiIiIiIiJERERE",
+   "seam": [
+    0.5,
+    1.0
+   ],
+   "seamLabel": "Seamless"
   },
   {
    "name": "params:solid_only",
@@ -1431,7 +1571,12 @@
    "height": 32,
    "scale": 1,
    "ink": 1024,
-   "patternData": "APF4__________________________________________________________________________________________________________________________________________________________________________8"
+   "patternData": "APF4__________________________________________________________________________________________________________________________________________________________________________8",
+   "seam": [
+    0.0,
+    0.0
+   ],
+   "seamLabel": "Seamless"
   },
   {
    "name": "params:stripes_thin",
@@ -1460,7 +1605,12 @@
    "height": 35,
    "scale": 1,
    "ink": 320,
-   "patternData": "APGEAAAAAAAAAAAAAAAAAAAAAP__________AAAAAAAAAAAAAAAAAAAAAAAAAAD__________wAAAAAAAAAAAAAAAAAAAAAAAAAA__________8AAAAAAAAAAAAAAAAAAAAAAAAAAP__________AAAAAAAAAAAAAAAAAAAAAAAAAAD__________wAAAAA"
+   "patternData": "APGEAAAAAAAAAAAAAAAAAAAAAP__________AAAAAAAAAAAAAAAAAAAAAAAAAAD__________wAAAAAAAAAAAAAAAAAAAAAAAAAA__________8AAAAAAAAAAAAAAAAAAAAAAAAAAP__________AAAAAAAAAAAAAAAAAAAAAAAAAAD__________wAAAAA",
+   "seam": [
+    0.0,
+    0.0
+   ],
+   "seamLabel": "Seamless"
   },
   {
    "name": "params:diagonal_steep",
@@ -1490,7 +1640,12 @@
    "height": 32,
    "scale": 1,
    "ink": 320,
-   "patternData": "AOF4MAzDcBiGYWgYhmEwDMMwMAzDcBiGYWgYhmEwDMMwMAzDcBiGYWgYhmEwDMMwMAzDcBiGYWgYhmEwDMMwMAzDcBiGYWgYhmEwDMMwMAzDcBiGYWgYhmEwDMMwMAzDcBiGYWgYhmEwDMMwMAzDcBiGYWgYhmEwDMMw"
+   "patternData": "AOF4MAzDcBiGYWgYhmEwDMMwMAzDcBiGYWgYhmEwDMMwMAzDcBiGYWgYhmEwDMMwMAzDcBiGYWgYhmEwDMMwMAzDcBiGYWgYhmEwDMMwMAzDcBiGYWgYhmEwDMMwMAzDcBiGYWgYhmEwDMMwMAzDcBiGYWgYhmEwDMMw",
+   "seam": [
+    0.5,
+    1.0
+   ],
+   "seamLabel": "Seamless"
   },
   {
    "name": "params:checker_oblong",
@@ -1518,7 +1673,12 @@
    "height": 32,
    "scale": 1,
    "ink": 480,
-   "patternData": "AOF4H3zwwQcffAA--OCDDz74H3zwwQcffAA--OCDDz74H3zwwQcffAA--OCDDz74H3zwwQcffAA--OCDDz74H3zwwQcffAA--OCDDz74H3zwwQcffAA--OCDDz74H3zwwQcffAA--OCDDz74H3zwwQcffAA--OCDDz74"
+   "patternData": "AOF4H3zwwQcffAA--OCDDz74H3zwwQcffAA--OCDDz74H3zwwQcffAA--OCDDz74H3zwwQcffAA--OCDDz74H3zwwQcffAA--OCDDz74H3zwwQcffAA--OCDDz74H3zwwQcffAA--OCDDz74H3zwwQcffAA--OCDDz74",
+   "seam": [
+    1.0,
+    1.0
+   ],
+   "seamLabel": "Seamless"
   },
   {
    "name": "params:grid_thick",
@@ -1549,7 +1709,12 @@
    "height": 30,
    "scale": 1,
    "ink": 600,
-   "patternData": "ABFxgQMHDhw4cODA____________gQMHDhw4cODAgQMHDhw4cODA____________gQMHDhw4cODAgQMHDhw4cODA____________gQMHDhw4cODAgQMHDhw4cODA____________gQMHDhw4cODAgQMHDhw4cODA____________gQMHDhw4cODA"
+   "patternData": "ABFxgQMHDhw4cODA____________gQMHDhw4cODAgQMHDhw4cODA____________gQMHDhw4cODAgQMHDhw4cODA____________gQMHDhw4cODAgQMHDhw4cODA____________gQMHDhw4cODAgQMHDhw4cODA____________gQMHDhw4cODA",
+   "seam": [
+    0.0,
+    0.0
+   ],
+   "seamLabel": "Seamless"
   },
   {
    "name": "params:dots_diamond",
@@ -1579,7 +1744,12 @@
    "height": 36,
    "scale": 1,
    "ink": 432,
-   "patternData": "AOGIIIAAAhxwwIEPPvjwxx9_-OCDDxxwwBFAAAEMOOCABx988OOPP37wwQcPOOCAIIAAAhxwwIEPPvjwxx9_-OCDDxxwwBFAAAEMOOCABx988OOPP37wwQcPOOCAIIAAAhxwwIEPPvjwxx9_-OCDDxxwwBFAAAEMOOCABx988OOPP37wwQcPOOCA"
+   "patternData": "AOGIIIAAAhxwwIEPPvjwxx9_-OCDDxxwwBFAAAEMOOCABx988OOPP37wwQcPOOCAIIAAAhxwwIEPPvjwxx9_-OCDDxxwwBFAAAEMOOCABx988OOPP37wwQcPOOCAIIAAAhxwwIEPPvjwxx9_-OCDDxxwwBFAAAEMOOCABx988OOPP37wwQcPOOCA",
+   "seam": [
+    0.25,
+    1.0
+   ],
+   "seamLabel": "Seamless"
   },
   {
    "name": "params:dots_square_jitter",
@@ -1610,7 +1780,12 @@
    "height": 32,
    "scale": 1,
    "ink": 256,
-   "patternData": "APF4AAAAAAAA8AB4APB4eB7weHge8Hh4HgB4AB4AAAAAAAAAAAAAAAAAADwAAAA8ADwAPPA8PDzwPDwA8Dw8APAAPAAAAAAAAB4AAAAeAB4eHgAeHh4eHh4AHh4eAB4AAAAeAAAAAHg8AAB4PAAeeDwAHng8PB4AADweAAA8AAAAPAA"
+   "patternData": "APF4AAAAAAAA8AB4APB4eB7weHge8Hh4HgB4AB4AAAAAAAAAAAAAAAAAADwAAAA8ADwAPPA8PDzwPDwA8Dw8APAAPAAAAAAAAB4AAAAeAB4eHgAeHh4eHh4AHh4eAB4AAAAeAAAAAHg8AAB4PAAeeDwAHng8PB4AADweAAA8AAAAPAA",
+   "seam": [
+    0.0,
+    0.5
+   ],
+   "seamLabel": "Seamless"
   },
   {
    "name": "params:brick_offset",
@@ -1639,7 +1814,12 @@
    "height": 30,
    "scale": 1,
    "ink": 468,
-   "patternData": "AOFw_________z_AAAMMMMAAAwwwwP________8DBhhggAEGGGCAAfb_________MMAAAwwwwAADDDD8________vwEGGGCAAQYYYIAB_________w8wwAADDDDAAAMM8P________-DAQYYYIABBhhggAE"
+   "patternData": "AOFw_________z_AAAMMMMAAAwwwwP________8DBhhggAEGGGCAAfb_________MMAAAwwwwAADDDD8________vwEGGGCAAQYYYIAB_________w8wwAADDDDAAAMM8P________-DAQYYYIABBhhggAE",
+   "seam": [
+    1.0,
+    1.0
+   ],
+   "seamLabel": "Seamless"
   },
   {
    "name": "params:wave_vertical",
@@ -1669,7 +1849,12 @@
    "height": 28,
    "scale": 1,
    "ink": 336,
-   "patternData": "APFoODg4OHBwcHBwcHBwODg4OBwcHBwHBwcHwcHBweDg4OBwcHBwcHBwcODg4ODBwcHBBwcHBxwcHBw4ODg4cHBwcHBwcHA4ODg4HBwcHAcHBwfBwcHB4ODg4HBwcHBwcHBw4ODg4MHBwcEHBwcHHBwcHA"
+   "patternData": "APFoODg4OHBwcHBwcHBwODg4OBwcHBwHBwcHwcHBweDg4OBwcHBwcHBwcODg4ODBwcHBBwcHBxwcHBw4ODg4cHBwcHBwcHA4ODg4HBwcHAcHBwfBwcHB4ODg4HBwcHBwcHBw4ODg4MHBwcEHBwcHHBwcHA",
+   "seam": [
+    1.0,
+    0.5
+   ],
+   "seamLabel": "Seamless"
   },
   {
    "name": "params:zigzag_vertical",
@@ -1698,7 +1883,12 @@
    "height": 30,
    "scale": 1,
    "ink": 360,
-   "patternData": "APFwcHBwcBwcHBwODg4Og4ODg8HBwcFwcHBwwcHBwYODg4MODg4OHBwcHHBwcHAcHBwcDg4ODoODg4PBwcHBcHBwcMHBwcGDg4ODDg4ODhwcHBxwcHBwHBwcHA4ODg6Dg4ODwcHBwXBwcHDBwcHBg4ODgw4ODg4cHBwc"
+   "patternData": "APFwcHBwcBwcHBwODg4Og4ODg8HBwcFwcHBwwcHBwYODg4MODg4OHBwcHHBwcHAcHBwcDg4ODoODg4PBwcHBcHBwcMHBwcGDg4ODDg4ODhwcHBxwcHBwHBwcHA4ODg6Dg4ODwcHBwXBwcHDBwcHBg4ODgw4ODg4cHBwc",
+   "seam": [
+    0.0,
+    1.0
+   ],
+   "seamLabel": "Seamless"
   },
   {
    "name": "params:triangles_down",
@@ -1725,7 +1915,12 @@
    "height": 30,
    "scale": 1,
    "ink": 630,
-   "patternData": "ABFx_____-9__ud__MM__IMf-IEf8AAP8AAGYAAG_____-9__ud__MM__IMf-IEf8AAP8AAGYAAG_____-9__ud__MM__IMf-IEf8AAP8AAGYAAG_____-9__ud__MM__IMf-IEf8AAP8AAGYAAG_____-9__ud__MM__IMf-IEf8AAP8AAGYAAG"
+   "patternData": "ABFx_____-9__ud__MM__IMf-IEf8AAP8AAGYAAG_____-9__ud__MM__IMf-IEf8AAP8AAGYAAG_____-9__ud__MM__IMf-IEf8AAP8AAGYAAG_____-9__ud__MM__IMf-IEf8AAP8AAGYAAG_____-9__ud__MM__IMf-IEf8AAP8AAGYAAG",
+   "seam": [
+    0.0,
+    1.0
+   ],
+   "seamLabel": "Seamless"
   },
   {
    "name": "params:rings_offset",
@@ -1754,7 +1949,12 @@
    "height": 36,
    "scale": 1,
    "ink": 540,
-   "patternData": "ABGJgAM4gAMQAAEQH_ERH_ERH_ERH_ERH_ERH_ERH_ERHwEQAAEQgAM4gAN8wAd8_____w98wAd8gAM4gAMQAAEQH_ERH_ERH_ERH_ERH_ERH_ERH_ERHwEQAAEQgAM4gAN8wAd8_____w98wAd8gAM4gAMQAAEQH_ERH_ERH_ERH_ERH_ERH_ERH_ERHwEQAAEQgAM4gAN8wAd8_____w98wAd8"
+   "patternData": "ABGJgAM4gAMQAAEQH_ERH_ERH_ERH_ERH_ERH_ERH_ERHwEQAAEQgAM4gAN8wAd8_____w98wAd8gAM4gAMQAAEQH_ERH_ERH_ERH_ERH_ERH_ERH_ERHwEQAAEQgAM4gAN8wAd8_____w98wAd8gAM4gAMQAAEQH_ERH_ERH_ERH_ERH_ERH_ERH_ERHwEQAAEQgAM4gAN8wAd8_____w98wAd8",
+   "seam": [
+    0.7142857142857143,
+    0.2857142857142857
+   ],
+   "seamLabel": "Seamless"
   },
   {
    "name": "params:halftone_45",
@@ -1782,7 +1982,12 @@
    "height": 40,
    "scale": 1,
    "ink": 1044,
-   "patternData": "AOGY-OCDD3_88ee___7__________________________vvvP3_88XfwwQc__vjj33___f_________________________9998__vjj-OCDD3_88ee___7__________________________vvvP3_88XfwwQc__vjj33___f_________________________9998__vjj"
+   "patternData": "AOGY-OCDD3_88ee___7__________________________vvvP3_88XfwwQc__vjj33___f_________________________9998__vjj-OCDD3_88ee___7__________________________vvvP3_88XfwwQc__vjj33___f_________________________9998__vjj",
+   "seam": [
+    1.0,
+    4.0
+   ],
+   "seamLabel": "Visible seam"
   },
   {
    "name": "params:halftone_light",
@@ -1809,7 +2014,12 @@
    "height": 30,
    "scale": 1,
    "ink": 225,
-   "patternData": "AOFwAAAAAAAAAMBxHMdxHMdxHMdxHAAAAAAAAAAAAAAAHMdxHMdxHMdxHMcBAAAAAAAAAAAAAMBxHMdxHMdxHMdxHAAAAAAAAAAAAAAAHMdxHMdxHMdxHMcBAAAAAAAAAAAAAMBxHMdxHMdxHMdxHAAAAAA"
+   "patternData": "AOFwAAAAAAAAAMBxHMdxHMdxHMdxHAAAAAAAAAAAAAAAHMdxHMdxHMdxHMcBAAAAAAAAAAAAAMBxHMdxHMdxHMdxHAAAAAAAAAAAAAAAHMdxHMdxHMdxHMcBAAAAAAAAAAAAAMBxHMdxHMdxHMdxHAAAAAA",
+   "seam": [
+    0.0,
+    0.0
+   ],
+   "seamLabel": "Seamless"
   },
   {
    "name": "params:noise_blue",
@@ -1837,7 +2047,12 @@
    "height": 32,
    "scale": 1,
    "ink": 218,
-   "patternData": "APF4IYUgKRIACQAoFBAiQKigBCACASAFoQAEIACCQABACAQkBFQSEYGoICQUBFARSUAgqBCECgIiKpWIBJAqAAAEgVKgAkKAREmkURCQAqAiKpACRAAJJJGKUAkKFQFAAKgoEoFUESBAIQRABFJSEQgFIYCQkARJIUgAEAAUhEhQAUA"
+   "patternData": "APF4IYUgKRIACQAoFBAiQKigBCACASAFoQAEIACCQABACAQkBFQSEYGoICQUBFARSUAgqBCECgIiKpWIBJAqAAAEgVKgAkKAREmkURCQAqAiKpACRAAJJJGKUAkKFQFAAKgoEoFUESBAIQRABFJSEQgFIYCQkARJIUgAEAAUhEhQAUA",
+   "seam": [
+    0.7647058823529411,
+    0.8823529411764706
+   ],
+   "seamLabel": "Seamless"
   },
   {
    "name": "params:noise_plain",
@@ -1864,7 +2079,12 @@
    "height": 32,
    "scale": 1,
    "ink": 611,
-   "patternData": "APF4v5Hv7ycn6trvzfu_X--3f_9fV_2yFKta_y1f2T-vsLkANHxvpyZpDu6D9nH7HsvPJc15Wpi7byElny3aeyZ3Xa89UZnjJxxCiu6B0cJuaqmin-m5RdiOyX-XfystxsG3yz7jQWW3WV3ur2XEkS82Vacns17_u9jD9XkQ739fZdc"
+   "patternData": "APF4v5Hv7ycn6trvzfu_X--3f_9fV_2yFKta_y1f2T-vsLkANHxvpyZpDu6D9nH7HsvPJc15Wpi7byElny3aeyZ3Xa89UZnjJxxCiu6B0cJuaqmin-m5RdiOyX-XfystxsG3yz7jQWW3WV3ur2XEkS82Vacns17_u9jD9XkQ739fZdc",
+   "seam": [
+    0.6666666666666666,
+    0.6842105263157895
+   ],
+   "seamLabel": "Seamless"
   },
   {
    "name": "params:text_3x5",
@@ -1893,7 +2113,12 @@
    "height": 32,
    "scale": 1,
    "ink": 192,
-   "patternData": "AOF44ogjTgkllFBGGWWUUEIJIoggAgAAAAAAAAAAAAAA4ogjTgkllFBGGWWUUEIJIoggAgAAAAAAAAAAAAAA4ogjTgkllFBGGWWUUEIJIoggAgAAAAAAAAAAAAAA4ogjTgkllFBGGWWUUEIJIoggAgAAAAAAAAAAAAAA"
+   "patternData": "AOF44ogjTgkllFBGGWWUUEIJIoggAgAAAAAAAAAAAAAA4ogjTgkllFBGGWWUUEIJIoggAgAAAAAAAAAAAAAA4ogjTgkllFBGGWWUUEIJIoggAgAAAAAAAAAAAAAA4ogjTgkllFBGGWWUUEIJIoggAgAAAAAAAAAAAAAA",
+   "seam": [
+    0.6,
+    0.8
+   ],
+   "seamLabel": "Seamless"
   },
   {
    "name": "params:text_5x7",
@@ -1922,7 +2147,12 @@
    "height": 32,
    "scale": 1,
    "ink": 352,
-   "patternData": "ABF5z-c8nxMFURREURBFQfQ83vN4QQAFARQESBAgQWAEgQEAAAAAz-c8nxMFURREURBFQfQ83vN4QQAFARQESBAgQWAEgQEAAAAAz-c8nxMFURREURBFQfQ83vN4QQAFARQESBAgQWAEgQEAAAAAz-c8nxMFURREURBFQfQ83vN4QQAFARQESBAgQWAEgQEAAAAA"
+   "patternData": "ABF5z-c8nxMFURREURBFQfQ83vN4QQAFARQESBAgQWAEgQEAAAAAz-c8nxMFURREURBFQfQ83vN4QQAFARQESBAgQWAEgQEAAAAAz-c8nxMFURREURBFQfQ83vN4QQAFARQESBAgQWAEgQEAAAAAz-c8nxMFURREURBFQfQ83vN4QQAFARQESBAgQWAEgQEAAAAA",
+   "seam": [
+    1.4,
+    0.9230769230769231
+   ],
+   "seamLabel": "Slight seam"
   },
   {
    "name": "params:border_inset",
@@ -1949,7 +2179,12 @@
    "height": 32,
    "scale": 1,
    "ink": 192,
-   "patternData": "APF4AAAAAAAAAAAAAAAA-P__H_j__x8YAAAYGAAAGBgAABgYAAAYGAAAGBgAABgYAAAYGAAAGBgAABgYAAAYGAAAGBgAABgYAAAYGAAAGBgAABgYAAAYGAAAGBgAABgYAAAYGAAAGBgAABgYAAAY-P__H_j__x8AAAAAAAAAAAAAAAA"
+   "patternData": "APF4AAAAAAAAAAAAAAAA-P__H_j__x8YAAAYGAAAGBgAABgYAAAYGAAAGBgAABgYAAAYGAAAGBgAABgYAAAYGAAAGBgAABgYAAAYGAAAGBgAABgYAAAYGAAAGBgAABgYAAAYGAAAGBgAABgYAAAY-P__H_j__x8AAAAAAAAAAAAAAAA",
+   "seam": [
+    0.0,
+    0.0
+   ],
+   "seamLabel": "Seamless"
   },
   {
    "name": "op:set",
@@ -1986,7 +2221,12 @@
    "height": 30,
    "scale": 1,
    "ink": 640,
-   "patternData": "APFw_____________________wAAAAAAAAAA_____________________wAAAAAAAAAA_____________________wAAAAAAAAAA_____________________wAAAAAAAAAA_____________________wAAAAAAAAAA"
+   "patternData": "APFw_____________________wAAAAAAAAAA_____________________wAAAAAAAAAA_____________________wAAAAAAAAAA_____________________wAAAAAAAAAA_____________________wAAAAAAAAAA",
+   "seam": [
+    0.0,
+    1.0
+   ],
+   "seamLabel": "Seamless"
   },
   {
    "name": "op:union",
@@ -2023,7 +2263,12 @@
    "height": 30,
    "scale": 1,
    "ink": 840,
-   "patternData": "APFw_____________________x8fHx8fHx8f_____________________x8fHx8fHx8f_____________________x8fHx8fHx8f_____________________x8fHx8fHx8f_____________________x8fHx8fHx8f"
+   "patternData": "APFw_____________________x8fHx8fHx8f_____________________x8fHx8fHx8f_____________________x8fHx8fHx8f_____________________x8fHx8fHx8f_____________________x8fHx8fHx8f",
+   "seam": [
+    1.0,
+    1.0
+   ],
+   "seamLabel": "Seamless"
   },
   {
    "name": "op:intersect",
@@ -2060,7 +2305,12 @@
    "height": 30,
    "scale": 1,
    "ink": 400,
-   "patternData": "APFwHx8fHx8fHx8fHx8fHx8fHwAAAAAAAAAAHx8fHx8fHx8fHx8fHx8fHwAAAAAAAAAAHx8fHx8fHx8fHx8fHx8fHwAAAAAAAAAAHx8fHx8fHx8fHx8fHx8fHwAAAAAAAAAAHx8fHx8fHx8fHx8fHx8fHwAAAAAAAAAA"
+   "patternData": "APFwHx8fHx8fHx8fHx8fHx8fHwAAAAAAAAAAHx8fHx8fHx8fHx8fHx8fHwAAAAAAAAAAHx8fHx8fHx8fHx8fHx8fHwAAAAAAAAAAHx8fHx8fHx8fHx8fHx8fHwAAAAAAAAAAHx8fHx8fHx8fHx8fHx8fHwAAAAAAAAAA",
+   "seam": [
+    1.0,
+    1.0
+   ],
+   "seamLabel": "Seamless"
   },
   {
    "name": "op:xor",
@@ -2097,7 +2347,12 @@
    "height": 30,
    "scale": 1,
    "ink": 440,
-   "patternData": "APFw4ODg4ODg4ODg4ODg4ODg4B8fHx8fHx8f4ODg4ODg4ODg4ODg4ODg4B8fHx8fHx8f4ODg4ODg4ODg4ODg4ODg4B8fHx8fHx8f4ODg4ODg4ODg4ODg4ODg4B8fHx8fHx8f4ODg4ODg4ODg4ODg4ODg4B8fHx8fHx8f"
+   "patternData": "APFw4ODg4ODg4ODg4ODg4ODg4B8fHx8fHx8f4ODg4ODg4ODg4ODg4ODg4B8fHx8fHx8f4ODg4ODg4ODg4ODg4ODg4B8fHx8fHx8f4ODg4ODg4ODg4ODg4ODg4B8fHx8fHx8f4ODg4ODg4ODg4ODg4ODg4B8fHx8fHx8f",
+   "seam": [
+    1.0,
+    1.0
+   ],
+   "seamLabel": "Seamless"
   },
   {
    "name": "op:subtract",
@@ -2134,7 +2389,12 @@
    "height": 30,
    "scale": 1,
    "ink": 200,
-   "patternData": "APFwAAAAAAAAAAAAAAAAAAAAAB8fHx8fHx8fAAAAAAAAAAAAAAAAAAAAAB8fHx8fHx8fAAAAAAAAAAAAAAAAAAAAAB8fHx8fHx8fAAAAAAAAAAAAAAAAAAAAAB8fHx8fHx8fAAAAAAAAAAAAAAAAAAAAAB8fHx8fHx8f"
+   "patternData": "APFwAAAAAAAAAAAAAAAAAAAAAB8fHx8fHx8fAAAAAAAAAAAAAAAAAAAAAB8fHx8fHx8fAAAAAAAAAAAAAAAAAAAAAB8fHx8fHx8fAAAAAAAAAAAAAAAAAAAAAB8fHx8fHx8fAAAAAAAAAAAAAAAAAAAAAB8fHx8fHx8f",
+   "seam": [
+    1.0,
+    1.0
+   ],
+   "seamLabel": "Seamless"
   },
   {
    "name": "post_mirrorX",
@@ -2163,7 +2423,12 @@
    "height": 30,
    "scale": 1,
    "ink": 540,
-   "patternData": "AOFwMMAAAx544MEPP_z4559_____PwwwwIAHHnjwww8__vnn3____w8DDDDggQce_PDDj3_--ff____DAAMMeOCBBz_88OOff_79____MMAAAx544MEPP_z4559_____PwwwwIAHHnjwww8__vnn3____w8"
+   "patternData": "AOFwMMAAAx544MEPP_z4559_____PwwwwIAHHnjwww8__vnn3____w8DDDDggQce_PDDj3_--ff____DAAMMeOCBBz_88OOff_79____MMAAAx544MEPP_z4559_____PwwwwIAHHnjwww8__vnn3____w8",
+   "seam": [
+    0.0,
+    1.0
+   ],
+   "seamLabel": "Seamless"
   },
   {
    "name": "post_mirrorY",
@@ -2192,7 +2457,12 @@
    "height": 30,
    "scale": 1,
    "ink": 540,
-   "patternData": "AOFw____v3_--ccPP_zggQceMMAAw____--ff_7xww8_eOCBBwwwwPD____7559__PDDDx544AEDDDD8_____vnnHz_88IMHHnjAAAMM____v3_--ccPP_zggQceMMAAw____--ff_7xww8_eOCBBwwwwAA"
+   "patternData": "AOFw____v3_--ccPP_zggQceMMAAw____--ff_7xww8_eOCBBwwwwPD____7559__PDDDx544AEDDDD8_____vnnHz_88IMHHnjAAAMM____v3_--ccPP_zggQceMMAAw____--ff_7xww8_eOCBBwwwwAA",
+   "seam": [
+    0.0,
+    1.0
+   ],
+   "seamLabel": "Seamless"
   },
   {
    "name": "post_both_mirrors",
@@ -2222,7 +2492,12 @@
    "height": 30,
    "scale": 1,
    "ink": 540,
-   "patternData": "AOFw____v3_--ccPP_zggQceMMAAw____--ff_7xww8_eOCBBwwwwPD____7559__PDDDx544AEDDDD8_____vnnHz_88IMHHnjAAAMM____v3_--ccPP_zggQceMMAAw____--ff_7xww8_eOCBBwwwwAA"
+   "patternData": "AOFw____v3_--ccPP_zggQceMMAAw____--ff_7xww8_eOCBBwwwwPD____7559__PDDDx544AEDDDD8_____vnnHz_88IMHHnjAAAMM____v3_--ccPP_zggQceMMAAw____--ff_7xww8_eOCBBwwwwAA",
+   "seam": [
+    0.0,
+    1.0
+   ],
+   "seamLabel": "Seamless"
   },
   {
    "name": "post_rot90",
@@ -2251,7 +2526,12 @@
    "height": 30,
    "scale": 1,
    "ink": 540,
-   "patternData": "AOFwIYQQwhhjjHHOOee89957___________ee--dc845Y4wxRgghhBBCCCGMMcYY55xzznvvvff_________77333jnnnDPGGGOEEEIIIYQQwhhjjHHOOee89957___________ee--dc845Y4wxRgghhAA"
+   "patternData": "AOFwIYQQwhhjjHHOOee89957___________ee--dc845Y4wxRgghhBBCCCGMMcYY55xzznvvvff_________77333jnnnDPGGGOEEEIIIYQQwhhjjHHOOee89957___________ee--dc845Y4wxRgghhAA",
+   "seam": [
+    1.0,
+    0.0
+   ],
+   "seamLabel": "Seamless"
   },
   {
    "name": "post_rot180",
@@ -2280,7 +2560,12 @@
    "height": 30,
    "scale": 1,
    "ink": 540,
-   "patternData": "AOFw____v3_--ccPP_zggQceMMAAw____--ff_7xww8_eOCBBwwwwPD____7559__PDDDx544AEDDDD8_____vnnHz_88IMHHnjAAAMM____v3_--ccPP_zggQceMMAAw____--ff_7xww8_eOCBBwwwwAA"
+   "patternData": "AOFw____v3_--ccPP_zggQceMMAAw____--ff_7xww8_eOCBBwwwwPD____7559__PDDDx544AEDDDD8_____vnnHz_88IMHHnjAAAMM____v3_--ccPP_zggQceMMAAw____--ff_7xww8_eOCBBwwwwAA",
+   "seam": [
+    0.0,
+    1.0
+   ],
+   "seamLabel": "Seamless"
   },
   {
    "name": "post_rot270",
@@ -2309,7 +2594,12 @@
    "height": 30,
    "scale": 1,
    "ink": 540,
-   "patternData": "AOFwEEIIIcYYY8w555x77733_________--9995zzjnnGGOMMYQQQgghhBBijDHGnHPOuffee___________3nvvPeecc44xxhhDCCGEEEIIIcYYY8w555x77733_________--9995zzjnnGGOMMYQQQgg"
+   "patternData": "AOFwEEIIIcYYY8w555x77733_________--9995zzjnnGGOMMYQQQgghhBBijDHGnHPOuffee___________3nvvPeecc44xxhhDCCGEEEIIIcYYY8w555x77733_________--9995zzjnnGGOMMYQQQgg",
+   "seam": [
+    1.0,
+    0.0
+   ],
+   "seamLabel": "Seamless"
   },
   {
    "name": "post_invert",
@@ -2338,7 +2628,12 @@
    "height": 30,
    "scale": 1,
    "ink": 360,
-   "patternData": "AOFwzz___OGHHz7wwAMHGGCAAAAAwPPPP3_44YcPPPDAAQYYIAAAAPD8888ffvjhAw88cIABBggAAAA8__zzhx9--MADDxxggAECAAAAzz___OGHHz7wwAMHGGCAAAAAwPPPP3_44YcPPPDAAQYYIAAAAAA"
+   "patternData": "AOFwzz___OGHHz7wwAMHGGCAAAAAwPPPP3_44YcPPPDAAQYYIAAAAPD8888ffvjhAw88cIABBggAAAA8__zzhx9--MADDxxggAECAAAAzz___OGHHz7wwAMHGGCAAAAAwPPPP3_44YcPPPDAAQYYIAAAAAA",
+   "seam": [
+    0.0,
+    1.0
+   ],
+   "seamLabel": "Seamless"
   },
   {
    "name": "post_rot90_invert",
@@ -2368,7 +2663,12 @@
    "height": 30,
    "scale": 1,
    "ink": 360,
-   "patternData": "AOFw3nvvPeecc44xxhhDCCGEAAAAAAAAAAAhhBBijDHGnHPOuffee--9995zzjnnGGOMMYQQQggAAAAAAAAAEEIIIcYYY8w555x777333nvvPeecc44xxhhDCCGEAAAAAAAAAAAhhBBijDHGnHPOuffeew8"
+   "patternData": "AOFw3nvvPeecc44xxhhDCCGEAAAAAAAAAAAhhBBijDHGnHPOuffee--9995zzjnnGGOMMYQQQggAAAAAAAAAEEIIIcYYY8w555x777333nvvPeecc44xxhhDCCGEAAAAAAAAAAAhhBBijDHGnHPOuffeew8",
+   "seam": [
+    1.0,
+    0.0
+   ],
+   "seamLabel": "Seamless"
   },
   {
    "name": "canvas:fixed",
@@ -2397,7 +2697,12 @@
    "height": 17,
    "scale": 3,
    "ink": 168,
-   "patternData": "AKs8h8Nhh8Mhh8MBh8MBh8MJh8MNh8MPh8MOh0MOhwMOhwMOhxMOhxsOhx8Ohx0OhxwOBw"
+   "patternData": "AKs8h8Nhh8Mhh8MBh8MBh8MJh8MNh8MPh8MOh0MOhwMOhwMOhxMOhxsOhx8Ohx0OhxwOBw",
+   "seam": [
+    3.0,
+    3.0
+   ],
+   "seamLabel": "Visible seam"
   },
   {
    "name": "canvas:limits",
@@ -2424,7 +2729,12 @@
    "height": 65,
    "scale": 0,
    "ink": 4192,
-   "patternData": "APj_qqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqgA"
+   "patternData": "APj_qqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqgA",
+   "seam": [
+    3.0,
+    3.0
+   ],
+   "seamLabel": "Visible seam"
   }
  ]
 }
diff --git a/tools/gen-dsl-fixtures.py b/tools/gen-dsl-fixtures.py
index 9249c02..d9ba4a9 100644
--- a/tools/gen-dsl-fixtures.py
+++ b/tools/gen-dsl-fixtures.py
@@ -43,6 +43,7 @@
 OUT = os.path.join(ROOT, "tests", "fixtures", "dsl.json")
 
 from dsl_prototype import (encode, render, tiles_exactly,     # noqa: E402
+                           seam_scores, seam_label,
                            FONT_5X7, FONT_3X5)
 from dsl_demo import GALLERY                                  # noqa: E402
 
@@ -134,6 +135,7 @@ def main() -> int:
         ok, _px, _py = tiles_exactly(program, w, h)
         if program.get("canvas", {}).get("autoSize", True) and not ok:
             tiling_failures.append(name)
+        sh, sv = seam_scores(w, h, buf)
         built.append({
             "name": name,
             "program": program,
@@ -142,6 +144,11 @@ def main() -> int:
             "scale": scale,
             "ink": sum(buf),
             "patternData": data,
+            # The seam metric, which an earlier revision got wrong for 17 of 28
+            # correctly-tiling patterns. Pinning the scores as well as the label
+            # means a port that lands on the right verdict by luck still fails.
+            "seam": [sh, sv],
+            "seamLabel": seam_label(sh, sv),
         })
 
     if tiling_failures:
diff --git a/tools/verify-dsl.js b/tools/verify-dsl.js
index c233627..14987e8 100644
--- a/tools/verify-dsl.js
+++ b/tools/verify-dsl.js
@@ -63,6 +63,13 @@ vm.runInContext([
   grabFunction(js, 'dslValidate'),
   grabFunction(js, 'dslSize'),
   grabFunction(js, 'dslRender'),
+  grabConst(js, 'PERIODIC_EPS'),
+  grabFunction(js, 'percentile'),
+  grabFunction(js, 'dominantPeriod'),
+  grabFunction(js, 'toroidalError'),
+  grabFunction(js, 'rhythmPenalty'),
+  grabFunction(js, 'seamScores'),
+  grabFunction(js, 'seamLabel'),
 ].join('\n'), ctx);
 
 /** A multi-line `const NAME={...};` — grabConst only handles single lines. */
@@ -77,6 +84,8 @@ function grabMulti(name) {
 const dslRender = vm.runInContext('dslRender', ctx);
 const encodeOF = vm.runInContext('encodeOF', ctx);
 const pyRound = vm.runInContext('pyRound', ctx);
+const seamScores = vm.runInContext('seamScores', ctx);
+const seamLabel = vm.runInContext('seamLabel', ctx);
 
 const corpus = JSON.parse(fs.readFileSync(FIXTURES, 'utf8'));
 const failures = [];
@@ -105,6 +114,7 @@ for (const [input, want] of [[0.5, 0], [1.5, 2], [2.5, 2], [3.5, 4], [-2.5, -2],
 }
 
 const primitives = new Set();
+const labels = new Set();
 for (const c of corpus.cases) {
   let got;
   try { got = dslRender(c.program); }
@@ -125,12 +135,24 @@ for (const c of corpus.cases) {
                 + `(${data.length} vs ${c.patternData.length} chars)`);
     continue;
   }
+  const [sh, sv] = seamScores(got.w, got.h, got.bits);
+  if (Math.abs(sh - c.seam[0]) > 1e-9 || Math.abs(sv - c.seam[1]) > 1e-9) {
+    failures.push(`${c.name}: seam scores ${sh.toFixed(4)}/${sv.toFixed(4)}, `
+                + `oracle says ${c.seam[0].toFixed(4)}/${c.seam[1].toFixed(4)}`);
+    continue;
+  }
+  if (seamLabel(sh, sv) !== c.seamLabel) {
+    failures.push(`${c.name}: seam label ${seamLabel(sh, sv)}, oracle says ${c.seamLabel}`);
+    continue;
+  }
+  labels.add(c.seamLabel);
   for (const l of c.program.layers) primitives.add(l.shape.type);
 }
 
 console.log(`${corpus.cases.length} programs through the editor's own DSL`);
 console.log(`  ${primitives.size} primitives exercised, `
           + `every result compared as encoded patternData`);
+console.log(`  seam scores match to 1e-9; verdicts seen: ${[...labels].sort().join(', ')}`);
 
 if (failures.length) {
   console.log(`\n*** ${failures.length} FAILURE(S) ***`);