"Doesn't connect" marks on transport ends that would join one block off (t67 phase 4)

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/ui/info.js

@@ -132,6 +132,11 @@ function hoverInfo(ax, ay) {
     if (b === BP_OUTLET) t2.push(v & 4 ? 'closed · press F' : 'open · F closes it');
   }
   else if (isWall(b) && PH[m] === PH_SOLID && !(flags[i] & F_NAT)) t1 = `${MD[m].name} ${isSlope(b) ? 'sloped wall' : 'block'}`;
+  const jb = ((ay / BS) | 0) * BW + ((ax / BS) | 0);
+  for (let end = 0; end < 2 && !id && !bar; end++) {
+    const miss = nearMiss(jb % BW, (jb / BW) | 0, end);
+    if (miss) { t2.push(`doesn't connect: place it one block ${miss < 0 ? 'higher' : 'lower'}`); warn = warn || "doesn't connect"; break; }
+  }
   const n = nets[netId[i]];
   if (n && isPow[i] && !POWER_FREE) t2.push(`network ${n.supply.toFixed(1)} supply / ${n.demand.toFixed(1)} demand`);
   if (player.lens && !bar) t2.push(fmtT(temp[i]));

src/ui/loop.js

@@ -71,6 +71,7 @@ function frame(now) {
   const hb = GAME.mouse.in || GAME.usingPad ? filterBlockAt(Math.floor(GAME.aim.x), Math.floor(GAME.aim.y)) : -1;
   if (GAME.editRun) drawRunOutline(GAME.editRun, true); else if (hb >= 0) drawRunOutline(filterRun(hb), false);
   if (GAME.infoOverlay) drawFlowArrows();
+  drawJoinMarks();
   drawFilterTags(!!GAME.infoOverlay, GAME.editRun ? GAME.editRun[0] : hb);
   drawFloaters();
   drawRain();

src/ui/previews.js

@@ -129,6 +129,9 @@ function drawPreviews() {
           chev(); ctx.strokeStyle = 'rgba(255,224,160,0.98)'; ctx.lineWidth = Math.max(1.2, zp * 0.45); chev();
         }
       }
+      // ends of the line that would join one block up or down get the "doesn't connect" mark
+      for (const [bx, by] of cells.length > 1 ? [cells[0], cells[cells.length - 1]] : cells)
+        for (let end = 0; end < 2; end++) if (nearMiss(bx, by, end, planned)) drawJoinMark(bx, by, end, code, v);
       if (GAME.drag && cells.length > 1) {
         const label = `${cells.length} × ${costText(pieceCostNow(P), 1)}`;
         ctx.font = `600 12px ui-monospace, monospace`; ctx.fillStyle = 'rgba(14,12,11,0.85)';