v0.4.8 — the Limits bound the whole district, the nine spots really are nine, and an action points at its square

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01YQAJ4dND7enLj54eLyiF2C

src/engine/apply.ts

@@ -77,6 +77,7 @@ import {
   opposite,
   reachableDestinations,
   variantsFor,
+  withinLimits,
 } from './track.ts';
 
 export type ApplyResult =
@@ -1105,6 +1106,9 @@ function checkPlay(
         if (placement.row === area.runningRow && !carriesThroughTrack(proto)) {
           return 'BREAKS_RUNNING_TRACK';
         }
+        // Same reasoning: a siding reaching past your own sign JOINS perfectly well, and is refused
+        // because it leaves your territory (§2.1). `canPlaceAt` enforces it too — this only names it.
+        if (!withinLimits(area, placement)) return 'OUTSIDE_LIMITS';
         return canPlaceAt(area, placement, proto) ? null : 'NOT_CONNECTED';
       }
 
@@ -1123,6 +1127,10 @@ function checkPlay(
        * main line.
        */
       if (placement.row === area.runningRow) return 'ON_RUNNING_TRACK';
+      // A Facility CARRIES TRACK — "placing a Facility places track" (§11.2) — so it is bounded by
+      // the Limits exactly as a siding is. An industry outside them is how a district used to leave
+      // its own territory.
+      if (!withinLimits(area, placement)) return 'OUTSIDE_LIMITS';
       // Q4 — a lockout prevents BUILDING both in one district: no duplicate, and never a producer
       // alongside the consumer of the same commodity.
       if (isLockedOut(area, card.kind.facility)) return 'FACILITY_LOCKED';
@@ -1133,6 +1141,18 @@ function checkPlay(
     case 'modifier': {
       if (!placement) return 'NO_PLACEMENT';
       if (area.grid.has(coordKey(placement))) return 'NOT_CONNECTED';
+      /**
+       * NOT ON THE RUNNING TRACK ROW — AND NOT BOUNDED BY THE LIMITS EITHER. Jesse's call, both
+       * halves.
+       *
+       * A Modifier is not track (§9), so unlike a siding it may hang outside the Limits: a Facility
+       * standing at the limit has three of its nine spots out there, and refusing them would make
+       * the card unplayable exactly where the district ends. What it may NOT do is stand in the row
+       * the Running Track grows along. Inside the Limits that row is always full, so this bites only
+       * beyond the sign — which is the ground the main extends onto, and a Modifier parked there
+       * would block your own sign from moving outward (§2.1) with nothing on screen to warn you.
+       */
+      if (placement.row === area.runningRow) return 'ON_RUNNING_TRACK';
       // One of a kind per Office Area, as with industries (Q4) — no district gets two Ice Houses.
       if (hasModifierInArea(area, card.kind.modifier)) return 'FACILITY_LOCKED';
       // §9 — a Modifier is not track. It must sit adjacent to a Facility THAT CAN HOST IT (one of