No placebo buttons: accept-overhang only offered when it would help

Eric clicked accept-overhang on two boxes in a Kallax cube and got an
"overhang ✓" pill with no lane behind it. The cube's flat pile claims
11.7 of 13.25 inches of width, leaving 1.55 inches of standing lane —
acknowledging waives depth and height, never width, so nothing changed.
That opening is overfull, not overhung, and the button was a placebo.

The sheet now probes before offering: a laneless resident gets the
accept button only when acknowledging would actually land it a lane;
otherwise it's marked "no room" with the honest tooltip. Acknowledged
boxes that DID land show "▮ standing, proud" (their lane isn't
flippable — proud of the shelf is the whole point), plus the
retractable "overhang ✓". Verified against the live wall: the three
Etherfields monoliths on the tower's big row read standing-proud, the
squeezed cube residents read no-room, zero page errors.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_016jXZFSTZQKzAC8fqpWSz9g

data/locations.json

@@ -84,6 +84,7 @@
     "opening_id": "library-kallax-c4"
   },
   "157969:237864": {
+    "acknowledged": true,
     "note": "",
     "opening_id": "library-kallax-b1"
   },
@@ -108,6 +109,7 @@
     "opening_id": "library-kallax-c4"
   },
   "166109:253058": {
+    "acknowledged": true,
     "note": "",
     "opening_id": "library-kallax-b1"
   },
@@ -151,6 +153,10 @@
     "note": "",
     "opening_id": "library-kallax-d2"
   },
+  "1784:110926": {
+    "note": "",
+    "opening_id": "library-right-shelving-2-d1"
+  },
   "181304:536289": {
     "note": "",
     "opening_id": "library-kallax-b1"
@@ -263,6 +269,10 @@
     "note": "",
     "opening_id": "library-kallax-b3"
   },
+  "258849:449806": {
+    "note": "",
+    "opening_id": "library-right-shelving-2-d1"
+  },
   "258:20840": {
     "note": "",
     "opening_id": "library-kallax-b3"
@@ -284,8 +294,9 @@
     "opening_id": "library-kallax-c2"
   },
   "280794:458300": {
+    "acknowledged": true,
     "note": "",
-    "opening_id": "library-kallax-d3"
+    "opening_id": "library-right-shelving-e1"
   },
   "283155:462049": {
     "note": "",
@@ -295,6 +306,19 @@
     "note": "",
     "opening_id": "library-kallax-d4"
   },
+  "290840:474978": {
+    "note": "",
+    "opening_id": "library-right-shelving-e1"
+  },
+  "291130:475387": {
+    "acknowledged": true,
+    "note": "",
+    "opening_id": "library-right-shelving-e1"
+  },
+  "291131:475388": {
+    "note": "",
+    "opening_id": "library-right-shelving-e1"
+  },
   "291457:476060": {
     "note": "",
     "opening_id": "library-kallax-d3"
@@ -311,6 +335,10 @@
     "note": "",
     "opening_id": "library-kallax-c2"
   },
+  "311654": {
+    "note": "",
+    "opening_id": "library-right-shelving-2-d1"
+  },
   "31260:297589": {
     "note": "",
     "opening_id": "library-kallax-d3"
@@ -351,6 +379,11 @@
     "note": "",
     "opening_id": "library-kallax-b2"
   },
+  "351544:588185": {
+    "acknowledged": true,
+    "note": "",
+    "opening_id": "library-right-shelving-e1"
+  },
   "352819:591147": {
     "note": "",
     "opening_id": "library-kallax-d1"
@@ -369,12 +402,16 @@
   },
   "358880:603694": {
     "note": "",
-    "opening_id": "library-kallax-d3"
+    "opening_id": "library-right-shelving-e1"
   },
   "362205:612448": {
     "note": "",
     "opening_id": "library-kallax-d4"
   },
+  "380459:743266": {
+    "note": "",
+    "opening_id": "library-right-shelving-2-d1"
+  },
   "380837:650545": {
     "note": "",
     "opening_id": "library-kallax-c1"