1{2 "family": "surface",3 "about": "What the ground is, before any cell is named: the surface extent every system divides, and which systems are willing to divide it. The three surfaceExtent branches — a declared lens surface, a raster window, neither — are the whole of the fallback ladder.",4 "cases": [5 {6 "name": "extent-from-lens-surface",7 "ground": "test/square-1024",8 "call": "surfaceExtent",9 "args": [],10 "expect": [11 0,12 -1024,13 1024,14 015 ],16 "handDerived": true17 },18 {19 "name": "extent-from-lens-bounds",20 "ground": "test/square-1024-bounds",21 "call": "surfaceExtent",22 "args": [],23 "expect": [24 128,25 -512,26 640,27 -25628 ],29 "handDerived": true30 },31 {32 "name": "extent-from-world-square",33 "ground": "test/square-1024-no-lens",34 "call": "surfaceExtent",35 "args": [],36 "expect": [37 0,38 -1024,39 1024,40 041 ],42 "handDerived": true43 },44 {45 "name": "extent-sphere",46 "ground": "test/sphere-8192x4096",47 "call": "surfaceExtent",48 "args": [],49 "expect": [50 0,51 -4096,52 8192,53 054 ]55 },56 {57 "name": "systems-on-a-plane",58 "ground": "test/square-1024",59 "call": "applicableSystems",60 "args": [],61 "expect": [62 "geohash"63 ],64 "note": "S2 only divides a map that declares what its picture is of; geohash divides anything.",65 "handDerived": true66 },67 {68 "name": "systems-on-a-sphere",69 "ground": "test/sphere-8192x4096",70 "call": "applicableSystems",71 "args": [],72 "expect": [73 "geohash",74 "s2"75 ],76 "handDerived": true77 },78 {79 "name": "geohash-applies-to-a-plane",80 "ground": "test/square-1024",81 "system": "geohash",82 "call": "appliesTo",83 "args": [],84 "expect": true,85 "handDerived": true86 },87 {88 "name": "s2-refuses-a-plane",89 "ground": "test/square-1024",90 "system": "s2",91 "call": "appliesTo",92 "args": [],93 "expect": false,94 "handDerived": true95 },96 {97 "name": "s2-applies-to-a-sphere",98 "ground": "test/sphere-8192x4096",99 "system": "s2",100 "call": "appliesTo",101 "args": [],102 "expect": true,103 "handDerived": true104 },105 {106 "name": "geohash-max-level",107 "ground": "test/sphere-8192x4096",108 "system": "geohash",109 "call": "maxLevel",110 "args": [],111 "expect": 3,112 "handDerived": true113 },114 {115 "name": "geohash-input-length",116 "ground": "test/sphere-8192x4096",117 "system": "geohash",118 "call": "inputLength",119 "args": [],120 "expect": 3,121 "handDerived": true122 },123 {124 "name": "s2-max-level",125 "ground": "test/sphere-8192x4096",126 "system": "s2",127 "call": "maxLevel",128 "args": [],129 "expect": 11,130 "note": "Port levels count the root as 0 and the six faces as 1, so the S2 level-10 floor is port level 11.",131 "handDerived": true132 },133 {134 "name": "s2-input-length",135 "ground": "test/sphere-8192x4096",136 "system": "s2",137 "call": "inputLength",138 "args": [],139 "expect": 6,140 "handDerived": true141 },142 {143 "name": "geohash-applies-to-the-anchored-city",144 "ground": "bend-or/2026-08-02/0",145 "system": "geohash",146 "call": "appliesTo",147 "args": [],148 "expect": true,149 "note": "Geohash divides anything; here it divides it for REAL — the plane declares an earth Mercator window, so its hashes are genuine WGS84 addresses.",150 "handDerived": true151 },152 {153 "name": "s2-still-refuses-the-anchored-city",154 "ground": "bend-or/2026-08-02/0",155 "system": "s2",156 "call": "appliesTo",157 "args": [],158 "expect": false,159 "note": "The earth anchoring changes nothing for S2: the surface says plane, and S2 divides only spheres.",160 "handDerived": true161 },162 {163 "name": "systems-on-the-anchored-city",164 "ground": "bend-or/2026-08-02/0",165 "call": "applicableSystems",166 "args": [],167 "expect": [168 "geohash"169 ],170 "handDerived": true171 },172 {173 "name": "geohash-max-level-on-the-anchored-city",174 "ground": "bend-or/2026-08-02/0",175 "system": "geohash",176 "call": "maxLevel",177 "args": [],178 "expect": 3,179 "note": "Three layers of precision on every ground; only where the layers START moves.",180 "handDerived": true181 },182 {183 "name": "geohash-input-length-on-the-anchored-city",184 "ground": "bend-or/2026-08-02/0",185 "system": "geohash",186 "call": "inputLength",187 "args": [],188 "expect": 6,189 "note": "The ground-aware floor: baseDepth 4 (the smallest depth whose cell spans fit the window's 0.32909 by 0.23650 degrees — depth 4's latitude span 0.17578125 fits where its longitude span 0.3515625 misses) plus the two layers under it. The navigator's maxlength follows this number.",190 "handDerived": true191 }192 ]193}