AdaWorldAPI · AdaWorldAPI · Jul 10, 2026 · Jul 10, 2026 · Jul 10, 2026
diff --git a/claude-notes/plans/2026-07-10-garmin-dem-satellite-skin.md b/claude-notes/plans/2026-07-10-garmin-dem-satellite-skin.md
@@ -80,3 +80,20 @@ the render on mobile; the full grid is the desktop birdview.
   both reuse the DEM+skin pipeline; Havel is flat lowland → skin-dominant.
 - **Sentinel-2 skin** — swap the ESRI source for `GrandCanyon_S2_20260620.tif`
   (source-agnostic; the skin just comes from the demgrid rgb).
+
+## /osm dual basemap (2026-07-10, follow-up shipped)
+- The `/osm` slippy cockpit gets a **basemap toggle**: OSM map ↔ ESRI World Imagery
+  satellite — the SAME keyless imagery the ver-9 terrain skins drape from, so the flat
+  map and the 3D scenes share one imagery truth. Same tile addresses, same HHTL keys —
+  two skins.
+- Server (`osm_tiles.rs`): `SAT_TILE_URL` + `sat_tile_url()` (ESRI is **z/y/x** — row
+  before column; the shared `fill_template` encodes the swap), both locate/tile-meta
+  responses now report `sat_tile_url`/`sat_source` (additive JSON). Test asserts the
+  axis order.
+- Page (`osm.rs`): `BASEMAPS` table (src template + attribution + next), `sat`/`osm`
+  toggle button in the map controls, attribution swaps with the source (OSM
+  contributors ↔ Esri/Maxar/Earthstar).
+- Verified headless on the extracted page: toggle OSM→sat→OSM, srcs swap with the
+  z/y/x order CORRECT, attribution follows. cockpit-server itself cannot compile in
+  this container (rusty_v8 static-lib download blocked by egress policy) — Rust side
+  mirrors the existing tested pattern; CI runs the tests.
diff --git a/crates/cockpit-server/src/osm.rs b/crates/cockpit-server/src/osm.rs
@@ -57,9 +57,9 @@ const PAGE: &str = r##"<!doctype html>
 <div id="app">
   <div id="map">
     <div id="tiles"></div>
-    <div class="ctl"><button id="zin">+</button><button id="zout">−</button></div>
+    <div class="ctl"><button id="zin">+</button><button id="zout">−</button><button id="base" title="basemap: OSM map ↔ ESRI satellite (same tiles, same HHTL address — two skins)" style="width:auto;padding:0 8px;font-size:12px">sat</button></div>
     <div class="hint">drag to pan · click a point for its HHTL key</div>
-    <div class="attr">© <a href="https://www.openstreetmap.org/copyright">OpenStreetMap</a> contributors</div>
+    <div class="attr" id="attr">© <a href="https://www.openstreetmap.org/copyright">OpenStreetMap</a> contributors</div>
   </div>
   <div id="panel">
     <h1>OSM cockpit</h1>
@@ -91,6 +91,19 @@ const map=document.getElementById('map'), tilesEl=document.getElementById('tiles
 let z=12;                       // Berlin-ish default view
 let cx=lon2x(13.404954,z), cy=lat2y(52.520008,z);  // center in fractional tile units
 
+// ── dual map: OSM (z/x/y) ↔ ESRI World Imagery satellite (z/y/x — row first!).
+// Same slippy addresses, same HHTL keys — two skins. Mirrors cockpit-server::
+// osm_tiles::{OSM_TILE_URL, SAT_TILE_URL}; the locate API reports both URLs.
+const BASEMAPS={
+  osm:{ src:(z,x,y)=>`https://tile.openstreetmap.org/${z}/${x}/${y}.png`,
+        attr:'© <a href="https://www.openstreetmap.org/copyright">OpenStreetMap</a> contributors',
+        next:'sat' },
+  sat:{ src:(z,x,y)=>`https://server.arcgisonline.com/ArcGIS/rest/services/World_Imagery/MapServer/tile/${z}/${y}/${x}`,
+        attr:'Powered by <a href="https://www.esri.com/">Esri</a> — Source: Esri, Maxar, Earthstar Geographics',
+        next:'osm' },
+};
+let basemap='osm';
+
 function render(){
   const w=map.clientWidth, h=map.clientHeight, n=Math.pow(2,z);
   tilesEl.innerHTML='';
@@ -99,10 +112,11 @@ function render(){
   tilesEl.style.transform=`translate(${ox}px,${oy}px)`;
   const x0=Math.floor(cx - w/512)-1, x1=Math.floor(cx + w/512)+1;
   const y0=Math.floor(cy - h/512)-1, y1=Math.floor(cy + h/512)+1;
+  const bm=BASEMAPS[basemap];
   for(let ty=y0;ty<=y1;ty++) for(let tx=x0;tx<=x1;tx++){
     const wx=((tx%n)+n)%n; if(ty<0||ty>=n) continue;
     const img=new Image();
-    img.src=`https://tile.openstreetmap.org/${z}/${wx}/${ty}.png`;
+    img.src=bm.src(z,wx,ty);
     img.style.left=(tx*256)+'px'; img.style.top=(ty*256)+'px';
     tilesEl.appendChild(img);
   }
@@ -123,6 +137,13 @@ function zoom(d){ const nz=Math.max(0,Math.min(19,z+d)); if(nz===z) return;
   const f=Math.pow(2,nz-z); cx*=f; cy*=f; z=nz; render(); }
 document.getElementById('zin').onclick=e=>{ e.stopPropagation(); zoom(1); };
 document.getElementById('zout').onclick=e=>{ e.stopPropagation(); zoom(-1); };
+// basemap toggle — the button names the OTHER skin (what you'll switch TO);
+// attribution follows the active source (OSM contributors ↔ Esri).
+document.getElementById('base').onclick=e=>{ e.stopPropagation();
+  basemap=BASEMAPS[basemap].next;
+  e.target.textContent=BASEMAPS[basemap].next;
+  document.getElementById('attr').innerHTML=BASEMAPS[basemap].attr;
+  render(); };
 map.addEventListener('wheel',e=>{ e.preventDefault(); zoom(e.deltaY<0?1:-1); },{passive:false});
 
 // ── click → server-side HHTL key ──
@@ -144,7 +165,9 @@ map.addEventListener('click',async e=>{
     document.getElementById('heel').textContent='0x'+d.hhtl.heel.toString(16).padStart(4,'0');
     document.getElementById('hip').textContent='0x'+d.hhtl.hip.toString(16).padStart(4,'0');
     document.getElementById('twig').textContent='0x'+d.hhtl.twig.toString(16).padStart(4,'0');
-    document.getElementById('src').textContent=d.tile_url;
+    // tile source follows the ACTIVE basemap (the locate API reports both URLs) —
+    // on satellite, showing the OSM URL would mismatch the visible tiles.
+    document.getElementById('src').textContent=basemap==='sat'?d.sat_tile_url:d.tile_url;
   }catch(err){ document.getElementById('src').textContent='locate failed: '+err; }
 });
 

diff --git a/crates/cockpit-server/src/osm_tiles.rs b/crates/cockpit-server/src/osm_tiles.rs
@@ -27,18 +27,40 @@ use std::f64::consts::PI;
 /// by the client; the cockpit only computes the address.
 pub const OSM_TILE_URL: &str = "https://tile.openstreetmap.org/{z}/{x}/{y}.png";
 
+/// The satellite basemap source — ESRI World Imagery, the SAME keyless slippy
+/// grid the DEM/skin bakes drape from (`scripts/fetch_iceland_dem.py`), so the
+/// dual map (OSM ↔ satellite) and the ver-9 terrain skins share one imagery
+/// truth. NOTE the path order: ESRI is **z/y/x** (row before column), unlike
+/// the OSM z/x/y — the template placeholders encode that swap.
+pub const SAT_TILE_URL: &str =
+    "https://server.arcgisonline.com/ArcGIS/rest/services/World_Imagery/MapServer/tile/{z}/{y}/{x}";
+
 /// Native HHTL depth: 3 tiers × 8 levels = 24 quadtree levels (zoom 0..=24).
 pub const HHTL_DEPTH: u32 = 24;
 
-/// The concrete tile-source URL for a `z/x/y` address.
-#[must_use]
-pub fn tile_url(z: u32, x: u32, y: u32) -> String {
-    OSM_TILE_URL
+/// Fill a slippy-tile URL template (`{z}`/`{x}`/`{y}`) for an address. The
+/// template carries the axis order, so OSM (z/x/y) and ESRI (z/y/x) both fill
+/// correctly through the same call.
+fn fill_template(template: &str, z: u32, x: u32, y: u32) -> String {
+    template
         .replace("{z}", &z.to_string())
         .replace("{x}", &x.to_string())
         .replace("{y}", &y.to_string())
 }
 
+/// The concrete OSM tile-source URL for a `z/x/y` address.
+#[must_use]
+pub fn tile_url(z: u32, x: u32, y: u32) -> String {
+    fill_template(OSM_TILE_URL, z, x, y)
+}
+
+/// The concrete SATELLITE (ESRI World Imagery) tile URL for the same `z/x/y`
+/// address — the dual-map partner of [`tile_url`].
+#[must_use]
+pub fn sat_tile_url(z: u32, x: u32, y: u32) -> String {
+    fill_template(SAT_TILE_URL, z, x, y)
+}
+
 /// WebMercator (EPSG:3857) forward: geographic `(lon, lat)` → slippy tile
 /// `(x, y)` at zoom `z`. `x` grows east, `y` grows south (TMS-flipped is the
 /// caller's concern). Clamped to the valid `0..2^z` range.
@@ -151,6 +173,10 @@ pub async fn osm_locate_handler(Query(q): Query<LocateQuery>) -> Json<serde_json
         "lon": q.lon, "lat": q.lat, "z": z, "x": x, "y": y,
         "tile_url": tile_url(z, x, y),
         "source": OSM_TILE_URL,
+        // Dual map: the SAME address on the satellite basemap (ESRI World
+        // Imagery, z/y/x) — one HHTL key, two skins.
+        "sat_tile_url": sat_tile_url(z, x, y),
+        "sat_source": SAT_TILE_URL,
         "hhtl": hhtl,
         "geo_domain": "0x0F",
     }))
@@ -169,6 +195,8 @@ pub async fn osm_tile_meta_handler(
         "z": z, "x": x, "y": y,
         "tile_url": tile_url(z, x, y),
         "source": OSM_TILE_URL,
+        "sat_tile_url": sat_tile_url(z, x, y),
+        "sat_source": SAT_TILE_URL,
         "hhtl": hhtl,
         "resolved": { "z": rz, "x": rx, "y": ry },
         "geo_domain": "0x0F",
@@ -187,6 +215,16 @@ mod tests {
         );
     }
 
+    #[test]
+    fn sat_tile_url_swaps_to_esri_z_y_x_order() {
+        // Same address, satellite skin — and the ESRI path is z/y/x (row before
+        // column), the classic trap the template encodes: y=5677 precedes x=8749.
+        assert_eq!(
+            sat_tile_url(14, 8749, 5677),
+            "https://server.arcgisonline.com/ArcGIS/rest/services/World_Imagery/MapServer/tile/14/5677/8749"
+        );
+    }
+
     #[test]
     fn null_island_is_the_center_tile() {
         // lon=0, lat=0 at z=1 → the 2×2 grid's (1,1) corner (center of the world).