diff --git a/internal/check-nested-token-delivery.mjs b/internal/check-nested-token-delivery.mjs
index 94bc4b362..acbeddbf9 100644
--- a/internal/check-nested-token-delivery.mjs
+++ b/internal/check-nested-token-delivery.mjs
@@ -97,6 +97,16 @@ if (leaves.length < MIN_LEAVES) {
   process.exit(1)
 }
 
+// ★ THE AUTO CONTRACT (2026-09-26, by project decision: no Mapbox token in the public repo). With the
+// build config's "token" EMPTY — the shipped default — a leaf must carry NO token, and must instead carry
+// the runtime engine ladder (EXPLICIT / HAS_TOKEN): with no token it draws MapLibre, keyless; with one
+// from the host, ?tk=, a paste or a token service, Mapbox. A builder who opts into baking a token
+// ("token": "pk.…" in their own config) gets the original check: every leaf carries it.
+let bakedToken = ''
+try { bakedToken = String(JSON.parse(readFileSync(join(ROOT, 'vite.doxa-maps-build-config.json'), 'utf8')).token || '') } catch { /* none */ }
+const BAKED = TOKEN_RE.test(bakedToken)
+const AUTO_RE = /var EXPLICIT = [^;]*;[\s\S]*?var HAS_TOKEN = /
+
 const missing = []
 let checked = 0
 for (const leaf of leaves) {
@@ -108,9 +118,15 @@ for (const leaf of leaves) {
   }
   checked++
   const html = readFileSync(abs, 'utf8')
-  if (!TOKEN_RE.test(html)) {
+  if (BAKED && !TOKEN_RE.test(html)) {
     missing.push({ ...leaf, why: 'no pk. token baked into the leaf — a nested map here would get NOTHING' })
   }
+  if (!BAKED && TOKEN_RE.test(html)) {
+    missing.push({ ...leaf, why: 'a pk. token is in the leaf, but the build config bakes none — a token leaked into public output' })
+  }
+  if (!BAKED && !AUTO_RE.test(html)) {
+    missing.push({ ...leaf, why: 'no runtime engine ladder (EXPLICIT/HAS_TOKEN) — with no token this leaf cannot fall back to MapLibre' })
+  }
 }
 
 // The other direction: a token must never be compiled into a .js bundle.
@@ -127,7 +143,7 @@ console.log(`NESTED-TOKEN: ${checked} shipped leaf page(s) checked, ${(manifest.
 
 if (missing.length || inBundles.length) {
   if (missing.length) {
-    console.error(`\nNESTED-TOKEN: FAIL — ${missing.length} leaf page(s) ship without a token:`)
+    console.error(`\nNESTED-TOKEN: FAIL — ${missing.length} leaf page(s) break the token contract (${BAKED ? 'baked token' : 'auto, no token'}):`)
     for (const m of missing.slice(0, 20)) console.error(`  ✗ ${m.bundle}/${m.profile}\n      ${m.url}\n      ${m.why}`)
     if (missing.length > 20) console.error(`  … +${missing.length - 20} more`)
     console.error(
@@ -151,6 +167,7 @@ if (missing.length || inBundles.length) {
 }
 
 console.log(`NESTED-TOKEN: tree public/${treeName}/ (name from ${treeNameSource}).`)
-console.log('NESTED-TOKEN: PASS — every shipped leaf carries its own token, and no bundle does.')
+console.log(BAKED ? 'NESTED-TOKEN: PASS — every shipped leaf carries its own token, and no bundle does.'
+  : 'NESTED-TOKEN: PASS (auto) — no leaf or bundle carries a token, and every leaf picks its engine at runtime (MapLibre keyless without one).')
 console.log('  This is DELIVERY only. It does not prove a basemap paints: that needs a real GPU and')
 console.log('  a token whose URL restrictions allow the serving host (see verify:map-paint).')
diff --git a/internal/check-provider-switch.mjs b/internal/check-provider-switch.mjs
index 686252160..270a62945 100644
--- a/internal/check-provider-switch.mjs
+++ b/internal/check-provider-switch.mjs
@@ -78,9 +78,17 @@ let OWN_SERVER = null
   }
 }
 
-async function run(provider) {
+// A well-formed FAKE public token (never a real one): enough for the Mapbox engine to start and make its
+// requests, which is all the comparison run needs. Requests that carry it are aborted, never sent.
+const FAKE_TK = ['pk', Buffer.from(JSON.stringify({ u: 'provider-switch-check' })).toString('base64url'), 'c2ln'].join('.')
+
+async function run(provider, token = '') {
   const b = await chromium.launch({ args: ['--use-gl=swiftshader', '--enable-unsafe-swiftshader'] })
   const pg = await b.newPage({ viewport: { width: 1280, height: 900 } })
+  if (token) {
+    await pg.addInitScript((tk) => { window.MAP_TOKEN = tk }, token)
+    await pg.route((u) => /(^|\.)mapbox\.com$/i.test(u.hostname) && u.searchParams.has('access_token'), (r) => r.abort())
+  }
   const hosts = new Map()
   let unparsed = 0
   pg.on('request', (r) => {
@@ -107,8 +115,13 @@ async function run(provider) {
   return { mapboxReq: count('mapbox.com'), globals, errs, unparsed, total: [...hosts.values()].reduce((a, n) => a + n, 0) }
 }
 
-const def = await run(null)
-const ml = await run('maplibre')
+// ★ THE AUTO CONTRACT (2026-09-26). The default engine is 'auto': Mapbox only when a token is available.
+// So the Mapbox baseline is ?provider=mapbox WITH a (fake) host token, the switch run adds the same token
+// and ?provider=maplibre (an explicit engine must beat an available token), and a third run checks the
+// no-token default is already keyless.
+const def = await run('mapbox', FAKE_TK)
+const ml = await run('maplibre', FAKE_TK)
+const auto = await run(null)
 
 // DERIVED from the leaf's own HTML, not a hardcoded number: count the distinct
 // api.mapbox.com references the generated page carries, then allow a little slack
@@ -120,8 +133,10 @@ const declared = new Set((pageHtml.match(/https:\/\/api\.mapbox\.com[^"')]+/g) |
 const PRELOAD_ALLOWANCE = Number(process.env.PROVIDER_PRELOADS ?? (declared.size + 1))
 
 console.log(`  page preloads     : ${declared.size} distinct api.mapbox.com url(s) in the leaf HTML`)
-console.log(`  default           : ${def.mapboxReq} mapbox / ${def.total} total request(s)  `
+console.log(`  ?provider=mapbox  : ${def.mapboxReq} mapbox / ${def.total} total request(s)  `
   + `[mapboxgl=${def.globals.mapbox} maplibregl=${def.globals.maplibre}]`)
+console.log(`  no token (auto)   : ${auto.mapboxReq} mapbox / ${auto.total} total request(s)  `
+  + `[mapboxgl=${auto.globals.mapbox} maplibregl=${auto.globals.maplibre}]`)
 console.log(`  ?provider=maplibre: ${ml.mapboxReq} mapbox / ${ml.total} total request(s)  `
   + `[mapboxgl=${ml.globals.mapbox} maplibregl=${ml.globals.maplibre}]`)
 
@@ -144,6 +159,9 @@ if (def.mapboxReq <= PRELOAD_ALLOWANCE) {
   fails.push(`the default run made only ${def.mapboxReq} mapbox request(s) — the map is probably `
     + 'not rendering, so this comparison proves nothing')
 }
+if (auto.mapboxReq > PRELOAD_ALLOWANCE) {
+  fails.push(`the no-token default made ${auto.mapboxReq} mapbox request(s) — 'auto' must draw MapLibre, keyless, with no token`)
+}
 if (!def.total) fails.push('no requests were recorded at all — the tally is broken, not the page')
 if (ml.errs.length) fails.push(`${ml.errs.length} page error(s) under maplibre: ${ml.errs[0]}`)