diff --git a/changelog.d/fixes/7661-fumadocs-devdep.md b/changelog.d/fixes/7661-fumadocs-devdep.md
new file mode 100644
index 0000000000..7340d36184
--- /dev/null
+++ b/changelog.d/fixes/7661-fumadocs-devdep.md
@@ -0,0 +1 @@
+- fix(packaging): move fumadocs-mdx from dependencies to devDependencies to avoid pulling its build-only yuku-analyzer/yuku-ast toolchain into `npm install -g omniroute` (#7661)
diff --git a/package-lock.json b/package-lock.json
index d5eb7bd8fd..c5b8978f8a 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -36,7 +36,6 @@
         "fetch-socks": "^1.3.3",
         "fflate": "^0.8.3",
         "fumadocs-core": "^16.10.5",
-        "fumadocs-mdx": "^15.0.7",
         "fumadocs-ui": "^16.10.5",
         "http-proxy-middleware": "^4.0.0",
         "https-proxy-agent": "^9.0.0",
@@ -104,7 +103,7 @@
         "@testing-library/jest-dom": "^6.9.1",
         "@testing-library/react": "^16.3.2",
         "@types/better-sqlite3": "^7.6.13",
-        "@types/bun": "*",
+        "@types/bun": "latest",
         "@types/node": "^26.1.0",
         "@types/react": "^19.2.15",
         "@types/react-dom": "^19.2.3",
@@ -121,6 +120,7 @@
         "eslint-config-next": "16.2.10",
         "eslint-plugin-sonarjs": "^4.1.0",
         "fast-check": "^4.8.0",
+        "fumadocs-mdx": "^15.0.7",
         "glob": "^13.0.6",
         "httpyac": "^6.16.7",
         "husky": "^9.1.7",
@@ -4976,6 +4976,7 @@
       "version": "3.1.1",
       "resolved": "https://registry.npmjs.org/@mdx-js/mdx/-/mdx-3.1.1.tgz",
       "integrity": "sha512-f6ZO2ifpwAQIpzGWaBQT2TXxPv6z3RBzQKpVftEWN78Vl/YweF1uwussDx8ECAXVtr3Rs89fKyG9YlzUs9DyGQ==",
+      "dev": true,
       "license": "MIT",
       "dependencies": {
         "@types/estree": "^1.0.0",
@@ -12844,6 +12845,7 @@
       "cpu": [
         "arm64"
       ],
+      "dev": true,
       "optional": true,
       "os": [
         "darwin"
@@ -12856,6 +12858,7 @@
       "cpu": [
         "x64"
       ],
+      "dev": true,
       "optional": true,
       "os": [
         "darwin"
@@ -12868,6 +12871,7 @@
       "cpu": [
         "x64"
       ],
+      "dev": true,
       "optional": true,
       "os": [
         "freebsd"
@@ -12880,6 +12884,7 @@
       "cpu": [
         "arm"
       ],
+      "dev": true,
       "libc": [
         "glibc"
       ],
@@ -12895,6 +12900,7 @@
       "cpu": [
         "arm"
       ],
+      "dev": true,
       "libc": [
         "musl"
       ],
@@ -12910,6 +12916,7 @@
       "cpu": [
         "arm64"
       ],
+      "dev": true,
       "libc": [
         "glibc"
       ],
@@ -12925,6 +12932,7 @@
       "cpu": [
         "arm64"
       ],
+      "dev": true,
       "libc": [
         "musl"
       ],
@@ -12940,6 +12948,7 @@
       "cpu": [
         "x64"
       ],
+      "dev": true,
       "libc": [
         "glibc"
       ],
@@ -12955,6 +12964,7 @@
       "cpu": [
         "x64"
       ],
+      "dev": true,
       "libc": [
         "musl"
       ],
@@ -12970,6 +12980,7 @@
       "cpu": [
         "arm64"
       ],
+      "dev": true,
       "optional": true,
       "os": [
         "win32"
@@ -12982,6 +12993,7 @@
       "cpu": [
         "x64"
       ],
+      "dev": true,
       "optional": true,
       "os": [
         "win32"
@@ -12991,6 +13003,7 @@
       "version": "0.5.43",
       "resolved": "https://registry.npmjs.org/@yuku-toolchain/types/-/types-0.5.43.tgz",
       "integrity": "sha512-kSpvPntnXw5+lYjO71ffBEnQ5ycQ74KGIYknh0TS4xeyCuBkOqxyJumxZkMhLBBUCLjDAbx2+Icnr3Zh4ftjpQ==",
+      "dev": true,
       "license": "MIT"
     },
     "node_modules/a-sync-waterfall": {
@@ -13052,6 +13065,7 @@
       "version": "5.3.2",
       "resolved": "https://registry.npmjs.org/acorn-jsx/-/acorn-jsx-5.3.2.tgz",
       "integrity": "sha512-rq9s+JNhf0IChjtDXxllJ7g41oZk5SlXtp0LHwyA5cejwn7vKmKp4pPri6YEePv2PU65sAsegbXtIinmDFDXgQ==",
+      "dev": true,
       "license": "MIT",
       "peerDependencies": {
         "acorn": "^6.0.0 || ^7.0.0 || ^8.0.0"
@@ -13593,6 +13607,7 @@
       "version": "1.9.0",
       "resolved": "https://registry.npmjs.org/astring/-/astring-1.9.0.tgz",
       "integrity": "sha512-LElXdjswlqjWrPpJFg1Fx4wpkOCxj1TDHlSV4PlaRxHGWko024xICaa97ZkMfs6DRKlCguiAI+rbXv5GWwXIkg==",
+      "dev": true,
       "license": "MIT",
       "bin": {
         "astring": "bin/astring"
@@ -14679,6 +14694,7 @@
       "version": "5.0.0",
       "resolved": "https://registry.npmjs.org/chokidar/-/chokidar-5.0.0.tgz",
       "integrity": "sha512-TQMmc3w+5AxjpL8iIiwebF73dRDF4fBIieAqGn9RGCWaEVwQ6Fb2cGe31Yns0RRIzii5goJ1Y7xbMwo1TxMplw==",
+      "dev": true,
       "license": "MIT",
       "dependencies": {
         "readdirp": "^5.0.0"
@@ -15327,6 +15343,7 @@
       "version": "2.1.0",
       "resolved": "https://registry.npmjs.org/collapse-white-space/-/collapse-white-space-2.1.0.tgz",
       "integrity": "sha512-loKTxY1zCOuG4j9f6EPnuyyYkf58RnhhWTvRoZEokgB+WbdXehfjFviyOVYkqzEWz1Q5kRiZdBYS5SwxbQYwzw==",
+      "dev": true,
       "license": "MIT",
       "funding": {
         "type": "github",
@@ -17860,6 +17877,7 @@
       "version": "2.0.0",
       "resolved": "https://registry.npmjs.org/esast-util-from-estree/-/esast-util-from-estree-2.0.0.tgz",
       "integrity": "sha512-4CyanoAudUSBAn5K13H4JhsMH6L9ZP7XbLVe/dKybkxMO7eDyLsT8UHl9TRNrU2Gr9nz+FovfSIjuXWJ81uVwQ==",
+      "dev": true,
       "license": "MIT",
       "dependencies": {
         "@types/estree-jsx": "^1.0.0",
@@ -17876,6 +17894,7 @@
       "version": "2.0.1",
       "resolved": "https://registry.npmjs.org/esast-util-from-js/-/esast-util-from-js-2.0.1.tgz",
       "integrity": "sha512-8Ja+rNJ0Lt56Pcf3TAmpBZjmx8ZcK5Ts4cAzIOjsjevg9oSXJnl6SUQ2EevU8tv3h6ZLWmoKL5H4fgWvdvfETw==",
+      "dev": true,
       "license": "MIT",
       "dependencies": {
         "@types/estree-jsx": "^1.0.0",
@@ -18616,6 +18635,7 @@
       "version": "3.0.1",
       "resolved": "https://registry.npmjs.org/estree-util-build-jsx/-/estree-util-build-jsx-3.0.1.tgz",
       "integrity": "sha512-8U5eiL6BTrPxp/CHbs2yMgP8ftMhR5ww1eIKoWRMlqvltHF8fZn5LRDvTKuxD3DUn+shRbLGqXemcP51oFCsGQ==",
+      "dev": true,
       "license": "MIT",
       "dependencies": {
         "@types/estree-jsx": "^1.0.0",
@@ -18642,6 +18662,7 @@
       "version": "1.0.0",
       "resolved": "https://registry.npmjs.org/estree-util-scope/-/estree-util-scope-1.0.0.tgz",
       "integrity": "sha512-2CAASclonf+JFWBNJPndcOpA8EMJwa0Q8LUFJEKqXLW6+qBvbFZuF5gItbQOs/umBUkjviCSDCbBwU2cXbmrhQ==",
+      "dev": true,
       "license": "MIT",
       "dependencies": {
         "@types/estree": "^1.0.0",
@@ -18656,6 +18677,7 @@
       "version": "2.0.0",
       "resolved": "https://registry.npmjs.org/estree-util-to-js/-/estree-util-to-js-2.0.0.tgz",
       "integrity": "sha512-WDF+xj5rRWmD5tj6bIqRi6CkLIXbbNQUcxQHzGysQzvHmdYG2G7p/Tf0J0gpxGgkeMZNTIjT/AoSvC9Xehcgdg==",
+      "dev": true,
       "license": "MIT",
       "dependencies": {
         "@types/estree-jsx": "^1.0.0",
@@ -18683,6 +18705,7 @@
       "version": "2.0.0",
       "resolved": "https://registry.npmjs.org/estree-util-visit/-/estree-util-visit-2.0.0.tgz",
       "integrity": "sha512-m5KgiH85xAhhW8Wta0vShLcUvOsh3LLPI2YVwcbio1l7E09NTLL1EyMZFM1OyWowoH0skScNbhOPl4kcBgzTww==",
+      "dev": true,
       "license": "MIT",
       "dependencies": {
         "@types/estree-jsx": "^1.0.0",
@@ -18697,6 +18720,7 @@
       "version": "3.0.3",
       "resolved": "https://registry.npmjs.org/estree-walker/-/estree-walker-3.0.3.tgz",
       "integrity": "sha512-7RUKfXgSMMkzt6ZuXmqapOurLGPPfgj6l9uRZ7lRGolvk0y2yocc35LdcxKC5PQZdn2DMqioAQ2NoWcrTKmm6g==",
+      "dev": true,
       "license": "MIT",
       "dependencies": {
         "@types/estree": "^1.0.0"
@@ -19699,6 +19723,7 @@
       "version": "15.2.0",
       "resolved": "https://registry.npmjs.org/fumadocs-mdx/-/fumadocs-mdx-15.2.0.tgz",
       "integrity": "sha512-+yBP8QYw5wA9LF5eVdMhwbP7KT1OF4B/YfC6PZoD2jz0amZi1B+6QHTI6XoRRSTmhWrI4cL5LU1DspW0itk+NA==",
+      "dev": true,
       "license": "MIT",
       "dependencies": {
         "@mdx-js/mdx": "^3.1.1",
@@ -25691,6 +25716,7 @@
       "version": "0.30.21",
       "resolved": "https://registry.npmjs.org/magic-string/-/magic-string-0.30.21.tgz",
       "integrity": "sha512-vd2F4YUyEXKGcLHoq+TEyCjxueSeHnFxyyjNp80yg0XV4vUhnDer/lvvlqM/arB5bXQN5K2/3oinyCRyx8T2CQ==",
+      "dev": true,
       "license": "MIT",
       "dependencies": {
         "@jridgewell/sourcemap-codec": "^1.5.5"
@@ -25753,6 +25779,7 @@
       "version": "2.0.0",
       "resolved": "https://registry.npmjs.org/markdown-extensions/-/markdown-extensions-2.0.0.tgz",
       "integrity": "sha512-o5vL7aDWatOTX8LzaS1WMoaoxIiLRQJuIKKe2wAw6IeULDHaqbiqiggmx+pKvZDb1Sj+pE46Sn1T7lCqfFtg1Q==",
+      "dev": true,
       "license": "MIT",
       "engines": {
         "node": ">=16"
@@ -26491,6 +26518,7 @@
       "version": "3.0.1",
       "resolved": "https://registry.npmjs.org/micromark-extension-mdx-expression/-/micromark-extension-mdx-expression-3.0.1.tgz",
       "integrity": "sha512-dD/ADLJ1AeMvSAKBwO22zG22N4ybhe7kFIZ3LsDI0GlsNr2A3KYxb0LdC1u5rj4Nw+CHKY0RVdnHX8vj8ejm4Q==",
+      "dev": true,
       "funding": [
         {
           "type": "GitHub Sponsors",
@@ -26517,6 +26545,7 @@
       "version": "3.0.2",
       "resolved": "https://registry.npmjs.org/micromark-extension-mdx-jsx/-/micromark-extension-mdx-jsx-3.0.2.tgz",
       "integrity": "sha512-e5+q1DjMh62LZAJOnDraSSbDMvGJ8x3cbjygy2qFEi7HCeUT4BDKCvMozPozcD6WmOt6sVvYDNBKhFSz3kjOVQ==",
+      "dev": true,
       "license": "MIT",
       "dependencies": {
         "@types/estree": "^1.0.0",
@@ -26539,6 +26568,7 @@
       "version": "2.0.0",
       "resolved": "https://registry.npmjs.org/micromark-extension-mdx-md/-/micromark-extension-mdx-md-2.0.0.tgz",
       "integrity": "sha512-EpAiszsB3blw4Rpba7xTOUptcFeBFi+6PY8VnJ2hhimH+vCQDirWgsMpz7w1XcZE7LVrSAUGb9VJpG9ghlYvYQ==",
+      "dev": true,
       "license": "MIT",
       "dependencies": {
         "micromark-util-types": "^2.0.0"
@@ -26552,6 +26582,7 @@
       "version": "3.0.0",
       "resolved": "https://registry.npmjs.org/micromark-extension-mdxjs/-/micromark-extension-mdxjs-3.0.0.tgz",
       "integrity": "sha512-A873fJfhnJ2siZyUrJ31l34Uqwy4xIFmvPY1oj+Ean5PHcPBYzEsvqvWGaWcfEIr11O5Dlw3p2y0tZWpKHDejQ==",
+      "dev": true,
       "license": "MIT",
       "dependencies": {
         "acorn": "^8.0.0",
@@ -26572,6 +26603,7 @@
       "version": "3.0.0",
       "resolved": "https://registry.npmjs.org/micromark-extension-mdxjs-esm/-/micromark-extension-mdxjs-esm-3.0.0.tgz",
       "integrity": "sha512-DJFl4ZqkErRpq/dAPyeWp15tGrcrrJho1hKK5uBS70BCtfrIFg81sqcTVu3Ta+KD1Tk5vAtBNElWxtAa+m8K9A==",
+      "dev": true,
       "license": "MIT",
       "dependencies": {
         "@types/estree": "^1.0.0",
@@ -26636,6 +26668,7 @@
       "version": "2.0.3",
       "resolved": "https://registry.npmjs.org/micromark-factory-mdx-expression/-/micromark-factory-mdx-expression-2.0.3.tgz",
       "integrity": "sha512-kQnEtA3vzucU2BkrIa8/VaSAsP+EJ3CKOvhMuJgOEGg9KDC6OAY6nSnNDVRiVNRqj7Y4SlSzcStaH/5jge8JdQ==",
+      "dev": true,
       "funding": [
         {
           "type": "GitHub Sponsors",
@@ -26864,6 +26897,7 @@
       "version": "2.0.3",
       "resolved": "https://registry.npmjs.org/micromark-util-events-to-acorn/-/micromark-util-events-to-acorn-2.0.3.tgz",
       "integrity": "sha512-jmsiEIiZ1n7X1Rr5k8wVExBQCg5jy4UXVADItHmNk1zkwEVhBuIUKRu3fqv+hs4nxLISi2DQGlqIOGiFxgbfHg==",
+      "dev": true,
       "funding": [
         {
           "type": "GitHub Sponsors",
@@ -32158,6 +32192,7 @@
       "version": "5.0.0",
       "resolved": "https://registry.npmjs.org/readdirp/-/readdirp-5.0.0.tgz",
       "integrity": "sha512-9u/XQ1pvrQtYyMpZe7DXKv2p5CNvyVwzUB6uhLAnQwHMSgKMBR62lc7AHljaeteeHXn11XTAaLLUVZYVZyuRBQ==",
+      "dev": true,
       "license": "MIT",
       "engines": {
         "node": ">= 20.19.0"
@@ -32210,6 +32245,7 @@
       "version": "1.0.0",
       "resolved": "https://registry.npmjs.org/recma-build-jsx/-/recma-build-jsx-1.0.0.tgz",
       "integrity": "sha512-8GtdyqaBcDfva+GUKDr3nev3VpKAhup1+RvkMvUxURHpW7QyIvk9F5wz7Vzo06CEMSilw6uArgRqhpiUcWp8ew==",
+      "dev": true,
       "license": "MIT",
       "dependencies": {
         "@types/estree": "^1.0.0",
@@ -32225,6 +32261,7 @@
       "version": "1.0.1",
       "resolved": "https://registry.npmjs.org/recma-jsx/-/recma-jsx-1.0.1.tgz",
       "integrity": "sha512-huSIy7VU2Z5OLv6oFLosQGGDqPqdO1iq6bWNAdhzMxSJP7RAso4fCZ1cKu8j9YHCZf3TPrq4dw3okhrylgcd7w==",
+      "dev": true,
       "license": "MIT",
       "dependencies": {
         "acorn-jsx": "^5.0.0",
@@ -32245,6 +32282,7 @@
       "version": "1.0.0",
       "resolved": "https://registry.npmjs.org/recma-parse/-/recma-parse-1.0.0.tgz",
       "integrity": "sha512-OYLsIGBB5Y5wjnSnQW6t3Xg7q3fQ7FWbw/vcXtORTnyaSFscOtABg+7Pnz6YZ6c27fG1/aN8CjfwoUEUIdwqWQ==",
+      "dev": true,
       "license": "MIT",
       "dependencies": {
         "@types/estree": "^1.0.0",
@@ -32261,6 +32299,7 @@
       "version": "1.0.0",
       "resolved": "https://registry.npmjs.org/recma-stringify/-/recma-stringify-1.0.0.tgz",
       "integrity": "sha512-cjwII1MdIIVloKvC9ErQ+OgAtwHBmcZ0Bg4ciz78FtbT8In39aAYbaA7zvxQ61xVMSPE8WxhLwLbhif4Js2C+g==",
+      "dev": true,
       "license": "MIT",
       "dependencies": {
         "@types/estree": "^1.0.0",
@@ -32504,6 +32543,7 @@
       "version": "1.0.0",
       "resolved": "https://registry.npmjs.org/rehype-recma/-/rehype-recma-1.0.0.tgz",
       "integrity": "sha512-lqA4rGUf1JmacCNWWZx0Wv1dHqMwxzsDWYMTowuplHF3xH0N/MmrZ/G3BDZnzAkRmxDadujCjaKM2hqYdCBOGw==",
+      "dev": true,
       "license": "MIT",
       "dependencies": {
         "@types/estree": "^1.0.0",
@@ -32553,6 +32593,7 @@
       "version": "3.1.1",
       "resolved": "https://registry.npmjs.org/remark-mdx/-/remark-mdx-3.1.1.tgz",
       "integrity": "sha512-Pjj2IYlUY3+D8x00UJsIOg5BEvfMyeI+2uLPn9VO9Wg4MEtN/VTIq2NEJQfde9PnX15KgtHyl9S0BcTnWrIuWg==",
+      "dev": true,
       "license": "MIT",
       "dependencies": {
         "mdast-util-mdx": "^3.0.0",
@@ -33961,6 +34002,7 @@
       "version": "0.7.6",
       "resolved": "https://registry.npmjs.org/source-map/-/source-map-0.7.6.tgz",
       "integrity": "sha512-i5uvt8C3ikiWeNZSVZNWcfZPItFQOsYTUAOkcUPGd8DqDy1uOUikjt5dG+uRlwyvR108Fb9DOd4GvXfT0N2/uQ==",
+      "dev": true,
       "license": "BSD-3-Clause",
       "engines": {
         "node": ">= 12"
@@ -35941,6 +35983,7 @@
       "version": "2.0.0",
       "resolved": "https://registry.npmjs.org/unist-util-position-from-estree/-/unist-util-position-from-estree-2.0.0.tgz",
       "integrity": "sha512-KaFVRjoqLyF6YXCbVLNad/eS4+OfPQQn2yOd7zF/h5T/CSL2v8NpN6a5TPvtbXthAGw5nG+PuTtq+DdIZr+cRQ==",
+      "dev": true,
       "license": "MIT",
       "dependencies": {
         "@types/unist": "^3.0.0"
@@ -35954,6 +35997,7 @@
       "version": "5.0.0",
       "resolved": "https://registry.npmjs.org/unist-util-remove-position/-/unist-util-remove-position-5.0.0.tgz",
       "integrity": "sha512-Hp5Kh3wLxv0PHj9m2yZhhLt58KzPtEYKQQ4yxfYFEO7EvHwzyDYnduhHnY1mDxoqr7VUwVuHXk9RXKIiYS1N8Q==",
+      "dev": true,
       "license": "MIT",
       "dependencies": {
         "@types/unist": "^3.0.0",
@@ -37527,6 +37571,7 @@
       "version": "0.6.3",
       "resolved": "https://registry.npmjs.org/yuku-analyzer/-/yuku-analyzer-0.6.3.tgz",
       "integrity": "sha512-RQ02dPtOa5d2AA3Np45EWD3EJUwZDruCrMMulPwUT/9GK1P7aKAhjaxG4Jv/1qqzMUIt0RUe3Dn2RR6d7+qTrA==",
+      "dev": true,
       "license": "MIT",
       "dependencies": {
         "@yuku-toolchain/types": "0.5.43"
diff --git a/package.json b/package.json
index 0fbeaf37a6..28e75a4077 100644
--- a/package.json
+++ b/package.json
@@ -254,7 +254,6 @@
     "fetch-socks": "^1.3.3",
     "fflate": "^0.8.3",
     "fumadocs-core": "^16.10.5",
-    "fumadocs-mdx": "^15.0.7",
     "fumadocs-ui": "^16.10.5",
     "http-proxy-middleware": "^4.0.0",
     "https-proxy-agent": "^9.0.0",
@@ -345,6 +344,7 @@
     "eslint-config-next": "16.2.10",
     "eslint-plugin-sonarjs": "^4.1.0",
     "fast-check": "^4.8.0",
+    "fumadocs-mdx": "^15.0.7",
     "glob": "^13.0.6",
     "httpyac": "^6.16.7",
     "husky": "^9.1.7",
diff --git a/tests/unit/npm-runtime-deps-fumadocs-mdx-7661.test.ts b/tests/unit/npm-runtime-deps-fumadocs-mdx-7661.test.ts
new file mode 100644
index 0000000000..ae74b161ac
--- /dev/null
+++ b/tests/unit/npm-runtime-deps-fumadocs-mdx-7661.test.ts
@@ -0,0 +1,59 @@
+import { test } from "node:test";
+import assert from "node:assert/strict";
+import { readFileSync, readdirSync, statSync } from "node:fs";
+import { join, resolve, extname } from "node:path";
+import { fileURLToPath } from "node:url";
+
+const REPO_ROOT = resolve(fileURLToPath(import.meta.url), "../../../");
+
+function listSourceFiles(dir: string, exts: string[]): string[] {
+  const out: string[] = [];
+  let entries: string[];
+  try {
+    entries = readdirSync(dir);
+  } catch {
+    return out;
+  }
+  for (const entry of entries) {
+    if (entry === "node_modules" || entry === ".git" || entry === ".source") continue;
+    const full = join(dir, entry);
+    const st = statSync(full);
+    if (st.isDirectory()) out.push(...listSourceFiles(full, exts));
+    else if (exts.includes(extname(entry))) out.push(full);
+  }
+  return out;
+}
+
+test("#7661 — fumadocs-mdx must not be a runtime dependency (npm install -g ETARGET exposure)", () => {
+  const pkg = JSON.parse(readFileSync(join(REPO_ROOT, "package.json"), "utf8"));
+  const deps: Record<string, string> = pkg.dependencies || {};
+  const devDeps: Record<string, string> = pkg.devDependencies || {};
+
+  assert.ok(
+    !("fumadocs-mdx" in deps),
+    'fumadocs-mdx is declared under "dependencies" — npm install -g omniroute fetches it ' +
+      "and its transitive yuku-analyzer/yuku-ast native-binding tree even though nothing at " +
+      'runtime imports it. Move it to "devDependencies".'
+  );
+
+  assert.ok(
+    "fumadocs-mdx" in devDeps || "fumadocs-mdx" in deps,
+    "fumadocs-mdx must remain declared somewhere"
+  );
+
+  const runtimeDirs = ["src", "open-sse", "bin"].map((d) => join(REPO_ROOT, d));
+  const runtimeFiles = runtimeDirs.flatMap((d) =>
+    listSourceFiles(d, [".ts", ".tsx", ".js", ".mjs", ".cjs"])
+  );
+  assert.ok(runtimeFiles.length > 100, "sanity: scanner should find the runtime source tree");
+
+  const offenders = runtimeFiles.filter((f) => {
+    const src = readFileSync(f, "utf8");
+    return /from\s+["']fumadocs-mdx(\/|["'])|require\(\s*["']fumadocs-mdx(\/|["'])/.test(src);
+  });
+  assert.deepEqual(
+    offenders,
+    [],
+    `fumadocs-mdx is imported at runtime by: ${offenders.join(", ")}`
+  );
+});