diff --git a/package.json b/package.json
index 3f45f32..96e961a 100644
--- a/package.json
+++ b/package.json
@@ -28,7 +28,7 @@
     "LICENSE"
   ],
   "scripts": {
-    "test": "npm run typecheck && tsx tests/test-pure-functions.ts && tsx tests/test-models.ts && tsx tests/test-pricing.ts && tsx tests/test-cost.ts && tsx tests/test-oauth.ts && tsx tests/test-abort.ts && tsx tests/test-stream.ts && tsx tests/test-retry.ts && node tests/test-pi-local.mjs && node tests/test-omp-compat.mjs",
+    "test": "npm run typecheck && tsx tests/test-package-manifest.ts && tsx tests/test-pure-functions.ts && tsx tests/test-models.ts && tsx tests/test-pricing.ts && tsx tests/test-cost.ts && tsx tests/test-oauth.ts && tsx tests/test-abort.ts && tsx tests/test-stream.ts && tsx tests/test-retry.ts && node tests/test-pi-local.mjs && node tests/test-omp-compat.mjs",
     "typecheck": "tsc --noEmit",
     "format:check": "prettier --check '**/*.{ts,mjs,json,md}'",
     "format": "prettier --write '**/*.{ts,mjs,json,md}'",
diff --git a/tests/test-package-manifest.ts b/tests/test-package-manifest.ts
new file mode 100644
index 0000000..a01434f
--- /dev/null
+++ b/tests/test-package-manifest.ts
@@ -0,0 +1,28 @@
+import assert from "node:assert/strict"
+import { readFile } from "node:fs/promises"
+import { describe, it } from "node:test"
+
+interface PackageManifest {
+  dependencies?: Record<string, string>
+  peerDependencies?: Record<string, string>
+  peerDependenciesMeta?: Record<string, { optional?: boolean }>
+}
+
+const CORE_PEERS = ["@earendil-works/pi-ai", "@earendil-works/pi-coding-agent"] as const
+
+async function readPackageManifest(): Promise<PackageManifest> {
+  const contents = await readFile(new URL("../package.json", import.meta.url), "utf-8")
+  return JSON.parse(contents) as PackageManifest
+}
+
+describe("package manifest", () => {
+  it("uses pi's bundled core packages instead of installing private runtime copies", async () => {
+    const manifest = await readPackageManifest()
+
+    for (const packageName of CORE_PEERS) {
+      assert.equal(manifest.dependencies?.[packageName], undefined)
+      assert.equal(manifest.peerDependencies?.[packageName], "*")
+      assert.equal(manifest.peerDependenciesMeta?.[packageName]?.optional, true)
+    }
+  })
+})