diff --git a/packages/compiler/src/index.ts b/packages/compiler/src/index.ts
index 474d61e46..472f5cd14 100644
--- a/packages/compiler/src/index.ts
+++ b/packages/compiler/src/index.ts
@@ -1376,7 +1376,7 @@ async function compileTracked(
     const helperObjectRoute =
       opts.nativeProgramObject === true || usesPrecompiledRuntimePack(opts, "llvm");
     // Calls into Node record the libnode pack, keyed by its manifest (node-islands/libnode.ts).
-    const libnodeKey = libnodeCacheKey(opts.libnode, process.env, dirname(entryPath));
+    const libnodeKey = libnodeCacheKey(opts.libnode);
     const routeOptions: Omit<
       EarlyExecutableCacheOptions,
       "implementation" | "implementationDependencies" | "nativeEnvironment"
diff --git a/packages/compiler/src/node-islands/libnode-pack.ts b/packages/compiler/src/node-islands/libnode-pack.ts
index fb6669cac..a43fde48e 100644
--- a/packages/compiler/src/node-islands/libnode-pack.ts
+++ b/packages/compiler/src/node-islands/libnode-pack.ts
@@ -186,12 +186,13 @@ export function readLibnodePack(
   return { root, manifest };
 }
 
-/** The nearest `node_modules/<name>` directory walking up from `from`. */
+/** The nearest `node_modules/<name>` directory with a built pack (a
+ * manifest.json) walking up from `from`. */
 function findInstalled(name: string, from: string): string | null {
   let dir = resolve(from);
   for (;;) {
     const candidate = join(dir, "node_modules", name);
-    if (existsSync(join(candidate, "package.json"))) return candidate;
+    if (existsSync(join(candidate, "manifest.json"))) return candidate;
     const parent = dirname(dir);
     if (parent === dir) return null;
     dir = parent;
@@ -200,7 +201,9 @@ function findInstalled(name: string, from: string): string | null {
 
 function resolveNextToCompiler(name: string): string | null {
   try {
-    return dirname(createRequire(import.meta.url).resolve(`${name}/package.json`));
+    const dir = dirname(createRequire(import.meta.url).resolve(`${name}/package.json`));
+    // An unbuilt workspace package is not a pack.
+    return existsSync(join(dir, "manifest.json")) ? dir : null;
   } catch {
     return null;
   }
diff --git a/packages/compiler/src/node-islands/libnode.test.ts b/packages/compiler/src/node-islands/libnode.test.ts
index c62783a47..d6ca4bf83 100644
--- a/packages/compiler/src/node-islands/libnode.test.ts
+++ b/packages/compiler/src/node-islands/libnode.test.ts
@@ -93,13 +93,8 @@ describe("the recorded libnode pack", () => {
 });
 
 describe("the libnode pack in an executable's cache key", () => {
-  test("is absent without --libnode, SCRIPTC_LIBNODE or an installed pack", () => {
-    const installed = findInstalledLibnodePack({
-      targetName: hostLibnodeTarget(),
-      projectDir: "/nonexistent",
-    });
-    if (installed === null) expect(libnodeCacheKey(undefined, {}, "/nonexistent")).toBeUndefined();
-    else expect(libnodeCacheKey(undefined, {}, "/nonexistent")).toContain(installed);
+  test("is absent without --libnode or SCRIPTC_LIBNODE", () => {
+    expect(libnodeCacheKey(undefined, {})).toBeUndefined();
   });
 
   test("changes when the pack in the same directory is upgraded", () => {
diff --git a/packages/compiler/src/node-islands/libnode.ts b/packages/compiler/src/node-islands/libnode.ts
index be6eaff65..cb4e7e21c 100644
--- a/packages/compiler/src/node-islands/libnode.ts
+++ b/packages/compiler/src/node-islands/libnode.ts
@@ -119,24 +119,20 @@ export function libnodeRecord(
 }
 
 /** The part of an executable's cache key that names its libnode pack, or
- * undefined when neither --libnode nor SCRIPTC_LIBNODE is set and no pack
- * is installed. It holds the option, the pack directory and a digest of the
- * pack's manifest.json, so that a pack upgraded in place (another Node
- * version, bridge ABI or file list) gives cached executables a new key
- * instead of their old record. */
+ * undefined when neither --libnode nor SCRIPTC_LIBNODE is set. It holds the
+ * option, the pack directory and a digest of the pack's manifest.json, so
+ * that a pack upgraded in place (another Node version, bridge ABI or file
+ * list) gives cached executables a new key instead of their old record.
+ * An installed @scriptc/libnode-<platform> pack needs no part: it versions
+ * in lockstep with the compiler, whose version every key already holds, so
+ * the bootstrap's routed cache keeps serving builds where one is installed. */
 export function libnodeCacheKey(
   option: string | undefined,
   env: NodeJS.ProcessEnv = process.env,
-  projectDir: string = process.cwd(),
 ): string | undefined {
   const fromEnv = env["SCRIPTC_LIBNODE"];
-  const installed =
-    option === undefined && fromEnv === undefined
-      ? findInstalledLibnodePack({ targetName: hostLibnodeTarget(), projectDir })
-      : null;
-  if (option === undefined && fromEnv === undefined && installed === null) return undefined;
-  const source =
-    installed ?? (option !== undefined && option !== "beside" ? option : (fromEnv ?? ""));
+  if (option === undefined && fromEnv === undefined) return undefined;
+  const source = option !== undefined && option !== "beside" ? option : (fromEnv ?? "");
   let manifest = "none";
   if (isAbsolute(source)) {
     try {