@@ -513,7 +513,7 @@ it.layer(
               ChildProcessSpawner.ChildProcessSpawner,
               stdoutSpawner(() => {
                 probes++;
-                return JSON.stringify(version);
+                return JSON.stringify({ "@example/package-tool": { latest: version } });
               }),
             ),
             Effect.tap((capabilities) =>
@@ -685,6 +685,7 @@ it.layer(
           packageName: "@example/package-tool",
           latestVersion: null,
           lookupLatestVersion: expect.anything(),
+          latestVersionCacheKey: expect.any(String),
           update: {
             command: `npm install -g --prefix ${tempDir} --allow-scripts=@example/package-tool @example/package-tool@latest`,
             executable: "npm",
 
@@ -949,7 +949,7 @@ export const resolvePackageManagedProviderMaintenance = Effect.fn(
   if (npmPrefix) {
     const services = yield* Effect.context<ProviderMaintenanceResolverServices>();
     // npm 12 requires script approval to install native binaries; older npm only warns about the flag.
-    return makeProviderMaintenanceCapabilities({
+    const capabilities = makeProviderMaintenanceCapabilities({
       provider: definition.provider,
       packageName,
       updateExecutable: "npm",
@@ -970,6 +970,15 @@ export const resolvePackageManagedProviderMaintenance = Effect.fn(
         Effect.provideContext(services),
       ),
     });
+    return {
+      ...capabilities,
+      latestVersionCacheKey: [
+        "npm-global",
+        normalizeCommandPath(npmPrefix),
+        packageName,
+        environmentCacheKey(context.env),
+      ].join("\0"),
+    };
   }
 
   const homebrew = homebrewOwnershipFromCommandPath(context.realCommandPath);