diff --git a/test/cli/install/registry/bun-install-registry.test.ts b/test/cli/install/registry/bun-install-registry.test.ts
index c2acdc61f69424..71240dbe2ddf5d 100644
--- a/test/cli/install/registry/bun-install-registry.test.ts
+++ b/test/cli/install/registry/bun-install-registry.test.ts
@@ -21,6 +21,7 @@ import {
   toHaveBins,
   toMatchNodeModulesAt,
   writeShebangScript,
+  stderrForInstall,
 } from "harness";
 import { join, resolve, sep } from "path";
 import { readdirSorted } from "../dummy.registry";
@@ -548,10 +549,14 @@ describe("publish", async () => {
       setAuthHeader?: boolean;
       otpFail?: boolean;
       npmNotice?: boolean;
+      expectedCI?: string;
     }) {
       return async function (req: Request) {
         const { token, setAuthHeader = true, otpFail = false, npmNotice = false } = opts;
         if (req.url.includes("otp-pkg")) {
+          if (opts.expectedCI) {
+            expect(req.headers.get("user-agent")).toContain("ci/" + opts.expectedCI);
+          }
           if (req.headers.get("npm-otp") === token) {
             if (otpFail) {
               return new Response(
@@ -698,6 +703,47 @@ describe("publish", async () => {
       expect(exitCode).toBe(0);
       expect(err).toContain(`note: visit http://localhost:${mockRegistry.port}/auth to login`);
     });
+
+    const fakeCIEnvs = [
+      { ci: "expo-application-services", envs: { EAS_BUILD: "hi" } },
+      { ci: "codemagic", envs: { CM_BUILD_ID: "hi" } },
+      { ci: "vercel", envs: { "NOW_BUILDER": "hi" } },
+    ];
+    for (const envInfo of fakeCIEnvs) {
+      test(`CI user agent name: ${envInfo.ci}`, async () => {
+        const token = await generateRegistryUser(`otp-${envInfo.ci}`, "otp");
+        using mockRegistry = Bun.serve({
+          port: 0,
+          fetch: mockRegistryFetch({ token, expectedCI: envInfo.ci }),
+        });
+
+        const bunfig = `
+        [install]
+        cache = false
+        registry = { url = "http://localhost:${mockRegistry.port}", token = "${token}" }`;
+
+        await Promise.all([
+          rm(join(import.meta.dir, "packages", "otp-pkg-4"), { recursive: true, force: true }),
+          write(join(packageDir, "bunfig.toml"), bunfig),
+          write(
+            join(packageDir, "package.json"),
+            JSON.stringify({
+              name: "otp-pkg-4",
+              version: "4.4.4",
+              dependencies: {
+                "otp-pkg-4": "4.4.4",
+              },
+            }),
+          ),
+        ]);
+
+        const { out, err, exitCode } = await publish(
+          { ...env, ...envInfo.envs, ...{ BUILDKITE: undefined, GITHUB_ACTIONS: undefined } },
+          packageDir,
+        );
+        expect(exitCode).toBe(0);
+      });
+    }
   });
 
   test("can publish a package then install it", async () => {
@@ -7873,7 +7919,7 @@ for (const forceWaiterThread of isLinux ? [false, true] : [false]) {
             env: testEnv,
           });
 
-          let err = await Bun.readableStreamToText(stderr);
+          let err = stderrForInstall(await Bun.readableStreamToText(stderr));
           expect(err).toContain("Saved lockfile");
           expect(err).not.toContain("not found");
           expect(err).not.toContain("error:");
@@ -7906,7 +7952,7 @@ for (const forceWaiterThread of isLinux ? [false, true] : [false]) {
             env: testEnv,
           }));
 
-          err = await Bun.readableStreamToText(stderr);
+          err = stderrForInstall(await Bun.readableStreamToText(stderr));
           expect(err).not.toContain("Saved lockfile");
           expect(err).not.toContain("not found");
           expect(err).not.toContain("error:");
@@ -7940,7 +7986,7 @@ for (const forceWaiterThread of isLinux ? [false, true] : [false]) {
             env: testEnv,
           });
 
-          const err = await Bun.readableStreamToText(stderr);
+          const err = stderrForInstall(await Bun.readableStreamToText(stderr));
           expect(err).toContain("Saved lockfile");
           expect(err).not.toContain("not found");
           expect(err).not.toContain("error:");
@@ -7980,7 +8026,7 @@ for (const forceWaiterThread of isLinux ? [false, true] : [false]) {
             env: testEnv,
           });
 
-          let err = await Bun.readableStreamToText(stderr);
+          let err = stderrForInstall(await Bun.readableStreamToText(stderr));
           expect(err).toContain("Saved lockfile");
           expect(err).not.toContain("not found");
           expect(err).not.toContain("error:");
@@ -8067,7 +8113,7 @@ for (const forceWaiterThread of isLinux ? [false, true] : [false]) {
           env: testEnv,
         });
 
-        let err = await Bun.readableStreamToText(stderr);
+        let err = stderrForInstall(await Bun.readableStreamToText(stderr));
         expect(err).toContain("Saved lockfile");
         expect(err).not.toContain("not found");
         expect(err).not.toContain("error:");
@@ -8102,7 +8148,7 @@ for (const forceWaiterThread of isLinux ? [false, true] : [false]) {
           env: testEnv,
         }));
 
-        err = await Bun.readableStreamToText(stderr);
+        err = stderrForInstall(await Bun.readableStreamToText(stderr));
         expect(err).not.toContain("Saved lockfile");
         expect(err).not.toContain("not found");
         expect(err).not.toContain("error:");
@@ -8140,7 +8186,7 @@ for (const forceWaiterThread of isLinux ? [false, true] : [false]) {
           env: testEnv,
         });
 
-        let err = await Bun.readableStreamToText(stderr);
+        let err = stderrForInstall(await Bun.readableStreamToText(stderr));
         expect(err).toContain("Saved lockfile");
         expect(err).not.toContain("not found");
         expect(err).not.toContain("error:");
@@ -8187,7 +8233,7 @@ for (const forceWaiterThread of isLinux ? [false, true] : [false]) {
           env: testEnv,
         }));
 
-        err = await Bun.readableStreamToText(stderr);
+        err = stderrForInstall(await Bun.readableStreamToText(stderr));
         expect(err).toContain("Saved lockfile");
         expect(err).not.toContain("not found");
         expect(err).not.toContain("error:");
diff --git a/test/harness.ts b/test/harness.ts
index fd49ed84ca106a..bb4201261a7848 100644
--- a/test/harness.ts
+++ b/test/harness.ts
@@ -1006,7 +1006,7 @@ export async function runBunInstall(
   });
   expect(stdout).toBeDefined();
   expect(stderr).toBeDefined();
-  let err = (await new Response(stderr).text()).replace(/warn: Slow filesystem.*/g, "");
+  let err = stderrForInstall(await new Response(stderr).text());
   expect(err).not.toContain("panic:");
   if (!options?.allowErrors) {
     expect(err).not.toContain("error:");
@@ -1022,6 +1022,11 @@ export async function runBunInstall(
   return { out, err, exited };
 }
 
+// stderr with `slow filesystem` warning removed
+export function stderrForInstall(err: string) {
+  return err.replace(/warn: Slow filesystem.*/g, "");
+}
+
 export async function runBunUpdate(
   env: NodeJS.ProcessEnv,
   cwd: string,