From 2282c0cd6211d248db12874cc2d128352a2512cb Mon Sep 17 00:00:00 2001
From: 7hokerz <hamahama0925@gmail.com>
Date: Wed, 4 Feb 2026 14:13:18 +0900
Subject: [PATCH 1/2] fix: append bucket name to V4 policy URL in emulator mode

---
 src/file.ts  |  6 +++++-
 test/file.ts | 17 +++++++++++++++++
 2 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/src/file.ts b/src/file.ts
index 5c6f4e681..7a85ae96e 100644
--- a/src/file.ts
+++ b/src/file.ts
@@ -2937,7 +2937,11 @@ class File extends ServiceObject<File, FileMetadata> {
 
         let url: string;
 
-        if (this.storage.customEndpoint) {
+        const EMULATOR_HOST = process.env.STORAGE_EMULATOR_HOST;
+
+        if (this.storage.customEndpoint && typeof EMULATOR_HOST === 'string') {
+          url = `${this.storage.apiEndpoint}/${this.bucket.name}`;
+        } else if (this.storage.customEndpoint) {
           url = this.storage.apiEndpoint;
         } else if (options.virtualHostedStyle) {
           url = `https://${this.bucket.name}.storage.${universe}/`;
diff --git a/test/file.ts b/test/file.ts
index b9a96f8cb..f27de05b4 100644
--- a/test/file.ts
+++ b/test/file.ts
@@ -3578,6 +3578,23 @@ describe('File', () => {
       );
     });
 
+    it('should append bucket name to the URL when using the emulator', done => {
+      const emulatorHost = 'http://127.0.0.1:9199';
+
+      process.env.STORAGE_EMULATOR_HOST = emulatorHost;
+      STORAGE.apiEndpoint = emulatorHost;
+      STORAGE.customEndpoint = true;
+
+      file.generateSignedPostPolicyV4(
+        CONFIG,
+        (err: Error, res: SignedPostPolicyV4Output) => {
+          assert.ifError(err);
+          assert.strictEqual(res.url, `${emulatorHost}/${BUCKET.name}`);
+          done();
+        }
+      );
+    });
+
     describe('expires', () => {
       it('should accept Date objects', done => {
         const expires = new Date(Date.now() + 1000 * 60);

From 55fcf7f25723ac42498f47935e3cdc3ca5849eaa Mon Sep 17 00:00:00 2001
From: 7hokerz <hamahama0925@gmail.com>
Date: Mon, 9 Feb 2026 16:10:04 +0900
Subject: [PATCH 2/2] fix: Set temporary env variables for testing and cleanup

---
 test/file.ts | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/test/file.ts b/test/file.ts
index f27de05b4..14b2070aa 100644
--- a/test/file.ts
+++ b/test/file.ts
@@ -3580,6 +3580,9 @@ describe('File', () => {
 
     it('should append bucket name to the URL when using the emulator', done => {
       const emulatorHost = 'http://127.0.0.1:9199';
+      const originalApiEndpoint = STORAGE.apiEndpoint;
+      const originalCustomEndpoint = STORAGE.customEndpoint;
+      const originalEnvHost = process.env.STORAGE_EMULATOR_HOST;
 
       process.env.STORAGE_EMULATOR_HOST = emulatorHost;
       STORAGE.apiEndpoint = emulatorHost;
@@ -3588,6 +3591,14 @@ describe('File', () => {
       file.generateSignedPostPolicyV4(
         CONFIG,
         (err: Error, res: SignedPostPolicyV4Output) => {
+          STORAGE.apiEndpoint = originalApiEndpoint;
+          STORAGE.customEndpoint = originalCustomEndpoint;
+          if (originalEnvHost) {
+            process.env.STORAGE_EMULATOR_HOST = originalEnvHost;
+          } else {
+            delete process.env.STORAGE_EMULATOR_HOST;
+          }
+
           assert.ifError(err);
           assert.strictEqual(res.url, `${emulatorHost}/${BUCKET.name}`);
           done();