diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index d291b02..6c9fed2 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -154,3 +154,36 @@ jobs:
         }
         Write-Host "Successfully downloaded artifact without decompressing: $rawFile (size: $($fileInfo.Length) bytes)"
       shell: pwsh
+
+    # Regression test for artifact filename vs content-type mismatch
+    # When an archived artifact has a name with a file extension that doesn't
+    # match the blob type (e.g. "report.txt" but blob is zip), the server
+    # should append .zip to the content-disposition filename.
+    - name: Create and upload archived artifact with misleading extension
+      shell: bash
+      run: |
+        mkdir -p path/to/extension-test
+        echo '{"key": "value"}' > path/to/extension-test/data.json
+    - uses: actions/upload-artifact@v4
+      with:
+        name: report.txt-${{ matrix.runs-on }}
+        path: path/to/extension-test/data.json
+
+    - name: Download misleading-extension artifact without decompressing
+      uses: ./
+      with:
+        name: report.txt-${{ matrix.runs-on }}
+        path: ext-test/raw
+        skip-decompress: true
+
+    - name: Verify downloaded file has .zip extension appended
+      shell: bash
+      run: |
+        expected="ext-test/raw/report.txt-${{ matrix.runs-on }}.zip"
+        if [ -f "$expected" ]; then
+          echo "PASS: Downloaded file has .zip appended: $expected"
+        else
+          echo "FAIL: Expected $expected but got:"
+          ls -al ext-test/raw/
+          exit 1
+        fi