Prefer final_url over original URL for archive format detection in download paths

Author: Copilot

src/specify_cli/__init__.py

@@ -2632,14 +2632,17 @@ def preset_add(
             from .extensions import detect_archive_format as _det_fmt
 
             with tempfile.TemporaryDirectory() as tmpdir:
-                archive_fmt = _det_fmt(from_url)
                 final_url = from_url
+                archive_fmt = ""
                 try:
                     with urllib.request.urlopen(from_url, timeout=60) as response:
                         final_url = response.geturl()
+                        content_type = response.headers.get("Content-Type", "")
+                        # Prefer the post-redirect URL for format detection;
+                        # fall back to the original URL only as a last hint.
+                        archive_fmt = _det_fmt(final_url, content_type)
                         if not archive_fmt:
-                            content_type = response.headers.get("Content-Type", "")
-                            archive_fmt = _det_fmt(final_url, content_type)
+                            archive_fmt = _det_fmt(from_url)
                         archive_data = response.read()
                 except urllib.error.URLError as e:
                     console.print(f"[red]Error:[/red] Failed to download: {e}")
@@ -3657,18 +3660,22 @@ def extension_add(
                 console.print("Only install extensions from sources you trust.\n")
                 console.print(f"Downloading from {from_url}...")
 
-                # Download archive to temp location; detect format from URL or Content-Type.
+                # Download archive to temp location; detect format from the
+                # post-redirect URL (with Content-Type fallback), only using
+                # the original URL as a last hint.
                 download_dir = project_root / ".specify" / "extensions" / ".cache" / "downloads"
                 download_dir.mkdir(parents=True, exist_ok=True)
-                archive_fmt = detect_archive_format(from_url)
+                final_url = from_url
+                archive_fmt = ""
                 archive_path = None
 
                 try:
                     with urllib.request.urlopen(from_url, timeout=60) as response:
                         final_url = response.geturl()
+                        content_type = response.headers.get("Content-Type", "")
+                        archive_fmt = detect_archive_format(final_url, content_type)
                         if not archive_fmt:
-                            content_type = response.headers.get("Content-Type", "")
-                            archive_fmt = detect_archive_format(final_url, content_type)
+                            archive_fmt = detect_archive_format(from_url)
                         archive_data = response.read()
 
                     # Re-validate scheme after any redirect (scheme-downgrade guard).

src/specify_cli/extensions.py

@@ -2156,17 +2156,19 @@ def download_extension(self, extension_id: str, target_dir: Optional[Path] = Non
 
         version = ext_info.get("version", "unknown")
 
-        # Detect archive format from URL; resolve via Content-Type when needed.
-        # `final_url` may differ from `download_url` if the server redirects.
-        archive_fmt = detect_archive_format(download_url)
-
-        # Download the archive
+        # Download the archive. Determine the archive format from the
+        # post-redirect URL first (with Content-Type fallback); only use the
+        # original `download_url` as a last hint if the final URL gives no
+        # signal.
+        final_url = download_url
+        archive_fmt = ""
         try:
             with self._open_url(download_url, timeout=60) as response:
                 final_url = response.geturl()
+                content_type = response.headers.get("Content-Type", "")
+                archive_fmt = detect_archive_format(final_url, content_type)
                 if not archive_fmt:
-                    content_type = response.headers.get("Content-Type", "")
-                    archive_fmt = detect_archive_format(final_url, content_type)
+                    archive_fmt = detect_archive_format(download_url)
                 archive_data = response.read()
 
         except urllib.error.URLError as e:

src/specify_cli/presets.py

@@ -2313,16 +2313,18 @@ def download_pack(
 
         version = pack_info.get("version", "unknown")
 
-        # Detect archive format from URL; resolve via Content-Type when needed.
-        # `final_url` may differ from `download_url` if the server redirects.
-        archive_fmt = detect_archive_format(download_url)
-
+        # Determine the archive format from the post-redirect URL first
+        # (with Content-Type fallback); only use the original `download_url`
+        # as a last hint if the final URL gives no signal.
+        final_url = download_url
+        archive_fmt = ""
         try:
             with self._open_url(download_url, timeout=60) as response:
                 final_url = response.geturl()
+                content_type = response.headers.get("Content-Type", "")
+                archive_fmt = detect_archive_format(final_url, content_type)
                 if not archive_fmt:
-                    content_type = response.headers.get("Content-Type", "")
-                    archive_fmt = detect_archive_format(final_url, content_type)
+                    archive_fmt = detect_archive_format(download_url)
                 archive_data = response.read()
 
         except urllib.error.URLError as e: