fix: read sandbox dependencies when opening remote files (#3250)

Fixes a bug in which users were prompted for sandbox only when editing
local files.

marimo/_cli/sandbox.py

@@ -106,8 +106,9 @@ def _pyproject_toml_to_requirements_txt(
 
 
 def get_dependencies_from_filename(name: str) -> List[str]:
-    if not name or not os.path.exists(name):
+    if not name:
         return []
+
     try:
         contents, _ = FileContentReader().read_file(name)
         return _get_dependencies(contents) or []
@@ -185,7 +186,8 @@ def prompt_run_in_sandbox(name: str | None) -> bool:
             "This notebook has inlined package dependencies.\n"
             + green(
                 "Run in a sandboxed venv containing this notebook's "
-                "dependencies?"
+                "dependencies?",
+                bold=True,
             ),
             default=True,
         )

tests/_cli/test_sandbox.py

@@ -37,6 +37,14 @@ def test_get_dependencies():
     ]
 
 
+def test_get_dependencies_github():
+    url = "https://github.com/marimo-team/marimo/blob/a1e1be3190023a86650904249f911b2e6ffb8fac/examples/third_party/leafmap/leafmap_example.py"
+    assert get_dependencies_from_filename(url) == [
+        "leafmap==0.41.0",
+        "marimo",
+    ]
+
+
 def test_no_dependencies():
     SCRIPT = """
 import marimo