Preserve leading '/' when opening tree filter and add initial_text parameter

sqlit/domains/explorer/ui/mixins/tree_filter.py

@@ -42,13 +42,17 @@ class TreeFilterMixin:
         "procedures",
     }
 
-    def action_tree_filter(self: TreeFilterMixinHost) -> None:
+    def action_tree_filter(self: TreeFilterMixinHost, initial_text: str | None = None) -> None:
         """Open the tree filter."""
         if not self.object_tree.has_focus:
             self.object_tree.focus()
 
+        if initial_text is None:
+            opened_with_slash = getattr(self, "_last_key_char", None) == "/" or getattr(self, "_last_key", None) == "slash"
+            initial_text = "/" if opened_with_slash else ""
+
         self._tree_filter_visible = True
-        self._tree_filter_text = ""
+        self._tree_filter_text = initial_text
         self._tree_filter_query = ""
         self._tree_filter_fuzzy = False
         self._tree_filter_regex_mode = False
@@ -162,7 +166,7 @@ def on_key(self: TreeFilterMixinHost, event: Any) -> None:
                 return
 
             if key == "/":
-                self.action_tree_filter()
+                self.action_tree_filter("/")
                 event.prevent_default()
                 event.stop()
                 return
@@ -185,7 +189,7 @@ def on_key(self: TreeFilterMixinHost, event: Any) -> None:
         char = getattr(event, "character", None)
         if char and char.isprintable():
             if char == "/" and not self._tree_filter_typing:
-                self.action_tree_filter()
+                self.action_tree_filter("/")
                 event.prevent_default()
                 event.stop()
                 return
@@ -232,7 +236,7 @@ def _update_tree_filter(self: TreeFilterMixinHost) -> None:
             self._tree_filter_matches = []
             self._tree_filter_applied = False
             self._ensure_tree_filter_search_nodes_loaded()
-            self.tree_filter_input.set_filter("", 0, total)
+            self.tree_filter_input.set_filter(raw_text, 0, total)
             return
 
         self._ensure_tree_filter_search_nodes_loaded()

sqlit/shared/ui/protocols/explorer.py

@@ -46,7 +46,7 @@ def _get_node_kind(self, node: Any) -> str:
     def _activate_tree_node(self, node: Any) -> None:
         ...
 
-    def action_tree_filter(self) -> None:
+    def action_tree_filter(self, initial_text: str | None = None) -> None:
         ...
 
     def action_tree_filter_close(self) -> None:

tests/unit/test_tree_filter.py

@@ -187,3 +187,29 @@ def test_tree_filter_invalid_regex_does_not_raise() -> None:
     assert host._tree_filter_regex_error
     assert host._tree_filter_matches == []
     assert host.tree_filter_input.last_filter == (r"/(orders", 0, 2)
+
+
+def test_tree_filter_opened_by_slash_keeps_slash_visible() -> None:
+    root = FakeNode("root")
+    root.add("Tables", FolderNode(folder_type="tables"))
+    host = FakeTreeFilterHost(root)
+    host._last_key = "slash"
+    host._last_key_char = "/"
+
+    host.action_tree_filter()
+
+    assert host._tree_filter_text == "/"
+    assert host._tree_filter_regex_mode is True
+    assert host.tree_filter_input.last_filter == ("/", 0, 1)
+
+
+def test_tree_filter_empty_regex_prefix_remains_visible() -> None:
+    root = FakeNode("root")
+    root.add("Tables", FolderNode(folder_type="tables"))
+    host = FakeTreeFilterHost(root)
+    host._tree_filter_text = "/"
+
+    host._update_tree_filter()
+
+    assert host._tree_filter_regex_mode is True
+    assert host.tree_filter_input.last_filter == ("/", 0, 1)