fix(delete-modal): close modal after successful delete

The success path of handleConfirm() never reset the isSubmitting flag,
so hide()'s early-return guard (line 209: 'if (isSubmitting) return')
kept the modal visible after a successful delete — leaving the user
looking at a stuck 'Deleting...' dialog while the card had already been
removed by the WebSocket SERIES_DELETED event.

Reset isSubmitting and the confirm button text before calling hide(),
and capture currentKey into a local before hide() nulls it so the
follow-up removeSeries() call receives the right key.

tests/frontend/test_delete_modal.py

@@ -318,6 +318,121 @@ class TestDeleteModalSeriesManagerIntegration:
         assert remove_called_with == [key]
 
 
+class TestDeleteModalModalCloseAfterSuccess:
+    """Regression tests for the bug where the modal stayed visible after a
+    successful delete because isSubmitting was never reset on the success path.
+
+    Source-level tests (the JS is not run in pytest): they assert that the
+    handleConfirm success branch (a) clears isSubmitting before hide(), and
+    (b) removes the card via a key captured before hide() nulls currentKey.
+    """
+
+    @staticmethod
+    def _read_source():
+        import os
+        path = os.path.join(
+            os.path.dirname(__file__),
+            '..', '..',
+            'src', 'server', 'web', 'static', 'js', 'index', 'delete-modal.js'
+        )
+        with open(path, 'r') as f:
+            return f.read()
+
+    def test_isSubmitting_reset_on_success_path(self):
+        """isSubmitting must be reset to false after a successful delete,
+        otherwise hide()'s early-return guard keeps the modal visible."""
+        src = self._read_source()
+
+        # Locate the success branch: it begins with "Delete succeeded:" log
+        success_idx = src.find("Delete succeeded:")
+        assert success_idx > 0, "Could not find Delete succeeded log line"
+
+        # Everything between the success log and the catch block belongs to
+        # the success path.
+        catch_idx = src.find("} catch (err)", success_idx)
+        assert catch_idx > 0, "Could not find catch block after success path"
+
+        success_branch = src[success_idx:catch_idx]
+
+        # The flag must be reset in this branch...
+        assert "isSubmitting = false" in success_branch, (
+            "isSubmitting is never reset on the success path — "
+            "this is the bug that left the modal visible with 'Deleting...'"
+        )
+
+        # ...BEFORE hide() is called.
+        reset_pos = success_branch.find("isSubmitting = false")
+        hide_pos = success_branch.find("hide();")
+        assert reset_pos > 0 and hide_pos > 0, (
+            "Could not locate isSubmitting reset or hide() call"
+        )
+        assert reset_pos < hide_pos, (
+            "isSubmitting must be cleared BEFORE hide() — otherwise hide()'s "
+            "guard (`if (isSubmitting) return`) bails out and the modal stays"
+        )
+
+    def test_modal_hidden_class_added_on_success(self):
+        """After the success-path cleanup, hide() must run and apply the
+        'hidden' class. We verify by checking hide() is reached after the
+        isSubmitting reset (covered above) and that the reset precedes the
+        removal of the card from the grid."""
+        src = self._read_source()
+
+        success_idx = src.find("Delete succeeded:")
+        catch_idx = src.find("} catch (err)", success_idx)
+        success_branch = src[success_idx:catch_idx]
+
+        reset_pos = success_branch.find("isSubmitting = false")
+        hide_pos = success_branch.find("hide();")
+        remove_pos = success_branch.find("removeSeries(")
+
+        assert 0 < reset_pos < hide_pos < remove_pos, (
+            "Order on success path must be: "
+            "isSubmitting reset -> hide() -> removeSeries()"
+        )
+
+    def test_removeSeries_uses_captured_key_not_live_currentKey(self):
+        """hide() nulls currentKey on line ~211. If removeSeries reads the
+        live currentKey AFTER hide(), it gets null and silently no-ops. The
+        fix captures the key into a local before hide() runs."""
+        src = self._read_source()
+
+        success_idx = src.find("Delete succeeded:")
+        catch_idx = src.find("} catch (err)", success_idx)
+        success_branch = src[success_idx:catch_idx]
+
+        # There must be a local capture of the key before hide().
+        assert "var deletedKey = currentKey;" in success_branch, (
+            "Success path must capture currentKey into a local before "
+            "hide() nulls it — otherwise removeSeries(currentKey) would be "
+            "a silent no-op."
+        )
+
+        # The removeSeries call must reference the captured local, not
+        # currentKey directly.
+        capture_pos = success_branch.find("var deletedKey = currentKey;")
+        remove_pos = success_branch.find("removeSeries(deletedKey)")
+        assert capture_pos > 0 and remove_pos > 0, (
+            "removeSeries must be called with the captured deletedKey"
+        )
+        assert capture_pos < remove_pos, (
+            "Capture must happen BEFORE removeSeries reads it"
+        )
+
+    def test_confirm_button_text_reset_on_success(self):
+        """The button text is changed to 'Deleting...' during submit and must
+        be reverted to 'Delete' so the modal is in a clean state if reopened."""
+        src = self._read_source()
+
+        success_idx = src.find("Delete succeeded:")
+        catch_idx = src.find("} catch (err)", success_idx)
+        success_branch = src[success_idx:catch_idx]
+
+        assert "confirmBtn.textContent = 'Delete'" in success_branch, (
+            "Confirm button text must be reset to 'Delete' on the success path"
+        )
+
+
 class TestDeleteModalConstants:
     """Tests for SERIES_DELETED WebSocket event constant."""