Let individual SEPA debits be excluded from an export, not just all-or-nothing

The SEPA export dialog always exported every pending direct debit in the
filtered date range with no way to hold one back -- e.g. a member whose
Rücklastschrift is still being clarified had to either be collected again
regardless or the whole run skipped. The table now supports multi-select
(everything selected by default) and the CSV/XML/mail exports only include
the currently selected rows. Deselection survives the refresh() that
_prepare() runs right before exporting (tracked by member_id, not row index,
so a debit newly appearing after a requery still defaults to selected).

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

src/ccma/ui/sepa_dialog.py

@@ -40,7 +40,7 @@ class SepaExportDialog(tk.Toplevel):
 
     def _build_ui(self) -> None:
         self.columnconfigure(0, weight=1)
-        self.rowconfigure(2, weight=1)
+        self.rowconfigure(3, weight=1)
         filters = ttk.Frame(self, padding=12)
         filters.grid(row=0, column=0, sticky="ew")
         ttk.Label(filters, text="Fällig ab").grid(row=0, column=0)
@@ -57,10 +57,23 @@ class SepaExportDialog(tk.Toplevel):
         )
         ttk.Button(filters, text="Liste aktualisieren", command=self.refresh).grid(row=0, column=6)
         ttk.Label(self, textvariable=self.summary_var, style="Mono.TLabel").grid(
-            row=1, column=0, sticky="w", padx=12, pady=(0, 8)
+            row=1, column=0, sticky="w", padx=12, pady=(0, 2)
         )
+        ttk.Label(
+            self,
+            text=(
+                "Standardmäßig sind alle Lastschriften ausgewählt -- einzelne mit Strg+Klick "
+                "abwählen (z. B. während eine Rücklastschrift geklärt wird), um sie erst bei "
+                "einem späteren Einzug zu berücksichtigen."
+            ),
+            style="Muted.TLabel",
+            wraplength=960,
+        ).grid(row=2, column=0, sticky="w", padx=12, pady=(0, 8))
         self.table = ttk.Treeview(
-            self, columns=("number", "name", "iban", "mandate", "purpose", "amount"), show="headings"
+            self,
+            columns=("number", "name", "iban", "mandate", "purpose", "amount"),
+            show="headings",
+            selectmode="extended",
         )
         for key, label, width, anchor in (
             ("number", "Mitglied", 100, "w"), ("name", "Kontoinhaber", 170, "w"),
@@ -69,9 +82,10 @@ class SepaExportDialog(tk.Toplevel):
         ):
             self.table.heading(key, text=label)
             self.table.column(key, width=width, anchor=anchor)
-        self.table.grid(row=2, column=0, sticky="nsew", padx=12)
+        self.table.grid(row=3, column=0, sticky="nsew", padx=12)
+        self.table.bind("<<TreeviewSelect>>", lambda _event: self._update_summary())
         footer = ttk.Frame(self, padding=12)
-        footer.grid(row=3, column=0, sticky="ew")
+        footer.grid(row=4, column=0, sticky="ew")
         footer.columnconfigure(0, weight=1)
         ttk.Label(footer, textvariable=self.warning_var).grid(row=0, column=0, sticky="w")
         ttk.Button(footer, text="CSV-Liste speichern", command=self._save_csv).grid(
@@ -107,6 +121,14 @@ class SepaExportDialog(tk.Toplevel):
         return due_from, due, collection
 
     def refresh(self) -> None:
+        # Preserve which members were deliberately deselected across a refresh (e.g.
+        # _prepare() re-querying right before an export) by identity, not by row index
+        # -- a debit newly appearing in the requeried list still defaults to selected.
+        previously_deselected = {
+            self.debits[int(iid)].member_id
+            for iid in self.table.get_children()
+            if iid not in self.table.selection()
+        }
         try:
             due_from, due, _collection = self._dates()
             self.debits, self.warnings = pending_direct_debits(
@@ -116,18 +138,39 @@ class SepaExportDialog(tk.Toplevel):
             messagebox.showerror("SEPA-Liste konnte nicht erstellt werden", str(exc), parent=self)
             return
         self.table.delete(*self.table.get_children())
-        for debit in self.debits:
+        for index, debit in enumerate(self.debits):
             self.table.insert(
-                "", "end",
+                "", "end", iid=str(index),
                 values=(debit.member_number, debit.account_holder, debit.iban,
                         debit.mandate_reference, debit.purpose, f"{debit.amount:.2f} EUR"),
             )
-        total = sum((item.amount for item in self.debits), Decimal("0"))
+        self.table.selection_set(
-        self.summary_var.set(f"{len(self.debits)} Lastschrift(en) · Summe {total:.2f} EUR")
+            [
+                str(index)
+                for index, debit in enumerate(self.debits)
+                if debit.member_id not in previously_deselected
+            ]
+        )
+        self._update_summary()
         self.warning_var.set(
             f"{len(self.warnings)} unvollständige(s) Mandat(e) übersprungen." if self.warnings else ""
         )
 
+    def _selected_debits(self) -> list:
+        return [self.debits[int(iid)] for iid in sorted(self.table.selection(), key=int)]
+
+    def _update_summary(self) -> None:
+        selected = self._selected_debits()
+        total = sum((item.amount for item in self.debits), Decimal("0"))
+        if len(selected) == len(self.debits):
+            self.summary_var.set(f"{len(self.debits)} Lastschrift(en) · Summe {total:.2f} EUR")
+            return
+        selected_total = sum((item.amount for item in selected), Decimal("0"))
+        self.summary_var.set(
+            f"{len(selected)} von {len(self.debits)} Lastschrift(en) ausgewählt · "
+            f"Summe {selected_total:.2f} EUR (gesamt {total:.2f} EUR)"
+        )
+
     def _prepare(self) -> tuple[date, date, date] | None:
         self.refresh()
         if not self.debits:
@@ -135,6 +178,11 @@ class SepaExportDialog(tk.Toplevel):
                 "Keine Lastschriften", "Für den Stichtag ist nichts einzuziehen.", parent=self
             )
             return None
+        if not self._selected_debits():
+            messagebox.showinfo(
+                "Keine Auswahl", "Bitte mindestens eine Lastschrift auswählen.", parent=self
+            )
+            return None
         if self.warnings and not messagebox.askyesno(
             "Unvollständige Mandate",
             "\n".join(self.warnings[:10]) + "\n\nMit den übrigen Lastschriften fortfahren?",
@@ -157,7 +205,7 @@ class SepaExportDialog(tk.Toplevel):
             return
         target = self._target(".csv", "CSV-Datei", dates[2])
         if target:
-            write_csv(target, self.debits, collection_date=dates[2])
+            write_csv(target, self._selected_debits(), collection_date=dates[2])
             messagebox.showinfo("Export gespeichert", f"CSV gespeichert:\n{target}", parent=self)
 
     def _save_xml(self) -> None:
@@ -169,7 +217,7 @@ class SepaExportDialog(tk.Toplevel):
             return
         try:
             write_pain008(
-                target, self.debits, collection_date=dates[2],
+                target, self._selected_debits(), collection_date=dates[2],
                 organization=self.repository.get_configuration().get("organization") or {},
             )
         except RepositoryError as exc:
@@ -180,7 +228,7 @@ class SepaExportDialog(tk.Toplevel):
     def _open_mail_export(self) -> None:
         dates = self._prepare()
         if dates:
-            SepaMailExportDialog(self, self.repository, self.debits, dates[2])
+            SepaMailExportDialog(self, self.repository, self._selected_debits(), dates[2])
 
 
 class SepaMailExportDialog(tk.Toplevel):