fix(kanban): preserve shared attachment blobs

hermes_cli/kanban_db.py

@@ -1901,11 +1901,16 @@ def delete_attachment(conn: sqlite3.Connection, attachment_id: int) -> Optional[
         if att is None:
             return None
         conn.execute("DELETE FROM task_attachments WHERE id = ?", (attachment_id,))
+        has_remaining_blob_reference = conn.execute(
+            "SELECT 1 FROM task_attachments WHERE stored_path = ? LIMIT 1",
+            (att.stored_path,),
+        ).fetchone() is not None
         _append_event(conn, att.task_id, "attachment_removed", {"filename": att.filename})
-    with contextlib.suppress(OSError):
-        p = Path(att.stored_path)
-        if p.is_file():
-            p.unlink()
+    if not has_remaining_blob_reference:
+        with contextlib.suppress(OSError):
+            p = Path(att.stored_path)
+            if p.is_file():
+                p.unlink()
     return att
 
 

tests/plugins/test_kanban_attachments.py

@@ -111,6 +111,7 @@ def test_add_list_get_delete_attachment(kanban_home, tmp_path):
         conn.close()
 
 
+
 def test_delete_attachment_missing_returns_none(kanban_home):
     conn = kbc.connect()
     try:
@@ -119,6 +120,36 @@ def test_delete_attachment_missing_returns_none(kanban_home):
         conn.close()
 
 
+def test_delete_attachment_keeps_blob_referenced_by_another_row(kanban_home):
+    conn = kbc.connect()
+    try:
+        task_id = _make_task(conn)
+        blob = kb.task_attachments_dir(task_id) / "shared.txt"
+        blob.parent.mkdir(parents=True, exist_ok=True)
+        blob.write_bytes(b"shared attachment")
+
+        first_id = kb.add_attachment(
+            conn,
+            task_id,
+            filename="first.txt",
+            stored_path=str(blob),
+            size=blob.stat().st_size,
+        )
+        second_id = kb.add_attachment(
+            conn,
+            task_id,
+            filename="second.txt",
+            stored_path=str(blob),
+            size=blob.stat().st_size,
+        )
+
+        assert kb.delete_attachment(conn, first_id) is not None
+        assert blob.exists(), "a surviving attachment row must keep its shared blob"
+        assert kb.get_attachment(conn, second_id) is not None
+    finally:
+        conn.close()
+
+
 def test_attachments_root_is_per_board(kanban_home, monkeypatch):
     # default board uses <root>/kanban/attachments
     default_root = kb.attachments_root(board="default")
@@ -292,5 +323,3 @@ def test_cli_attach_attachments_and_rm(kanban_home, tmp_path):
         assert kb.list_attachments(conn, task_id) == []
     finally:
         conn.close()
-
-