Reuse shared IMAP message listing path

src/govoplan_mail/backend/sending/imap.py

@@ -915,6 +915,71 @@ def _mock_raw_bytes(record: dict[str, Any]) -> bytes:
     return "\n".join(lines).encode("utf-8", errors="replace")
 
 
+def _mock_mailbox_page_offset(
+    records: list[dict[str, Any]],
+    *,
+    offset: int,
+    after_uid: str | None,
+    expected_uidvalidity: str | None,
+) -> tuple[int, bool]:
+    if expected_uidvalidity and expected_uidvalidity != "mock-v1":
+        return 0, True
+    if after_uid:
+        record_ids = [str(record.get("id") or "") for record in records]
+        try:
+            return record_ids.index(str(after_uid)) + 1, False
+        except ValueError:
+            return 0, True
+    return min(offset, len(records)), False
+
+
+def _mock_message_summary(record: dict[str, Any]) -> ImapMailboxMessageSummary:
+    return _message_summary_from_raw(
+        uid=str(record.get("id") or ""),
+        folder=_mock_record_folder(record),
+        raw=_mock_raw_bytes(record),
+        flags=["\\Seen"] if record.get("kind") == "imap_append" else [],
+        size_bytes=int(record.get("size_bytes") or 0) or None,
+    )
+
+
+def _list_mock_imap_messages(
+    *,
+    host: str,
+    port: int,
+    security: str,
+    folder: str,
+    limit: int,
+    offset: int,
+    after_uid: str | None,
+    expected_uidvalidity: str | None,
+) -> ImapMailboxMessageListResult:
+    records = [
+        record
+        for record in list_records(limit=500)
+        if _mock_folder_matches(record, folder)
+    ]
+    effective_offset, cursor_reset = _mock_mailbox_page_offset(
+        records,
+        offset=offset,
+        after_uid=after_uid,
+        expected_uidvalidity=expected_uidvalidity,
+    )
+    page_records = records[effective_offset : effective_offset + limit]
+    return ImapMailboxMessageListResult(
+        host=host,
+        port=port,
+        security=security,
+        folder=folder,
+        messages=[_mock_message_summary(record) for record in page_records],
+        total_count=len(records),
+        offset=effective_offset,
+        limit=limit,
+        uidvalidity="mock-v1",
+        cursor_reset=cursor_reset,
+    )
+
+
 def list_imap_messages(
     *,
     imap_config: ImapConfig,
@@ -929,88 +994,29 @@ def list_imap_messages(
     host, port = _require_imap_config(imap_config)
     folder, limit, offset = _normalize_mailbox_page(folder=folder, limit=limit, offset=offset)
     if is_mock_imap_host(imap_config.host):
-        records = [record for record in list_records(limit=500) if _mock_folder_matches(record, folder)]
+        return _list_mock_imap_messages(
-        cursor_reset = False
-        if expected_uidvalidity and expected_uidvalidity != "mock-v1":
-            effective_offset = 0
-            cursor_reset = True
-        elif after_uid:
-            record_ids = [str(record.get("id") or "") for record in records]
-            try:
-                effective_offset = record_ids.index(str(after_uid)) + 1
-            except ValueError:
-                effective_offset = 0
-                cursor_reset = True
-        else:
-            effective_offset = min(offset, len(records))
-        page_records = records[effective_offset:effective_offset + limit]
-        messages = [
-            _message_summary_from_raw(
-                uid=str(record.get("id") or ""),
-                folder=_mock_record_folder(record),
-                raw=_mock_raw_bytes(record),
-                flags=["\\Seen"] if record.get("kind") == "imap_append" else [],
-                size_bytes=int(record.get("size_bytes") or 0) or None,
-            )
-            for record in page_records
-        ]
-        return ImapMailboxMessageListResult(
             host=host,
             port=port,
             security=imap_config.security.value,
             folder=folder,
-            messages=messages,
-            total_count=len(records),
-            offset=effective_offset,
             limit=limit,
-            uidvalidity="mock-v1",
+            offset=offset,
-            cursor_reset=cursor_reset,
+            after_uid=after_uid,
+            expected_uidvalidity=expected_uidvalidity,
         )
 
     client = _open_imap(imap_config)
     try:
-        total_count, uidvalidity = _select_readonly(client, folder)
+        return _list_imap_messages_on_client(
-        if after_uid is None and expected_uidvalidity is None:
+            client,
-            page_sequences = _paged_descending_sequences(total_count, offset=offset, limit=limit)
-            messages = _fetch_message_summaries_by_sequence(client, page_sequences, folder)
-            return ImapMailboxMessageListResult(
-                host=host,
-                port=port,
-                security=imap_config.security.value,
-                folder=folder,
-                messages=messages,
-                total_count=total_count,
-                offset=offset,
-                limit=limit,
-                uidvalidity=None,
-                cursor_reset=False,
-            )
-        uids = _search_message_uids(client)
-        cursor_reset = False
-        effective_after_uid = after_uid
-        effective_offset = offset
-        if expected_uidvalidity and expected_uidvalidity != uidvalidity:
-            effective_after_uid = None
-            effective_offset = 0
-            cursor_reset = True
-        page_uids, effective_offset, anchor_missing = _paged_descending_uids(
-            uids,
-            offset=effective_offset,
-            limit=limit,
-            after_uid=effective_after_uid,
-        )
-        messages = _fetch_message_summaries_by_uid(client, page_uids, folder)
-        return ImapMailboxMessageListResult(
             host=host,
             port=port,
             security=imap_config.security.value,
             folder=folder,
-            messages=messages,
-            total_count=len(uids) if uids else total_count,
-            offset=effective_offset,
             limit=limit,
-            uidvalidity=uidvalidity,
+            offset=offset,
-            cursor_reset=cursor_reset or anchor_missing,
+            after_uid=after_uid,
+            expected_uidvalidity=expected_uidvalidity,
         )
     finally:
         try:

tests/test_imap_parser.py

@@ -18,6 +18,7 @@ from govoplan_mail.backend.sending.imap import (
     _select_readonly,
     _sequence_set,
     append_message_to_sent,
+    list_imap_messages,
 )
 
 
@@ -79,6 +80,91 @@ class ImapFolderParserTests(unittest.TestCase):
 
 
 class ImapMessagePaginationTests(unittest.TestCase):
+    def test_mock_message_cursor_preserves_order_and_resets_when_stale(self):
+        records = [
+            {
+                "id": "3",
+                "kind": "smtp",
+                "raw_eml": "Subject: Three\r\n\r\nBody",
+                "size_bytes": 26,
+            },
+            {
+                "id": "2",
+                "kind": "smtp",
+                "raw_eml": "Subject: Two\r\n\r\nBody",
+                "size_bytes": 24,
+            },
+        ]
+        config = ImapConfig(host="mock.imap.local")
+
+        with patch(
+            "govoplan_mail.backend.sending.imap.list_records",
+            return_value=records,
+        ):
+            page = list_imap_messages(
+                imap_config=config,
+                after_uid="3",
+                expected_uidvalidity="mock-v1",
+                limit=1,
+            )
+            reset_page = list_imap_messages(
+                imap_config=config,
+                after_uid="3",
+                expected_uidvalidity="stale",
+                limit=1,
+            )
+
+        self.assertEqual([message.uid for message in page.messages], ["2"])
+        self.assertEqual(page.offset, 1)
+        self.assertFalse(page.cursor_reset)
+        self.assertEqual([message.uid for message in reset_page.messages], ["3"])
+        self.assertEqual(reset_page.offset, 0)
+        self.assertTrue(reset_page.cursor_reset)
+
+    def test_real_message_listing_delegates_to_shared_client_path(self):
+        class Client:
+            logged_out = False
+
+            def logout(self):
+                self.logged_out = True
+
+        client = Client()
+        expected = object()
+        config = ImapConfig(host="imap.example.org")
+
+        with (
+            patch(
+                "govoplan_mail.backend.sending.imap._open_imap",
+                return_value=client,
+            ),
+            patch(
+                "govoplan_mail.backend.sending.imap._list_imap_messages_on_client",
+                return_value=expected,
+            ) as list_on_client,
+        ):
+            result = list_imap_messages(
+                imap_config=config,
+                folder=" Archive ",
+                limit=25,
+                offset=5,
+                after_uid="42",
+                expected_uidvalidity="7",
+            )
+
+        self.assertIs(result, expected)
+        self.assertTrue(client.logged_out)
+        list_on_client.assert_called_once_with(
+            client,
+            host="imap.example.org",
+            port=993,
+            security="tls",
+            folder="Archive",
+            limit=25,
+            offset=5,
+            after_uid="42",
+            expected_uidvalidity="7",
+        )
+
     def test_full_message_fetch_uses_partial_range_and_deployment_limit(self):
         class Client:
             command = ""