Verify each finding against the current code and only fix it if needed.

Inline comments:
In `@docker-compose.yml`:
- Line 34: Uncomment or add the SKIP_TOPIC_IDS environment mapping in
docker-compose.yml so the container receives the .env value by default;
specifically ensure the service's environment includes the line setting
SKIP_TOPIC_IDS to ${SKIP_TOPIC_IDS:-} (or ${SKIP_TOPIC_IDS} if you prefer no
default) so values from .env are propagated into the container at startup.

In `@src/config.py`:
- Around line 371-377: The per-chat debug lines leak chat/topic identifiers (cid
and topics) via logger.debug; remove or replace the loop that logs f"  Chat
{cid}: skipping topics {topics}" in the skip_topic_ids handling. Instead keep
only the aggregated logger.info summary (using total_topics and
len(self.skip_topic_ids)) or log non-identifying metrics (e.g., number of chats
affected and distribution counts) and ensure references to skip_topic_ids remain
but never emit cid or topic IDs.

In `@src/listener.py`:
- Around line 800-817: The metric semantics are inconsistent: when
self.config.listen_new_messages is False the code increments
stats["new_messages_received"] before filtering by should_skip_topic, but when
True it increments after the topic skip check; to unify semantics (count only
messages that pass topic filtering) move the early-return branch for
listen_new_messages (including the stats increment and return) to after
reply_to_top_id is computed and after the should_skip_topic check so that
extract_topic_id(message), self.config.should_skip_topic(chat_id,
reply_to_top_id) and the skip-return logic run first, then increment
stats["new_messages_received"] and return when listen_new_messages is False;
update or add a brief comment near self.config.listen_new_messages,
extract_topic_id, should_skip_topic and stats["new_messages_received"]
explaining the chosen semantics.

In `@src/message_utils.py`:
- Around line 4-18: The function extract_topic_id is missing a type annotation
for its message parameter; add a type hint to the signature (e.g., change def
extract_topic_id(message) -> int | None: to def extract_topic_id(message: Any)
-> int | None:) and import Any from typing at the top of the module, or replace
Any with the concrete message type used in the project (e.g., Telegram Message
class) if available; keep the existing logic and return type unchanged and
update any imports accordingly.

In `@src/telegram_backup.py`:
- Around line 749-752: The loop over messages using self.client.iter_messages
skips messages in excluded forum topics (config.should_skip_topic +
extract_topic_id) but does not record that skipped ranges are intentionally
ignored, so detect_message_gaps() will repeatedly rediscover them; fix by, when
you hit a skipped topic inside that iter_messages loop, explicitly mark the gap
as ignored (e.g. call whatever gap-ignore API your codebase uses—insert an
ignored placeholder row or call self.mark_gap_ignored / self.db.mark_gap_ignored
with chat_id, gap_start, gap_end and topic_id) so detect_message_gaps() will not
report that range again; ensure the marking uses the same identifiers
detect_message_gaps expects.
- Around line 1665-1667: The debug log in the skip logic currently includes
user-controlled topic titles; update the logger call inside the block that
checks should_skip_topic(chat_id, topic.id) to remove any PII by only logging
the topic identifier (topic.id) and not topic.title—i.e., change the
logger.debug that references topic.title to a message that mentions only
topic.id (and any static context text) in the method where the loop performs
should_skip_topic checks.

In `@tests/test_config.py`:
- Around line 585-598: The nested context managers in
test_skip_topic_ids_invalid_format_non_integer (the two nested with statements
that use patch.dict(os.environ, env_vars, clear=True) and
self.assertRaises(ValueError)) should be collapsed into a single with statement
so Ruff SIM117 is not triggered; replace the nested withs around the Config()
instantiation with a single combined context manager that includes both
patch.dict(...) and self.assertRaises(ValueError) so the test still asserts the
exception while satisfying the linter.

---

Outside diff comments:
In `@src/telegram_backup.py`:
- Around line 663-696: Skipped messages currently bypass updating the sync
cursor so running_max_id never advances; inside the loop over iter_messages (in
the async for message ... block) update running_max_id for every message (use
running_max_id = max(running_max_id, message.id)) before continuing when
self.config.should_skip_topic(chat_id, extract_topic_id(message)) is true so
that skipped forum-topic messages still advance the cursor while still not being
added to batch_data or processed by _process_message/_commit_batch.

In `@tests/test_telegram_backup.py`:
- Around line 419-422: The async helper fake_iter currently uses "return"
followed by a dummy "yield" with an invalid "# noqa: unreachable" comment;
change fake_iter to be a real async generator without the bogus noqa by removing
the early return and using a harmless conditional yield (e.g., "if False:
yield") or placing the "yield" before returning so the function is an async
generator; update the function fake_iter in tests/test_telegram_backup.py
accordingly and drop the invalid "# noqa: unreachable" directive.

---

Nitpick comments:
In `@tests/test_config.py`:
- Around line 518-519: The new test suite uses unittest.TestCase
(TestSkipTopicIds) but our project requires pytest-style tests; convert the
class-based TestSkipTopicIds into one or more pytest functions using pytest
fixtures instead of class setup/teardown and remove the unittest.TestCase
inheritance and any self.* usage; replace methods like setUp/tearDown with
fixtures (or module/class-level fixtures) and rename test methods to plain
functions prefixed with test_ so pytest discovers them (e.g.,
test_skip_topic_ids_behavior), ensuring assertions use plain assert and fixtures
are referenced as function args.