Improved code quality with more idiomatic Python patterns and safer initialization.

crabstero/__main__.py

@@ -80,10 +80,20 @@ def _parse_args(argv: list[str] | None = None) -> argparse.Namespace:
             ' variable or "crabstero.db").'
         ),
     )
+    workers_env = os.environ.get("INGESTION_WORKERS", "4")
+    try:
+        workers_default = int(workers_env)
+    except ValueError:
+        logger.warning(
+            "Invalid INGESTION_WORKERS value '%s', defaulting to 4.",
+            workers_env,
+        )
+        workers_default = 4
+
     parser.add_argument(
         "--ingestion-workers",
         type=int,
-        default=int(os.environ.get("INGESTION_WORKERS", "4")),
+        default=workers_default,
         help=(
             "Number of concurrent ingestion workers"
             " (default: INGESTION_WORKERS environment"

crabstero/bot.py

@@ -30,6 +30,7 @@ from crabstero.cache import IngestCache
 from crabstero.database import Database
 from crabstero.listeners import interaction, message, server_events
 from crabstero.metrics import (
+    CHANNEL_INGESTION_ERRORS,
     DISCORD_EVENTS,
     DISCORD_LATENCY,
     GUILD_COUNT,
@@ -83,10 +84,11 @@ class Crabstero(commands.Bot):
             discord.TextChannel | discord.VoiceChannel
         ] = asyncio.Queue()
         self._ingestion_workers: list[asyncio.Task[None]] = []
-        self.db: Database
+        self._db: Database | None = None
         self.ingest_cache = IngestCache()
 
         self._metrics_address = metrics_address
+        self._metrics_server: MetricsServer | None = None
 
         DISCORD_LATENCY.set_function(lambda: self.latency)
         GUILD_COUNT.set_function(lambda: len(self.guilds))
@@ -95,15 +97,31 @@ class Crabstero(commands.Bot):
         repo_url = "https://git.logal.dev/LogalDeveloper/Crabstero"
         self.http.user_agent = f"DiscordBot ({repo_url}, {crabstero_version})"
 
+    @property
+    def db(self) -> Database:
+        """The active database connection.
+
+        :raises RuntimeError: If accessed before :meth:`setup_hook` has run.
+        """
+        if self._db is None:
+            raise RuntimeError("Database is not initialized")
+        return self._db
+
+    @property
+    def ingest_only(self) -> bool:
+        """Whether the bot is running in ingest-only mode."""
+        return self._ingest_only
+
     async def setup_hook(self) -> None:
         """Open the database, start ingestion workers, and load all cogs."""
-        self.db = await Database.connect(self._database_path)
+        self._db = await Database.connect(self._database_path)
         self.ingest_cache.start()
         self._start_ingestion_workers()
 
         if self._metrics_address is not None:
-            self._metrics_server = MetricsServer(*self._metrics_address)
-            await self._metrics_server.start()
+            server = MetricsServer(*self._metrics_address)
+            await server.start()
+            self._metrics_server = server
 
         if not self._ingest_only:
             await interaction.setup(self)
@@ -143,13 +161,9 @@ class Crabstero(commands.Bot):
         """Log that the bot has started successfully."""
         logger.info("Crabstero started!")
 
-    async def start(self, token: str = "", *, reconnect: bool = True) -> None:
-        """Start the bot using the stored token by default.
-
-        :param token: Optional token override. Falls back to the stored token if empty.
-        :param reconnect: Whether to automatically reconnect on disconnect.
-        """
-        await super().start(token or self._token, reconnect=reconnect)
+    async def start(self, **kwargs: object) -> None:
+        """Start the bot using the token provided at initialization."""
+        await super().start(self._token, **kwargs)
 
     async def close(self) -> None:
         """Cancel ingestion workers, close the database, and then the bot connection."""
@@ -161,10 +175,10 @@ class Crabstero(commands.Bot):
         await asyncio.gather(*self._ingestion_workers, return_exceptions=True)
         self._ingestion_workers.clear()
         self.ingest_cache.stop()
-        if hasattr(self, "_metrics_server"):
+        if self._metrics_server is not None:
             await self._metrics_server.stop()
-        if hasattr(self, "db"):
-            await self.db.close()
+        if self._db is not None:
+            await self._db.close()
         await super().close()
 
     def queue_channel_for_ingestion(
@@ -188,5 +202,8 @@ class Crabstero(commands.Bot):
             channel = await self._ingestion_queue.get()
             try:
                 await ingest_channel(channel, self.db)
+            except Exception:
+                CHANNEL_INGESTION_ERRORS.inc()
+                logger.exception("Ingestion failed for channel %s", channel.id)
             finally:
                 self._ingestion_queue.task_done()

crabstero/listeners/__init__.py

@@ -1 +1,15 @@
+# Copyright 2026 Logan Fick
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
 """Listener cogs for Discord events."""

crabstero/listeners/interaction.py

@@ -47,7 +47,7 @@ class InteractionCog(commands.Cog):
         name="pingme",
         description=(
             "Opts into (or back out of) receiving pings"
-            " for generated message which mention you."
+            " for generated messages which mention you."
         ),
     )
     async def pingme(self, interaction: discord.Interaction) -> None:

crabstero/listeners/message.py

@@ -58,7 +58,7 @@ class MessageCog(commands.Cog):
 
         metrics.MESSAGES_PROCESSED.inc()
 
-        if self.bot._ingest_only:
+        if self.bot.ingest_only:
             # In ingest-only mode, never reply — only ingest eligible messages.
             if message.type == discord.MessageType.default and not isinstance(
                 channel, discord.Thread

crabstero/listeners/server_events.py

@@ -62,13 +62,13 @@ class ServerEventsCog(commands.Cog):
             value=f"{guild.member_count} members",
         )
 
-        if guild.icon:
+        if guild.icon is not None:
             embed.set_image(url=guild.icon.url)
 
         embed.set_footer(text=f"{len(self.bot.guilds)} total servers")
 
         app_info = await self.bot.application_info()
-        if app_info.owner:
+        if app_info.owner is not None:
             with contextlib.suppress(discord.HTTPException):
                 await app_info.owner.send(embed=embed)
 

crabstero/markov.py

@@ -19,6 +19,7 @@ to represent frequency weight. Random selection via ORDER BY RANDOM()
 LIMIT 1 naturally preserves this weighting.
 """
 
+import itertools
 import re
 from typing import TYPE_CHECKING
 
@@ -31,6 +32,19 @@ if TYPE_CHECKING:
 # as is common on Discord.
 DEFAULT_SENTENCE_END = "\u00a7"
 
+_TERMINATORS = frozenset({DEFAULT_SENTENCE_END, ".", "!", "?"})
+_MULTI_SPACE = re.compile(r" +")
+_SENTENCE_SPLIT = re.compile(r"(?<=[.!?]) ")
+
+
+def _normalize_whitespace(text: str) -> str:
+    """Collapse runs of spaces into single spaces and strip edges.
+
+    :param text: The raw text to normalize.
+    :return: The normalized text.
+    """
+    return _MULTI_SPACE.sub(" ", text.strip())
+
 
 def is_complete_sentence(sentence: str) -> bool:
     """Check whether a sentence ends with a valid terminator.
@@ -44,7 +58,7 @@ def is_complete_sentence(sentence: str) -> bool:
     if not sentence:
         return False
 
-    return sentence[-1] in (DEFAULT_SENTENCE_END, ".", "!", "?")
+    return sentence[-1] in _TERMINATORS
 
 
 def _split_sentences(paragraph: str) -> list[str]:
@@ -55,8 +69,8 @@ def _split_sentences(paragraph: str) -> list[str]:
     """
     if not is_complete_sentence(paragraph):
         paragraph += DEFAULT_SENTENCE_END
-    normalized = re.sub(r" +", " ", paragraph.strip().replace("\n", " "))
-    return re.split(r"(?<=[.!?]) ", normalized)
+    normalized = _normalize_whitespace(paragraph.replace("\n", " "))
+    return _SENTENCE_SPLIT.split(normalized)
 
 
 def _tokenize_sentence(
@@ -69,14 +83,10 @@ def _tokenize_sentence(
     """
     if not is_complete_sentence(sentence):
         sentence += DEFAULT_SENTENCE_END
-    words = re.sub(r" +", " ", sentence.strip()).split(" ")
+    words = _normalize_whitespace(sentence).split()
 
-    start_words: list[str] = []
-    transitions: list[tuple[str, str]] = []
-    for i in range(len(words) - 1):
-        if i == 0:
-            start_words.append(words[i])
-        transitions.append((words[i], words[i + 1]))
+    start_words: list[str] = [words[0]] if len(words) >= 2 else []
+    transitions: list[tuple[str, str]] = list(itertools.pairwise(words))
     return start_words, transitions
 
 
@@ -162,8 +172,7 @@ async def generate(
                 " Chat a bit more so I can learn how this channel talks!"
             )
 
-        parts: list[str] = []
-        parts.append(word)
+        parts: list[str] = [word]
         current_length = len(word)
 
         # The loop is skipped if the start word already ends a sentence (e.g. "Yes.").
@@ -185,17 +194,14 @@ async def generate(
             current_length += 1 + len(word)  # +1 for the joining space.
 
             if current_length >= hard_limit:
-                result = " ".join(parts)[:hard_limit]
-                # Strip the internal sentence-end marker if it ended up at the boundary.
-                if result and result[-1] == DEFAULT_SENTENCE_END:
-                    result = result[:-1]
-                metrics.GENERATED_MESSAGE_LENGTH.observe(len(result))
-                return result
+                break
 
         result = " ".join(parts)
+        if current_length >= hard_limit:
+            result = result[:hard_limit]
 
         # Strip the internal sentence-end marker so it never appears in output.
-        if result and result[-1] == DEFAULT_SENTENCE_END:
+        if result.endswith(DEFAULT_SENTENCE_END):
             result = result[:-1]
 
         metrics.GENERATED_MESSAGE_LENGTH.observe(len(result))

crabstero/messages.py

@@ -66,7 +66,7 @@ async def reply_to_message(db: Database, message: discord.Message) -> None:
     else:
         channel_id = channel.id
 
-    body = await markov.generate(db, channel_id, 750, 1000)
+    body = await markov.generate(db, channel_id)
 
     embed = None
 
@@ -76,8 +76,10 @@ async def reply_to_message(db: Database, message: discord.Message) -> None:
         and channel.permissions_for(guild.me).embed_links
     ):
         embed = discord.Embed(
-            title=await markov.generate(db, channel_id, 200, 300),
-            description=await markov.generate(db, channel_id, 300, 500),
+            title=await markov.generate(db, channel_id, soft_limit=200, hard_limit=300),
+            description=await markov.generate(
+                db, channel_id, soft_limit=300, hard_limit=500
+            ),
         )
 
         random_image = await db.get_random_image(channel_id)

crabstero/tasks/__init__.py

@@ -1 +1,15 @@
+# Copyright 2026 Logan Fick
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
 """Background tasks for Crabstero."""

crabstero/tasks/ingestion.py

@@ -59,40 +59,32 @@ async def ingest_channel(
     :param channel: The channel to ingest.
     :param db: The database instance.
     """
-    try:
-        if not channel.permissions_for(channel.guild.me).read_message_history:
-            logger.warning(
-                "[%s] Unable to ingest channel history"
-                " due to lacking permissions. Ignoring.",
-                channel.id,
-            )
-            return
-
-        if await db.is_channel_ingested(channel.id):
-            return
-
-        await db.mark_channel_ingested(channel.id)
-
-        logger.info("[%s] Starting ingestion of textable channel history.", channel.id)
-
-        with metrics.CHANNEL_INGESTION_DURATION.time():
-            count = 0
-            async for message in channel.history(limit=MAXIMUM_MESSAGES_PER_CHANNEL):
-                count += 1
-                await ingest_message(db, message)
-
-        metrics.CHANNEL_INGESTION_MESSAGES.observe(count)
-
-        logger.info(
-            "[%s] Ingestion of channel history complete. %d messages ingested.",
-            channel.id,
-            count,
-        )
-        metrics.CHANNELS_INGESTED.inc()
-
-    except Exception:
-        metrics.CHANNEL_INGESTION_ERRORS.inc()
-        logger.exception(
-            "[%s] An error occurred while ingesting textable channel history!",
+    if not channel.permissions_for(channel.guild.me).read_message_history:
+        logger.warning(
+            "[%s] Unable to ingest channel history"
+            " due to lacking permissions. Ignoring.",
             channel.id,
         )
+        return
+
+    if await db.is_channel_ingested(channel.id):
+        return
+
+    await db.mark_channel_ingested(channel.id)
+
+    logger.info("[%s] Starting ingestion of textable channel history.", channel.id)
+
+    with metrics.CHANNEL_INGESTION_DURATION.time():
+        count = 0
+        async for message in channel.history(limit=MAXIMUM_MESSAGES_PER_CHANNEL):
+            count += 1
+            await ingest_message(db, message)
+
+    metrics.CHANNEL_INGESTION_MESSAGES.observe(count)
+
+    logger.info(
+        "[%s] Ingestion of channel history complete. %d messages ingested.",
+        channel.id,
+        count,
+    )
+    metrics.CHANNELS_INGESTED.inc()

tests/__init__.py

@@ -1 +1,15 @@
+# Copyright 2026 Logan Fick
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
 """Test suite for Crabstero."""

tests/conftest.py

@@ -21,12 +21,12 @@ import pytest
 from crabstero.database import Database
 
 if TYPE_CHECKING:
-    from collections.abc import AsyncIterator
+    from collections.abc import AsyncGenerator
     from pathlib import Path
 
 
 @pytest.fixture
-async def db(tmp_path: Path) -> AsyncIterator[Database]:
+async def db(tmp_path: Path) -> AsyncGenerator[Database]:
     """Yield a Database backed by a temporary SQLite file."""
     database = await Database.connect(str(tmp_path / "test.db"))
     yield database

tests/test_uningest.py

@@ -55,7 +55,7 @@ class TestIngestUningestCycle:
 
         assert await db.get_random_image(1) is None
 
-    async def test_cache_round_trip(self) -> None:
+    def test_cache_round_trip(self) -> None:
         """Cache put then pop returns the original entry."""
         cache = IngestCache()
         entry = CachedMessage(