fix(storage): address repository review feedback

backend/packages/storage/store/persistence/base_model.py

@@ -6,20 +6,17 @@ from sqlalchemy.dialects.mysql import LONGTEXT
 from sqlalchemy.ext.asyncio import AsyncAttrs
 from sqlalchemy.orm import DeclarativeBase, Mapped, MappedAsDataclass, declared_attr, mapped_column
 
-from store.common import DataBaseType
-from store.config.app_config import get_app_config
 from store.utils import get_timezone
 
-timezone = get_timezone()
-app_config = get_app_config()
 
-# SQLite autoincrement only works with INTEGER PRIMARY KEY (not BIGINT)
-_id_type = Integer if app_config.storage.driver == DataBaseType.sqlite else BigInteger
+def current_time() -> datetime:
+    return get_timezone().now()
+
 
 id_key = Annotated[
     int,
     mapped_column(
-        _id_type,
+        BigInteger().with_variant(Integer, "sqlite"),
         primary_key=True,
         unique=True,
         index=True,
@@ -33,9 +30,14 @@ id_key = Annotated[
 class UniversalText(TypeDecorator[str]):
     """Cross-dialect long text type (LONGTEXT on MySQL, Text on PostgreSQL)."""
 
-    impl = LONGTEXT if DataBaseType.mysql == app_config.storage.driver else Text
+    impl = Text
     cache_ok = True
 
+    def load_dialect_impl(self, dialect):  # noqa: ANN001
+        if dialect.name == "mysql":
+            return dialect.type_descriptor(LONGTEXT())
+        return dialect.type_descriptor(Text())
+
     def process_bind_param(self, value: str | None, dialect) -> str | None:  # noqa: ANN001
         return value
 
@@ -54,11 +56,13 @@ class TimeZone(TypeDecorator[datetime]):
         return datetime
 
     def process_bind_param(self, value: datetime | None, dialect) -> datetime | None:  # noqa: ANN001
+        timezone = get_timezone()
         if value is not None and value.utcoffset() != timezone.now().utcoffset():
             value = timezone.from_datetime(value)
         return value
 
     def process_result_value(self, value: datetime | None, dialect) -> datetime | None:  # noqa: ANN001
+        timezone = get_timezone()
         if value is not None and value.tzinfo is None:
             value = value.replace(tzinfo=timezone.tz_info)
         return value
@@ -70,14 +74,14 @@ class DateTimeMixin(MappedAsDataclass):
     created_time: Mapped[datetime] = mapped_column(
         TimeZone,
         init=False,
-        default_factory=timezone.now,
+        default_factory=current_time,
         sort_order=999,
         comment="Created at",
     )
     updated_time: Mapped[datetime | None] = mapped_column(
         TimeZone,
         init=False,
-        onupdate=timezone.now,
+        onupdate=current_time,
         sort_order=999,
         comment="Updated at",
     )

backend/packages/storage/store/persistence/factory.py

@@ -70,6 +70,8 @@ def _create_database_url(storage_config: StorageConfig) -> URL:
         url = make_url(storage_config.database_url)
         if storage_config.driver in (DataBaseType.postgresql, "postgres") and url.drivername == "postgresql":
             url = url.set(drivername="postgresql+asyncpg")
+        elif storage_config.driver == DataBaseType.mysql and url.drivername == "mysql":
+            url = url.set(drivername="mysql+aiomysql")
     else:
         url = URL.create(
             drivername=driver,

backend/packages/storage/store/repositories/contracts/run_event.py

@@ -34,6 +34,8 @@ class RunEvent(BaseModel):
 
 
 class RunEventRepositoryProtocol(Protocol):
+    # Sequence values are time-ordered integer cursors. The application layer
+    # owns the single-writer invariant for a thread while a run is active.
     async def append_batch(self, events: list[RunEventCreate]) -> list[RunEvent]: ...
 
     async def list_messages(

backend/packages/storage/store/repositories/db/run_event.py

@@ -1,6 +1,9 @@
 from __future__ import annotations
 
 import json
+import secrets
+import threading
+import time
 from typing import Any
 
 from sqlalchemy import delete, func, select
@@ -9,6 +12,26 @@ from sqlalchemy.ext.asyncio import AsyncSession
 from store.repositories.contracts.run_event import RunEvent, RunEventCreate, RunEventRepositoryProtocol
 from store.repositories.models.run_event import RunEvent as RunEventModel
 
+_SEQ_COUNTER_BITS = 12
+_SEQ_PROCESS_BITS = 9
+_SEQ_PROCESS_SALT = secrets.randbits(_SEQ_PROCESS_BITS)
+_SEQ_COUNTER_LIMIT = 1 << _SEQ_COUNTER_BITS
+_SEQ_TIMESTAMP_SHIFT = _SEQ_COUNTER_BITS + _SEQ_PROCESS_BITS
+_last_seq_millis = 0
+_seq_lock = threading.Lock()
+
+
+def _allocate_sequence_base(batch_size: int) -> int:
+    if batch_size >= _SEQ_COUNTER_LIMIT:
+        raise ValueError(f"Run event batch is too large: {batch_size} >= {_SEQ_COUNTER_LIMIT}")
+
+    global _last_seq_millis
+    now_ms = time.time_ns() // 1_000_000
+    with _seq_lock:
+        seq_ms = max(now_ms, _last_seq_millis + 1)
+        _last_seq_millis = seq_ms
+    return (seq_ms << _SEQ_TIMESTAMP_SHIFT) | (_SEQ_PROCESS_SALT << _SEQ_COUNTER_BITS)
+
 
 def _serialize_content(content: Any, metadata: dict[str, Any]) -> tuple[str, dict[str, Any]]:
     if not isinstance(content, str):
@@ -52,28 +75,17 @@ class DbRunEventRepository(RunEventRepositoryProtocol):
         if not events:
             return []
 
-        thread_ids = {event.thread_id for event in events}
-        seq_by_thread: dict[str, int] = {}
-        for thread_id in thread_ids:
-            max_seq = await self._session.scalar(
-                select(RunEventModel.seq)
-                .where(RunEventModel.thread_id == thread_id)
-                .order_by(RunEventModel.seq.desc())
-                .limit(1)
-                .with_for_update()
-            )
-            seq_by_thread[thread_id] = max_seq or 0
+        seq_base = _allocate_sequence_base(len(events))
 
         rows: list[RunEventModel] = []
 
-        for event in events:
-            seq_by_thread[event.thread_id] += 1
+        for index, event in enumerate(events, start=1):
             content, metadata = _serialize_content(event.content, dict(event.metadata))
             row = RunEventModel(
                 thread_id=event.thread_id,
                 run_id=event.run_id,
                 user_id=event.user_id,
-                seq=seq_by_thread[event.thread_id],
+                seq=seq_base + index,
                 event_type=event.event_type,
                 category=event.category,
                 content=content,

backend/packages/storage/store/repositories/models/feedback.py

@@ -5,10 +5,7 @@ from datetime import datetime
 from sqlalchemy import Integer, String, UniqueConstraint
 from sqlalchemy.orm import Mapped, mapped_column
 
-from store.persistence.base_model import DataClassBase, TimeZone, UniversalText
-from store.utils import get_timezone
-
-_tz = get_timezone()
+from store.persistence.base_model import DataClassBase, TimeZone, UniversalText, current_time
 
 
 class Feedback(DataClassBase):
@@ -33,7 +30,7 @@ class Feedback(DataClassBase):
         "created_at",
         TimeZone,
         init=False,
-        default_factory=_tz.now,
+        default_factory=current_time,
         sort_order=999,
         comment="Created at",
     )

backend/packages/storage/store/repositories/models/run.py

@@ -6,10 +6,7 @@ from typing import Any
 from sqlalchemy import JSON, Index, Integer, String
 from sqlalchemy.orm import Mapped, mapped_column
 
-from store.persistence.base_model import DataClassBase, TimeZone, UniversalText
-from store.utils import get_timezone
-
-_tz = get_timezone()
+from store.persistence.base_model import DataClassBase, TimeZone, UniversalText, current_time
 
 
 class Run(DataClassBase):
@@ -51,7 +48,7 @@ class Run(DataClassBase):
         "created_at",
         TimeZone,
         init=False,
-        default_factory=_tz.now,
+        default_factory=current_time,
         sort_order=999,
         comment="Created at",
     )
@@ -60,7 +57,7 @@ class Run(DataClassBase):
         TimeZone,
         init=False,
         default=None,
-        onupdate=_tz.now,
+        onupdate=current_time,
         sort_order=999,
         comment="Updated at",
     )

backend/packages/storage/store/repositories/models/run_event.py

@@ -3,13 +3,16 @@ from __future__ import annotations
 from datetime import datetime
 from typing import Any
 
-from sqlalchemy import JSON, Index, Integer, String, UniqueConstraint
+from sqlalchemy import JSON, BigInteger, Index, String, UniqueConstraint
 from sqlalchemy.orm import Mapped, mapped_column
 
-from store.persistence.base_model import DataClassBase, TimeZone, UniversalText, id_key
-from store.utils import get_timezone
-
-_tz = get_timezone()
+from store.persistence.base_model import (
+    DataClassBase,
+    TimeZone,
+    UniversalText,
+    current_time,
+    id_key,
+)
 
 
 class RunEvent(DataClassBase):
@@ -31,13 +34,13 @@ class RunEvent(DataClassBase):
     category: Mapped[str] = mapped_column(String(16), index=True)
 
     user_id: Mapped[str | None] = mapped_column(String(64), default=None, index=True)
-    seq: Mapped[int] = mapped_column(Integer, default=0, index=True)
+    seq: Mapped[int] = mapped_column(BigInteger, default=0, index=True)
     content: Mapped[str] = mapped_column(UniversalText, default="")
     meta: Mapped[dict[str, Any]] = mapped_column("event_metadata", JSON, default_factory=dict)
     created_at: Mapped[datetime] = mapped_column(
         TimeZone,
         init=False,
-        default_factory=_tz.now,
+        default_factory=current_time,
         sort_order=999,
         comment="Event timestamp",
     )

backend/packages/storage/store/repositories/models/thread_meta.py

@@ -6,10 +6,7 @@ from typing import Any
 from sqlalchemy import JSON, String
 from sqlalchemy.orm import Mapped, mapped_column
 
-from store.persistence.base_model import DataClassBase, TimeZone
-from store.utils import get_timezone
-
-_tz = get_timezone()
+from store.persistence.base_model import DataClassBase, TimeZone, current_time
 
 
 class ThreadMeta(DataClassBase):
@@ -31,7 +28,7 @@ class ThreadMeta(DataClassBase):
         "created_at",
         TimeZone,
         init=False,
-        default_factory=_tz.now,
+        default_factory=current_time,
         sort_order=999,
         comment="Created at",
     )
@@ -40,7 +37,7 @@ class ThreadMeta(DataClassBase):
         TimeZone,
         init=False,
         default=None,
-        onupdate=_tz.now,
+        onupdate=current_time,
         sort_order=999,
         comment="Updated at",
     )

backend/packages/storage/store/repositories/models/user.py

@@ -5,10 +5,7 @@ from datetime import datetime
 from sqlalchemy import Boolean, Index, String, text
 from sqlalchemy.orm import Mapped, mapped_column
 
-from store.persistence.base_model import DataClassBase, TimeZone
-from store.utils import get_timezone
-
-_tz = get_timezone()
+from store.persistence.base_model import DataClassBase, TimeZone, current_time
 
 
 class User(DataClassBase):
@@ -39,7 +36,7 @@ class User(DataClassBase):
     created_at: Mapped[datetime] = mapped_column(
         TimeZone,
         init=False,
-        default_factory=_tz.now,
+        default_factory=current_time,
         sort_order=999,
         comment="Created at",
     )