fix(v2): enforce M1 runtime persistence invariants

backend/alembic/env.py

@@ -3,17 +3,19 @@ from __future__ import annotations
 import importlib
 import os
 from logging.config import fileConfig
+from typing import Any
 
 from alembic import context
-from sqlalchemy import create_engine, pool
+from sqlalchemy import create_engine, event, pool
 from sqlalchemy.engine import URL, make_url
 
-Base = importlib.import_module("backup_tool.db.models").Base
+models = importlib.import_module("backup_tool.db.models")
+sqlite_runtime = importlib.import_module("backup_tool.db.sqlite")
 
 config = context.config
 if config.config_file_name is not None:
     fileConfig(config.config_file_name)
-target_metadata = Base.metadata
+target_metadata = models.Base.metadata
 
 
 def configured_url() -> str:
@@ -23,6 +25,19 @@ def configured_url() -> str:
     return raw_url
 
 
+def busy_timeout_ms() -> int:
+    raw_value = os.environ.get(
+        "BACKUP_TOOL_SQLITE_BUSY_TIMEOUT_MS", str(sqlite_runtime.DEFAULT_BUSY_TIMEOUT_MS)
+    )
+    try:
+        value = int(raw_value)
+    except ValueError as error:
+        raise RuntimeError("SQLite busy timeout must be an integer") from error
+    if value < 1_000 or value > 120_000:
+        raise RuntimeError("SQLite busy timeout must be between 1000 and 120000 ms")
+    return value
+
+
 def synchronous_url(raw_url: str) -> URL:
     url = make_url(raw_url)
     if url.drivername != "sqlite+aiosqlite":
@@ -44,10 +59,17 @@ def run_migrations_offline() -> None:
 
 
 def run_migrations_online() -> None:
+    timeout = busy_timeout_ms()
     engine = create_engine(
         synchronous_url(configured_url()),
         poolclass=pool.NullPool,
+        connect_args=sqlite_runtime.sqlite_connect_args(timeout),
     )
+
+    @event.listens_for(engine, "connect")
+    def configure_sqlite(dbapi_connection: Any, _connection_record: Any) -> None:
+        sqlite_runtime.configure_sqlite_connection(dbapi_connection)
+
     with engine.connect() as connection:
         context.configure(connection=connection, target_metadata=target_metadata, compare_type=True)
         with context.begin_transaction():