refactor(storage): route project DSNs and remove legacy backends

app/infra/db/project_routing.py

@@ -0,0 +1,65 @@
+from __future__ import annotations
+
+from contextlib import contextmanager
+from contextvars import ContextVar, Token
+from dataclasses import dataclass
+from typing import Iterator
+
+from psycopg.conninfo import make_conninfo
+
+from app.core.config import get_pgconn_string, get_timescaledb_pgconn_string
+
+
+@dataclass(frozen=True)
+class ActiveProjectRouting:
+    project_code: str
+    business_dsn: str
+    timescale_dsn: str | None = None
+
+
+_active_project_routing: ContextVar[ActiveProjectRouting | None] = ContextVar(
+    "active_project_routing",
+    default=None,
+)
+
+
+def get_active_project_routing() -> ActiveProjectRouting | None:
+    return _active_project_routing.get()
+
+
+@contextmanager
+def activate_project_routing(
+    routing: ActiveProjectRouting,
+) -> Iterator[ActiveProjectRouting]:
+    token: Token[ActiveProjectRouting | None] = _active_project_routing.set(routing)
+    try:
+        yield routing
+    finally:
+        _active_project_routing.reset(token)
+
+
+def _dsn_for_database(dsn: str, database_name: str) -> str:
+    return make_conninfo(dsn, dbname=database_name)
+
+
+def get_project_pgconn_string(db_name: str | None = None) -> str:
+    routing = get_active_project_routing()
+    if routing is None:
+        return get_pgconn_string(db_name=db_name)
+    if db_name is None or db_name == routing.project_code:
+        return routing.business_dsn
+    return _dsn_for_database(routing.business_dsn, db_name)
+
+
+def get_project_timescale_pgconn_string(db_name: str | None = None) -> str:
+    routing = get_active_project_routing()
+    if routing is None:
+        return get_timescaledb_pgconn_string(db_name=db_name)
+    if routing.timescale_dsn is None:
+        raise RuntimeError(
+            f"TimescaleDB routing is not configured for project {routing.project_code}"
+        )
+    # Legacy simulation code used to derive the Timescale database name from
+    # the project code. Project-scoped requests must instead use the complete
+    # iot_data DSN selected by metadata routing.
+    return routing.timescale_dsn