feat(backends,storage,core,markdown,infra): claude agent sdk backend, session store, transcript seeding, runner isolation

src/beaver_gateway/storage/__init__.py

@@ -1,14 +1,14 @@
 """SQLModel-backed persistence.
 
-Two tables — :class:`Token`, :class:`AuditLog` — plus a thin
-:class:`Database` wrapper around an async SQLAlchemy engine. The
-``GatewayRuntime`` carries the handle so auth (token verify / touch)
-and admin (token CRUD + audit listing) can reach it.
+Tokens, audit, conversations, Agent SDK transcript entries and per-turn
+usage, plus a thin :class:`Database` wrapper around an async SQLAlchemy
+engine. ``GatewayRuntime`` carries the handle.
 """
 
 from beaver_gateway.storage.db import (
     Database,
     append_audit,
+    append_usage,
     create_token,
     list_active_tokens,
     list_audit_records,
@@ -16,13 +16,18 @@ from beaver_gateway.storage.db import (
     revoke_token,
     touch_token,
 )
-from beaver_gateway.storage.models import AuditLog, Token
+from beaver_gateway.storage.models import AuditLog, Token, TranscriptEntry, Usage
+from beaver_gateway.storage.session_store import PostgresSessionStore
 
 __all__ = [
     "AuditLog",
     "Database",
+    "PostgresSessionStore",
     "Token",
+    "TranscriptEntry",
+    "Usage",
     "append_audit",
+    "append_usage",
     "create_token",
     "list_active_tokens",
     "list_audit_records",