feat(harness): add local session repository

harness/tht/session/repository.py

@@ -0,0 +1,43 @@
+"""Storage contract for the durable, user-owned session workflow state."""
+
+from __future__ import annotations
+
+from typing import Protocol, Sequence
+
+from tht.decisions import DecisionInput, DecisionRecord
+from tht.session.models import PrincipalContext, SessionManifest, SessionSnapshot
+
+
+class SessionRepository(Protocol):
+    """Persistence boundary shared by local files and the server database adapter."""
+
+    principal: PrincipalContext
+
+    def create(self, manifest: SessionManifest) -> SessionSnapshot: ...
+
+    def get(self, session_id: str) -> SessionSnapshot: ...
+
+    def save_manifest(self, manifest: SessionManifest) -> SessionSnapshot: ...
+
+    def read_artifact(self, session_id: str, key: str) -> str | None: ...
+
+    def write_artifact(self, session_id: str, key: str, content: str) -> None: ...
+
+    def append_decisions(
+        self, session_id: str, decisions: Sequence[DecisionInput | dict]
+    ) -> list[DecisionRecord]: ...
+
+    def get_preferences(self) -> dict: ...
+
+    def set_preferences(self, preferences: dict) -> None: ...
+
+    def delete(self, session_id: str) -> None: ...
+
+
+def build_session_repository(config, principal: PrincipalContext, *, home=None) -> SessionRepository:
+    """Build the local adapter for Task 1; server selection arrives with Task 2."""
+    from tht.config import local_tht_home
+    from tht.session.filesystem_repository import FilesystemSessionRepository
+
+    workspace = getattr(config, "_workspace_id", "default")
+    return FilesystemSessionRepository(home or local_tht_home(), workspace, principal)