Add full shell, replaceable Omics adapter and bilingual interaction

Implement approved specification #32 and tickets #33-#37. Keep host authentication server-verified and pin session interaction language. Compile scoped base selectors for browser compatibility and retain full gutters during CSS pruning.

harness/tht/session/filesystem_repository.py

@@ -106,6 +106,19 @@ class FilesystemSessionRepository:
         path = self._artifact_path(session_dir, key)
         return path.read_text() if path.exists() else None
 
+    def ensure_interaction_language(
+        self, session_id: str, workspace_language: str
+    ) -> SessionSnapshot:
+        from tht.session.store import pin_interaction_language
+
+        session_dir = self._session_dir(session_id)
+        with self._lock(session_dir):
+            self._require_existing(session_dir, session_id)
+            manifest = SessionManifest.from_yaml(session_dir / MANIFEST)
+            if pin_interaction_language(manifest, workspace_language):
+                self._write_manifest(session_dir, manifest)
+        return self.get(session_id)
+
     def write_artifact(self, session_id: str, key: str, content: str) -> None:
         session_dir = self._session_dir(session_id)
         with self._lock(session_dir):

harness/tht/session/language.py

@@ -0,0 +1,23 @@
+"""Session language policy, independent of workspace document content."""
+import re
+
+_LANGUAGE_TAG = re.compile(
+    r"(?P<language>[A-Za-z]{2,8})(?:-(?P<script>[A-Za-z]{4}))?"
+    r"(?:-(?P<region>[A-Za-z]{2}|[0-9]{3}))?"
+    r"(?P<rest>(?:-(?:[A-Za-z0-9]{5,8}|[0-9][A-Za-z0-9]{3}))*"
+    r"(?:-[0-9A-WY-Za-wy-z](?:-[A-Za-z0-9]{2,8})+)*"
+    r"(?:-[xX](?:-[A-Za-z0-9]{1,8})+)?)"
+)
+
+
+def validate_language_tag(value: str) -> str:
+    """Validate syntax and normalize casing without depending on UI catalogs."""
+    match = _LANGUAGE_TAG.fullmatch(value) if isinstance(value, str) else None
+    if match is None:
+        raise ValueError("interaction_language must be a BCP-47 language tag")
+    parts = [match["language"].lower()]
+    if match["script"]:
+        parts.append(match["script"].title())
+    if match["region"]:
+        parts.append(match["region"].upper())
+    return "-".join(parts) + match["rest"].lower()

harness/tht/session/models.py

@@ -8,7 +8,7 @@ from typing import Literal, Self
 
 import portalocker
 import yaml
-from pydantic import BaseModel, ConfigDict, Field
+from pydantic import BaseModel, ConfigDict, Field, field_validator
 
 from tht.decisions import DecisionRecord
 
@@ -119,10 +119,18 @@ class SessionManifest(_YamlModel):
     thinking: str | None = None
     workspace_id: str | None = None
     workspace_revision: str | None = None
+    interaction_language: str | None = None
     name: str | None = None
     archived: bool = False
     group: str | None = None
 
+    @field_validator("interaction_language")
+    @classmethod
+    def valid_interaction_language(cls, value: str | None) -> str | None:
+        from tht.session.language import validate_language_tag
+
+        return validate_language_tag(value) if value is not None else None
+
 
 class SessionSnapshot(BaseModel):
     """The current persisted session state, excluding the non-persistent chat stream."""

harness/tht/session/postgres_repository.py

@@ -306,6 +306,31 @@ class PostgresSessionRepository:
                 raise SessionError(f"Sessione non trovata: {manifest.id}")
         return self.get(manifest.id)
 
+    def ensure_interaction_language(
+        self, session_id: str, workspace_language: str
+    ) -> SessionSnapshot:
+        from tht.session.store import pin_interaction_language
+
+        self._require_uuid4(session_id)
+        with self._transaction() as connection:
+            self._lock_session(connection, session_id)
+            row = connection.execute(
+                text("SELECT manifest FROM thoth_sessions.sessions WHERE id = :id FOR UPDATE"),
+                {"id": session_id},
+            ).mappings().first()
+            if row is None:
+                raise SessionError(f"Sessione non trovata: {session_id}")
+            manifest = SessionManifest.model_validate(row["manifest"])
+            if pin_interaction_language(manifest, workspace_language):
+                connection.execute(
+                    text("UPDATE thoth_sessions.sessions "
+                         "SET manifest = CAST(:manifest AS jsonb), updated_at = pg_catalog.now() "
+                         "WHERE id = :id"),
+                    {"id": session_id,
+                     "manifest": json.dumps(manifest.model_dump(by_alias=True, mode="json"))},
+                )
+        return self.get(session_id)
+
     def read_artifact(self, session_id: str, key: str) -> str | None:
         self._require_uuid4(session_id)
         self._require_artifact_key(key)

harness/tht/session/repository.py

@@ -24,6 +24,10 @@ class SessionRepository(Protocol):
 
     def save_manifest(self, manifest: SessionManifest) -> SessionSnapshot: ...
 
+    def ensure_interaction_language(
+        self, session_id: str, workspace_language: str
+    ) -> SessionSnapshot: ...
+
     def read_artifact(self, session_id: str, key: str) -> str | None: ...
 
     def write_artifact(self, session_id: str, key: str, content: str) -> None: ...

harness/tht/session/store.py

@@ -135,7 +135,7 @@ def create_session(
 
 def new_session_manifest(
     question: str, db: DatabaseConfig, *, provider=None, model=None, thinking=None,
-    workspace_id=None, workspace_revision=None, name=None,
+    workspace_id=None, workspace_revision=None, name=None, interaction_language=None,
 ) -> SessionManifest:
     """Create an unsaved UUIDv4 manifest for a repository-owned session."""
     now = datetime.now(UTC)
@@ -145,9 +145,24 @@ def new_session_manifest(
         summary=_summarize(question), updated_at=now, updated_by=current_author(),
         provider=provider, model=model, thinking=thinking, workspace_id=workspace_id,
         workspace_revision=workspace_revision, name=name,
+        interaction_language=interaction_language,
     )
 
 
+def pin_interaction_language(manifest: SessionManifest, workspace_language: str) -> bool:
+    """Apply legacy compatibility once, while the repository holds its writer lock."""
+    from tht.session.language import validate_language_tag
+
+    if manifest.interaction_language is not None:
+        return False
+    if manifest.status == "finalized" or manifest.archived:
+        raise SessionError("Session is read-only (finalized or archived)")
+    manifest.interaction_language = validate_language_tag(workspace_language)
+    manifest.updated_at = datetime.now(UTC)
+    manifest.updated_by = current_author()
+    return True
+
+
 _ASSUMPTIONS_HEADING = re.compile(
     r"^#{1,6}\s+(?:assunzioni|assumptions)\s*$", re.IGNORECASE | re.MULTILINE
 )