feat: start resume sessions in new flow

backend/app/agent.py

@@ -17,6 +17,7 @@ from .fsm import (
     gate_allowed,
     initial_turn,
     missing_fields,
+    new_resume_transition,
     process_component_event,
     required_fields,
 )
@@ -867,7 +868,7 @@ class ResumeAgent(ResumeEditingMixin, OptimizationFlowMixin):
         return self.timeline(session_id)
 
     def timeline(self, session_id: str) -> TimelineResponse:
-        session = self._require_session(session_id)
+        session = self._advance_legacy_resume_source_stage(session_id)
         turns = self.database.list_turns(session_id)
         gate = self._gate(session)
         resume = self._resume_view(session)
@@ -885,6 +886,31 @@ class ResumeAgent(ResumeEditingMixin, OptimizationFlowMixin):
             trace_id=self._trace_id(),
         )
 
+    def _advance_legacy_resume_source_stage(self, session_id: str) -> dict[str, Any]:
+        """Move sessions parked on removed source/import screens into new-resume setup."""
+        session = self._require_session(session_id)
+        removed_stages = {Stage.RESUME_SOURCE_SELECT, Stage.RESUME_IMPORT_UPLOAD}
+        if Stage(session["stage"]) not in removed_stages or session.get("resume_id"):
+            return session
+
+        with self.database.transaction(immediate=True) as connection:
+            current = self.database.fetch_session(connection, session_id, for_update=True)
+            if current is None:
+                raise FSMError("session_not_found", "Session not found", status_code=404)
+            if Stage(current["stage"]) not in removed_stages or current.get("resume_id"):
+                return current
+
+            transition = new_resume_transition(current["profile"])
+            self.database.supersede_active_components(connection, session_id)
+            updated = self.database.update_session(
+                connection,
+                session_id,
+                stage=transition.stage,
+                profile=transition.profile,
+            )
+            self.database.insert_turn(connection, session_id=session_id, **transition.turn)
+        return updated
+
     def component_event(
         self, session_id: str, request: ComponentEventRequest
     ) -> ActionResponse: