fix(background-agent): route session prompts by directory

src/shared/index.ts

@@ -71,6 +71,7 @@ export * from "./project-discovery-dirs"
 export * from "./normalize-sdk-response"
 export * from "./record-type-guard"
 export * from "./session-directory-resolver"
+export * from "./session-route"
 export * from "./prompt-tools"
 export * from "./compaction-marker"
 export * from "./internal-initiator-marker"