System Overview

TrustRAG operates in two modes with a shared codebase.

Desktop Mode

Flutter Client (Windows / macOS / Linux / Android / iOS)
  └── HTTP/SSE
      └── Embedded Rust Backend (Axum)
          ├── Auth, workspace, document, search, chat, citation, review APIs
          ├── RAG orchestration and provider registry
          └── SQLite + FTS5

The Rust backend binary is bundled inside the Flutter app and started as a child process. Communication happens over localhost HTTP.

Server Mode

Flutter Client (Web / Desktop)
  └── HTTP/SSE via Caddy reverse proxy
      └── Rust Backend (Axum)
          ├── Full API surface
          ├── PostgreSQL + pgvector + pg_trgm
          ├── Redis (caching)
          ├── MinIO (object storage)
          └── Python Document Processor (FastAPI)

Key Design Decisions

Dual-Database Architecture

The backend compiles with either --features postgres or --features desktop. A db::compat module abstracts differences (UUID handling, timestamp functions, boolean literals).

Embedded Backend

Desktop apps bundle the Rust backend binary. The Flutter BackendManager starts it on launch and communicates via HTTP on a local port.

Feature Flags

[features]
default = ["postgres"]
postgres = ["sqlx/postgres"]
desktop = ["sqlx/sqlite"]