FieldMid Rust Edge Daemon

A read-only PowerSync daemon for monitoring critical field incidents on edge devices. Designed for rugged Linux hardware (industrial PCs, gateways, Raspberry Pi) deployed at remote sites. Features an interactive TUI dashboard and CLI tools for authentication, diagnostics, and incident viewing.

Tech Stack

• Rust (2024 edition)
• PowerSync SDK v0.0.4 — Real-time data sync
• SQLite (via rusqlite) — Local persistent storage
• Ratatui — Terminal UI dashboard
• Crossterm — Terminal control
• Tokio — Async runtime
• Supabase — Authentication and session management
• Serde — JSON serialization

Features

• Local-First & Offline-First — All data (incidents, join requests, user profiles) synced to local SQLite via PowerSync; queries read from local DB first, auto-syncs from cloud when local is empty
• Read-Only Sync — Receives incident data from PowerSync; strictly prevents local writes
• Interactive TUI — Live dashboard showing incidents, escalations, and sync status (auto-detects terminal)
• Headless Mode — Falls back to structured logging when no terminal is available (servers, containers)
• Join Request Management — View pending requests and interactively approve or reject them from the CLI via Supabase RPC
• Browser-Based Login — Authenticate via browser without credentials touching the terminal
• Role-Based Streams — Admins, supervisors, and field workers see different data scoped by 9 PowerSync Sync Streams
• WiFi Telemetry — Monitors signal quality from /proc/net/wireless
• Diagnostics — Built-in doctor command for connectivity and configuration troubleshooting
• curl Install — One-line installer script with platform detection and cargo fallback

Install

curl -fsSL https://fieldmid.com/install.sh | sh

Or build from source:

cargo install --git https://github.com/fieldmid/rust-edge-repo.git

Commands

fieldmid                         # Start daemon (TUI or headless)
fieldmid run                     # Explicit daemon start
fieldmid login                   # Authenticate (browser or email/password)
fieldmid logout                  # Clear session
fieldmid whoami                  # Show current session info
fieldmid users                   # List org users (admin/supervisor only)
fieldmid requests                # View and approve/reject join requests
fieldmid doctor                  # Diagnose environment, DB, DNS, connectivity
fieldmid check-connectivity      # Test PowerSync connection
fieldmid latest-incidents        # Show latest 20 incidents (syncs if local DB empty)
fieldmid install-hint            # Print install options
fieldmid help                    # Show help

Setup

1. Configuration

This binary ships with shared built-in service configuration for all users:

• POWERSYNC_URL: https://69b1eb15d42a433951017c06.powersync.journeyapps.com
• SUPABASE_URL: https://ktohrdqtvqimvcostvcu.supabase.co
• SUPABASE_ANON_KEY: publishable anon key (public)
• FIELDMID_DASHBOARD_URL: https://app.fieldmid.com

No .env file is required.

2. Build & Run

cargo build
cargo run

Or with specific commands:

cargo run -- login
cargo run -- doctor
cargo run -- latest-incidents

Authentication Flow

1. Run fieldmid login — choose browser login (recommended) or email/password
2. Browser opens Supabase auth page; no credentials enter the terminal
3. Session saved to ~/.fieldmid/session.json
4. Select organization (auto-selects if only one exists)
5. Supervisors select which site to monitor

Role-Based Data Streams

Role	Stream	Data
Admin	admin_overview	All org incidents (30-day window)
Supervisor	supervisor_site	All incidents for supervised site
Field Worker	—	Read-only incident access

Architecture

PowerSync Cloud
    |  (real-time sync)
Local SQLite (fieldmid-edge.db)
    |
Watcher threads (incidents, sync status, write guard)
    |
TUI Renderer (ratatui) or Headless Logger

Local Schema (7 tables synced via PowerSync):

• incidents — Safety incidents with severity and AI analysis
• sites — Monitored field sites
• escalations — Escalation tracking
• user_profiles — User roles, org membership, and status
• org_join_requests — Join requests with approval workflow
• notifications — In-app alerts and push notification payloads
• sync_logs — Local sync metadata (local-only, not synced to backend)

Local-First & Offline-First

• PowerSync-synced local SQLite — Incidents, join requests, user profiles, and notifications are synced to a local SQLite database via PowerSync
• Offline reads — All queries (latest-incidents, requests, TUI dashboard) read from local SQLite first. If the local DB is empty, the CLI auto-connects to PowerSync and syncs before showing data
• Offline request queue — Join requests read from the local replica are always available, even without connectivity
• Online actions — Approve/reject decisions are sent to Supabase via RPC when connectivity is available
• Opportunistic sync — The daemon continuously syncs in the background when connected; cached data is shown instantly when offline

Key Design Decisions

• Strict read-only — upload_data() always returns error to prevent accidental writes
• Auto-detect terminal — TUI mode when stdout/stdin are terminals, headless otherwise
• Device auto-ID — Combines hostname + hardware model for unique identification
• Session persistence — JSON file at ~/.fieldmid/session.json
• Write queue guard — Actively monitors and blocks any local modification attempts

Related Repos

Repo	Purpose
supabase-repo	Backend (provides edge_critical_feed PowerSync stream)
core-repo	Web dashboard for supervisors and admins
mobile-app-repo	Mobile app for field incident reporting
mastra-agents-repo	AI agents for triage and escalation
landing-page-repo	Marketing landing page