Getting Started
System Architecture

How all the parts of BuildOS fit together — explained for a product and business audience, without diving into implementation details.

The Big Picture

BuildOS is a multi-component system. Three distinct interfaces serve three distinct audiences, all backed by a shared data platform and a set of AI agents that run continuously in the background.

User Interfaces
🖥
Web Dashboard
Tom & Sarah & Mike
Desktop browser
📱
Mobile App
Carlos (field)
iPhone & Android
Core Platform
⚙️
BuildOS API
All business logic
Schedule engine
🗄
Database
PostgreSQL
Single source of truth
Job Queue
River (background tasks)
Scheduled & event-driven
External Services
🔐
FB-Brain
Identity & login
Agent coordination
🧠
Claude AI
Briefings & decisions
Tribunal reasoning
🌤
Tomorrow.io
Hourly weather forecasts
Site-specific
💬
Twilio & Firebase
SMS to subs
Push to field app

Three Interface Tiers

Tier 1 — Web Dashboard (Desktop)

The primary interface for Tom, Sarah, and Mike. A browser-based application that provides the full management experience: portfolio financials, project schedules and Gantt charts, the pre-construction pipeline Kanban, procurement tracking, fleet allocation, HR records, and the notification feed. This is a dark-themed, data-dense application designed for power users who are managing multiple projects simultaneously.

🖥
The web dashboard is built with modern web components — fast, responsive, and designed to work well on large monitors with multiple panels open side by side. No app install required.

Tier 2 — Mobile App (Field)

The interface for Carlos and field crews. A native mobile app (iPhone and Android) designed for outdoor use on construction sites. It shows the day's assigned tasks, allows progress reporting with photos and a percent-complete slider, handles GPS-tagged crew check-ins, and supports daily field log notes. Crucially, it is offline-first: everything a field worker needs for the day is pre-loaded, and any updates made without connectivity are stored locally and synced automatically the moment coverage is restored.

📶
No connectivity = no problem. The mobile app uses a local database on the device as a buffer. Updates are queued and synced in order when signal returns. The office sees a "pending sync" indicator until the data is confirmed — no data is ever lost.

Tier 3 — Background Agents (Autonomous)

The four AI agents operate entirely without a user interface — they run on a schedule (or in response to events) and write their outputs to the notification feed, send SMS messages, or queue actions for human approval. Users never "use" the agents directly; they experience them through the results that appear in their feed and on their phones. See AI Agents for full detail.

How Data Flows Through the System

A single field action — Carlos marking a task complete — illustrates how information moves through the platform:

1
Carlos taps "Complete" on his phone Field App
The app records the update locally with a GPS coordinate and photo. If offline, it queues it. If online, it sends it immediately.
2
BuildOS API receives the progress report API
The API validates the update, marks the task complete in the database, and checks for duplicate submissions (idempotency — safe to retry if there was a network hiccup).
3
Schedule engine recalculates CPM Engine
Because this task's completion unlocks dependent tasks, the schedule recalculates instantly. New early and late dates are written to the database for downstream tasks.
4
Mike receives a push notification Firebase
"[Carlos] completed WBS 9.2 — Second Floor Framing. Framing Inspection is next: April 8."
5
Tom's dashboard updates live Web Dashboard
The project's schedule progress and percent complete update in real time. Tom sees an accurate picture without any manual reporting.
6
Sub Liaison Agent triggers if next task needs a sub Agent
If "Framing Inspection" requires a subcontractor, the Sub Liaison Agent automatically sends an SMS confirmation to the inspector — without anyone asking it to.

Multi-Tenancy — One Platform, Many GC Firms

BuildOS is a multi-tenant platform. Each general contractor firm is a fully isolated organization. One firm's projects, financials, employees, and data are completely invisible to any other firm on the platform. All data is scoped to an organization — there is no sharing between tenants.

Within an organization, users are assigned roles (owner, admin, superintendent, field_worker) that determine what they can see and do. A superintendent at Firm A sees only Firm A's projects. See Roles & Permissions for the full breakdown.

The Job Queue — How Background Work Gets Done

Many of the most powerful things BuildOS does happen in the background, without a user triggering them. The platform uses a job queue — a scheduling system for background tasks — to orchestrate this work. Think of it as the engine room: all the scheduled and automatic tasks are queued up and executed reliably, even if the server was briefly unavailable.

JobWhen It RunsWhat It Does
Daily BriefingEvery day, 6 AM UTCGenerates the AI morning briefing for each superintendent
Procurement CheckEvery day, 5 AM UTCChecks all material lead times and updates status / creates alerts
Sub Liaison ScanEvery day, 12 PM UTCIdentifies upcoming tasks needing sub confirmation and sends SMS
Corporate RollupEvery day, 4 AM UTCAggregates all project budgets to the org-level dashboard
Certification AlertsEvery Monday, 7 AM UTCChecks for expiring employee certifications and creates alerts
Maintenance RemindersEvery Monday, 8 AM UTCSurfaces equipment due for service
Delay CascadeTriggered by delay reportsRecalculates the schedule when a sub reports a delay via SMS
Permit TransitionTriggered by permit approvalCreates the project and initializes the CPM schedule atomically
Hydrate ProjectTriggered on project createPopulates the project's full task list from the WBS template
Field Notification RetryTriggered by push failureRetries failed push notifications with exponential backoff

Identity & Security

BuildOS does not manage its own usernames and passwords. Authentication is handled by FB-Brain, an identity platform that issues secure login tokens (JWTs). When a user logs in, FB-Brain verifies their identity and provides BuildOS with a signed token that contains the user's role and organization. BuildOS trusts this token — it never handles passwords directly.

This means single sign-on is built in. If a firm already uses FB-Brain for other tools, the same login works for BuildOS. Role assignments are managed by the organization owner through the platform.

The AI agents use a separate, more restricted authentication channel (a signed webhook mechanism) so they cannot be impersonated. All communication between components is authenticated.

Data Integrity Guarantees

BuildOS is designed around a "no silent failures" principle. Several technical decisions exist specifically to prevent data corruption or subtle errors:

Zero rounding errors on money
All financial values are stored as whole cents (integers), never as decimals. This eliminates the floating-point rounding errors that cause spreadsheet totals to be off by a penny. Every monetary field also carries a currency code (USD or CAD) — the system never mixes currencies in a single calculation.
Deterministic scheduling
The CPM schedule engine uses integer math throughout — no floating point. Given the same inputs, it will always produce exactly the same schedule. This means schedules are auditable, reproducible, and immune to accumulated rounding drift over time.
Idempotent field sync
Every field progress report carries a unique ID. If Carlos's phone sends the same update twice (network retry), the server detects the duplicate and ignores the second one. No double-counting, no ghost completions.
Transactional permit gate
When a permit is approved, the transition from pipeline prospect to active project happens in a single database transaction — all steps succeed together or none do. There is no intermediate state where a project exists without a schedule, or a schedule exists without a project.