maybe-finance/maybe
The personal finance app for everyone
12 hidden assumptions · 6-stage pipeline · 6 components
Like any codebase, this fullstack makes assumptions it never checks — most are routine. The ones worth your attention are below.
Personal finance web app for tracking accounts, transactions, and financial health
Users interact with the Rails web interface to manage their financial accounts and view transaction data. HTTP requests flow through Rails controllers that authenticate users, query the PostgreSQL database for financial data, and render responses using reusable design system components. Background jobs handle data synchronization with external financial services, importing new transactions and updating account balances asynchronously.
Under the hood, the system uses 2 feedback loops, 3 data pools, 3 control points to manage its runtime behavior.
A 6-component fullstack. 844 files analyzed. Data flows through 6 distinct pipeline stages.
Hidden Assumptions
Most of what this code assumes is routine. These 3 are the ones most likely to cause trouble here. The rest are minor; they're under "Show everything".
If Stimulus controller file is named differently or naming convention changes, close button clicks fail silently with no visible error to users
Form submission buttons inside dialogs can submit invalid data or trigger navigation away from dialog without proper cleanup, leaving background modals stuck open
If any controller file has syntax errors, wrong extension, or doesn't export default class, entire Stimulus application fails to initialize breaking all interactive features
Show everything (9 more)
Placement string values like 'bottom-end' match exact Floating UI positioning API without validation
If this fails: Typos in placement ('botom-end') cause menus to render in default position instead of intended location, creating confusing UX where menus appear far from triggers
app/components/DS/menu.rb:initialize placement parameter
Header block content is HTML-safe and doesn't contain malicious scripts when passed through capture(&block)
If this fails: User-provided content in dialog headers could inject XSS attacks if content bypasses Rails sanitization elsewhere in the stack
app/components/DS/dialog.rb:renders_one :header block parameter
All DS::Button instances accept arbitrary data attributes and merge them properly with existing data attributes
If this fails: If DS::Button component overwrites data attributes instead of merging, dialog close functionality breaks as data-action gets lost
app/components/DS/dialog.rb:DS::Button.new with data actions
Array elements are rendered in order with subtitle always appearing between title and block content
If this fails: If subtitle is conditionally nil but block content exists, header layout breaks as subtitle spacing disappears creating visual inconsistency
app/components/DS/dialog.rb:safe_join([ title_div, subtitle, block_content ])
Stimulus target naming with double underscores gets properly converted to dashes in DOM and matches controller target definitions
If this fails: If target name conversion fails, menu button clicks don't register with Stimulus controller leaving menus unopenable
app/components/DS/menu.rb:data: { DS__menu_target: 'button' }
Application can handle loading all Stimulus controllers upfront without memory or performance constraints
If this fails: In large applications, eager loading all controllers increases initial page load time and memory usage even for pages that don't need most controllers
app/javascript/controllers/index.js:eager loading strategy
Offset value of 12 represents pixels and matches the unit system expected by Floating UI positioning library
If this fails: If Floating UI expects different units (em, rem, %) the menu positioning will be incorrect, potentially overlapping triggers or appearing off-screen
app/components/DS/menu.rb:offset parameter
Width classes like 'lg:max-w-[300px]' are valid Tailwind CSS classes and will be included in the compiled CSS
If this fails: If Tailwind CSS doesn't recognize arbitrary values or responsive prefixes, dialogs render without width constraints causing layout issues on different screen sizes
app/components/DS/dialog.rb:WIDTHS hash constants
DS::MenuItem component exists and is properly defined with compatible interface
If this fails: If DS::MenuItem is missing or has incompatible initialize signature, menu item rendering fails with obscure error messages
app/components/DS/menu.rb:renders_many :items, DS::MenuItem
Open the standalone hidden-assumptions report for maybe →
How Data Flows Through the System
Users interact with the Rails web interface to manage their financial accounts and view transaction data. HTTP requests flow through Rails controllers that authenticate users, query the PostgreSQL database for financial data, and render responses using reusable design system components. Background jobs handle data synchronization with external financial services, importing new transactions and updating account balances asynchronously.
- User Authentication — ApplicationController authenticates incoming requests using Rails sessions, redirecting unauthenticated users to login and establishing user context for data access [HTTP request with session → User] (config: SECRET_KEY_BASE, RAILS_FORCE_SSL)
- Request Routing — Rails router maps incoming URLs to specific controller actions based on REST conventions and custom routes defined in config/routes.rb [HTTP request → Controller action invocation]
- Data Retrieval — Controllers query ActiveRecord models to fetch user-specific financial data from PostgreSQL, applying filters and associations to load accounts, transactions, and related data [User context → Account and Transaction collections] (config: POSTGRES_USER, POSTGRES_PASSWORD, DB_HOST)
- Component Rendering — Views compose pages using DS design system components, passing data and configuration options to render interactive UI elements like dialogs, menus, and forms [Account and Transaction collections → HTML with Stimulus controllers]
- Frontend Interaction — Stimulus controllers attached to DOM elements handle user interactions, making AJAX requests, updating UI state, and managing component behavior like menu positioning [DOM events → UI state changes]
- Background Synchronization — SyncJob processes run asynchronously to fetch data from external financial services, parse transaction feeds, and update account balances in the database [Account sync settings → Updated transactions and balances] (config: REDIS_URL)
Data Models
The data structures that flow between stages — the contracts that hold the system together.
app/models/user.rbActiveRecord model with email, encrypted_password, and authentication fields plus preferences and settings
Created during registration, authenticated on login, referenced throughout the app for data ownership and permissions
app/models/account.rbActiveRecord model with name, account_type, balance, currency, institution details, and sync settings
Created manually or via data import, updated with balance changes, categorized by type (checking, savings, investment, etc.)
app/models/transaction.rbActiveRecord model with amount, date, description, category, account_id, and metadata for categorization and analysis
Created from bank imports or manual entry, categorized for analysis, aggregated for reporting and balance calculations
app/components/DS/*.rbRuby hashes with variant, size, icon, text, styling options, and behavioral flags like auto_open or destructive
Passed from controllers to views, validated in component initializers, converted to HTML attributes and CSS classes
System Behavior
How the system operates at runtime — where data accumulates, what loops, what waits, and what controls what.
Data Pools
Primary data store containing users, accounts, transactions, and financial metadata with Rails migrations managing schema evolution
Stores ActionCable WebSocket connections and background job queues for real-time features and async processing
Server-side session storage maintaining user authentication state and temporary UI preferences across requests
Feedback Loops
- Account Balance Updates (training-loop, balancing) — Trigger: New transaction import or manual entry. Action: Recalculate account balance by summing all transaction amounts and update the account record. Exit: Balance matches transaction sum.
- Data Sync Retry (retry, balancing) — Trigger: Failed external API call during account synchronization. Action: Background job reschedules itself with exponential backoff to retry data fetch from financial institution. Exit: Successful data sync or max retry limit reached.
Delays
- Background Job Processing (async-processing, ~Variable based on external API response times) — Account data synchronization happens asynchronously, users see loading states until jobs complete
- Component Rendering (cache-ttl, ~Milliseconds per component) — Design system components validate props and generate CSS classes on each render
Control Points
- Self-hosted Mode (feature-flag) — Controls: Enables self-hosting features and disables SaaS-specific functionality. Default: true
- SSL Configuration (env-var) — Controls: Forces HTTPS connections and SSL certificate validation in production. Default: RAILS_FORCE_SSL, RAILS_ASSUME_SSL
- Database Connection Pool (runtime-toggle) — Controls: Maximum number of concurrent database connections available to the Rails application. Default: RAILS_MAX_THREADS (default 3)
Technology Stack
Web framework providing MVC structure, ORM, routing, and asset pipeline for the personal finance application
Primary database storing user accounts, financial transactions, and application data with ACID compliance
JavaScript framework adding progressive enhancement and interactivity to server-rendered HTML components
Caching layer and message broker for ActionCable WebSocket connections and background job queues
Utility-first CSS framework used within design system components for consistent styling and responsive design
JavaScript library handling dynamic positioning of dropdown menus and tooltips with collision detection
Key Components
- ApplicationController (orchestrator) — Base controller providing authentication, authorization, error handling, and common request processing for all HTTP endpoints
app/controllers/application_controller.rb - DS::Dialog (adapter) — Reusable modal and drawer component that renders structured content with header, body, and actions using Stimulus for interaction behavior
app/components/DS/dialog.rb - DS::Menu (adapter) — Dropdown menu component with floating UI positioning that handles button triggers, menu items, and click-outside behavior
app/components/DS/menu.rb - AccountsController (orchestrator) — Handles CRUD operations for financial accounts, including creation, editing, balance updates, and data synchronization
app/controllers/accounts_controller.rb - TransactionsController (orchestrator) — Manages transaction display, filtering, categorization, and bulk operations for financial transaction data
app/controllers/transactions_controller.rb - SyncJob (processor) — Background job that synchronizes account data with external financial institutions, updating balances and importing new transactions
app/jobs/sync_job.rb
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Frequently Asked Questions
What is maybe used for?
Personal finance web app for tracking accounts, transactions, and financial health maybe-finance/maybe is a 6-component fullstack written in Ruby. Data flows through 6 distinct pipeline stages. The codebase contains 844 files.
How is maybe architected?
maybe is organized into 4 architecture layers: Web Interface, Business Logic, Data Layer, Configuration. Data flows through 6 distinct pipeline stages. This layered structure keeps concerns separated and modules independent.
How does data flow through maybe?
Data moves through 6 stages: User Authentication → Request Routing → Data Retrieval → Component Rendering → Frontend Interaction → .... Users interact with the Rails web interface to manage their financial accounts and view transaction data. HTTP requests flow through Rails controllers that authenticate users, query the PostgreSQL database for financial data, and render responses using reusable design system components. Background jobs handle data synchronization with external financial services, importing new transactions and updating account balances asynchronously. This pipeline design reflects a complex multi-stage processing system.
What technologies does maybe use?
The core stack includes Ruby on Rails (Web framework providing MVC structure, ORM, routing, and asset pipeline for the personal finance application), PostgreSQL (Primary database storing user accounts, financial transactions, and application data with ACID compliance), Stimulus (JavaScript framework adding progressive enhancement and interactivity to server-rendered HTML components), Redis (Caching layer and message broker for ActionCable WebSocket connections and background job queues), Tailwind CSS (Utility-first CSS framework used within design system components for consistent styling and responsive design), Floating UI (JavaScript library handling dynamic positioning of dropdown menus and tooltips with collision detection). A focused set of dependencies that keeps the build manageable.
What system dynamics does maybe have?
maybe exhibits 3 data pools (PostgreSQL Database, Redis Cache), 2 feedback loops, 3 control points, 2 delays. The feedback loops handle training-loop and retry. These runtime behaviors shape how the system responds to load, failures, and configuration changes.
What design patterns does maybe use?
3 design patterns detected: Design System Components, Stimulus Controllers, Rails Convention over Configuration.
Analyzed on April 20, 2026 by CodeSea. Written by Karolina Sarna.