On January 4, 2026, at the start of Session 037, FLIN had a component system but no component library. Developers could create custom components -- define a .flin file, write some markup, pass some props -- but there was nothing pre-built. No Button. No Card. No Modal. No Table. Every FLIN developer had to build every UI element from scratch.
Forty-five minutes later, FlinUI v1.0.0 existed: 70 production-ready components across 7 categories, a complete design token system, dark mode support, responsive breakpoints, and an interactive demo application. Eighty-one .flin files. 11,697 lines of code. One commit.
This is the story of that sprint -- how we parallelized the work across six AI agents, designed a consistent component API, and shipped a complete UI library in less time than most developers spend configuring their build tools.
The Decision: Build It All at Once
Thales had a specific vision. He did not want a minimal component library that would grow over time. He wanted a complete library that a developer could use on day one to build a real application. Buttons, inputs, cards, tables, modals, forms, navigation -- everything.
The reasoning was commercial. FLIN was competing for attention against frameworks that had mature ecosystems. A developer evaluating FLIN would ask: "Can I build my dashboard with this?" If the answer was "yes, but you need to create your own button component first," FLIN would lose that evaluation. If the answer was "yes, just write ," FLIN would win.
So the goal was clear: build a complete UI library in a single session. Not a prototype. Not a "good enough for demos" version. Production-ready components with proper props, sensible defaults, accessibility attributes, and consistent styling.
The Strategy: Parallel Agents
Building 70 components sequentially would take hours. Each component requires designing its API (props), writing the markup, handling edge cases, and ensuring consistency with the rest of the library. At 10 minutes per component, 70 components would take 12 hours.
Instead, we used parallel agents. Session 037 ran six agents in two batches of three:
Batch 1 (three agents in parallel): - Agent 1: Theme system (tokens, dark mode, animations, responsive) + Basic components (15) - Agent 2: Layout components (10) + Data display components (15) - Agent 3: Form components (10) + Feedback components (10)
Batch 2 (three agents in parallel): - Agent 4: Navigation components (10) + remaining Data display components - Agent 5: Index files for each category + integration testing - Agent 6: Demo application + documentation
Each agent had a specification: the component name, its props, its expected behavior, and a reference to the design tokens it should use. The agents did not need to coordinate with each other because the design token system was defined first -- every agent used the same colors, spacing, typography, and shadows.
The Theme System: Design Tokens First
Before building a single component, we built the design token system. This was the foundation that ensured consistency across all 70 components:
// tokens.flin -- 50+ design tokens// Colors primary = "#007bff" primary_hover = "#0056b3" secondary = "#6c757d" success = "#28a745" warning = "#ffc107" danger = "#dc3545" info = "#17a2b8"
// Spacing scale (in pixels) space_0 = "0" space_1 = "0.25rem" // 4px space_2 = "0.5rem" // 8px space_3 = "0.75rem" // 12px space_4 = "1rem" // 16px space_6 = "1.5rem" // 24px space_8 = "2rem" // 32px
// Typography font_family = "-apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif" font_size_sm = "0.875rem" font_size_base = "1rem" font_size_lg = "1.125rem" font_size_xl = "1.25rem"
// Border radius radius_sm = "0.25rem" radius_md = "0.375rem" radius_lg = "0.5rem" radius_full = "9999px"
// Shadows shadow_sm = "0 1px 2px rgba(0,0,0,0.05)" shadow_md = "0 4px 6px rgba(0,0,0,0.1)" shadow_lg = "0 10px 15px rgba(0,0,0,0.1)" ```
The dark mode file extended these tokens:
// dark.flin
bg_primary = "#1a1a2e"
bg_secondary = "#16213e"
bg_surface = "#0f3460"
text_primary = "#e2e8f0"
text_secondary = "#a0aec0"
border_color = "#2d3748"With design tokens defined, each agent could build components that looked consistent without any inter-agent communication. A Button built by Agent 1 would use the same primary color and radius_md border radius as a Badge built by Agent 3.
The Component API Convention
Every component followed the same API pattern:
1. Read props with defaults 2. Compute derived values 3. Render markup with design tokens
// Button.flin
label = props.label || ""
variant = props.variant || "default"
size = props.size || "md"
disabled = props.disabled || false
loading = props.loading || false// Variant styles bg = { "default": "#e2e8f0", "primary": "#007bff", "success": "#28a745", "danger": "#dc3545", "warning": "#ffc107" }[variant]
text_color = { "default": "#1a202c", "primary": "#ffffff", "success": "#ffffff", "danger": "#ffffff", "warning": "#1a202c" }[variant]
// Size styles padding = { "sm": "0.25rem 0.5rem", "md": "0.5rem 1rem", "lg": "0.75rem 1.5rem" }[size]
font = { "sm": "0.875rem", "md": "1rem", "lg": "1.125rem" }[size]
```
This pattern repeats across all 70 components. Props with defaults. Variant mapping via maps. Style computation. Conditional rendering. The consistency means that a developer who understands one component understands all of them.
The Seven Categories
Basic Components (15)
Button, Input, Textarea, Select, Checkbox, Radio, Switch, Slider, Text, Link, Icon, Image, Avatar, Badge, Tag.
These are the atoms of the UI. Every application needs buttons, text inputs, and labels. Every dashboard needs badges and avatars. Every form needs checkboxes and selects. Fifteen components that cover 80% of basic UI needs.
Layout Components (10)
Container, Stack, Grid, Flex, Box, Divider, Spacer, Center, AspectRatio, Wrap.
Layout components control how other components are arranged on the page. Stack arranges children vertically or horizontally with consistent spacing. Grid creates a CSS grid with configurable columns. Container provides max-width constraints. These ten components replace 90% of custom CSS layout code.
<Stack direction="vertical" gap={4}>
<Text size="lg" weight="bold">User Profile</Text>
<Grid cols={2} gap={4}>
<Input label="First Name" value={firstName} />
<Input label="Last Name" value={lastName} />
</Grid>
<Textarea label="Bio" value={bio} rows={4} />
<Button variant="primary">Save Profile</Button>
</Stack>Data Display (15)
Card, CardHeader, CardBody, CardFooter, Table, List, ListItem, Progress, Spinner, Skeleton, Empty, Code, Kbd, Stat, Accordion.
Data display components present information. Cards for grouped content. Tables for tabular data. Progress bars for loading states. Skeleton components for content placeholders. The Stat component is particularly useful for dashboards:
<Grid cols={4} gap={4}>
<Stat label="Total Users" value="12,847" change="+12%" />
<Stat label="Revenue" value="$48,290" change="+8%" />
<Stat label="Active Sessions" value="1,247" />
<Stat label="Error Rate" value="0.12%" change="-3%" />
</Grid>Form Components (10)
Form, FormField, FormError, FormHelp, DatePicker, TimePicker, ColorPicker, FileUpload, Autocomplete, PinInput.
Beyond the basic inputs (which are in the Basic category), form components handle complex input scenarios. DatePicker for selecting dates. FileUpload for handling file attachments. Autocomplete for searchable dropdowns. PinInput for verification codes.
Feedback Components (10)
Alert, Toast, Modal, ModalHeader, ModalBody, ModalFooter, Drawer, Popover, Tooltip, Notification.
Feedback components communicate state to the user. Alerts for inline messages. Toasts for temporary notifications. Modals for confirmations and forms. Tooltips for contextual help.
Navigation Components (10)
Navbar, NavbarBrand, NavbarMenu, NavbarItem, Sidebar, SidebarItem, Tabs, Tab, Breadcrumb, Pagination.
Navigation components structure the application. Navbar for the top bar. Sidebar for the side menu. Tabs for content sections. Breadcrumb for hierarchical navigation. Pagination for long lists.
Theme System (5)
tokens.flin, dark.flin, animations.flin, responsive.flin, index.flin.
The theme system provides the design foundation. Not visual components, but the values that visual components use.
The File Structure
The final structure of FlinUI v1.0.0:
flinui/
basic/ 16 files (15 components + index)
layout/ 11 files (10 components + index)
data/ 15 files (15 components)
forms/ 11 files (10 components + index)
feedback/ 11 files (10 components + index)
navigation/ 11 files (10 components + index)
theme/ 5 files (theme utilities)
index.flin 1 file (main index)Total: 81 .flin files, 428KB ```
Eighty-one files. Each one a self-contained component or utility. No build step required to use them -- drop the flinui/ directory into your project, and every component is immediately available.
The Demo Application
The final piece was an interactive demo that showcased every component:
// examples/flinui-demo.flin
current_tab = "basic"
{if current_tab == "basic"}
// ... other tabs ```
The demo itself used zero imports. Every component referenced in the demo file was discovered automatically from the flinui/ directory. The demo was both a showcase and a test -- if the demo rendered correctly, every component worked.
Forty-Five Minutes: The Timeline
- Minutes 0-5: Design token system (tokens.flin, dark.flin)
- Minutes 5-8: Agent specifications written (component names, props, behavior)
- Minutes 8-25: Batch 1 (3 agents, 35 components + theme system)
- Minutes 25-40: Batch 2 (3 agents, 35 components + index files + demo)
- Minutes 40-45: Final review, commit, tag v0.61.0
The parallelization made this possible. Three agents writing components simultaneously meant we produced three components per minute during the peak period. The design token system, defined upfront, ensured that all components looked consistent despite being written by different agents.
The Commit
feat: FlinUI v1.0.0 - Complete UI Component Library (Phase 13)83 files changed, 11,697 insertions(+) ```
One commit. 11,697 lines. A complete UI library. Tagged as v0.61.0 and pushed to GitHub.
What Was Missing (and What Came Next)
Session 037 built the core 70 components, but some advanced components were deferred:
- DataTable (sortable, filterable table) -- added in Session 038
- Tree (hierarchical data display) -- added in Session 038
- Timeline (event timeline) -- added in Session 038
- Menu (context menu) -- added in Session 038
- Stepper (step-by-step wizard) -- added in Session 038
- BottomNav (mobile navigation) -- added in Session 038
These were deliberately deferred because they are complex components that require more design thought than the basic ones. A Modal is a div with an overlay. A DataTable is a complete data management interface with sorting, filtering, pagination, and column resizing. Shipping the simpler components first gave us a usable library immediately, and the complex components followed in the next session.
What Made This Possible
Three factors enabled the 70-component sprint.
The zero-import component system. Because components are just .flin files that are automatically discovered, creating 70 components meant creating 70 files. No registration, no configuration, no build step.
The design token system. Defining tokens first meant agents could work independently without producing visually inconsistent results. Every button uses the same primary color. Every card uses the same shadow_md. Consistency was architectural, not manual.
Parallel AI agents. Six agents working simultaneously, each with a clear specification and shared design tokens. The agents did not need to communicate with each other -- they just needed to follow the same conventions.
The result: a complete UI library in 45 minutes. Not a toy library. Not a "version 0.1" that needs months of polish. A library that a developer can use today to build a real application.
---
This is Part 82 of the "How We Built FLIN" series, documenting how a CEO in Abidjan and an AI CTO built 70 UI components in a single 45-minute session.
Series Navigation: - [81] FlinUI: Zero-Import Component System - [82] From Zero to 70 Components in One Session (you are here) - [83] FlinUI Complete: 365+ Components - [84] Charts and Data Visualization Components