Mosaic Agent Skill

Mosaic UI

Two things live under Mosaic, and this skill covers the how-to for both:

• Styled components are authored with slot recipes — one recipe owns a

part's slot identity (data-cl-slot), variants, state, and appearance

cascade; useRecipe resolves it and hands back per-slot props to spread.

• Flows follow a machine → controller → view split that keeps Clerk

resource logic out of visual components and makes behavior testable without a

running Clerk app:

machine     Pure flow rules: states, events, guards, async invokes, errors.
            No React hooks. No Clerk hooks. No Clerk resource objects.

controller  Clerk/data adapter: reads Clerk hooks/resources, injects async
            effects into machine context, gates permissions, derives view props.
            The only layer that may import Clerk hooks or call resource methods.

view        Rendering only: receives a snapshot plus explicit props, renders UI,
            sends events. No Clerk imports. No data-fetching. No mutations.

references/mosaic-architecture.md (repo root, read by all agents) is the

canonical contract for the whole design system — tokens, theme delivery, the

data-cl-* styling API, slot recipes, appearance/cascade/scope, and the "Flow

and data architecture" section that defines the split. Read it for the _what_;

this skill is the _how-to_.

Which reference to read

| You are… | Read |

| -------------------------------------------------------------------- | ------------------------------------------------------ |

| Building on / authoring a headless primitive (@clerk/headless) | references/headless.md |

| Styling a component with StyleX (tokens, stylex.create, CSS build) | references/stylex.md |

| Building an enter/exit transition, or any motion that reads as wrong | references/motion.md |

| Styling a component the legacy way (slot recipes, useRecipe) | references/styling.md |

| Authoring or debugging a state machine, or wiring one to React | references/machines.md → in-tree machine/README.md |

| Writing the controller (Clerk adapter, permissions, revalidate) | references/controllers.md |

| Writing the view (rendering a snapshot, sending events) | references/views.md |

| Testing a machine, controller, or view | references/testing.md |

| Migrating a legacy component into Mosaic (the end-to-end workflow) | references/migration.md |

| Running the parity audit that guards a migration | references/parity-audit.md |

The migration workflow (migration.md) ties the flow references together: it

treats the legacy component as the spec and drives you through the machine,

controller, and view layers, then verifies parity with parity-audit.md.