Container/View Pattern

This skill provides guidance and validation for the Container/View component pattern used in this codebase.

Pattern Overview

The Container/View pattern separates components into two distinct files:

• Container (*Container.tsx): Handles logic, state, API calls, data fetching, and event handlers
• View (*View.tsx): Handles rendering UI only, receiving all data and callbacks as props
• Index (index.tsx): Exports the Container as the default component

Where This Pattern Applies

The Container/View pattern is required in these directories:

| Directory | Applies | Notes | | ------------------------ | ------- | ------------------------- | | features/*/components/ | Yes | All feature components | | features/*/screens/ | Yes | All feature screens | | components/ | Yes | Shared components | | screens/ | Yes | Shared screens | | components/ui/ | No | UI primitives (GlueStack) | | components/shared/ | No | Simple shared utilities | | components/icons/ | No | Icon components |

When to Use This Skill

• Creating a new component in any of the directories above
• Validating that existing components follow the pattern
• Refactoring a component to follow the pattern
• Reviewing code for pattern compliance

Creating a New Component

Option 1: Use the Skill Generator Script

Run the skill's generator script for any component type:

python3 "${CLAUDE_PLUGIN_ROOT:-node_modules/@codyswann/lisa/plugins/lisa-expo}/skills/container-view-pattern/scripts/create_component.py" <type> <name> [feature]

The :- default is load-bearing. This skill ships inside the Lisa plugin, not in the consumer's .claude/skills/, and CLAUDE_PLUGIN_ROOT is not exported into an agent's Bash environment — so a bare .claude/skills/… path names a file that does not exist in a consumer, and a bare "${CLAUDE_PLUGIN_ROOT}/…" expands to an absolute /skills/… and exits 1. The default resolves from the consumer repository root, which is where the script is actually invoked.

Component Types:

| Type | Command | Creates in | | ----------------- | ---------------------------------------------------------------- | ----------------------------------------------- | | Global component | create_component.py global-component PlayerCard | components/PlayerCard/ | | Feature component | create_component.py feature-component PlayerCard player-kanban | features/player-kanban/components/PlayerCard/ | | Global screen | create_component.py global-screen Settings | screens/Settings/ | | Feature screen | create_component.py feature-screen Main dashboard | features/dashboard/screens/Main/ |

Option 2: Manual Creation

Create the following directory structure:

ComponentName/
├── ComponentNameContainer.tsx
├── ComponentNameView.tsx
└── index.tsx

Container Component Requirements

Container components handle all business logic:

1. Single View render: A Container's returned tree is only its corresponding View component — no other UI elements beside it. This constrains what the Container renders, not what it holds: a Container may define a callback that returns JSX (a renderItem passed down as a prop is the common case), and that is where such a callback belongs once a View may no longer call hooks.
2. State management: Use useState, useReducer
3. Data fetching: Use GraphQL hooks, API calls
4. Memoization: Wrap all computed values in useMemo
5. Event handlers: Wrap all handlers in useCallback with proper dependencies
6. Formatting: All data transformation and formatting logic
7. Conditional logic: Determine what state to pass to View (loading, error, empty flags)

Container Code Order (enforced by ESLint)

Containers must follow this specific order:

const ExampleContainer = () => {
  // 1. Variables, state, useMemo, useCallback (same group)
  const [state, setState] = useState();
  const computed = useMemo(() => state * 2, [state]);
  const handleClick = useCallback(() => {}, []);

  // 2. useEffect hooks
  useEffect(() => {
    // side effects
  }, []);

  // 3. Return statement (always last)
  return <ExampleView />;
};

Container Template

import { useCallback, useMemo, useState } from "react";
import ComponentNameView from "./ComponentNameView";

/**
 * Props for the ComponentName component.
 */
interface ComponentNameProps {
  readonly id: string;
}

/**
 * Container component that manages state and logic for ComponentName.
 * @param props - Component properties
 * @param props.id - The unique identifier
 */
const ComponentNameContainer = ({ id }: ComponentNameProps) => {
  // State
  const [isLoading, setIsLoading] = useState(false);

  // Memoized computed values
  const formattedData = useMemo(() => {
    return data?.toUpperCase() ?? "";
  }, [data]);

  // Event handlers wrapped in useCallback
  const handleSubmit = useCallback(() => {
    setIsLoading(true);
  }, []);

  return (
    <ComponentNameView
      formattedData={formattedData}
      isLoading={isLoading}
      onSubmit={handleSubmit}
    />
  );
};

export default ComponentNameContainer;

View Component Requirements

View components carry no statements and no hooks. That is the guarantee, and it is deliberately narrower than "pure": {Date.now()} and {Math.random() > 0.5 ? … : …} sit happily inside an expression body and no rule below rejects them. Claiming purity here would repeat the defect this section was rewritten to fix — see Validation.

1. Expression-bodied arrow function: The View component must be const XView = (props) => (...). Not () => { return (...); }, and not function XView(props) { ... } — a function declaration cannot have an expression body, so declaration form always carries a statement list. This is the requirement; the other two shapes are the two ways of failing it.
2. No statements: The component body is a single JSX expression.
3. memo wrapper: Export with memo() for performance optimization
4. displayName: Set ComponentName.displayName = "ComponentName"
5. Readonly props: All props should be marked as readonly
6. No hooks anywhere in the file: No call of the shape use + an uppercase letter — useState, useEffect, useMemo, useCallback, and every project-local custom hook alike. The ban is on the shape, not on a list of names: the call that motivated this gate was a project-local hook that no name list would have contained. useMemo and useCallback are caught for the same reason — a data hook and a render helper are indistinguishable by name, and this document already forbade useMemo in a View. There is no exemption list, no per-site waiver, and no opt-out flag; a View that calls a hook is fixed by moving the hook into the Container.
7. No logic: All conditional rendering should use ternary expressions in JSX. Unlike 1, 2 and 6, this one is not lint-enforced — see the second table under Validation.

View Template

import { memo } from "react";

import { Box } from "@/components/ui/box";
import { Text } from "@/components/ui/text";

/**
 * Props for the ComponentNameView component.
 */
interface ComponentNameViewProps {
  readonly formattedData: string;
  readonly isLoading: boolean;
  readonly onSubmit: () => void;
}

/**
 * View component that renders the ComponentName UI.
 * @param props - Component properties
 * @param props.formattedData - Pre-formatted display data
 * @param props.isLoading - Loading state indicator
 * @param props.onSubmit - Submit handler callback
 */
const ComponentNameView = ({
  formattedData,
  isLoading,
  onSubmit,
}: ComponentNameViewProps) => (
  <Box testID="COMPONENT_NAME.CONTAINER">
    {isLoading ? <Text>Loading...</Text> : <Text>{formattedData}</Text>}
  </Box>
);

ComponentNameView.displayName = "ComponentNameView";

export default memo(ComponentNameView);

Index File

Export the Container as the default:

export { default } from "./ComponentNameContainer";

Validation

ESLint Rules

Each row names the numbered requirement it enforces. Every requirement above appears in exactly one of the two tables, so a requirement with no rule is visible as such rather than implied to be covered.

For most of this skill's life the table below listed four rules under the heading "the following ESLint rules enforce the pattern" — and none of them enforced requirement 6 or 7. That false assurance is why nobody checked, and why a declaration-form View with a hook in it passed lint for years.

| Rule | Enforces | Description | | ------------------------------------------------- | --------- | ----------------------------------------------------------------- | | component-structure/enforce-component-structure | structure | Validates directory structure and file naming | | component-structure/no-return-in-view | 1, 2 | View must be an arrow function with an expression body | | component-structure/no-hooks-in-view | 6 | No use[A-Z]…() call anywhere in a View file, by shape not name | | no-restricted-imports (View files) | 6 | No React hook named-import, and no **/hooks/** import | | component-structure/require-memo-in-view | 3, 4 | Ensures View uses memo and displayName | | component-structure/single-component-per-file | structure | One component per file |

no-hooks-in-view and no-restricted-imports are two independent axes, not one duplicated: a hook re-exported through a barrel escapes the import patterns, and an import with no call site yet escapes the call matcher.

What lint does NOT enforce

| Requirement | Why not | | --------------------------------- | -------------------------------------------------------------------------------------------------------- | | 5 — readonly props | A convention on the props interface; carried by review and the templates above. | | 7 — no logic beyond ternaries | "Logic" has no AST shape. {Date.now()} and {Math.random() > 0.5 ? … : …} are legal expression bodies. |

Manual Validation

Run the validation script to check a component:

python3 "${CLAUDE_PLUGIN_ROOT:-node_modules/@codyswann/lisa/plugins/lisa-expo}/skills/container-view-pattern/scripts/validate_component.py" <path-to-component-directory>

The script is a fast pre-check, not the gate: it reads one component directory with regexes, while ESLint reads the AST of every file. When they disagree, ESLint is right.

Run ESLint to check all components:

bun run lint

Note: Replace bun with your project's package manager (npm, yarn, pnpm) as needed.

Common Violations

Container Violations

| Issue | Resolution | | ------------------------------------ | ----------------------------------------------------------- | | Returning UI elements besides View | Container's returned tree is ONLY the corresponding View | | Rendering multiple components | Move all UI to View; Container returns only View | | Missing useMemo for objects/arrays | Wrap computed values in useMemo | | Missing useCallback for functions | Wrap handlers in useCallback | | Logic in View component | Move logic to Container | | Inline function props | Create memoized handler |

View Violations

| Issue | Resolution | | ------------------------------------ | ------------------------------------------------- | | Using block body { return } | Convert to arrow shorthand () => (...) | | Declared as function XView() {…} | Convert to const XView = (props) => (...) | | Missing memo wrapper | Add export default memo(ComponentView) | | Missing displayName | Add ComponentView.displayName = "ComponentView" | | Contains hooks (including custom) | Move hooks to Container | | Contains state | Move state to Container |

Extracting Helper Functions

When View components exceed ESLint's cognitive complexity threshold (28), extract render helper functions. For simple cases, prefer inline JSX:

/**
 * Renders the loading skeleton state.
 * @param props - Helper function properties
 * @param props.isDark - Whether dark mode is active
 */
function renderLoadingState(props: { readonly isDark: boolean }) {
  const { isDark } = props;
  return <LoadingSkeleton isDark={isDark} />;
}

const ComponentView = ({ isLoading, isDark }: Props) => (
  <Box>{isLoading ? renderLoadingState({ isDark }) : <Content />}</Box>
);

A local render helper may be a function declaration. Requirement 1 is about the View component, not about the word function appearing in the file — which is why it is stated as "expression-bodied arrow" rather than as a ban on declarations. The helper is still inside a View file, so requirement 6 applies to it: it may not call a hook either.

Event Handler Naming Convention

• Container: Use handle* prefix (e.g., handleSubmit, handleClick)
• View props: Use on* prefix (e.g., onSubmit, onClick)

// Container
const handleSubmit = useCallback(() => { ... }, []);
return <ComponentView onSubmit={handleSubmit} />;

// View
const ComponentView = ({ onSubmit }: Props) => (
  <Button onPress={onSubmit}>Submit</Button>
);

Reference Documentation

For detailed examples and edge cases, read:

• references/patterns.md - Common patterns and anti-patterns
• references/examples.md - Complete component examples