pattern-implement

Write ONE sub-pattern with minimal stub UI. No styling, just basic inputs/buttons to verify data flow.

Always use pattern() - expose actions as Stream for testability.

1. Leaf patterns first (no dependencies on other patterns)
2. Container patterns (compose leaf patterns)
3. main.tsx last (composes everything)

• docs/common/patterns/ - especially meta/ for generalizable idioms
• docs/common/concepts/action.md - action() for local state
• docs/common/concepts/handler.md - handler() for reusable logic
• docs/common/concepts/reactivity.md - Cell behavior, .get()/.set()
• docs/common/concepts/identity.md - equals() for object comparison

action() - Closes over local state in pattern body:

```tsx

const inputValue = Cell.of("");

const submit = action(() => {

items.push({ text: inputValue.get() });

inputValue.set("");

});

```

handler() - Reused with different bindings:

```tsx

const deleteItem = handler; index: number }>(

(_, { items, index }) => items.set(items.get().toSpliced(index, 1))

);

// In JSX: onClick={deleteItem({ items, index })}

```

Rendering sub-patterns - Use function calls, not JSX:

```tsx

// ✅ Correct

{items.map((item) => ItemPattern({ item, allItems: items }))}

// ❌ Wrong - JSX fails with typed Output

{items.map((item) => )}

```

• Pattern compiles: deno task ct check pattern.tsx --no-run
• Minimal UI renders inputs/buttons
• Ready for testing