# makeComputed

Builds a read-only Computed projection from a Versioned source.

## Signatures

```ts
export declare function makeComputed<R0, E0, A, E, R, E2, R2, C, E3, R3>(input: Versioned.Versioned<R0, E0, A, E, R, A, E2, R2>, f: (a: A) => Effect.Effect<C, E3, R3>): Computed<C, E0 | E | E2 | E3, R0 | R2 | R3 | Exclude<R, Scope.Scope>>;
```

## Why

Applies the same Effectful projection to current reads and pushed versions, preserving all three
Versioned channels without granting writes to the source.

## Ownership and lifetime

Current reads cache the transformed input by source version within each Effect Context. The
pushed channel uses `Subject.hold`: observers with the same Context object share one upstream
session and its retained projection; distinct Context objects have separate sessions. The last
observer ends its session and clears its held value. The observing Scope owns cleanup.