# Decision: Embedded And Standalone Surfaces Are Separate

**Date:** 2026-03-15
**Status:** active

## Context

`chart` has two legitimate use cases:

- embedded inside another Go application that already knows how to locate and pass a snapshot
- run as a standalone local tool for manual inspection of a JSON file

These two use cases need different first-screen behavior.

The embedded case must stay clean and must not force upload controls into a host application's UI.

The standalone case still needs a practical way to open a snapshot from the browser.

## Decision

The project exposes two handler surfaces:

- `viewer.NewHandler(...)` for embedded mode
- `viewer.NewStandaloneHandler(...)` for standalone mode

Embedded mode renders the viewer without upload controls on `GET /`.

Standalone mode renders a first-screen upload form on `GET /` and posts the selected snapshot to `/render`.

Both modes share the same read-only snapshot renderer and the same `/render` behavior once snapshot bytes are provided.

## Consequences

- Host applications can embed `chart` without inheriting standalone upload UI.
- The standalone binary remains usable without requiring an external host application.
- Future UI work must keep embedded and standalone entry surfaces separate.