Split embedded and standalone chart surfaces

bible-local/architecture/api-surface.md

@@ -4,30 +4,41 @@
 
 The package is intended to be embedded by other Go applications.
 
-Expected package shape:
+Current package shape:
 
 - `viewer.RenderHTML(snapshot []byte) ([]byte, error)`
-- `viewer.NewHandler(...) http.Handler`
+- `viewer.NewHandler(viewer.HandlerOptions{...}) http.Handler`
+- `viewer.NewStandaloneHandler(viewer.HandlerOptions{...}) http.Handler`
 
-Exact signatures may change during implementation, but the integration model is fixed:
+Integration model:
 
 - embedding app provides the JSON
 - chart renders HTML
+- embedded mode does not own snapshot selection UI
+- standalone mode may provide a local upload screen on `GET /`
 
 ## Expected Runtime Endpoints
 
 These endpoints are expected for the standalone binary only:
 
-- `GET /` - viewer page
-- `POST /render` - accept one Reanimator JSON payload and return rendered HTML or JSON render result
+- `GET /` - upload page
+- `POST /render` - accept one Reanimator JSON payload and return rendered HTML
 - `GET /healthz` - basic process health
 
+Embedded handler endpoints:
+
+- `GET /` - empty viewer shell with no upload controls
+- `POST /render` - accept one Reanimator JSON payload and return rendered HTML
+- `GET /healthz` - basic process health
+- `GET /static/...` - embedded static assets
+
 ## UI Route Rules
 
 - No multi-product navigation
 - No upload wizard with preview/confirm/execute stages
 - No collector/API-connect workflow
 - No background job polling API
+- Embedded mode must not force a file picker into host applications
 
 ## Response Rules