The browser half, for one React and its Flight (by their pinned aliases, so it shares the app's React): `serverComponent()` makes the stub component that renders a server component's tree, read with Flight's client. The browser components (contexts, `lazy` ones) a tree names are found by hash, as Parcel's runtime would load them (`parcelRequire`): those of the stubs rendered.
The file a server component's tree is kept in on a static site (`_app/trees/<name>.json`), by what it was rendered from: the component's hash and its props, as encoded (the key `__TCM_TREES__` has it by). 128 bits of four FNV-1a hashes, so the browser names it the same without `crypto.subtle`, which a page served over plain HTTP lacks.