Publish a GitHub release with WebAssembly assets so shinylive can install shinyreact

[schloerke]

Problem

shinyreact can't be used in a shinylive app (Quarto {shinylive-r} block, or
shinylive::export()) because there is no WebAssembly binary for it anywhere, and
the one mechanism shinylive has for GitHub-installed packages needs a release that
this repo doesn't have.

shinylive:::get_github_wasm_assets() handles exactly this case. When a package is
installed from GitHub, it reads RemoteUsername / RemoteRepo / RemoteRef from
the installed DESCRIPTION and looks for a GitHub release tagged with that ref,
carrying library.data* and library.js.metadata assets:

tags <- gh::gh("/repos/{user}/{repo}/releases/tags/{ref}", ...)
library_data     <- Filter(\(i) grepl("library.data", i$name, fixed = TRUE), tags$assets)
library_metadata <- Filter(\(i) i$name == "library.js.metadata",             tags$assets)

This repo has zero releases, so gh::gh() 404s and the Quarto render aborts:

Error in `get_github_wasm_assets()`:
  Can't find GitHub release for github::posit-dev/shinyreact@HEAD
! Ensure a GitHub release exists for the package repository reference: "HEAD".

Reproduce

pak::pak("posit-dev/shinyreact/pkg-r")   # note: R package is in the pkg-r subdir

Then render a Quarto revealjs/html doc containing:

```{shinylive-r}
#| standalone: true
library(shiny)
library(shinyreact)
# ... any shinyreact app
```

Proposed fix

Build and attach WebAssembly assets on release with
https://github.com/r-wasm/actions (build-rwasm / release-rwasm). Two
repo-specific details:

• The R package lives in pkg-r/, not the repo root, so the action needs the
  subdirectory configured. (For the same reason, plain
  pak::pak("posit-dev/shinyreact") fails with "Can't find R package in GitHub
  repo" — it must be posit-dev/shinyreact/pkg-r.)
• The release tag has to match the RemoteRef recorded at install time. A default
  pak::pak("posit-dev/shinyreact/pkg-r") records RemoteRef: HEAD, so a release
  tagged HEAD is what an unpinned install looks for; a versioned tag works for
  users who install that ref explicitly.

shinyreact itself is pure R, so nothing needs compiling for wasm — but its
Imports include brio, which does have C code. brio 1.1.5 is already on
repo.r-wasm.org, so a runtime install resolves it fine as long as
https://repo.r-wasm.org stays in the repo list.

Things that do not solve this

• Adding the package to an r-universe. r-universe does build wasm binaries, but
  currently only for R 4.6 (bin/emscripten/contrib/4.6/), and shinylive 0.10.8
  runs R 4.5.1 (wasm32-unknown-emscripten). Separately, shinylive's resolver
  keys off GitHub releases, not the r-universe repo — an r-universe install has no
  Remote* fields, so it gets treated as CRAN-ish and is looked for on
  repo.r-wasm.org.

Current workaround

For https://github.com/schloerke/presentation-2026-09-15-posit-conf-shinyreact
(a posit::conf(2026) talk), the deck ships its own single-package webR repo and
installs at runtime:

webr::install(
  "shinyreact",
  repos = c("<deck>/wasm-repo", "https://repo.r-wasm.org")
)

with SHINYLIVE_WASM_PACKAGES=0 set at render time purely to skip the
get_github_wasm_assets() lookup above. That works, but every consumer has to
rebuild and host a binary themselves. A release with wasm assets removes all of it.

[schloerke]

Downstream tracking issue for the consumer side: schloerke/presentation-2026-09-15-posit-conf-shinyreact#7 — removes the vendored wasm-repo/ and the runtime webr::install() once a release with wasm assets exists.