fix(android): actually download remote http(s) jsBundleSource#43
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Loading a sandbox from a remote URL never worked on Android: - `createBundleLoader` mapped an http(s) source to `JSBundleLoader.createFileLoader(url)`, but that loader calls `loadScriptFromFile`, which treats its argument as a local path — a remote URL is never downloaded. - Even with a working loader, the sandbox ReactHost was created with developer support enabled, so in dev builds the runtime ignored the loader and fetched the bundle from Metro using `jsMainModulePath`, turning `http://host/x.bundle` into `http://localhost:8081/http://host/x.bundle.bundle` (a 404). Fix: - Prefetch the remote bundle to a cache file off the main thread (avoids NetworkOnMainThreadException) and load it via `createCachedBundleFromNetworkLoader`, preserving the source URL for stack traces. Returns null (existing failure path) on download error. - Disable developer support for remote (http/https) sources only, so the runtime uses our loader instead of Metro. Local asset/name sources keep dev support and Fast Refresh. Verified on a device: host loads the sandbox bundle from a remote HTTP URL in a debug build, renders, and exchanges messages both ways. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
The remote (http/https) loader downloaded the bundle on every sandbox VM creation, so each cold start re-fetched the full bundle and failed when offline. Treat a remote URL as immutable: if the cached file for that exact URL already exists, reuse it and skip the network. Repeated loads (cold starts) become instant and work offline; a partial/failed download is deleted so a later load retries cleanly. To publish an update, change the URL (version segment or `?v=` query) — a new URL misses the cache and is fetched once. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
createCachedBundleFromNetworkLoader loads the cached file with
loadSynchronously=false. On RN 0.85 bridgeless this executes the bundle
before the TurboModule JSI bindings are installed on the runtime, so the
bundle's InitializeCore hits TurboModuleRegistry.getEnforcing('PlatformConstants')
with no proxy registered and the sandbox VM aborts. Because this happens
before the sandbox error handler is installed, it escalates to a native
fatal and takes the host process down with it.
Load the already-downloaded cache file synchronously via
JSBundleLoader.createFileLoader(path, sourceURL, true) — mirroring how the
built-in asset loader runs the main bundle — so the runtime is ready before
the bundle runs. The original URL is kept as sourceURL for stack traces.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
- Extract remote bundle download logic into a private downloadRemoteBundle() function for clarity - Shorten the two inline comments in createBundleLoader to 2 lines each Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
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Supersedes #37 — incorporates all of @akelmanson's work with review feedback applied.
Summary
Loading a sandbox from a remote URL (
jsBundleSource="https://…/x.bundle") did not work on Android. Two issues compounded:createBundleLoadermapped anhttp(s)source toJSBundleLoader.createFileLoader(url), which treats its argument as a local file path — a remote URL never resolves.ReactHostImplwith dev support enabled ignoresjsBundleLoaderand fetches through Metro, mangling the URL intohttp://localhost:8081/http://host/x.bundle.bundle→ 404.Fix
NetworkOnMainThreadException), then load it viaJSBundleLoader.createFileLoader(cacheFile, sourceUrl, true)— synchronous load required on RN 0.85 bridgeless to sequence after TurboModule JSI bindingshttp(s)sources so Metro doesn't intercept the loaddownloadRemoteBundle()private functionChanges from #37
downloadRemoteBundle()(requested by @CAMOBAP)Co-authored-by: akelmanson akelmanson@users.noreply.github.com
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