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Merged
cknitt merged 2 commits into from
Aug 17, 2026
+18 −6
Merged

Prevent stale developer playground PR previews #8556

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d15a81f
Prevent stale developer playground PR previews
cknitt Aug 16, 2026
dc43ce5
Document developer playground cache fix
cknitt Aug 17, 2026
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1 change: 1 addition & 0 deletions CHANGELOG.md
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Original file line number Diff line number Diff line change
Expand Up @@ -28,6 +28,7 @@
- Preserve parentheses around multiplication, division, and modulo expressions used as exponents. https://github.com/rescript-lang/rescript/pull/8550
- Preserve multibyte characters when wrapping long source lines in compiler code frames. https://github.com/rescript-lang/rescript/pull/8520
- Fix reanalyze optional-argument diagnostics for functions passed or returned as first-class values. https://github.com/rescript-lang/rescript/pull/8321
- Prevent the developer playground from loading stale compiler and library assets after PR preview updates. https://github.com/rescript-lang/rescript/pull/8556

#### :memo: Documentation

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23 changes: 17 additions & 6 deletions packages/dev-playground/src/CompilerApi.res
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Expand Up @@ -171,6 +171,14 @@ let isConfiguredVersion = version =>
let isLoadableVersion = version =>
version->isConfiguredVersion || version->previewVersionRoot->Option.isSome

// A PR preview URL is reused after every push, while the CDN caches its assets.
let previewCacheBust = Date.now()->Float.toString
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let versionAssetUrl = (version, path) => {
let url = `${versionRoot(version)}/${path}`
version->isPreviewVersion ? `${url}?cacheBust=${previewCacheBust}` : url
}
Comment on lines +177 to +180

@chatgpt-codex-connector chatgpt-codex-connector Bot Aug 17, 2026

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P1 Badge Add regression coverage for preview asset cache busting

Add an automated test covering this URL-generation behavior: a pr-123 selection should apply the same cache-busting value to compiler.js and both runtime-library scripts, while configured and local versions remain unchanged. The commit currently relies only on manual verification, so a later loader refactor could silently restore the stale-preview behavior this bug fix addresses.

AGENTS.md reference: AGENTS.md:L169-L174

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@cknitt cknitt Aug 17, 2026

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The developer playground does not currently have an automated test harness. Adding one would require introducing and wiring up new test infrastructure, which feels outside the scope of this targeted cache fix.


let selectableCompilerVersions = activeVersion =>
if activeVersion->isConfiguredVersion || !(activeVersion->previewVersionRoot->Option.isSome) {
availableCompilerVersions
Expand Down Expand Up @@ -362,16 +370,20 @@ let loadRuntimeLibraries = async version => {
switch activeLibraryVersion.contents {
| Some(activeVersion) if activeVersion === selectedVersion => ()
| _ =>
let root = versionRoot(selectedVersion)
let _ = await loadScript(`${root}/compiler-builtins/cmij.js`, ~cache=false)
let _ = await loadScript(
versionAssetUrl(selectedVersion, "compiler-builtins/cmij.js"),
~cache=false,
)

let libraries = try {
let _ = await loadScript(`${root}/@rescript/react/cmij.js`, ~cache=false)
let _ = await loadScript(
versionAssetUrl(selectedVersion, "@rescript/react/cmij.js"),
~cache=false,
)
["compiler-builtins", "@rescript/react"]
} catch {
| _ => ["compiler-builtins"]
}

loadedLibrariesByVersion->Map.set(selectedVersion, libraries)
activeLibraryVersion := Some(selectedVersion)
}
Expand All @@ -389,8 +401,7 @@ let ensureCompilerApi = async version => {
await loadRuntimeLibraries(selectedVersion)
compilerApis->getMapValueOrThrow(selectedVersion, "Compiler API was not cached")
} else {
let root = versionRoot(selectedVersion)
await loadScript(`${root}/compiler.js`)
await loadScript(versionAssetUrl(selectedVersion, "compiler.js"))
let api = switch Api.global {
| Some(api) if hasFunction(api, "make") => api
| _ => JsError.throwWithMessage("rescript_compiler global was not registered by compiler.js")
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