Fix v13 playground imports

apps/docs/e2e/Playground.cy.res

@@ -98,6 +98,30 @@ describe("Playground", () => {
     )
   })
 
+  it("should run exception code with v13.0.0-alpha.6", () => {
+    let code = `exception HttpError({status: int})
+
+let isRetriable: exn => bool = error =>
+  switch error {
+  | HttpError({status: 502 | 503 | 504}) => true
+  | _ => false
+  }
+
+Console.log(isRetriable(HttpError({status: 500})))`
+    let compressedCode = LzString.lzString.compressToEncodedURIComponent(code)
+    visit(`/try?version=v13.0.0-alpha.6&code=${compressedCode}`)
+    waitForPlayground()
+
+    get("pre.whitespace-pre-wrap")->shouldContainText("Primitive_exceptions.mjs")->ignore
+    getByTestId("control-panel")
+    ->find("button")
+    ->containsChainable("Run")
+    ->click
+    ->ignore
+
+    get("div.whitespace-pre-wrap pre")->shouldContainText("false")->ignore
+  })
+
   it("should open the landing page example in the playground with code and compiled output", () => {
     containsSelector("a", "Edit this example in Playground")
     ->scrollIntoView

apps/guide/__tests__/GuideRuntime_.test.res

@@ -124,6 +124,32 @@ test("normalizes old compiler runtime import filenames", async () => {
   )->toBe("core__array")
 })
 
+test("resolves v13 exception imports to the published runtime file", async () => {
+  let compilerVersion = Semver.parse("v13.0.0-alpha.6")->Option.getOrThrow
+  let url = GuideRuntimeImport.url(
+    ~bundleBaseUrl="https://cdn.rescript-lang.org",
+    ~compilerVersion,
+    "./stdlib/Primitive_exceptions.mjs",
+  )
+
+  expect(url)->toBe(
+    "https://cdn.rescript-lang.org/v13.0.0-alpha.6/compiler-builtins/stdlib/Primitive_exceptions.js",
+  )
+})
+
+test("preserves runtime imports that already use the published extension", async () => {
+  let compilerVersion = Semver.parse("v12.3.1")->Option.getOrThrow
+  let url = GuideRuntimeImport.url(
+    ~bundleBaseUrl="https://cdn.rescript-lang.org",
+    ~compilerVersion,
+    "./stdlib/Stdlib_Array.js",
+  )
+
+  expect(url)->toBe(
+    "https://cdn.rescript-lang.org/v12.3.1/compiler-builtins/stdlib/Stdlib_Array.js",
+  )
+})
+
 test("normalizes old compiler versions for runtime imports", async () => {
   let alpha7 = Semver.parse("v12.0.0-alpha.7")->Option.getOrThrow
   let alpha9 = Semver.parse("v12.0.0-alpha.9")->Option.getOrThrow

packages/playground/src/CompilerManagerHook.res

@@ -41,8 +41,15 @@ module CdnMeta = {
   let getLibraryCmijUrl = (baseUrl, version, libraryName: string): string =>
     `${baseUrl}/${Semver.toString(version)}/${libraryName}/cmij.js`
 
-  let getStdlibRuntimeUrl = (baseUrl, version, filename) =>
+  let getStdlibRuntimeUrl = (baseUrl, version, filename) => {
+    // The compiler emits .mjs imports, while the published runtime bundles use .js.
+    let filename = if filename->String.endsWith(".mjs") {
+      filename->String.slice(~start=0, ~end=-4) ++ ".js"
+    } else {
+      filename
+    }
     `${baseUrl}/${Semver.toString(version)}/compiler-builtins/stdlib/${filename}`
+  }
 }
 
 module FinalResult = {