oven-sh · robobun · Aug 7, 2026 · Aug 7, 2026 · Aug 7, 2026 · Aug 7, 2026
diff --git a/src/jsc/RuntimeTranspilerStore.rs b/src/jsc/RuntimeTranspilerStore.rs
@@ -994,7 +994,7 @@ impl TranspilerJob {
                 _ => (ptr::null_mut(), 0),
             };
             self.resolved_source = OwnedResolvedSource::from(ResolvedSource {
-                source_code: String::clone_latin1(&parse_result.source.contents),
+                source_code: String::clone_utf8(&parse_result.source.contents),
                 already_bundled: true,
                 bytecode_cache,
                 bytecode_cache_size,

diff --git a/src/runtime/jsc_hooks.rs b/src/runtime/jsc_hooks.rs
@@ -2787,8 +2787,15 @@ fn transpile_source_code_inner(
                         }
                         _ => (core::ptr::null_mut(), 0),
                     };
+                    if is_main {
+                        // Same as the transpiler-cache-hit return below: leaving
+                        // `has_loaded` false sends unknown-extension imports to
+                        // the `Loader::Tsx` fallback instead of `Loader::File`.
+                        // SAFETY: per fn contract — `jsc_vm` is the live per-thread VM.
+                        unsafe { (*jsc_vm).has_loaded = true };
+                    }
                     return Ok(OwnedResolvedSource::from(ResolvedSource {
-                        source_code: bun_core::String::clone_latin1(&source.contents),
+                        source_code: bun_core::String::clone_utf8(&source.contents),
                         specifier: input_specifier.dupe_ref(),
                         source_url: create_if_different(input_specifier, path.text),
                         already_bundled: true,
@@ -2931,6 +2938,14 @@ fn transpile_source_code_inner(
                     };
                     let (bytecode_cache, bytecode_cache_size) =
                         node_compile_cache_blob.unwrap_or((core::ptr::null_mut(), 0));
+                    if is_main {
+                        // Without this, a cache hit for the entry point leaves
+                        // `has_loaded` false and later imports with unknown
+                        // extensions fall back to `Loader::Tsx` instead of
+                        // `Loader::File`.
+                        // SAFETY: per fn contract — `jsc_vm` is the live per-thread VM.
+                        unsafe { (*jsc_vm).has_loaded = true };
+                    }
                     return Ok(OwnedResolvedSource::from(ResolvedSource {
                         source_code,
                         specifier: input_specifier.dupe_ref(),

diff --git a/test/bundler/transpiler/runtime-transpiler.test.ts b/test/bundler/transpiler/runtime-transpiler.test.ts
@@ -48,6 +48,57 @@ describe("// @bun", () => {
     expect(stdout.toString()).toBe("Hello world!\n");
     expect(exitCode).toBe(0);
   });
+
+  // https://github.com/oven-sh/bun/issues/37161
+  const nonAscii = "\u2014\u00b7\u2713 K\u00e4ufer";
+  test("raw utf-8 decodes as utf-8, not latin-1 (import)", async () => {
+    using dir = tempDir("bun-pragma-utf8-import", {
+      "pragma.js": `// @bun\nexport const text = "${nonAscii}";\n`,
+    });
+    const { text } = await import(`${dir}/pragma.js`);
+    expect(text).toBe(nonAscii);
+  });
+
+  test("raw utf-8 decodes as utf-8, not latin-1 (require)", async () => {
+    using dir = tempDir("bun-pragma-utf8-require", {
+      "pragma.js": `// @bun\nexport const text = "${nonAscii}";\n`,
+    });
+    const { text } = require(`${dir}/pragma.js`);
+    expect(text).toBe(nonAscii);
+  });
+
+  test("entry point with pragma keeps unknown-extension imports on the file loader", async () => {
+    using dir = tempDir("bun-pragma-file-loader", {
+      "asset.hbs": "<!DOCTYPE html>\n<html></html>\n",
+      "entry.js": `// @bun\nimport asset from "./asset.hbs";\nconsole.log(typeof asset);\n`,
+    });
+    await using proc = Bun.spawn({
+      cmd: [bunExe(), "entry.js"],
+      env: bunEnv,
+      cwd: String(dir),
+      stderr: "pipe",
+    });
+    const [stdout, stderr, exitCode] = await Promise.all([proc.stdout.text(), proc.stderr.text(), proc.exited]);
+    expect(stderr).toBe("");
+    expect(stdout).toBe("string\n");
+    expect(exitCode).toBe(0);
+  });
+
+  test("raw utf-8 decodes as utf-8, not latin-1 (entry point)", async () => {
+    using dir = tempDir("bun-pragma-utf8-entry", {
+      "pragma.js": `// @bun\nconst DASH = "\u2014";\nconsole.log([...DASH].map(c => c.codePointAt(0).toString(16)).join(" "));\n`,
+    });
+    await using proc = Bun.spawn({
+      cmd: [bunExe(), "pragma.js"],
+      env: bunEnv,
+      cwd: String(dir),
+      stderr: "pipe",
+    });
+    const [stdout, stderr, exitCode] = await Promise.all([proc.stdout.text(), proc.stderr.text(), proc.exited]);
+    expect(stderr).toBe("");
+    expect(stdout).toBe("2014\n");
+    expect(exitCode).toBe(0);
+  });
 });
 
 describe("json imports", () => {

diff --git a/test/cli/run/transpiler-cache.test.ts b/test/cli/run/transpiler-cache.test.ts
@@ -81,6 +81,17 @@ describe("transpiler cache", () => {
     expect(await bunRun(join(temp_dir, "a.js"), env)).toSpawn("a");
     expect(!existsSync(cache_dir)).toBeTrue();
   });
+  test("cache hit on the entry point keeps unknown-extension imports on the file loader", async () => {
+    writeFileSync(join(temp_dir, "asset.hbs"), "<!DOCTYPE html>\n<html></html>\n");
+    const padding = "// " + Buffer.alloc(8 * 1024, "x").toString() + "\n";
+    writeFileSync(join(temp_dir, "a.js"), `import asset from "./asset.hbs";\n${padding}console.log(typeof asset);\n`);
+    expect(await bunRun(join(temp_dir, "a.js"), env)).toSpawn("string");
+    expect(newCacheCount()).toBe(1);
+    // The second run loads the entry point from the transpiler cache; the
+    // unknown extension must still get the file loader, not the tsx fallback.
+    expect(await bunRun(join(temp_dir, "a.js"), env)).toSpawn("string");
+    expect(newCacheCount()).toBe(0);
+  });
   test("it is indeed content addressable", async () => {
     writeFileSync(join(temp_dir, "a.js"), dummyFile(50 * 1024, "1", "b"));
     expect(await bunRun(join(temp_dir, "a.js"), env)).toSpawn("b");