diff --git a/changelog.d/9243-ext-http-cgu-link-regression-test.md b/changelog.d/9243-ext-http-cgu-link-regression-test.md
new file mode 100644
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+++ b/changelog.d/9243-ext-http-cgu-link-regression-test.md
@@ -0,0 +1,13 @@
+Add an end-to-end regression test for #8907: a program that references a
+`cgu.0`-only stdlib symbol (`new Blob([...])`) with no `node:http` import must
+link and run.
+
+The bug (released v0.5.1220): #5831 leaked `external-http-client-pump` into
+perry-stdlib's `full` feature, which declares `js_ext_http_*` symbols defined
+only in `perry-ext-http`. That archive is linked per-program by the compile
+driver, and only when the program imports `node:http` — so a full-stdlib link
+without an http import left those references unresolved. The release packs
+stdlib into one monolithic `cgu.0` object, so any reference that pulls that
+member drags the http references in with it. Fixed by #5983 (v0.5.1239), which
+drops the pump from `full`; this pins the end-to-end link that the manifest-level
+guard in `issue_8587_prebuilt_stdlib_http_isolation` does not exercise.
diff --git a/crates/perry/tests/issue_8907_ext_http_cgu_link.rs b/crates/perry/tests/issue_8907_ext_http_cgu_link.rs
new file mode 100644
index 0000000000..afe7ea71f2
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+++ b/crates/perry/tests/issue_8907_ext_http_cgu_link.rs
@@ -0,0 +1,77 @@
+//! Regression test for #8907.
+//!
+//! Reported as "any program importing node:http fails to link" on the released
+//! 0.5.1220 macOS arm64 binary, with ~17 undefined `_js_ext_http_*` /
+//! `_js_http_*` symbols referenced from `libperry_stdlib.a`. The node:http
+//! framing is a red herring. The real trigger: prebuilt `libperry_stdlib.a`
+//! packs a large slice of stdlib into one monolithic `cgu.0` object, and that
+//! object *also* carries the unresolved `js_ext_http_*` references. Pulling the
+//! member for any symbol it uniquely defines drags those references into the
+//! link. Only a `node:http` import adds `libperry_ext_http.a` (which defines
+//! them), so a program that touches `cgu.0` without importing `node:http`
+//! links with the symbols unresolved.
+//!
+//! `new Blob(...)` is the minimal trigger: `js_blob_new` is defined only in
+//! `cgu.0`. No http, no compiled package — one line reproduces it on 0.5.1220
+//! and links on a fixed compiler. The original report hit it through a compiled
+//! `effect` package, which happens to reference a `cgu.0`-only symbol.
+//!
+//! A link failure makes `perry compile` exit non-zero, so asserting the compile
+//! succeeds is the test; running it confirms the member linked coherently.
+
+use std::path::PathBuf;
+use std::process::Command;
+
+/// Path to the `perry` compiler binary built for this integration-test crate.
+fn perry_bin() -> PathBuf {
+    PathBuf::from(env!("CARGO_BIN_EXE_perry"))
+}
+
+/// Compiles a program that references a `cgu.0`-only stdlib symbol (`Blob`)
+/// with no `node:http` import, and asserts it links and runs. Guards the
+/// #8907 regression where full-stdlib carried unresolved `js_ext_http_*`
+/// references unless `node:http` pulled `perry-ext-http` onto the link line.
+#[test]
+fn cgu0_program_links_without_http_ext_archive() {
+    let dir = tempfile::tempdir().expect("tempdir");
+    let root = dir.path();
+    let entry = root.join("blob.ts");
+    // Blob pulls js_blob_new, which lives only in the cgu.0 object that carries
+    // the ext-http references. No node:http import.
+    std::fs::write(
+        &entry,
+        "const b = new Blob([\"x\"]); console.log(b.size);\n",
+    )
+    .expect("write blob.ts");
+    let output = root.join("blob_bin");
+
+    let compile = Command::new(perry_bin())
+        .current_dir(root)
+        .arg("compile")
+        .arg(&entry)
+        .arg("-o")
+        .arg(&output)
+        .arg("--no-cache")
+        .output()
+        .expect("run perry compile");
+    assert!(
+        compile.status.success(),
+        "a Blob program with no node:http import failed to link — the #8907 \
+         ext-http / cgu.0 coupling regressed\nstdout:\n{}\nstderr:\n{}",
+        String::from_utf8_lossy(&compile.stdout),
+        String::from_utf8_lossy(&compile.stderr)
+    );
+
+    let run = Command::new(&output).output().expect("run compiled binary");
+    assert!(
+        run.status.success(),
+        "compiled binary failed at runtime\nstatus: {:?}\nstderr:\n{}",
+        run.status,
+        String::from_utf8_lossy(&run.stderr)
+    );
+    assert_eq!(
+        String::from_utf8_lossy(&run.stdout),
+        "1\n",
+        "Blob([\"x\"]).size is 1 byte"
+    );
+}