diff --git a/CLAUDE.md b/CLAUDE.md
index 79eb2673f3..d0cd935637 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -8,7 +8,7 @@ This file provides guidance to Claude Code (claude.ai/code) when working with co
 
 Perry is a native TypeScript compiler written in Rust that compiles TypeScript source code directly to native executables. It uses SWC for TypeScript parsing and LLVM for code generation.
 
-**Current Version:** 0.5.1370
+**Current Version:** 0.5.1371
 
 
 ## TypeScript Parity Status
diff --git a/Cargo.lock b/Cargo.lock
index ec5cc72a43..1e18c36143 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -5547,7 +5547,7 @@ checksum = "9b4f627cb1b25917193a259e49bdad08f671f8d9708acfd5fe0a8c1455d87220"
 
 [[package]]
 name = "perry"
-version = "0.5.1370"
+version = "0.5.1371"
 dependencies = [
  "anyhow",
  "base64",
@@ -5607,14 +5607,14 @@ dependencies = [
 
 [[package]]
 name = "perry-api-manifest"
-version = "0.5.1370"
+version = "0.5.1371"
 dependencies = [
  "serde",
 ]
 
 [[package]]
 name = "perry-audio-miniaudio"
-version = "0.5.1370"
+version = "0.5.1371"
 dependencies = [
  "cc",
  "libc",
@@ -5622,7 +5622,7 @@ dependencies = [
 
 [[package]]
 name = "perry-codegen"
-version = "0.5.1370"
+version = "0.5.1371"
 dependencies = [
  "anyhow",
  "inkwell",
@@ -5639,7 +5639,7 @@ dependencies = [
 
 [[package]]
 name = "perry-codegen-arkts"
-version = "0.5.1370"
+version = "0.5.1371"
 dependencies = [
  "anyhow",
  "perry-hir",
@@ -5647,7 +5647,7 @@ dependencies = [
 
 [[package]]
 name = "perry-codegen-glance"
-version = "0.5.1370"
+version = "0.5.1371"
 dependencies = [
  "anyhow",
  "perry-hir",
@@ -5655,7 +5655,7 @@ dependencies = [
 
 [[package]]
 name = "perry-codegen-js"
-version = "0.5.1370"
+version = "0.5.1371"
 dependencies = [
  "anyhow",
  "perry-dispatch",
@@ -5664,7 +5664,7 @@ dependencies = [
 
 [[package]]
 name = "perry-codegen-swiftui"
-version = "0.5.1370"
+version = "0.5.1371"
 dependencies = [
  "anyhow",
  "perry-hir",
@@ -5672,7 +5672,7 @@ dependencies = [
 
 [[package]]
 name = "perry-codegen-wasm"
-version = "0.5.1370"
+version = "0.5.1371"
 dependencies = [
  "anyhow",
  "base64",
@@ -5684,7 +5684,7 @@ dependencies = [
 
 [[package]]
 name = "perry-codegen-wear-tiles"
-version = "0.5.1370"
+version = "0.5.1371"
 dependencies = [
  "anyhow",
  "perry-hir",
@@ -5692,7 +5692,7 @@ dependencies = [
 
 [[package]]
 name = "perry-container-compose"
-version = "0.5.1370"
+version = "0.5.1371"
 dependencies = [
  "anyhow",
  "async-trait",
@@ -5721,14 +5721,14 @@ dependencies = [
 
 [[package]]
 name = "perry-container-e2e"
-version = "0.5.1370"
+version = "0.5.1371"
 dependencies = [
  "anyhow",
 ]
 
 [[package]]
 name = "perry-diagnostics"
-version = "0.5.1370"
+version = "0.5.1371"
 dependencies = [
  "serde",
  "serde_json",
@@ -5736,7 +5736,7 @@ dependencies = [
 
 [[package]]
 name = "perry-dispatch"
-version = "0.5.1370"
+version = "0.5.1371"
 
 [[package]]
 name = "perry-doc-fixture-my-bindings"
@@ -5747,7 +5747,7 @@ dependencies = [
 
 [[package]]
 name = "perry-doc-tests"
-version = "0.5.1370"
+version = "0.5.1371"
 dependencies = [
  "anyhow",
  "clap",
@@ -5762,7 +5762,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-ads"
-version = "0.5.1370"
+version = "0.5.1371"
 dependencies = [
  "block2",
  "objc2",
@@ -5772,7 +5772,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-argon2"
-version = "0.5.1370"
+version = "0.5.1371"
 dependencies = [
  "argon2",
  "perry-ffi",
@@ -5780,7 +5780,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-axios"
-version = "0.5.1370"
+version = "0.5.1371"
 dependencies = [
  "perry-ffi",
  "reqwest",
@@ -5789,7 +5789,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-bcrypt"
-version = "0.5.1370"
+version = "0.5.1371"
 dependencies = [
  "bcrypt",
  "perry-ffi",
@@ -5797,7 +5797,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-better-sqlite3"
-version = "0.5.1370"
+version = "0.5.1371"
 dependencies = [
  "perry-ffi",
  "rusqlite",
@@ -5805,7 +5805,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-cheerio"
-version = "0.5.1370"
+version = "0.5.1371"
 dependencies = [
  "perry-ffi",
  "scraper",
@@ -5813,7 +5813,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-commander"
-version = "0.5.1370"
+version = "0.5.1371"
 dependencies = [
  "perry-ffi",
  "perry-runtime",
@@ -5821,7 +5821,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-cron"
-version = "0.5.1370"
+version = "0.5.1371"
 dependencies = [
  "chrono",
  "cron",
@@ -5831,7 +5831,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-dayjs"
-version = "0.5.1370"
+version = "0.5.1371"
 dependencies = [
  "chrono",
  "perry-ffi",
@@ -5839,7 +5839,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-decimal"
-version = "0.5.1370"
+version = "0.5.1371"
 dependencies = [
  "perry-ffi",
  "rust_decimal",
@@ -5847,7 +5847,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-dotenv"
-version = "0.5.1370"
+version = "0.5.1371"
 dependencies = [
  "perry-ffi",
  "serde_json",
@@ -5855,7 +5855,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-ethers"
-version = "0.5.1370"
+version = "0.5.1371"
 dependencies = [
  "perry-ffi",
  "rand 0.10.1",
@@ -5863,7 +5863,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-events"
-version = "0.5.1370"
+version = "0.5.1371"
 dependencies = [
  "perry-ffi",
  "perry-runtime",
@@ -5871,14 +5871,14 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-exponential-backoff"
-version = "0.5.1370"
+version = "0.5.1371"
 dependencies = [
  "perry-ffi",
 ]
 
 [[package]]
 name = "perry-ext-fastify"
-version = "0.5.1370"
+version = "0.5.1371"
 dependencies = [
  "bytes",
  "http-body-util",
@@ -5896,7 +5896,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-fetch"
-version = "0.5.1370"
+version = "0.5.1371"
 dependencies = [
  "bytes",
  "lazy_static",
@@ -5909,7 +5909,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-http"
-version = "0.5.1370"
+version = "0.5.1371"
 dependencies = [
  "bytes",
  "h2",
@@ -5933,7 +5933,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-ioredis"
-version = "0.5.1370"
+version = "0.5.1371"
 dependencies = [
  "lazy_static",
  "perry-ffi",
@@ -5943,7 +5943,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-jsonwebtoken"
-version = "0.5.1370"
+version = "0.5.1371"
 dependencies = [
  "base64",
  "jsonwebtoken",
@@ -5954,7 +5954,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-lru-cache"
-version = "0.5.1370"
+version = "0.5.1371"
 dependencies = [
  "lru",
  "perry-ffi",
@@ -5963,7 +5963,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-moment"
-version = "0.5.1370"
+version = "0.5.1371"
 dependencies = [
  "chrono",
  "perry-ffi",
@@ -5971,7 +5971,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-mongodb"
-version = "0.5.1370"
+version = "0.5.1371"
 dependencies = [
  "bson",
  "futures-util",
@@ -5983,7 +5983,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-mysql2"
-version = "0.5.1370"
+version = "0.5.1371"
 dependencies = [
  "chrono",
  "perry-ffi",
@@ -5993,7 +5993,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-nanoid"
-version = "0.5.1370"
+version = "0.5.1371"
 dependencies = [
  "nanoid",
  "perry-ffi",
@@ -6002,7 +6002,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-net"
-version = "0.5.1370"
+version = "0.5.1371"
 dependencies = [
  "bytes",
  "perry-ffi",
@@ -6015,7 +6015,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-node-forge"
-version = "0.5.1370"
+version = "0.5.1371"
 dependencies = [
  "const-oid 0.9.6",
  "der 0.7.10",
@@ -6034,7 +6034,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-nodemailer"
-version = "0.5.1370"
+version = "0.5.1371"
 dependencies = [
  "lettre",
  "perry-ffi",
@@ -6044,7 +6044,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-pdf"
-version = "0.5.1370"
+version = "0.5.1371"
 dependencies = [
  "perry-ffi",
  "printpdf",
@@ -6052,7 +6052,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-pg"
-version = "0.5.1370"
+version = "0.5.1371"
 dependencies = [
  "perry-ffi",
  "sqlx",
@@ -6061,7 +6061,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-ratelimit"
-version = "0.5.1370"
+version = "0.5.1371"
 dependencies = [
  "governor",
  "perry-ffi",
@@ -6069,7 +6069,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-sharp"
-version = "0.5.1370"
+version = "0.5.1371"
 dependencies = [
  "fast_image_resize",
  "image",
@@ -6079,14 +6079,14 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-slugify"
-version = "0.5.1370"
+version = "0.5.1371"
 dependencies = [
  "perry-ffi",
 ]
 
 [[package]]
 name = "perry-ext-streams"
-version = "0.5.1370"
+version = "0.5.1371"
 dependencies = [
  "lazy_static",
  "perry-ffi",
@@ -6095,7 +6095,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-undici"
-version = "0.5.1370"
+version = "0.5.1371"
 dependencies = [
  "perry-ffi",
  "perry-runtime",
@@ -6104,7 +6104,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-uuid"
-version = "0.5.1370"
+version = "0.5.1371"
 dependencies = [
  "perry-ffi",
  "uuid",
@@ -6112,7 +6112,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-validator"
-version = "0.5.1370"
+version = "0.5.1371"
 dependencies = [
  "perry-ffi",
  "regex",
@@ -6122,7 +6122,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-ws"
-version = "0.5.1370"
+version = "0.5.1371"
 dependencies = [
  "futures-util",
  "lazy_static",
@@ -6135,7 +6135,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-zlib"
-version = "0.5.1370"
+version = "0.5.1371"
 dependencies = [
  "brotli",
  "flate2",
@@ -6145,7 +6145,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ffi"
-version = "0.5.1370"
+version = "0.5.1371"
 dependencies = [
  "dashmap",
  "once_cell",
@@ -6154,7 +6154,7 @@ dependencies = [
 
 [[package]]
 name = "perry-hir"
-version = "0.5.1370"
+version = "0.5.1371"
 dependencies = [
  "anyhow",
  "perry-api-manifest",
@@ -6172,7 +6172,7 @@ dependencies = [
 
 [[package]]
 name = "perry-parser"
-version = "0.5.1370"
+version = "0.5.1371"
 dependencies = [
  "anyhow",
  "perry-diagnostics",
@@ -6184,7 +6184,7 @@ dependencies = [
 
 [[package]]
 name = "perry-runtime"
-version = "0.5.1370"
+version = "0.5.1371"
 dependencies = [
  "anyhow",
  "base64",
@@ -6226,14 +6226,14 @@ dependencies = [
 
 [[package]]
 name = "perry-runtime-static"
-version = "0.5.1370"
+version = "0.5.1371"
 dependencies = [
  "perry-runtime",
 ]
 
 [[package]]
 name = "perry-stdlib"
-version = "0.5.1370"
+version = "0.5.1371"
 dependencies = [
  "aes 0.8.4",
  "aes 0.9.1",
@@ -6328,14 +6328,14 @@ dependencies = [
 
 [[package]]
 name = "perry-stdlib-static"
-version = "0.5.1370"
+version = "0.5.1371"
 dependencies = [
  "perry-stdlib",
 ]
 
 [[package]]
 name = "perry-transform"
-version = "0.5.1370"
+version = "0.5.1371"
 dependencies = [
  "anyhow",
  "perry-hir",
@@ -6344,14 +6344,14 @@ dependencies = [
 
 [[package]]
 name = "perry-ui"
-version = "0.5.1370"
+version = "0.5.1371"
 dependencies = [
  "perry-ui-model",
 ]
 
 [[package]]
 name = "perry-ui-android"
-version = "0.5.1370"
+version = "0.5.1371"
 dependencies = [
  "base64",
  "itoa",
@@ -6368,7 +6368,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ui-geisterhand"
-version = "0.5.1370"
+version = "0.5.1371"
 dependencies = [
  "rand 0.10.1",
  "serde",
@@ -6378,7 +6378,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ui-gtk4"
-version = "0.5.1370"
+version = "0.5.1371"
 dependencies = [
  "base64",
  "cairo-rs 0.22.0",
@@ -6401,7 +6401,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ui-ios"
-version = "0.5.1370"
+version = "0.5.1371"
 dependencies = [
  "base64",
  "block2",
@@ -6417,7 +6417,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ui-macos"
-version = "0.5.1370"
+version = "0.5.1371"
 dependencies = [
  "base64",
  "block2",
@@ -6432,7 +6432,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ui-model"
-version = "0.5.1370"
+version = "0.5.1371"
 
 [[package]]
 name = "perry-ui-test"
@@ -6443,11 +6443,11 @@ dependencies = [
 
 [[package]]
 name = "perry-ui-testkit"
-version = "0.5.1370"
+version = "0.5.1371"
 
 [[package]]
 name = "perry-ui-tvos"
-version = "0.5.1370"
+version = "0.5.1371"
 dependencies = [
  "base64",
  "block2",
@@ -6463,7 +6463,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ui-visionos"
-version = "0.5.1370"
+version = "0.5.1371"
 dependencies = [
  "base64",
  "block2",
@@ -6479,7 +6479,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ui-watchos"
-version = "0.5.1370"
+version = "0.5.1371"
 dependencies = [
  "block2",
  "libc",
@@ -6492,7 +6492,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ui-windows"
-version = "0.5.1370"
+version = "0.5.1371"
 dependencies = [
  "base64",
  "libc",
@@ -6509,14 +6509,14 @@ dependencies = [
 
 [[package]]
 name = "perry-ui-windows-winui"
-version = "0.5.1370"
+version = "0.5.1371"
 dependencies = [
  "perry-ui-windows",
 ]
 
 [[package]]
 name = "perry-updater"
-version = "0.5.1370"
+version = "0.5.1371"
 dependencies = [
  "anyhow",
  "base64",
@@ -6532,7 +6532,7 @@ dependencies = [
 
 [[package]]
 name = "perry-wasm-host"
-version = "0.5.1370"
+version = "0.5.1371"
 dependencies = [
  "wasmi",
 ]
diff --git a/Cargo.toml b/Cargo.toml
index 1f26d934ba..0d34ec862e 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -315,7 +315,7 @@ codegen-units = 16
 codegen-units = 16
 
 [workspace.package]
-version = "0.5.1370"
+version = "0.5.1371"
 edition = "2021"
 license = "MIT"
 repository = "https://github.com/PerryTS/perry"
diff --git a/changelog.d/7653-pin-object-ext-link.md b/changelog.d/7653-pin-object-ext-link.md
new file mode 100644
index 0000000000..d936bbca4a
--- /dev/null
+++ b/changelog.d/7653-pin-object-ext-link.md
@@ -0,0 +1,44 @@
+**`fix(gc)`: pin long-lived and malloc-resident objects without the space classifier (#7650 follow-up).**
+
+#7650 routed every `GC_FLAG_PINNED` write through `gc::pin_object`, which reaches
+`arena::classify_heap_space`. That new edge kept a reference chain alive that
+`-Wl,-dead_strip` had been removing, and **five `perry-ext-*` crates stopped
+linking**:
+
+```
+Undefined symbols for architecture arm64:
+  "_js_blob_new",                     referenced from: … fetch_globals::global_this_blob_thunk
+  "_js_fetch_with_options",           referenced from: … global_fetch::global_this_fetch_thunk
+  "_js_fetch_notify_signal_aborted",  referenced from: … url::abort::fire_abort_listeners
+```
+
+`perry-ext-{pdf,lru-cache,node-forge,mongodb,http}`. They link a **feature-stripped**
+runtime through `perry-ffi`'s `runtime-link`, so those thunks have no definition
+and only survived because the stripper removed them.
+
+Bisected rather than guessed: the commit before #7650 builds all five clean,
+#7650 does not, and reverting **only** the two `perry-runtime` call sites
+restores the link. `perry-stdlib`'s `async_bridge` keeps `pin_object` — its
+`js_promise_new()` promises really are Eden-resident and must arm the young-pin
+latch.
+
+`pin_object_non_young` does the flag write directly for the sites #7650's own
+comments already document as long-lived (`string/format.rs`, the interned format
+buffer) and malloc-resident (`thread.rs`, the spawn promise and its handle) —
+they never needed the classifier. Making `pin_object` conservative instead
+(arming for any `GC_FLAG_ARENA` object) would also remove the edge, but it would
+arm on exactly these long-lived pins and throw away the preflight skip #7645
+bought.
+
+**The claim is checked, not asserted.** `debug_assert` catches a young object in
+test builds, and `pin_object_non_young_call_sites_are_never_young`
+(`gc/tests/copying/latch.rs`) asserts non-youngness for each real call site plus
+a control proving the predicate is not vacuously false for everything. Sabotage:
+forcing the predicate false reddens the control (0 compile errors, test binary
+reached).
+
+**Why no gate caught it.** `cargo-test` scopes per-PR runs to the changed crates'
+reverse-dependency closure (`scripts/ci_test_scope.py`); the full workspace runs
+on tags and nightly only. `perry-ext-*` is outside the closure of a
+`perry-runtime` GC change, so this could only have surfaced at the next tag.
+Found by running `cargo test --release --workspace` by hand against `main`.
diff --git a/crates/perry-runtime/src/gc/mod.rs b/crates/perry-runtime/src/gc/mod.rs
index f5f4304d59..547e2a2710 100644
--- a/crates/perry-runtime/src/gc/mod.rs
+++ b/crates/perry-runtime/src/gc/mod.rs
@@ -103,7 +103,8 @@ mod pin;
 #[cfg(test)]
 pub(crate) use pin::test_reset_young_pin_latch;
 pub use pin::{
-    copied_minor_preflight_skips, copied_minor_preflight_walks, pin_object, unpin_object,
+    copied_minor_preflight_skips, copied_minor_preflight_walks, pin_object, pin_object_non_young,
+    unpin_object,
 };
 use pin::{note_preflight_skipped, note_preflight_walked, young_pin_latch_armed};
 mod copying;
diff --git a/crates/perry-runtime/src/gc/pin.rs b/crates/perry-runtime/src/gc/pin.rs
index b6fdcf2d20..5f3f7146ee 100644
--- a/crates/perry-runtime/src/gc/pin.rs
+++ b/crates/perry-runtime/src/gc/pin.rs
@@ -114,6 +114,58 @@ pub unsafe fn pin_object(header: *mut GcHeader) {
     (*header).gc_flags |= GC_FLAG_PINNED;
 }
 
+/// Set `GC_FLAG_PINNED` on an object the CALLER has already proven cannot be
+/// young-arena resident, without consulting the space classifier.
+///
+/// # Why this exists, and why it is not merely an optimisation
+///
+/// [`pin_object`] reaches `crate::arena::classify_heap_space`, and that edge is
+/// load-bearing for a reason that has nothing to do with the GC: the
+/// `perry-ext-*` crates link a **feature-stripped** runtime through
+/// `perry-ffi`'s `runtime-link` and are built with `-Wl,-dead_strip`.
+/// Introducing this call from `thread.rs` / `string/format.rs` kept a reference
+/// chain alive that the stripper had previously removed, and five ext crates
+/// stopped linking with `Undefined symbols: _js_blob_new,
+/// _js_fetch_with_options, _js_fetch_notify_signal_aborted` (#7650, bisected to
+/// that commit against a clean parent). `cargo-test` scopes per-PR runs to the
+/// changed crates' reverse-dependency closure and the FULL workspace is
+/// tag/nightly-only, so no per-PR gate could have seen it.
+///
+/// Making [`pin_object`] conservative instead — arming the latch for any
+/// `GC_FLAG_ARENA` object — would also remove the edge, but it would arm on
+/// exactly the long-lived pins this variant serves (`format.rs` pins long-lived
+/// strings), throwing away the preflight skip #7645 bought.
+///
+/// # Safety
+///
+/// As [`pin_object`], **plus** the caller must guarantee `header` is malloc
+/// space, `Longlived`, or `Old`. Pinning a young-arena object through here
+/// leaves the latch disarmed, and a copying minor will then relocate a pinned
+/// object — memory corruption, not a missed optimisation. `debug_assert` catches
+/// it in test builds, and the claim is checked for every real call site by
+/// `pin_object_non_young_call_sites_are_never_young` in
+/// `gc/tests/copying/latch.rs`; **add a case there when you add a caller.**
+#[inline]
+pub unsafe fn pin_object_non_young(header: *mut GcHeader) {
+    if header.is_null() {
+        return;
+    }
+    debug_assert!(
+        !pin_constrains_copying_minor(header),
+        "pin_object_non_young called on a young-arena object: the young-pin \
+         latch stays disarmed and the copying minor will relocate it"
+    );
+    (*header).gc_flags |= GC_FLAG_PINNED;
+}
+
+/// Test accessor for the young-pin predicate, so
+/// `pin_object_non_young_call_sites_are_never_young` can assert the invariant
+/// its callers rest on without duplicating the classification logic.
+#[cfg(test)]
+pub(crate) unsafe fn pin_constrains_copying_minor_for_tests(header: *mut GcHeader) -> bool {
+    pin_constrains_copying_minor(header)
+}
+
 /// Clear `GC_FLAG_PINNED` on `header`. Does **not** disarm the latch — see the
 /// module docs on why the latch is monotone.
 ///
diff --git a/crates/perry-runtime/src/gc/tests/copying/latch.rs b/crates/perry-runtime/src/gc/tests/copying/latch.rs
index 7742fcfba7..bafa500250 100644
--- a/crates/perry-runtime/src/gc/tests/copying/latch.rs
+++ b/crates/perry-runtime/src/gc/tests/copying/latch.rs
@@ -277,3 +277,56 @@ fn pin_latch_sabotage_child() {
     let _ = collect_minor_trace(GcTriggerKind::Direct);
     panic!("copying minor relocated a pinned young object without aborting");
 }
+
+/// #7650 follow-up: every `pin_object_non_young` call site must really be
+/// non-young, because that variant deliberately skips the space classifier and
+/// therefore leaves the latch disarmed.
+///
+/// The variant exists for a LINK reason, not a GC one — `pin_object` reaches
+/// `arena::classify_heap_space`, and that edge kept a reference chain alive
+/// that `-Wl,-dead_strip` had been removing, breaking five `perry-ext-*` crates
+/// with `Undefined symbols: _js_blob_new, _js_fetch_with_options, …` (#7650,
+/// bisected). The full workspace test is tag/nightly-only, so a per-PR run
+/// cannot see it. The safety property is therefore asserted here rather than at
+/// the call, and it is only as good as this list: **add a case when you add a
+/// caller.**
+///
+/// Callers as of this change:
+/// * `string/format.rs` — the interned format buffer, allocated long-lived.
+/// * `thread.rs` (x2) — the spawn promise and its handle, malloc-resident, so
+///   they carry no `GC_FLAG_ARENA` and the predicate short-circuits.
+#[test]
+fn pin_object_non_young_call_sites_are_never_young() {
+    let _guard = CopyingNurseryTestGuard::new(1);
+
+    unsafe {
+        // `string/format.rs` pins a LONG-LIVED allocation.
+        let longlived = crate::string::js_string_from_bytes_longlived(b"x".as_ptr(), 1);
+        let ll_header = header_from_user_ptr(longlived as *const u8) as *mut GcHeader;
+        assert!(
+            !crate::gc::pin::pin_constrains_copying_minor_for_tests(ll_header),
+            "format.rs pins a long-lived string; if that allocation ever moved \
+             to Eden, pin_object_non_young there would become memory corruption"
+        );
+
+        // `thread.rs` pins MALLOC-resident promise state: no GC_FLAG_ARENA, so
+        // the predicate short-circuits before any space classification.
+        let mut synthetic = std::ptr::read(ll_header);
+        synthetic.gc_flags &= !crate::gc::GC_FLAG_ARENA;
+        assert!(
+            !crate::gc::pin::pin_constrains_copying_minor_for_tests(&mut synthetic),
+            "a header without GC_FLAG_ARENA is malloc space and can never be \
+             Eden/FromSurvivor"
+        );
+
+        // Control: a plain nursery object IS young, so the predicate the two
+        // assertions above rely on is not vacuously false for everything.
+        let young = young_leaf();
+        let y_header = header_from_user_ptr(young as *const u8) as *mut GcHeader;
+        assert!(
+            crate::gc::pin::pin_constrains_copying_minor_for_tests(y_header),
+            "control: a nursery object must be reported young, or this test \
+             proves nothing about the two assertions above"
+        );
+    }
+}
diff --git a/crates/perry-runtime/src/string/format.rs b/crates/perry-runtime/src/string/format.rs
index 0d8d4c8ae9..fe0a8ef083 100644
--- a/crates/perry-runtime/src/string/format.rs
+++ b/crates/perry-runtime/src/string/format.rs
@@ -88,7 +88,7 @@ pub extern "C" fn js_number_to_string(value: f64) -> *mut StringHeader {
             // this does not arm the young-pin latch (#7645).
             let gc_header =
                 (ptr as *const u8).sub(crate::gc::GC_HEADER_SIZE) as *mut crate::gc::GcHeader;
-            crate::gc::pin_object(gc_header);
+            crate::gc::pin_object_non_young(gc_header);
         }
         SMALL_INT_CACHE.with(|c| unsafe {
             // GC_STORE_AUDIT(ROOT): SMALL_INT_CACHE is scanned by scan_small_int_cache_roots_mut.
diff --git a/crates/perry-runtime/src/thread.rs b/crates/perry-runtime/src/thread.rs
index 1aeda5db14..dbb4bc4a83 100644
--- a/crates/perry-runtime/src/thread.rs
+++ b/crates/perry-runtime/src/thread.rs
@@ -1488,7 +1488,7 @@ unsafe fn spawn_impl(closure_val: f64) -> *mut crate::promise::Promise {
     // Pin the promise so GC doesn't collect it while the thread is running.
     // Malloc-resident (see above), so this does not arm the young-pin latch.
     let promise_header = (promise as *mut u8).sub(gc::GC_HEADER_SIZE) as *mut gc::GcHeader;
-    gc::pin_object(promise_header);
+    gc::pin_object_non_young(promise_header);
 
     let promise_usize = promise as usize;
     // #6185: the promise lives in the SPAWNING agent's heap, so that is the
@@ -1615,7 +1615,7 @@ pub fn thread_job_begin() {
 /// `promise` must be a live promise allocation preceded by an 8-byte GcHeader.
 pub unsafe fn pin_promise(promise: *mut crate::promise::Promise) {
     let header = (promise as *mut u8).sub(gc::GC_HEADER_SIZE) as *mut gc::GcHeader;
-    gc::pin_object(header);
+    gc::pin_object_non_young(header);
 }
 
 /// Resolve the promise at `promise_usize` with a UTF-8 string on the agent that