diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 131c210e3..dccb26da3 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -368,21 +368,28 @@ jobs:
             # auto-optimize *integration* tests (tests/*.rs — each shells out to
             # `perry compile`, ~4–6 min apiece, ~30 of them) are NOT run per-PR;
             # they run in the nightly full job, on release tags, and on demand
-            # via the `run-extended-tests` label. Unit-test binaries are small,
-            # so builds parallelize safely (no serialization / clean churn) and
-            # there is no staticlib dependency to build.
+            # via the `run-extended-tests` label. No staticlib dependency to
+            # build (no integration tests).
             #
+            # Each crate's test binary statically links the whole runtime, so
+            # building many at once OOMs the runner (same reason the FULL path
+            # uses CARGO_BUILD_JOBS=1). Serialize here too, and drop crates with
+            # no `src/` unit tests (their lib test binary has zero tests yet
+            # still pays the heavy link).
+            export CARGO_BUILD_JOBS=1
             # perry-runtime first, single-threaded (process-global state); it is
             # a lib-only crate, so filter to --lib.
             if printf '%s\n' "$scope" | grep -qx 'perry-runtime'; then
               RUST_TEST_THREADS=1 cargo test --lib -p perry-runtime
             fi
-            rest="$(printf '%s\n' "$scope" | grep -vx 'perry-runtime' || true)"
+            rest="$(printf '%s\n' "$scope" | grep -vx 'perry-runtime' \
+              | python3 scripts/ci_test_scope.py --with-tests || true)"
+            echo "Crates with unit tests in scope:"; printf '%s\n' "$rest"
             if [ -n "$rest" ]; then
-              # One parallel invocation across the rest of the scope. `cargo test
-              # --lib` errors if NO selected package has a library (a perry-only
-              # diff → just the bin-only `perry` crate), so include --lib only
-              # when some selected crate has one; --bins is always safe.
+              # One invocation across the rest of the scope. `cargo test --lib`
+              # errors if NO selected package has a library (a perry-only diff →
+              # just the bin-only `perry` crate), so include --lib only when some
+              # selected crate has one; --bins is always safe.
               pkg_args="$(printf '%s\n' "$rest" | sed 's/^/-p /' | tr '\n' ' ')"
               if printf '%s\n' "$rest" | python3 scripts/ci_test_scope.py --has-lib; then
                 target_filter="--lib --bins"
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 6e569c348..5a7e42c06 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,21 @@
+## v0.5.1186 — fix(ci): per-PR cargo-test link-OOM — serialize fast-path links + skip zero-unit-test crates
+
+The #5411 fast per-PR path built every affected crate's unit-test binary in one
+unbounded-parallel `cargo test --lib --bins -p ...` invocation. Each test binary
+statically links the whole runtime, so a wide-fan-out diff (a perry-runtime change
+selects ~50 crates) linked ~50 huge binaries at once and the runner OOMed
+(`linking with \`cc\` failed`) — the exact failure the FULL path avoids with
+`CARGO_BUILD_JOBS=1`. Surfaced on #5402 (Tier 2 touches perry-runtime).
+
+- `.github/workflows/test.yml` — the fast path now sets `CARGO_BUILD_JOBS=1`
+  (serialize the heavy links; no OOM) and filters the scope through
+  `ci_test_scope.py --with-tests`, dropping crates with no `src/` unit tests
+  (~13 zero-test FFI shims in the wide case) whose lib test binary would link the
+  runtime for zero tests.
+- `scripts/ci_test_scope.py` — new `--with-tests` mode: prints the subset of stdin
+  package names whose `src/` contains a `#[test]` / `#[tokio::test]` (unit tests
+  the `--lib --bins` filter actually runs; integration-only crates are excluded).
+
 ## v0.5.1185 — perf(ci): make per-PR cargo-test fast (<10 min) — unit tests for affected crates; integration tests move to nightly/tags
 
 The `cargo-test` gate took ~90 min: it built the **entire workspace** in debug,
diff --git a/CLAUDE.md b/CLAUDE.md
index d23c68ce0..14e4f69a4 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:** 0.5.1185
+**Current Version:** 0.5.1186
 
 
 ## TypeScript Parity Status
diff --git a/Cargo.lock b/Cargo.lock
index 999dfaa09..e6762a47d 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -5283,7 +5283,7 @@ checksum = "9b4f627cb1b25917193a259e49bdad08f671f8d9708acfd5fe0a8c1455d87220"
 
 [[package]]
 name = "perry"
-version = "0.5.1185"
+version = "0.5.1186"
 dependencies = [
  "anyhow",
  "base64",
@@ -5340,14 +5340,14 @@ dependencies = [
 
 [[package]]
 name = "perry-api-manifest"
-version = "0.5.1185"
+version = "0.5.1186"
 dependencies = [
  "serde",
 ]
 
 [[package]]
 name = "perry-audio-miniaudio"
-version = "0.5.1185"
+version = "0.5.1186"
 dependencies = [
  "cc",
  "libc",
@@ -5355,7 +5355,7 @@ dependencies = [
 
 [[package]]
 name = "perry-codegen"
-version = "0.5.1185"
+version = "0.5.1186"
 dependencies = [
  "anyhow",
  "log",
@@ -5370,7 +5370,7 @@ dependencies = [
 
 [[package]]
 name = "perry-codegen-arkts"
-version = "0.5.1185"
+version = "0.5.1186"
 dependencies = [
  "anyhow",
  "perry-hir",
@@ -5379,7 +5379,7 @@ dependencies = [
 
 [[package]]
 name = "perry-codegen-glance"
-version = "0.5.1185"
+version = "0.5.1186"
 dependencies = [
  "anyhow",
  "perry-hir",
@@ -5387,7 +5387,7 @@ dependencies = [
 
 [[package]]
 name = "perry-codegen-js"
-version = "0.5.1185"
+version = "0.5.1186"
 dependencies = [
  "anyhow",
  "perry-dispatch",
@@ -5397,7 +5397,7 @@ dependencies = [
 
 [[package]]
 name = "perry-codegen-swiftui"
-version = "0.5.1185"
+version = "0.5.1186"
 dependencies = [
  "anyhow",
  "perry-hir",
@@ -5406,7 +5406,7 @@ dependencies = [
 
 [[package]]
 name = "perry-codegen-wasm"
-version = "0.5.1185"
+version = "0.5.1186"
 dependencies = [
  "anyhow",
  "base64",
@@ -5419,7 +5419,7 @@ dependencies = [
 
 [[package]]
 name = "perry-codegen-wear-tiles"
-version = "0.5.1185"
+version = "0.5.1186"
 dependencies = [
  "anyhow",
  "perry-hir",
@@ -5427,7 +5427,7 @@ dependencies = [
 
 [[package]]
 name = "perry-container-compose"
-version = "0.5.1185"
+version = "0.5.1186"
 dependencies = [
  "anyhow",
  "async-trait",
@@ -5456,14 +5456,14 @@ dependencies = [
 
 [[package]]
 name = "perry-container-e2e"
-version = "0.5.1185"
+version = "0.5.1186"
 dependencies = [
  "anyhow",
 ]
 
 [[package]]
 name = "perry-diagnostics"
-version = "0.5.1185"
+version = "0.5.1186"
 dependencies = [
  "serde",
  "serde_json",
@@ -5471,7 +5471,7 @@ dependencies = [
 
 [[package]]
 name = "perry-dispatch"
-version = "0.5.1185"
+version = "0.5.1186"
 
 [[package]]
 name = "perry-doc-fixture-my-bindings"
@@ -5482,7 +5482,7 @@ dependencies = [
 
 [[package]]
 name = "perry-doc-tests"
-version = "0.5.1185"
+version = "0.5.1186"
 dependencies = [
  "anyhow",
  "clap",
@@ -5497,14 +5497,14 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-ads"
-version = "0.5.1185"
+version = "0.5.1186"
 dependencies = [
  "perry-ffi",
 ]
 
 [[package]]
 name = "perry-ext-argon2"
-version = "0.5.1185"
+version = "0.5.1186"
 dependencies = [
  "argon2",
  "perry-ffi",
@@ -5512,7 +5512,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-axios"
-version = "0.5.1185"
+version = "0.5.1186"
 dependencies = [
  "perry-ffi",
  "reqwest",
@@ -5521,7 +5521,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-bcrypt"
-version = "0.5.1185"
+version = "0.5.1186"
 dependencies = [
  "bcrypt",
  "perry-ffi",
@@ -5529,7 +5529,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-better-sqlite3"
-version = "0.5.1185"
+version = "0.5.1186"
 dependencies = [
  "perry-ffi",
  "rusqlite",
@@ -5537,7 +5537,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-cheerio"
-version = "0.5.1185"
+version = "0.5.1186"
 dependencies = [
  "perry-ffi",
  "scraper",
@@ -5545,7 +5545,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-commander"
-version = "0.5.1185"
+version = "0.5.1186"
 dependencies = [
  "perry-ffi",
  "perry-runtime",
@@ -5553,7 +5553,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-cron"
-version = "0.5.1185"
+version = "0.5.1186"
 dependencies = [
  "chrono",
  "cron 0.16.0",
@@ -5563,7 +5563,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-dayjs"
-version = "0.5.1185"
+version = "0.5.1186"
 dependencies = [
  "chrono",
  "perry-ffi",
@@ -5571,7 +5571,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-decimal"
-version = "0.5.1185"
+version = "0.5.1186"
 dependencies = [
  "perry-ffi",
  "rust_decimal",
@@ -5579,7 +5579,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-dotenv"
-version = "0.5.1185"
+version = "0.5.1186"
 dependencies = [
  "perry-ffi",
  "serde_json",
@@ -5587,7 +5587,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-ethers"
-version = "0.5.1185"
+version = "0.5.1186"
 dependencies = [
  "perry-ffi",
  "rand 0.8.6",
@@ -5595,7 +5595,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-events"
-version = "0.5.1185"
+version = "0.5.1186"
 dependencies = [
  "perry-ffi",
  "perry-runtime",
@@ -5603,14 +5603,14 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-exponential-backoff"
-version = "0.5.1185"
+version = "0.5.1186"
 dependencies = [
  "perry-ffi",
 ]
 
 [[package]]
 name = "perry-ext-fastify"
-version = "0.5.1185"
+version = "0.5.1186"
 dependencies = [
  "bytes",
  "http-body-util",
@@ -5627,7 +5627,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-fetch"
-version = "0.5.1185"
+version = "0.5.1186"
 dependencies = [
  "lazy_static",
  "perry-ffi",
@@ -5639,7 +5639,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-http"
-version = "0.5.1185"
+version = "0.5.1186"
 dependencies = [
  "lazy_static",
  "perry-ext-http-server",
@@ -5652,7 +5652,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-http-server"
-version = "0.5.1185"
+version = "0.5.1186"
 dependencies = [
  "bytes",
  "h2",
@@ -5675,7 +5675,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-ioredis"
-version = "0.5.1185"
+version = "0.5.1186"
 dependencies = [
  "lazy_static",
  "perry-ffi",
@@ -5685,7 +5685,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-jsonwebtoken"
-version = "0.5.1185"
+version = "0.5.1186"
 dependencies = [
  "base64",
  "jsonwebtoken",
@@ -5696,7 +5696,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-lru-cache"
-version = "0.5.1185"
+version = "0.5.1186"
 dependencies = [
  "lru",
  "perry-ffi",
@@ -5704,7 +5704,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-moment"
-version = "0.5.1185"
+version = "0.5.1186"
 dependencies = [
  "chrono",
  "perry-ffi",
@@ -5712,7 +5712,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-mongodb"
-version = "0.5.1185"
+version = "0.5.1186"
 dependencies = [
  "bson",
  "futures-util",
@@ -5724,7 +5724,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-mysql2"
-version = "0.5.1185"
+version = "0.5.1186"
 dependencies = [
  "chrono",
  "perry-ffi",
@@ -5734,7 +5734,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-nanoid"
-version = "0.5.1185"
+version = "0.5.1186"
 dependencies = [
  "nanoid",
  "perry-ffi",
@@ -5743,7 +5743,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-net"
-version = "0.5.1185"
+version = "0.5.1186"
 dependencies = [
  "perry-ffi",
  "perry-runtime",
@@ -5755,7 +5755,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-nodemailer"
-version = "0.5.1185"
+version = "0.5.1186"
 dependencies = [
  "lettre",
  "perry-ffi",
@@ -5765,7 +5765,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-pdf"
-version = "0.5.1185"
+version = "0.5.1186"
 dependencies = [
  "perry-ffi",
  "printpdf",
@@ -5773,7 +5773,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-pg"
-version = "0.5.1185"
+version = "0.5.1186"
 dependencies = [
  "perry-ffi",
  "sqlx",
@@ -5782,7 +5782,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-ratelimit"
-version = "0.5.1185"
+version = "0.5.1186"
 dependencies = [
  "governor",
  "perry-ffi",
@@ -5790,7 +5790,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-sharp"
-version = "0.5.1185"
+version = "0.5.1186"
 dependencies = [
  "base64",
  "image",
@@ -5799,14 +5799,14 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-slugify"
-version = "0.5.1185"
+version = "0.5.1186"
 dependencies = [
  "perry-ffi",
 ]
 
 [[package]]
 name = "perry-ext-streams"
-version = "0.5.1185"
+version = "0.5.1186"
 dependencies = [
  "lazy_static",
  "perry-ffi",
@@ -5815,7 +5815,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-uuid"
-version = "0.5.1185"
+version = "0.5.1186"
 dependencies = [
  "perry-ffi",
  "uuid",
@@ -5823,7 +5823,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-validator"
-version = "0.5.1185"
+version = "0.5.1186"
 dependencies = [
  "perry-ffi",
  "regex",
@@ -5833,7 +5833,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-ws"
-version = "0.5.1185"
+version = "0.5.1186"
 dependencies = [
  "futures-util",
  "lazy_static",
@@ -5845,7 +5845,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-zlib"
-version = "0.5.1185"
+version = "0.5.1186"
 dependencies = [
  "brotli",
  "flate2",
@@ -5854,7 +5854,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ffi"
-version = "0.5.1185"
+version = "0.5.1186"
 dependencies = [
  "dashmap",
  "once_cell",
@@ -5863,7 +5863,7 @@ dependencies = [
 
 [[package]]
 name = "perry-hir"
-version = "0.5.1185"
+version = "0.5.1186"
 dependencies = [
  "anyhow",
  "perry-api-manifest",
@@ -5881,7 +5881,7 @@ dependencies = [
 
 [[package]]
 name = "perry-parser"
-version = "0.5.1185"
+version = "0.5.1186"
 dependencies = [
  "anyhow",
  "perry-diagnostics",
@@ -5893,7 +5893,7 @@ dependencies = [
 
 [[package]]
 name = "perry-runtime"
-version = "0.5.1185"
+version = "0.5.1186"
 dependencies = [
  "anyhow",
  "base64",
@@ -5926,7 +5926,7 @@ dependencies = [
 
 [[package]]
 name = "perry-stdlib"
-version = "0.5.1185"
+version = "0.5.1186"
 dependencies = [
  "aes 0.8.4",
  "aes-gcm",
@@ -6018,7 +6018,7 @@ dependencies = [
 
 [[package]]
 name = "perry-transform"
-version = "0.5.1185"
+version = "0.5.1186"
 dependencies = [
  "anyhow",
  "perry-hir",
@@ -6028,7 +6028,7 @@ dependencies = [
 
 [[package]]
 name = "perry-types"
-version = "0.5.1185"
+version = "0.5.1186"
 dependencies = [
  "anyhow",
  "thiserror 1.0.69",
@@ -6036,14 +6036,14 @@ dependencies = [
 
 [[package]]
 name = "perry-ui"
-version = "0.5.1185"
+version = "0.5.1186"
 dependencies = [
  "perry-ui-model",
 ]
 
 [[package]]
 name = "perry-ui-android"
-version = "0.5.1185"
+version = "0.5.1186"
 dependencies = [
  "base64",
  "itoa",
@@ -6060,7 +6060,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ui-geisterhand"
-version = "0.5.1185"
+version = "0.5.1186"
 dependencies = [
  "rand 0.8.6",
  "serde",
@@ -6070,7 +6070,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ui-gtk4"
-version = "0.5.1185"
+version = "0.5.1186"
 dependencies = [
  "base64",
  "cairo-rs",
@@ -6093,7 +6093,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ui-ios"
-version = "0.5.1185"
+version = "0.5.1186"
 dependencies = [
  "base64",
  "block2",
@@ -6109,7 +6109,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ui-macos"
-version = "0.5.1185"
+version = "0.5.1186"
 dependencies = [
  "base64",
  "block2",
@@ -6124,7 +6124,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ui-model"
-version = "0.5.1185"
+version = "0.5.1186"
 
 [[package]]
 name = "perry-ui-test"
@@ -6132,11 +6132,11 @@ version = "0.1.0"
 
 [[package]]
 name = "perry-ui-testkit"
-version = "0.5.1185"
+version = "0.5.1186"
 
 [[package]]
 name = "perry-ui-tvos"
-version = "0.5.1185"
+version = "0.5.1186"
 dependencies = [
  "base64",
  "block2",
@@ -6152,7 +6152,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ui-visionos"
-version = "0.5.1185"
+version = "0.5.1186"
 dependencies = [
  "base64",
  "block2",
@@ -6168,7 +6168,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ui-watchos"
-version = "0.5.1185"
+version = "0.5.1186"
 dependencies = [
  "block2",
  "libc",
@@ -6181,7 +6181,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ui-windows"
-version = "0.5.1185"
+version = "0.5.1186"
 dependencies = [
  "base64",
  "libc",
@@ -6198,14 +6198,14 @@ dependencies = [
 
 [[package]]
 name = "perry-ui-windows-winui"
-version = "0.5.1185"
+version = "0.5.1186"
 dependencies = [
  "perry-ui-windows",
 ]
 
 [[package]]
 name = "perry-updater"
-version = "0.5.1185"
+version = "0.5.1186"
 dependencies = [
  "base64",
  "ed25519-dalek",
@@ -6219,7 +6219,7 @@ dependencies = [
 
 [[package]]
 name = "perry-wasm-host"
-version = "0.5.1185"
+version = "0.5.1186"
 dependencies = [
  "wasmi",
 ]
diff --git a/Cargo.toml b/Cargo.toml
index 02653513f..3de0fc748 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -215,7 +215,7 @@ strip = false
 codegen-units = 16
 
 [workspace.package]
-version = "0.5.1185"
+version = "0.5.1186"
 edition = "2021"
 license = "MIT"
 repository = "https://github.com/PerryTS/perry"
diff --git a/scripts/ci_test_scope.py b/scripts/ci_test_scope.py
index a2c0c8865..6b742198c 100755
--- a/scripts/ci_test_scope.py
+++ b/scripts/ci_test_scope.py
@@ -26,6 +26,8 @@
 Usage:  <changed-files> | python3 scripts/ci_test_scope.py [--full]
 """
 import json
+import os
+import re
 import subprocess
 import sys
 
@@ -137,9 +139,54 @@ def _has_lib_mode() -> int:
     return 0 if has else 1
 
 
+_TEST_ATTR = re.compile(r"#\[\s*(?:tokio::)?test\b")
+
+
+def _with_tests_mode() -> int:
+    """Print the subset of stdin package names whose source contains unit tests.
+
+    The per-PR fast path serializes test-binary links to avoid OOM (each crate's
+    test binary statically links the whole runtime); building a test binary for a
+    crate with *zero* `#[test]`s is pure wasted link time. Filtering them out
+    keeps the wide-fan-out case (a perry-runtime change selects ~50 crates, ~30 of
+    which are zero-test FFI shims) under the time budget. Conservative: a crate is
+    kept if any `.rs` under its dir has a `#[test]` / `#[tokio::test]` attribute.
+    """
+    names = set(sys.stdin.read().split())
+    md = _load_metadata()
+    for p in md["packages"]:
+        if p["name"] not in names:
+            continue
+        # Only scan `src/` — the fast path runs `--lib --bins`, i.e. unit tests
+        # compiled into the lib/bin targets. Integration tests under `tests/`
+        # are NOT run per-PR, so a crate whose only `#[test]`s live there must
+        # not be selected (its lib test binary would have zero tests yet still
+        # pay the heavy runtime link).
+        crate_dir = os.path.join(os.path.dirname(p["manifest_path"]), "src")
+        has_test = False
+        for root, _dirs, files in os.walk(crate_dir):
+            for fname in files:
+                if not fname.endswith(".rs"):
+                    continue
+                try:
+                    with open(os.path.join(root, fname), encoding="utf-8", errors="ignore") as fh:
+                        if _TEST_ATTR.search(fh.read()):
+                            has_test = True
+                            break
+                except OSError:
+                    pass
+            if has_test:
+                break
+        if has_test:
+            print(p["name"])
+    return 0
+
+
 def main() -> int:
     if "--has-lib" in sys.argv:
         return _has_lib_mode()
+    if "--with-tests" in sys.argv:
+        return _with_tests_mode()
 
     full = "--full" in sys.argv
     changed = [line.strip() for line in sys.stdin if line.strip()]