diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
index 7604be6293..2b952a976a 100644
--- a/.github/workflows/release.yml
+++ b/.github/workflows/release.yml
@@ -224,12 +224,14 @@ jobs:
   # ---------------------------------------------------------------------------
   build-darwin-arm64:
     name: Build macOS ARM64
-    # The shipped-profile library compile peaks near 12 GB and swaps on this
-    # free 7 GB runner (0.63.1's ARM64 build ran past a shorter limit twice),
-    # so the limit leaves only the tag canceller's 10 minutes below GitHub's
-    # 360-minute maximum.
-    runs-on: macos-26
-    timeout-minutes: 350
+    # The macOS release jobs run on CortexKit's rented Mac (12 cores, 16 GB,
+    # one job at a time, checkouts kept warm between jobs) until the rental
+    # ends on 21 November 2026; then they move back to `macos-26`. GitHub's
+    # free 7 GB runner swaps on the shipped-profile library compile, which
+    # peaks near 12 GB, and needed close to its 360-minute maximum. The rented
+    # Mac has no Rust or Bun on its PATH, so every job installs its toolchains.
+    runs-on: [self-hosted, rented-mac]
+    timeout-minutes: 150
     outputs:
       rust_version: ${{ steps.bundle.outputs.rust_version }}
     permissions:
@@ -306,8 +308,8 @@ jobs:
   build-darwin-x64:
     name: Build macOS x64
     # Same runner and limit as the ARM64 build; see the note there.
-    runs-on: macos-26
-    timeout-minutes: 350
+    runs-on: [self-hosted, rented-mac]
+    timeout-minutes: 150
     env:
       SCCACHE_GHA_ENABLED: "true"
       RUSTC_WRAPPER: sccache
@@ -590,6 +592,9 @@ jobs:
   e2e-darwin-arm64:
     name: Shipped E2E (macOS ARM64)
     needs: build-darwin-arm64
+    # Stays on GitHub's runner: the rented Mac downloads the 135 MB tested
+    # bundle at about 160 KB/s (14 minutes), while the suite itself takes a
+    # few minutes here.
     runs-on: macos-26
     # v0.62.0/v0.63.3/v0.63.4: 2.4/3.0/3.4 min; 10 min covers cold setup.
     timeout-minutes: 10
diff --git a/benchmarks/aft-search/slice-descriptors/land-release-macos-rented-mac.json b/benchmarks/aft-search/slice-descriptors/land-release-macos-rented-mac.json
new file mode 100644
index 0000000000..ebd574711e
--- /dev/null
+++ b/benchmarks/aft-search/slice-descriptors/land-release-macos-rented-mac.json
@@ -0,0 +1,8 @@
+{
+  "targeted_mechanism": "none",
+  "kind": "harness",
+  "slice_class": "non_ranking",
+  "fixtures": [
+    "harness-goldens"
+  ]
+}
diff --git a/scripts/lib/test_workflow_gates.py b/scripts/lib/test_workflow_gates.py
index df0a6eb7f2..afcc024700 100644
--- a/scripts/lib/test_workflow_gates.py
+++ b/scripts/lib/test_workflow_gates.py
@@ -741,7 +741,9 @@ def test_libtest_codegen_is_split_without_rebuilding_dependencies(self) -> None:
 
     def test_macos_jobs_use_free_github_runners(self) -> None:
         # AFT's repository is public, where GitHub's macOS runners are free;
-        # no job may name a paid runner provider.
+        # no job may name a paid runner provider. The macOS release jobs run
+        # on CortexKit's rented Mac until its rental ends on 21 November 2026
+        # (see the note on build-darwin-arm64 in release.yml).
         suite = workflow_gates.parse_workflow(str(REPO_ROOT / ".github/workflows/_unit-suite.yml"))
         release = workflow_gates.parse_workflow(str(REPO_ROOT / ".github/workflows/release.yml"))
         jobs = suite["jobs"]
@@ -750,7 +752,8 @@ def test_macos_jobs_use_free_github_runners(self) -> None:
         for name in ("unit-macos-libtest-archive", "unit-macos-libtest-shard", "unit-macos-bin-archive", "unit-macos-nextest-archive", "unit-macos-inventory-proof"):
             self.assertEqual(jobs[name]["runs-on"], "macos-26", name)
         for name in ("build-darwin-arm64", "build-darwin-x64"):
-            self.assertEqual(release["jobs"][name]["runs-on"], "macos-26", name)
+            self.assertEqual(release["jobs"][name]["runs-on"], ["self-hosted", "rented-mac"], name)
+        self.assertEqual(release["jobs"]["e2e-darwin-arm64"]["runs-on"], "macos-26")
         for workflow in (suite, release):
             self.assertEqual(
                 [name for name, job in workflow["jobs"].items() if "blacksmith" in str(job.get("runs-on", "")).lower()],