diff --git a/.github/workflows/quality-gates.yml b/.github/workflows/quality-gates.yml
index 2abab83..d53f35c 100644
--- a/.github/workflows/quality-gates.yml
+++ b/.github/workflows/quality-gates.yml
@@ -136,7 +136,7 @@ jobs:
           --wheel-dir dist
           --dependency-lock candidate-dependencies.lock
           --output-dir candidate-base
-          --commit "${CANDIDATE_COMMIT}"
+          --commit "${{ env.CANDIDATE_COMMIT }}"
           --workflow-run-id "${{ github.run_id }}"
           --workflow-run-attempt "${{ github.run_attempt }}"
       - name: Upload same-run Candidate base
@@ -184,7 +184,7 @@ jobs:
           --base-dir candidate-base
           --target "${{ matrix.target }}"
           --output-dir candidate-wheelhouse
-          --commit "${CANDIDATE_COMMIT}"
+          --commit "${{ env.CANDIDATE_COMMIT }}"
           --workflow-run-id "${{ github.run_id }}"
           --workflow-run-attempt "${{ github.run_attempt }}"
       - name: Upload same-run target wheelhouse
@@ -234,7 +234,7 @@ jobs:
           --windows-wheelhouse wheelhouse-windows
           --output-dir candidate-channel
           --base-url .
-          --commit "${CANDIDATE_COMMIT}"
+          --commit "${{ env.CANDIDATE_COMMIT }}"
           --workflow-run-id "${{ github.run_id }}"
           --workflow-run-attempt "${{ github.run_attempt }}"
       - name: Upload exact Candidate channel
diff --git a/agent-contract/README.md b/agent-contract/README.md
index 6ab0e96..27e5d78 100644
--- a/agent-contract/README.md
+++ b/agent-contract/README.md
@@ -122,8 +122,10 @@ keyring, null pip configuration, no ambient proxy/source/cache/target/prefix/use
 settings, and wheel-only strict hashes. Because the supported Python interface is a
 minor version rather than one patch release, locks containing
 `python_full_version` or `implementation_version` markers fail closed. Compatibility
-uses packaging's CPython tag model; macOS arm64 is conservatively bounded to its
-macOS 11 deployment baseline, including compatible `abi3` and `universal2` tags.
+uses packaging's CPython tag model; the macOS wheelhouse is bounded to deployment
+version 15.0 and requires a trusted local macOS version of 15.0 or newer before target
+selection. Compatible deployment tags through macOS 15, including `abi3` and
+`universal2`, are accepted.
 
 The public prompt remains anchored to the exact canonical immutable GitHub Release ID,
 tag, commit, and asset set. Builders accept only local `.` for Candidate assets and the
diff --git a/agent-contract/tests/test_candidate_wheelhouse.py b/agent-contract/tests/test_candidate_wheelhouse.py
index 63166f8..14fb2e9 100644
--- a/agent-contract/tests/test_candidate_wheelhouse.py
+++ b/agent-contract/tests/test_candidate_wheelhouse.py
@@ -233,7 +233,8 @@ def test_target_tags_accept_abi3_and_reject_newer_macos_or_wrong_architecture(wh
     assert compatible("cp310-abi3-macosx_11_0_arm64", "darwin-arm64-py311")
     assert compatible("cp310-abi3-macosx_11_0_universal2", "darwin-arm64-py311")
     assert compatible("cp310-abi3-win_amd64", "win32-amd64-py312")
-    assert not compatible("cp310-abi3-macosx_12_0_arm64", "darwin-arm64-py311")
+    assert compatible("cp310-abi3-macosx_12_0_arm64", "darwin-arm64-py311")
+    assert not compatible("cp310-abi3-macosx_16_0_arm64", "darwin-arm64-py311")
     assert not compatible("cp311-cp311-macosx_11_0_x86_64", "darwin-arm64-py311")
     assert not compatible("cp312-cp312-win32", "win32-amd64-py312")
 
@@ -280,6 +281,7 @@ def download(command, **kwargs):
     monkeypatch.setattr(module["platform"], "machine", lambda: "arm64")
     monkeypatch.setattr(module["sys"], "platform", "darwin")
     monkeypatch.setattr(module["sys"], "version_info", SimpleNamespace(major=3, minor=11))
+    monkeypatch.setattr(module["platform"], "mac_ver", lambda: ("15.7.1", ("", "", ""), ""))
     output = tmp_path / "acquired"
     module["acquire_wheelhouse"](base_dir, "darwin-arm64-py311", output, *COMMIT_RUN)
     command = captured["command"]
@@ -303,6 +305,26 @@ def download(command, **kwargs):
     )[0]["source"] == {"host": "pypi.org", "class": "default-public"}
 
 
+@pytest.mark.parametrize("macos_version", ["15.0", "15.7.1", "16.0"])
+def test_supported_macos_deployment_selects_target(wheelhouse_module, monkeypatch, macos_version):
+    module = wheelhouse_module
+    monkeypatch.setattr(module["platform"], "machine", lambda: "arm64")
+    monkeypatch.setattr(module["platform"], "mac_ver", lambda: (macos_version, ("", "", ""), ""))
+    monkeypatch.setattr(module["sys"], "platform", "darwin")
+    monkeypatch.setattr(module["sys"], "version_info", SimpleNamespace(major=3, minor=11))
+    module["_assert_target_host"]("darwin-arm64-py311")
+
+
+def test_older_macos_deployment_fails_before_acquisition(wheelhouse_module, monkeypatch):
+    module = wheelhouse_module
+    monkeypatch.setattr(module["platform"], "machine", lambda: "arm64")
+    monkeypatch.setattr(module["platform"], "mac_ver", lambda: ("14.7", ("", "", ""), ""))
+    monkeypatch.setattr(module["sys"], "platform", "darwin")
+    monkeypatch.setattr(module["sys"], "version_info", SimpleNamespace(major=3, minor=11))
+    with pytest.raises(module["WheelhouseError"], match="does not match"):
+        module["_assert_target_host"]("darwin-arm64-py311")
+
+
 @pytest.mark.parametrize("target, machine, sys_platform, version", [
     ("darwin-arm64-py311", "x86_64", "darwin", (3, 11)),
     ("darwin-arm64-py311", "arm64", "darwin", (3, 12)),
@@ -344,6 +366,7 @@ def test_candidate_builder_covers_nested_wheelhouses_and_offline_prompt(
     for relative in ("agent-contract", "appium-mcp-server", "pywinauto-mcp-server", "autogenesis-cli"):
         shutil.copytree(repo_root / relative, source / relative, ignore=shutil.ignore_patterns("__pycache__", ".pytest_cache", ".venv"))
     subprocess.run(["git", "init", "-q", str(source)], check=True)
+    subprocess.run(["git", "-C", str(source), "config", "core.longpaths", "true"], check=True)
     subprocess.run(["git", "-C", str(source), "add", "."], check=True)
     subprocess.run([
         "git", "-C", str(source), "-c", "user.name=Candidate Contract Test",
diff --git a/agent-contract/tools/build_candidate_release.py b/agent-contract/tools/build_candidate_release.py
index 42e8b5a..ca75ced 100644
--- a/agent-contract/tools/build_candidate_release.py
+++ b/agent-contract/tools/build_candidate_release.py
@@ -240,9 +240,10 @@ def main() -> None:
         acquire=(
             "Use only the two manifest-bound target wheelhouses, universal lock, complete offline-install lock, "
             "first-party wheels, and Skill bytes already present in the exact Actions artifact. Prove the native "
-            "host from local facts, then select exactly one compatible target: native macOS arm64 with CPython 3.11 "
-            "selects `darwin-arm64-py311`; native Windows x64 with CPython 3.12 selects `win32-amd64-py312`. "
-            "Reject Linux, WSL, another Python implementation/version/architecture, zero matches, or multiple matches. "
+            "host from trusted local facts, then select exactly one compatible target: native macOS 15 or newer on "
+            "arm64 with CPython 3.11 selects `darwin-arm64-py311`; native Windows x64 with CPython 3.12 selects "
+            "`win32-amd64-py312`. Reject older macOS, Linux, WSL, another Python implementation/version/architecture, "
+            "zero matches, or multiple matches. "
             "Verify the selected target manifest and every listed wheel against the Candidate manifest and complete "
             "checksums before installation. Do not query or use a package index, mirror, proxy, credential, package "
             "configuration, cache, source tree, VCS checkout, sdist, editable input, or installed distribution."
diff --git a/agent-contract/tools/candidate_wheelhouse.py b/agent-contract/tools/candidate_wheelhouse.py
index 8efa3ee..e771704 100644
--- a/agent-contract/tools/candidate_wheelhouse.py
+++ b/agent-contract/tools/candidate_wheelhouse.py
@@ -53,6 +53,7 @@
         "sys_platform": "darwin",
         "platform": "macos",
         "architecture": "arm64",
+        "deployment_version": "15.0",
         "os_name": "posix",
         "platform_system": "Darwin",
         "platform_machine": "arm64",
@@ -275,9 +276,8 @@ def _target_tags(target_key: str) -> frozenset[str]:
     target = TARGETS[target_key]
     python_version = tuple(int(value) for value in target["python_version"].split("."))
     if target["sys_platform"] == "darwin":
-        # Native arm64 exists from macOS 11 onward; this conservative baseline
-        # prevents a wheelhouse from claiming support via a newer deployment tag.
-        platforms = tuple(mac_platforms(version=(11, 0), arch="arm64"))
+        deployment_version = tuple(int(value) for value in target["deployment_version"].split("."))
+        platforms = tuple(mac_platforms(version=deployment_version, arch="arm64"))
     else:
         platforms = ("win_amd64",)
     tags = set(cpython_tags(python_version=python_version, platforms=platforms))
@@ -457,11 +457,18 @@ def _assert_target_host(target_key: str) -> None:
     machine = platform.machine().lower()
     architecture = "arm64" if machine in {"arm64", "aarch64"} else "amd64" if machine in {"amd64", "x86_64"} else machine
     observed_version = f"{sys.version_info.major}.{sys.version_info.minor}"
+    deployment_ok = True
+    if target["sys_platform"] == "darwin":
+        try:
+            deployment_ok = Version(platform.mac_ver()[0]) >= Version(target["deployment_version"])
+        except Exception:
+            deployment_ok = False
     if (
         sys.implementation.name != "cpython"
         or observed_version != target["python_version"]
         or sys.platform != target["sys_platform"]
         or architecture != target["architecture"]
+        or not deployment_ok
     ):
         raise WheelhouseError("acquisition host does not match the exact Candidate target")