diff --git a/packages/keel-broker-api/pyproject.toml b/packages/keel-broker-api/pyproject.toml
index ab1a84ba..be55e9f1 100644
--- a/packages/keel-broker-api/pyproject.toml
+++ b/packages/keel-broker-api/pyproject.toml
@@ -1,6 +1,6 @@
 [project]
 name = "keel-broker-api"
-version = "0.5.1"
+version = "0.5.2"
 description = "Broker port, domain types, capability model, and conformance suite for keel"
 requires-python = ">=3.14.4"
 dependencies = ["keel-core"]
diff --git a/packages/keel-broker-coinbase/pyproject.toml b/packages/keel-broker-coinbase/pyproject.toml
index ee5eaf66..f8799df1 100644
--- a/packages/keel-broker-coinbase/pyproject.toml
+++ b/packages/keel-broker-coinbase/pyproject.toml
@@ -1,6 +1,6 @@
 [project]
 name = "keel-broker-coinbase"
-version = "0.5.1"
+version = "0.5.2"
 description = "Coinbase Advanced Trade adapter for keel"
 requires-python = ">=3.14.4"
 dependencies = ["keel-core", "keel-broker-api", "coinbase-advanced-py>=1.8.4"]
diff --git a/packages/keel-broker-fake/pyproject.toml b/packages/keel-broker-fake/pyproject.toml
index 950c82ae..a4b3a738 100644
--- a/packages/keel-broker-fake/pyproject.toml
+++ b/packages/keel-broker-fake/pyproject.toml
@@ -1,6 +1,6 @@
 [project]
 name = "keel-broker-fake"
-version = "0.5.1"
+version = "0.5.2"
 description = "A deliberately divergent second broker adapter, to keep the port honest"
 requires-python = ">=3.14.4"
 dependencies = ["keel-core", "keel-broker-api"]
diff --git a/packages/keel-core/pyproject.toml b/packages/keel-core/pyproject.toml
index afcbf8d8..bc593cc9 100644
--- a/packages/keel-core/pyproject.toml
+++ b/packages/keel-core/pyproject.toml
@@ -1,6 +1,6 @@
 [project]
 name = "keel-core"
-version = "0.5.1"
+version = "0.5.2"
 description = "Shared domain types, configuration, and logging for keel"
 requires-python = ">=3.14.4"
 dependencies = ["pyyaml>=6.0.3", "python-dotenv>=1.2.2"]
diff --git a/pyproject.toml b/pyproject.toml
index 0743fc56..5ce7728c 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,6 +1,6 @@
 [project]
 name = "keel-trader"
-version = "0.5.1"
+version = "0.5.2"
 description = "Offline-first, broker-agnostic, rule-based spot-trading agent (halal policy by default)"
 readme = "README.md"
 authors = [
diff --git a/tests/test_schedule.py b/tests/test_schedule.py
index 701e2a0c..15fd527b 100644
--- a/tests/test_schedule.py
+++ b/tests/test_schedule.py
@@ -64,6 +64,7 @@
 import re
 import stat
 import subprocess
+import sys
 from dataclasses import dataclass
 from datetime import UTC, date, datetime, timedelta
 from pathlib import Path
@@ -74,6 +75,30 @@
 from keel.strategy.rules.turtle_breakout import _completed_days
 from keel.types import Candle, Granularity
 
+#: Reason shared by the runtime guard and the marker below, so both say the same thing.
+_MACOS_ONLY_REASON = (
+    "the real-script tests are macOS-only: the artifact under test IS a macOS deployment "
+    "(launchd + `osascript`), and the harness itself needs `sandbox-exec`, BSD `date -r` and "
+    "`chflags`, none of which exist on Linux"
+)
+
+#: For tests that touch macOS-only tooling (`chflags`) BEFORE reaching `_run_script`, where the
+#: runtime guard inside that helper would come too late to prevent a `FileNotFoundError`.
+_macos_only = pytest.mark.skipif(sys.platform != "darwin", reason=_MACOS_ONLY_REASON)
+
+
+def _require_macos() -> None:
+    """Skip, rather than error, when the real-script harness cannot run on this platform.
+
+    The schedule INVARIANT (exactly one cycle per UTC date, across both DST transitions) is
+    proven by the pure-Python model tests in this file, which run everywhere. What is macOS-only
+    is executing the shipped `keel-live-run.sh` itself -- and that is not a coverage gap worth
+    solving portably, because the script only ever runs on the macOS box that owns the launchd
+    job. Erroring on Linux CI instead of skipping is what turned `main` red after #174.
+    """
+    if sys.platform != "darwin":
+        pytest.skip(_MACOS_ONLY_REASON)
+
 REPO_ROOT = Path(__file__).resolve().parent.parent
 PLIST = REPO_ROOT / "com.keel.live.plist"
 RUN_SCRIPT = REPO_ROOT / "keel-live-run.sh"
@@ -560,6 +585,7 @@ def test_run_script_reads_the_clock_in_utc() -> None:
     assert re.search(r'^HOUR="\$\(\(10#\$HOUR_RAW\)\)"$', source, re.MULTILINE)
 
 
+@_macos_only
 def test_stamp_write_uses_atomic_temp_file_then_mv_with_readback() -> None:
     """Finding 2 (HIGH), the SOURCE-level pin for the post-cycle stamp write's design.
 
@@ -656,13 +682,14 @@ class Sandbox:
     '(version 1)(allow default)(deny process-exec (literal "/usr/bin/osascript"))'
 )
 
-
 def _run_script(script: Path, *, env: dict[str, str]) -> subprocess.CompletedProcess[str]:
     """Run `script` the way launchd would, except sandboxed against ever notifying for real.
 
     Every real-script invocation in this file goes through here (via `_run`) rather than calling
-    `subprocess.run` directly, so there is exactly one place that could forget the sandbox.
+    `subprocess.run` directly, so there is exactly one place that could forget the sandbox --
+    and exactly one place that decides this platform cannot run the real script at all.
     """
+    _require_macos()
     return subprocess.run(
         [_SANDBOX_EXEC, "-p", _DENY_OSASCRIPT_PROFILE, "/bin/bash", str(script)],
         capture_output=True,
@@ -1041,6 +1068,7 @@ def test_stamp_with_mode_000_is_still_replaceable_via_rename(tmp_path: Path) ->
         stamp_path.chmod(0o644)
 
 
+@_macos_only
 def test_immutable_regular_file_stamp_is_caught_by_the_preflight_round_trip(
     tmp_path: Path,
 ) -> None:
@@ -1091,6 +1119,7 @@ def test_immutable_regular_file_stamp_is_caught_by_the_preflight_round_trip(
         subprocess.run(["chflags", "nouchg", str(stamp_path)], check=False)
 
 
+@_macos_only
 def test_atomic_stamp_write_leaves_yesterdays_stamp_intact_on_failure(tmp_path: Path) -> None:
     """Finding 2 (HIGH): a torn/failed post-cycle write must never leave the stamp EMPTY or PARTIAL.
 
@@ -1127,6 +1156,7 @@ def test_atomic_stamp_write_leaves_yesterdays_stamp_intact_on_failure(tmp_path:
         subprocess.run(["chflags", "nouchg", str(stamp_path)], check=False)
 
 
+@_macos_only
 def test_stamp_write_failure_is_not_swallowed(tmp_path: Path) -> None:
     """Finding 2 (HIGH): a failed stamp write must be LOUD, not swallowed.
 
@@ -1149,6 +1179,7 @@ def test_stamp_write_failure_is_not_swallowed(tmp_path: Path) -> None:
         subprocess.run(["chflags", "nouchg", str(stamp_path)], check=False)
 
 
+@_macos_only
 def test_stamp_write_failure_halts_every_subsequent_trigger_until_cleared(tmp_path: Path) -> None:
     """Finding 1 (MEDIUM), part (b): the HALT SENTINEL closes the RESIDUAL window neither
     pre-flight layer can close -- $STAMP can still become unreplaceable in the gap BETWEEN a
diff --git a/uv.lock b/uv.lock
index 47c91603..22a3820e 100644
--- a/uv.lock
+++ b/uv.lock
@@ -275,7 +275,7 @@ wheels = [
 
 [[package]]
 name = "keel-broker-api"
-version = "0.5.1"
+version = "0.5.2"
 source = { editable = "packages/keel-broker-api" }
 dependencies = [
     { name = "keel-core" },
@@ -295,7 +295,7 @@ provides-extras = ["conformance"]
 
 [[package]]
 name = "keel-broker-coinbase"
-version = "0.5.1"
+version = "0.5.2"
 source = { editable = "packages/keel-broker-coinbase" }
 dependencies = [
     { name = "coinbase-advanced-py" },
@@ -312,7 +312,7 @@ requires-dist = [
 
 [[package]]
 name = "keel-broker-fake"
-version = "0.5.1"
+version = "0.5.2"
 source = { editable = "packages/keel-broker-fake" }
 dependencies = [
     { name = "keel-broker-api" },
@@ -327,7 +327,7 @@ requires-dist = [
 
 [[package]]
 name = "keel-core"
-version = "0.5.1"
+version = "0.5.2"
 source = { editable = "packages/keel-core" }
 dependencies = [
     { name = "python-dotenv" },
@@ -342,7 +342,7 @@ requires-dist = [
 
 [[package]]
 name = "keel-trader"
-version = "0.5.1"
+version = "0.5.2"
 source = { editable = "." }
 dependencies = [
     { name = "click" },