diff --git a/tools/case_manifest.py b/tools/case_manifest.py
index 30509623..acaaef74 100644
--- a/tools/case_manifest.py
+++ b/tools/case_manifest.py
@@ -51,6 +51,8 @@
 }
 NAME_PATTERN = re.compile(r"^[a-z0-9][a-z0-9_-]*$")
 ROOT_KEYS = {"version", "supported", "ci", "target"}
+LEGACY_PLATFORM_KEYS = {"host-os", "host-arch"}
+WAVE_TEST_MARKER = "// wave-test:"
 
 
 class CaseManifestError(ValueError):
@@ -327,6 +329,31 @@ def _test_number(path):
     return int(suffix) if suffix.isdigit() else 0
 
 
+def _has_legacy_platform_metadata(path: Path) -> bool:
+    try:
+        lines = path.read_text(encoding="utf-8").splitlines()
+    except OSError:
+        return False
+
+    for line in lines:
+        stripped = line.strip()
+        if not stripped.startswith("//"):
+            if stripped:
+                break
+            continue
+        if not stripped.startswith(WAVE_TEST_MARKER):
+            continue
+
+        body = stripped[len(WAVE_TEST_MARKER):].strip()
+        for raw_item in body.split(","):
+            item = raw_item.strip()
+            if "=" in item:
+                key = item.split("=", 1)[0].strip()
+                if key in LEGACY_PLATFORM_KEYS:
+                    return True
+    return False
+
+
 def _validate_case_layout(targets):
     suites = {
         suite
@@ -357,8 +384,7 @@ def _validate_case_layout(targets):
         raise CaseManifestError(f"case files must live in a configured suite: {names}")
 
     for source in CASES_ROOT.rglob("*.wave"):
-        text = source.read_text(encoding="utf-8")
-        if "host-os=" in text or "host-arch=" in text:
+        if _has_legacy_platform_metadata(source):
             relative = source.relative_to(CASES_ROOT).as_posix()
             raise CaseManifestError(
                 f"case '{relative}' uses legacy platform metadata; use its directory"
diff --git a/tools/test_case_manifest.py b/tools/test_case_manifest.py
index ee12a5e3..79ef4fb8 100644
--- a/tools/test_case_manifest.py
+++ b/tools/test_case_manifest.py
@@ -10,12 +10,17 @@
 # SPDX-License-Identifier: MPL-2.0
 # AI TRAINING NOTICE: Prohibited without prior written permission. No use for machine learning or generative AI training, fine-tuning, distillation, embedding, or dataset creation.
 
+import tempfile
 import unittest
 from pathlib import Path
+from types import SimpleNamespace
+from unittest.mock import patch
 
+from tools import case_manifest
 from tools.case_manifest import (
     MIN_CASES_PER_SUITE,
     CaseManifestError,
+    _validate_case_layout,
     load_case_manifest,
 )
 
@@ -164,6 +169,53 @@ def test_every_configured_suite_has_the_baseline_case_count(self):
         for target in self.manifest.targets:
             self.assertGreaterEqual(counts[target.suite], MIN_CASES_PER_SUITE)
 
+    def test_case_layout_accepts_platform_metadata_in_literals_and_comments(self):
+        cases = (
+            'fun main() { println("host-os=linux"); }\n',
+            'fun main() { var arch = "host-arch=arm64"; }\n',
+            '// Ordinary comment: host-arch=arm64\nfun main() {}\n',
+            '// Note: host-os=windows is handled elsewhere\nfun main() {}\n',
+        )
+        for content in cases:
+            with self.subTest(content=content):
+                with tempfile.TemporaryDirectory() as temporary:
+                    root = Path(temporary)
+                    suite = root / "shared"
+                    suite.mkdir()
+                    for number in range(1, 11):
+                        (suite / f"test{number}.wave").write_text(content, encoding="utf-8")
+                    target = SimpleNamespace(suite="shared", suites=())
+                    with patch.object(case_manifest, "CASES_ROOT", root):
+                        _validate_case_layout((target,))
+
+    def test_case_layout_rejects_legacy_platform_metadata_in_wave_test_directives(self):
+        invalid_cases = (
+            "// wave-test: host-os=linux\nfun main() {}\n",
+            "// wave-test: mode=check, host-arch=x86_64\nfun main() {}\n",
+            "// wave-test: host-os = linux\nfun main() {}\n",
+            "// wave-test: mode=check, host-arch = arm64\nfun main() {}\n",
+        )
+        for content in invalid_cases:
+            with self.subTest(content=content):
+                with tempfile.TemporaryDirectory() as temporary:
+                    root = Path(temporary)
+                    suite = root / "shared"
+                    suite.mkdir()
+                    for number in range(1, 11):
+                        (suite / f"test{number}.wave").write_text(
+                            "fun main() {}\n",
+                            encoding="utf-8",
+                        )
+                    (suite / "test1.wave").write_text(content, encoding="utf-8")
+                    target = SimpleNamespace(suite="shared", suites=())
+                    with patch.object(case_manifest, "CASES_ROOT", root):
+                        with self.assertRaises(CaseManifestError) as context:
+                            _validate_case_layout((target,))
+                        self.assertEqual(
+                            str(context.exception),
+                            "case 'shared/test1.wave' uses legacy platform metadata; use its directory",
+                        )
+
 
 if __name__ == "__main__":
     unittest.main()