Enforce draft KV strong-sync for CP HiCache hits

CP HiCache host hits must not advertise target residency unless the draft payload is also valid when EAGLE/MTP draft HiCache is attached. This closes target-only metadata paths by making the CP host-valid predicate and load replay fail fast, resets draft host storage with the target host pool, and records the P1-P3 strong-sync plan state.

The page-index validator is restored for CPU/fake-test tensors only, preserving unit-test coverage for malformed page spans without reintroducing CUDA hot-path host sync.

Constraint: CP shared KV + HiCache + EAGLE/MTP cannot safely demote malformed target/draft metadata to an ordinary cache miss

Rejected: keep permissive fallback for missing draft_host_indices | it can look like a successful cache hit while poisoning speculative acceptance

Rejected: re-enable generic CUDA tensor page validation | it can force host sync in the HiCache transfer hot path

Confidence: high

Scope-risk: moderate

Reversibility: clean

Directive: Do not add silent fallback around CP draft HiCache metadata; unexpected target/draft divergence should fail fast with node/rank context

Tested: remote container targeted tests: 5 passed

Tested: remote container files test_cp_hicache_metadata.py and test_hicache_controller_cp.py: 77 passed

Tested: remote container test_page_index_utils.py: 8 passed

Tested: local git diff --check and py_compile for modified Python files

Not-tested: full CP shared KV + HiCache + EAGLE/MTP ETE

Co-authored-by: OmX <omx@oh-my-codex.dev>

test/registered/unit/managers/test_hicache_controller_cp.py

@@ -541,6 +541,34 @@ class TestHiCacheControllerCPLoad(TestHiCacheControllerCPWrite):
         self.assertEqual(host_pool.loads, [])
         self.assertEqual(len(controller.ack_load_queue), 1)
 
+    def test_cp_load_zero_owned_rejects_missing_draft_metadata_when_draft_attached(self):
+        host_pool = FakeHostPool(torch.tensor([], dtype=torch.int64))
+        allocator = FakeAllocator(alloc_result=torch.arange(64, 68, dtype=torch.int64))
+        controller = self.make_controller(
+            host_pool,
+            allocator=allocator,
+            cp_rank=3,
+            draft_host_pool=FakeHostPool(torch.tensor([], dtype=torch.int64)),
+            draft_mem_pool_device=FakeDevicePool("draft"),
+        )
+        node = TreeNode()
+        node.host_len = 4
+        node.cp_hicache = CpHiCacheNodeMetadata(
+            logical_len=4,
+            owned_positions=torch.empty((0,), dtype=torch.int64),
+            host_indices=torch.empty((0,), dtype=torch.int64),
+            page_owners=torch.tensor([0], dtype=torch.int8),
+            page_size=4,
+        )
+
+        with self.assertRaisesRegex(RuntimeError, "draft KV restore requested"):
+            controller.load_cp([node], node_id=33)
+
+        self.assertEqual(allocator.owner_alloc_calls, [[0]])
+        self.assertEqual(allocator.frees[0].tolist(), [64, 65, 66, 67])
+        self.assertEqual(controller.load_queue, [])
+        self.assertEqual(controller.draft_load_queue, [])
+
     def test_cp_load_queues_cpu_host_indices_before_backend_moves(self):
         host_pool = FakeHostPool(torch.tensor([100, 101, 102, 103], dtype=torch.int64))
         allocator = FakeAllocator(alloc_result=torch.arange(64, 80, dtype=torch.int64))