Revert the tail-chunk co-batching gate from 54c056af because allowing a continued chunk to share the next CP bs>1 batch reopens the mixed chunk/page-tail scheduler risks we are currently avoiding. Keep the independent real-prefix budget accounting so chunked requests still contribute their carried prefix to CP cached-token and buffer estimates.\n\nConstraint: Chunked-prefill requests must remain solo until the CP split/page-tail contract is revalidated for mixed batches.\nRejected: Full revert of 54c056af | it would also drop true-prefix budget accounting and under-estimate cache/buffer pressure for admitted chunks.\nConfidence: high\nScope-risk: moderate\nDirective: Do not reintroduce tail-chunk co-batching without tests covering page-tail split, CP buffer admission, and ETE chunked+cache-hit replay.\nTested: Local py_compile for environ.py, schedule_policy.py, cp_shared_kv_compose.py, test_prefill_adder.py, test_cp_shared_kv_compose_v2_8rank.py.\nTested: Remote cjy-glm5-new PYTHONPATH=python pytest -q test/registered/unit/managers/test_prefill_adder.py -> 25 passed.\nTested: Remote cjy-glm5-new PYTHONPATH=python pytest -q test/registered/unit/mem_cache/test_cp_shared_kv_runtime.py -> 157 passed, 2 subtests passed.\nNot-tested: Full mixed replay with chunked-prefill traffic after service restart.