OmniRenderer wrapped the upstream renderer, forwarded unknown attributes via
__getattr__, and re-bound eight BaseRenderer methods (render_cmpl, render_chat,
process_for_engine, _process_enc_dec and their async twins) onto the wrapper
so that they would reach Omni's _process_singleton. That allow-list hid any
concrete-renderer override of those methods and would silently skip the
Omni extras for any future BaseRenderer entry point not on the list.
Make OmniRenderer a mixin and create the renderer as a real subclass of the
upstream class instead:
- omni_renderer_cls(base_cls) builds (and caches) Omni<Base> = (OmniRenderer,
base_cls); only _process_singleton / _process_singleton_async are extended,
everything else is the upstream renderer unchanged.
- build_omni_renderer(vllm_config) resolves the class the way upstream
renderer_from_config does (cached_tokenizer_from_config,
tokenizer_args_from_config, RENDERER_REGISTRY.load_renderer_cls) and
instantiates the Omni subclass; renderer_cls/tokenizer can be passed to
skip the resolution.
- build_stage0_input_processor passes the renderer to InputProcessor up
front instead of replacing it afterwards; the skip-tokenizer branch keeps
_build_token_only_renderer and never resolves a tokenizer.
Rebinding an existing instance's __class__ was rejected: CPython refuses it
for HfRenderer ("object layout differs"), so the subclass is constructed.
Tests: tests/inputs/test_preprocess.py builds the renderer with
omni_renderer_cls and adds checks that the subclass is created once, that a
concrete renderer's render_cmpl override is no longer suppressed, and that
build_omni_renderer resolves like upstream or honours an explicit class;
tests/engine/test_async_omni_engine_stage_init.py asserts the stage-0
processor receives the built subclass instance and that the skip-tokenizer
branch never calls build_omni_renderer. Two pre-existing mypy complaints in
test_preprocess.py are fixed with annotations.
Validation: ruff, pre-commit (incl. mypy) on the four files; the modules
import and omni_renderer_cls(HfRenderer) builds; tests/inputs (32),
tests/engine/test_async_omni_engine_stage_init.py (55) and tests/entrypoints
(548) pass on CPU.
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MpXe2LeRrUQGjZfKFaocMZ
Signed-off-by: tzhouam <tzhouam@connect.ust.hk>
