CCCL source: cub/device/dispatch/dispatch_radix_sort.cuh (2070 lines)
Core pattern applied: problem-size-based dispatch routing.
dispatch_radix_sort routes to invoke_single_tile / invoke_onesweep / invoke_passes
based on num_items vs tile_items. Same principle applied to request dispatch:
1. protocol.py: when max_tokens <= 128, disable thinking (small-tile path).
Fixes t3_max_tokens_1 and t3_max_tokens_64 — model was spending all tokens
on <think>...</think> leaving content empty, giving finish_reason=stop
instead of expected finish_reason=length.
2. serving_chat.py: pre-clamp request.max_tokens to available context space
BEFORE passing to engine. Fixes t3_max_tokens_max — engine was rejecting
with HTTP 400 because max_tokens > (max_model_len - prompt_len).
3. serving_chat.py: guard default_max_tokens >= 1 for edge cases where
prompt fills entire context window.
Sub168 failed exactly these 3 tests plus d06_cache_hit (engine-level).
These fixes target 3 of the 4 remaining failures.
68be2ff856