diff --git a/configs/sparse_parity_sdpo.yaml b/configs/sparse_parity_sdpo.yaml
index 9c0d68f..483a8dc 100644
--- a/configs/sparse_parity_sdpo.yaml
+++ b/configs/sparse_parity_sdpo.yaml
@@ -1,19 +1,19 @@
 # SDPO config for sparse parity challenge on 1x A100 80GB (a100-backup-1)
-# Adapted from autoresearch_sdpo.yaml for single GPU + shorter context
+# Qwen3-8B + LoRA r32, LR 5e-5, 4x parallel tool calls, 0.45 GPU mem util
 # Usage: bash scripts/run_sparse_parity.sh [experiment-name]
 
 defaults:
   - sdpo
   - _self_
 
-max_model_len: 32768
+max_model_len: 16384
 
 data:
   train_files: ["${vars.dir}/data/sparse_parity/train.parquet"]
   val_files: ["${vars.dir}/data/sparse_parity/test.parquet"]
   train_batch_size: 8
-  max_prompt_length: 8192
-  max_response_length: 24576
+  max_prompt_length: 4096
+  max_response_length: 12288
   apply_chat_template_kwargs: {"enable_thinking": true}
   return_raw_chat: True
   filter_overlong_prompts: True
@@ -22,17 +22,18 @@ data:
 
 actor_rollout_ref:
   model:
-    path: Qwen/Qwen3-14B
+    path: Qwen/Qwen3-8B
     trust_remote_code: True
     lora_rank: 32
     lora_alpha: 16
     target_modules: all-linear
+    enable_gradient_checkpointing: true
     override_config:
       attn_implementation: flash_attention_2
   actor:
     ppo_micro_batch_size_per_gpu: 1
     ppo_mini_batch_size: 8
-    ppo_max_token_len_per_gpu: ${max_model_len}
+    ppo_max_token_len_per_gpu: 16384
     use_dynamic_bsz: False
     ulysses_sequence_parallel_size: 1
     strategy: fsdp2
@@ -45,7 +46,7 @@ actor_rollout_ref:
       loss_mode: sdpo
     self_distillation:
       teacher_update_rate: 0.01
-      max_reprompt_len: 8192
+      max_reprompt_len: 4096
       is_clip: 2.0
       alpha: 1.0
       distillation_topk: 20
@@ -66,29 +67,22 @@ actor_rollout_ref:
     optim:
       optimizer: AdamW
       optimizer_impl: torch.optim
-      lr: 1e-6
+      lr: 3e-5
       lr_warmup_steps: 5
   rollout:
     name: vllm
     n: 1
     temperature: 1.0
     tensor_model_parallel_size: 1
-    gpu_memory_utilization: 0.55
+    gpu_memory_utilization: 0.35
     max_model_len: ${max_model_len}
     max_num_batched_tokens: ${max_model_len}
     calculate_log_probs: True
-    engine_kwargs:
-      vllm:
-        hf_overrides:
-          rope_scaling:
-            rope_type: yarn
-            factor: 1.0
-            original_max_position_embeddings: 32768
     multi_turn:
       enable: True
       max_user_turns: 10
       max_assistant_turns: 10
-      max_parallel_calls: 1
+      max_parallel_calls: 4
       max_tool_response_length: 10000
       tool_response_truncate_side: right
       tool_config_path: ${vars.dir}/configs/sparse_parity_bash_tool.yaml
@@ -119,7 +113,7 @@ critic:
     strategy: fsdp2
     ulysses_sequence_parallel_size: 1
   model:
-    path: Qwen/Qwen3-14B
+    path: Qwen/Qwen3-8B
 
 custom_reward_function:
   path: ${vars.dir}/training/reward.py
@@ -130,7 +124,7 @@ reward_model:
 trainer:
   project_name: sparse-parity-sdpo
   group_name: sparse-parity-sdpo
-  experiment_name: qwen3-14b-sdpo-lora32
+  experiment_name: qwen3-8b-sdpo-lora32
   n_gpus_per_node: 1
   nnodes: 1
   total_epochs: 1000
diff --git a/training/run_sdpo.py b/training/run_sdpo.py
index 97bb76d..70cf0f1 100644
--- a/training/run_sdpo.py
+++ b/training/run_sdpo.py
@@ -102,6 +102,11 @@ def run(self, config):
 def main(config):
     from verl.utils.device import auto_set_device
     auto_set_device(config)
+    # Force ppo_max_token_len_per_gpu to match max_model_len — Hydra structured
+    # config silently ignores YAML/CLI overrides for this interpolated field.
+    from omegaconf import OmegaConf, flag_override
+    with flag_override(config, "struct", False):
+        config.actor_rollout_ref.actor.ppo_max_token_len_per_gpu = config.max_model_len
     task_runner_class = ray.remote(num_cpus=1)(PatchedTaskRunner)
     run_ppo(config, task_runner_class=task_runner_class)