[ACL 2026] Chaining the Evidence: Robust Reinforcement Learning for Deep Search Agents with Citation-Aware Rubric Rewards

<div align="center">

</div> <div align="center"> <img src="./assets/test-time-scaling.png" alt="Multi-Turn RL Training" width="100%"> <p><em> </em></p> </div>

🔥 News

• [2026/04/08] Our paper has been accepted by ACL 2026!

• [2026/03/14] Our RL training and evaluation code have been fully open-sourced.

• [2026/03/12] Our SFT models and C-GRPO models have been fully open-sourced on Hugging Face.

• [2026/01/11] Our SFT trajectories and RL QA pairs with rubrics have been fully open-sourced on Hugging Face.

• [2026/01/11] Released the CaRR framework, implemented as a remote reward model server — now fully available in ./deepsearch_rm_with_rubrics.

• Model and training code are currently being organized – coming soon!

🚀 Overview

Existing Reinforcement Learning (RL) approaches for deep search agents primarily rely on binary outcome rewards (i.e., whether the final answer is correct). However, pure outcome rewards fail to capture the comprehensiveness and factuality of agents’ reasoning process, often leading to undesirable behaviors such as:

• Shortcut exploitation: Agents may find the answer using only partial information, ignoring complex constraints.

• Hallucinations: Agents may arrive at the correct answer via fortunate huallucinations.

Optimizing toward these flawed trajectories will result in agents with diminished robustness and suboptimal performance

To address these, we propose Citation-aware Rubric Rewards (CaRR) and Citation-aware Group Relative Policy Optimization (C-GRPO) to encourage deep search agents to conduct comprehensive, evidence-grounded reasoning.

---

✨ Key Features

1. Citation-Aware Rubric Rewards (CaRR)

<div align="center"> <img src="./assets/CaRR.png" alt="CaRR" width="100%"> <p><em></em></p> </div>

CaRR is a fine-grained reward framework for deep search agents that emphasizes reasoning comprehensiveness, factual grounding, and evidence connectivity. It decomposes complex, multi-hop questions into atomic, verifiable rubrics. A trajectory satisfies a rubric only if:

• Entity Identification: It explicitly identifies all hidden entities involved.

• Citation Grounding: The statement is fully supported by the cited web contents.

• Evidence Connectivity: The supported rubrics forms an evidence chain that connects to the final predicted answer.

2. Citation-aware Group Relative Policy Optimization (C-GRPO)

<div align="center"> <img src="./assets/C-GRPO.png" alt="C-GRPO" width="100%"> <p><em></em></p> </div>

C-GRPO extends Group Relative Policy Optimization (GRPO) by assigning an additional weighted citation-aware rubric reward to trajectories that have found the correct final answer. This encourages the model to improve accuracy and reasoning quality simultaneous, thereby promoting more robust policy learning.

---

📊 Experimental Results

Our RL experiments use Qwen3-4B-Thinking-2507 and Qwen3-30B-A3B-Thinking-2507 as backbone models, and use DeepDive as the training data.

Evaluation results on four challenging deep search benchmarks show that C-GRPO consistently outperforms standard outcome-based GRPO, and demonstrates superior test-time scaling capacity, effectively utilizing longer context budgets to improve performance:

<div align="center"> <img src="./assets/deep_search_performance.png" alt="C-GRPO" width="100%"> <p><em></em></p> </div>

C-GRPO agents also generalize well to open-ended deep research tasks:

<div align="center"> <img src="./assets/deep_research_bench_performance.png" alt="C-GRPO" width="50%"> <p><em></em></p> </div>

Environment Preparation

Step 0) Pull Slime Docker image

Recommended image (from slime/docker/version.txt):

docker pull slimerl/slime:nightly-dev-20260311a

Step 1) Generate and fill environment variables

bash scripts/setup/prepare_env.sh

Edit .env and fill at least the following fields:

• Workspace paths: CARR_ROOT, SLIME_ROOT
• Tool Server: SERP_API_KEY, JINA_API_KEY, TOOL_SERVER_PORT
• Training RM: DEEPSEEK_API_KEY, DEEPSEEK_BASE_URL, RM_TRAIN_PORT
• Evaluation RM: OPENAI_API_KEY, OPENAI_BASE_URL, RM_EVAL_PORT
• Data encryption/decryption: EVAL_DATA_PASSWORD
• Optional proxy: HTTP_PROXY, HTTPS_PROXY

Step 2) Start Tool Server

bash scripts/setup/start_tool_server.sh

Script configuration:

• Reads: SERP_API_KEY, JINA_API_KEY, TOOL_SERVER_PORT
• Optional: HTTP_PROXY (automatically applied when non-empty)
• Working directory: ${CARR_ROOT}/tool_server

Recommended health check after startup:

curl -sS http://127.0.0.1:${TOOL_SERVER_PORT:-7230}/ \
  -X POST \
  -H 'Content-Type: application/json' \
  -d '{"session_id":"health","name":"start_session","arguments":{},"remote_env_info":null}'

Step 3) Start training RM server (deepseek-chat)

bash scripts/setup/start_rm_deepseek.sh

Script configuration:

• Reads: RM_TRAIN_PORT, DEEPSEEK_BASE_URL, DEEPSEEK_API_KEY
• Model: deepseek-chat
• Working directory: ${CARR_ROOT}/deepsearch_rm_with_rubrics

Step 4) Start evaluation RM server (gpt-5-chat)

bash scripts/setup/evaluation_start_rm_gpt5.sh

Script configuration:

• Reads: RM_EVAL_PORT, OPENAI_BASE_URL, OPENAI_API_KEY
• Model: gpt-5-chat-2025-08-07
• Working directory: ${CARR_ROOT}/deepsearch_rm_with_rubrics

Step 5) Prepare and decrypt evaluation datasets

Dataset locations:

• Encrypted files: data/eval/*.jsonl.enc
• Decrypted files: data/eval_decrypted/*.jsonl

Before training or evaluation, decrypt datasets:

bash scripts/setup/decrypt_eval_data.sh

Script configuration:

• decrypt_eval_data.sh: reads EVAL_DATA_PASSWORD, decrypts data/eval/*.enc into data/eval_decrypted/*.jsonl

Training

Step 1) Convert 4B checkpoint (HF -> torch_dist)

bash scripts/setup/convert_4b.sh

Script configuration:

• Reads: SLIME_ROOT (defaults to ${CARR_ROOT}/slime if unset)
• Runs conversion command directly in slime/tools/convert_hf_to_torch_dist.py

Step 2) Convert 30B checkpoint (HF -> torch_dist)

bash scripts/setup/convert_30b.sh

Script configuration:

• Reads: SLIME_ROOT
• Runs conversion command directly in slime/tools/convert_hf_to_torch_dist.py

Step 3) Launch 4B training

bash scripts/training/training_run_4b-C-GRPO-rubric0.3.sh

Script configuration:

• Reads: SLIME_ROOT
• Run bash scripts/setup/decrypt_eval_data.sh once before training/evaluation
• Evaluation data source during training: data/eval_decrypted/ (filenames without -browser-oss)

Step 4) Launch 30B training

bash scripts/training/training_run_30b-C-GRPO-rubric0.3.sh

Script configuration:

• Reads: SLIME_ROOT
• Run bash scripts/setup/decrypt_eval_data.sh once before training/evaluation
• Evaluation data source during training: data/eval_decrypted/ (filenames without -browser-oss)

Evaluation

Step 1) Run 4B evaluation

bash scripts/eval/evaluation_run_4b.sh

Script configuration:

• Reads: SLIME_ROOT
• Reads data/eval_decrypted/*.jsonl (decrypt once in setup stage)

Step 2) Run 30B evaluation

bash scripts/eval/evaluation_run_30b.sh

Script configuration:

• Reads: SLIME_ROOT
• Reads data/eval_decrypted/*.jsonl (decrypt once in setup stage)

Recommended execution order

1. prepare_env.sh
2. start_tool_server.sh
3. start_rm_deepseek.sh
4. evaluation_start_rm_gpt5.sh
5. decrypt_eval_data.sh (in scripts/setup/)
6. convert_4b.sh (in scripts/setup/)
7. convert_30b.sh (in scripts/setup/)
8. training_run_4b-C-GRPO-rubric0.3.sh / training_run_30b-C-GRPO-rubric0.3.sh
9. evaluation_run_4b.sh / evaluation_run_30b.sh

---

Acknowledgments

• Built on top of Qwen3-4B-Thinking-2507 and Qwen3-30B-A3B-Thinking-2507 base models
• Uses DeepDive as the training datsets.
• Uses Slime framework for RL training
• Powered by Serper and Jina APIs for web access

---

📖 Citation

If you find our work useful, please consider citing:

@misc{lu2025deepdiveadvancingdeepsearch,
      title={Chaining the Evidence: Robust Reinforcement Learning for Deep Search Agents with Citation-Aware Rubric Rewards},
      author={Jiajie Zhang and Xin Lv and Ling Feng and Lei Hou and Juanzi Li},
      year={2025},
      eprint={2601.06021},
      archivePrefix={arXiv},
      primaryClass={cs.CL},
      url={https://arxiv.org/abs/2601.06021},
}