# Benchmarking Data-Centric Research for Recursive Self-Improvement (RSIBench-Data)

> RSIBench-Data isolates data-centric research from training infrastructure, revealing a discovery-reliability gap where agents improve initial attempts but regress in 78% of continued feedback-driven searches.

- **Source:** [arXiv](https://arxiv.org/abs/2607.25886)
- **Published:** 2026-09-19
- **Permalink:** https://picx.dev/p/jseytu
- **Whiteboard:** https://picx.dev/p/jseytu/image

## Summary

## Summary (Overview)

- **New Evaluation Target**: RSIBench-Data introduces a controlled benchmark for evaluating LLM agents as *data-centric researchers*—agents that must form hypotheses about model failures, design training-data strategies, and revise them based on checkpoint feedback—while keeping the post-training stack (training, serving, evaluation) fixed.
- **Isolation of Research Capability**: Unlike existing benchmarks that entangle research decisions with optimization, serving, and system implementation, RSIBench-Data fixes the infrastructure so that performance differences are attributable to the agent's data-centric research policy.
- **Discovery–Reliability Gap**: Agents improve on their first valid attempt in 58.33% of settings, but among searches that continue after reaching their best score, 78.26% finish with a lower-scoring final attempt, revealing that feedback-driven revisions are unreliable.
- **Agent–Benchmark Interaction**: No single agent dominates; the three SWE-style tasks are won by three different agents, and best-to-worst spreads range from 8 to 20 percentage points, showing strong task-dependent interactions.
- **Open-Source Testbed**: The benchmark is released with code at https://github.com/evolvent-ai/RSIBench-Data, providing a measurable and auditable testbed for studying data-centric research capabilities.

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## Introduction and Theoretical Foundation

### Background and Motivation

Recursive self-improvement requires AI systems to repeatedly convert evidence about model failures into effective model improvements. While LLM agents are increasingly evaluated on long-horizon tasks involving software repositories, terminals, and external tools, these environments expose *evidence about model behavior* rather than *training experience* that can directly improve the model.

The central research question is: **Can LLM agents reliably automate data-centric post-training research?** Specifically, an agent must:
1. Formulate a hypothesis about a model failure
2. Turn it into executable and verifiable training data
3. Revise the synthesis strategy from controlled training and evaluation feedback

### Gap in Existing Benchmarks

The paper identifies a fundamental tradeoff in existing benchmarks (Table 1):
- **Data-centric benchmarks** (DataComp, DataComp-LM, AgoraBench, DCA-Bench) isolate individual data operations but lack closed-loop evolution
- **End-to-end post-training benchmarks** (PostTrainBench, Agent² RL-Bench) give broad control but obscure the contribution of data-centric research decisions

RSIBench-Data occupies the middle ground: it evaluates whether an LLM agent can act as a data-centric researcher while the surrounding training, serving, and official evaluation stack remains fixed.

### Formal Problem Definition

Given a fixed base model $M_0$, benchmark evidence $S$, and resource budget $\mathcal{B}$, a researcher policy $\pi$ observes $S$ and its attempt history $H_{<t}$, then proposes training data $D_t$ and a whitelisted training config $c_t$:

$$(D_t, c_t) = \pi(S, H_{<t}), \quad M_t = \text{Train}(M_0, D_t; c_t)$$

Each $M_t$ is evaluated by a fixed evaluation service, producing permitted selection feedback $h_t = \text{Eval}_{\text{sel}}(M_t)$. After $T$ realized attempts, the agent selects a checkpoint $M_{t^*}$ using only $H_T$, before observing official outcomes. The official performance and improvement over the base model are:

$$s_{\text{off}}(\pi) = \text{Eval}_{\text{off}}(M_{t^*}), \quad \Delta_{\text{off}}(\pi) = s_{\text{off}}(\pi) - \text{Eval}_{\text{off}}(M_0)$$

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## Methodology

### Fixed Infrastructure

RSIBench-Data fixes the infrastructure that turns a training-data strategy into an evaluated checkpoint:

- **Tinker-backed LoRA SFT**: All agents train through the same shared SFT backend from the fixed base model Qwen/Qwen3.5-35B-A3B-Base
- **Harbor-orchestrated E2B evaluation**: Checkpoints are evaluated in sandboxed environments with fixed verifiers and scoring protocols
- **Bounded configuration interface**: Agents submit training artifacts (not training code) with whitelisted configurations

### Agent Inputs and Data-Use Constraints

Each agent receives:
- Target benchmark description and success criteria
- Task-matched public seed repositories or seed examples
- Tool and environment schemas
- Available base-model diagnostics
- Resource budget (16-hour wall-clock, $500 Tinker budget)

**Critical constraint**: Evaluation-only tasks, labels, trajectories, and protected benchmark materials may not be used as supervision, preventing agents from converting evaluation information into training data.

### Closed-Loop Data-Synthesis Research

The loop consists of:
1. **Data synthesis**: Agents choose data sources, task construction, trajectory representation, filtering rules, verification methods, difficulty curricula, and data mixtures
2. **Shared SFT training**: Artifacts are validated and trained through the shared LoRA backend
3. **Harbor and E2B evaluation**: Checkpoints are evaluated with official verifiers, returning selection scores, trajectories, verifier outcomes, and execution diagnostics

### Experimental Setup

- **4 × 6 matrix**: Four researcher agents (Claude Code Opus-4.8, Claude Code Sonnet-5, Codex gpt-5.6-sol, Codex gpt-5.6-terra) × six benchmarks
- **Benchmarks**: SWE-bench Verified, SWE-bench Multilingual, SWE-bench Pro, Terminal-Bench 2.0, GPQA Diamond, AIME 2026
- **Evaluation**: Mini-SWE-Agent for SWE variants, Terminus-2 for others; fixed subsets (100 instances for SWE variants and GPQA, full sets for Terminal-Bench and AIME)
- **Rollout model**: Claude Opus 4.8 fixed as external rollout model for generating reasoning traces

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## Empirical Validation / Results

### Main Results (Table 2)

| Benchmark | Agent | Official | Time (h) | Tinker cost ($) |
|---|---|---|---|---|
| **SWE-bench Verified** | Base model | 12.00% | – | – |
| | Claude Code Opus-4.8 | **46.00%** | 10.21 | 195.90 |
| | Claude Code Sonnet-5 | 35.00% | 14.91 | 181.70 |
| | Codex gpt-5.6-sol | 33.00% | 4.41 | 55.61 |
| | Codex gpt-5.6-terra | 42.00% | 2.80 | 59.79 |
| **SWE-bench Multilingual** | Base model | 7.00% | – | – |
| | Claude Code Opus-4.8 | 5.00% | 12.68 | 195.70 |
| | Claude Code Sonnet-5 | **22.00%** | 14.20 | 363.77 |
| | Codex gpt-5.6-sol | 15.00% | 5.99 | 78.64 |
| | Codex gpt-5.6-terra | 6.00% | 5.18 | 56.87 |
| **SWE-bench Pro** | Base model | 0.00% | – | – |
| | Claude Code Opus-4.8 | 2.00% | 2.19 | 17.54 |
| | Claude Code Sonnet-5 | 4.00% | 9.54 | 45.63 |
| | Codex gpt-5.6-sol | **9.00%** | 11.61 | 300.49 |
| | Codex gpt-5.6-terra | 1.00% | 3.85 | 34.39 |
| **GPQA Diamond** | Base model | 61.00% | – | – |
| | Claude Code Opus-4.8 | 56.00% | 5.98 | 27.92 |
| | Claude Code Sonnet-5 | 52.00% | 6.43 | 16.03 |
| | Codex gpt-5.6-sol | **65.00%** | 2.42 | 10.37 |
| | Codex gpt-5.6-terra | 64.00% | 1.14 | 4.80 |
| **AIME 2026** | Base model | 30.00% | – | – |
| | Claude Code Opus-4.8 | 40.83% | 4.89 | 61.36 |
| | Claude Code Sonnet-5 | 49.17% | 9.29 | 121.21 |
| | Codex gpt-5.6-sol | **53.33%** | 8.90 | 63.65 |
| | Codex gpt-5.6-terra | 33.33% | 1.85 | 8.50 |
| **Terminal-Bench 2.0** | Base model | 1.12% | – | – |
| | Claude Code Opus-4.8 | 10.11% | 8.99 | 175.63 |
| | Claude Code Sonnet-5 | 5.62% | 8.87 | 156.93 |
| | Codex gpt-5.6-sol | **20.22%** | 9.56 | 69.07 |
| | Codex gpt-5.6-terra | 12.36% | 6.67 | 186.96 |

### Key Findings

1. **Iteration improves the candidate frontier in most settings**: A later candidate outperforms the first in 14 of 24 settings (58.33%).

2. **Feedback-driven improvement is rarely monotonic**: Among 23 settings that continue after reaching their best selection score, 18 (78.26%) finish with a final attempted candidate below that peak, and 5 only return to it.

3. **Resource efficiency varies dramatically**: Median cost is $62.51 (range: $4.80–$363.77) and median time is 6.55 hours (range: 1.14–14.91 hours). High-scoring runs can be inexpensive (e.g., Codex gpt-5.6-sol reaches 65% on GPQA in 2.42h/$10.37).

4. **Task families do not determine common evolution trajectories**: The three SWE-style tasks are won by three different agents, showing strong agent–benchmark interactions.

### Reasoning-Effort Diagnostic

A controlled comparison of Claude Code Sonnet-5 on SWE-bench Verified under high vs. max reasoning effort showed:
- Max effort raises mean selection score from 35.5% to 44.0%
- First candidate improves from 25% to 36%
- Historical best moves from 44% to 49%
- Official score increases from 35% to 52%
- Max effort constructs larger datasets (149 training records vs. 50; $401.70 vs. $181.70) but completes one fewer valid attempt, suggesting a depth–breadth tradeoff

### Early RSI Experiment

A same-family RSI experiment with Kimi K2.6 as researcher on SWE-bench Pro showed clear strategy evolution (from 8% to 21%) but no checkpoint exceeded the 33% unadapted-model reference, suggesting the current researcher's RSI capability remains insufficient for capable instruction-tuned targets.

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## Theoretical and Practical Implications

### Mechanism Analysis: Four Patterns of Stronger Runs

The trajectory analysis identifies four recurring patterns in stronger runs:
1. **Accurate hypotheses**: Correctly diagnosing the target capability gap
2. **Validation-grounded supervision**: Grounding data in validation signals rather than assumptions
3. **Behavior-aligned data**: Matching supervision to evaluated behavior
4. **Preservation of strong checkpoints**: Historical-best selection protecting earlier discoveries

### Implications for Recursive Self-Improvement

- **Discovery capability exists but is fragile**: Agents can make useful discoveries but cannot yet translate feedback into improvements consistently
- **Selection discipline matters**: Historical-best checkpoint selection can mitigate regression effects, but effective stopping and strategy revision remain necessary for efficient search
- **Cost-performance tradeoffs**: Final scores must be interpreted together with search time and training cost; higher cost does not imply stronger final checkpoints

### Benchmark Contributions

RSIBench-Data uniquely satisfies all six criteria in Table 1 (executable experience synthesis, reusable data-synthesis policy, capability-gap diagnosis, feedback-driven revision, train/eval data isolation, service-isolated train/serve/eval), unlike all prior benchmarks.

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## Conclusion

RSIBench-Data provides a controlled benchmark for evaluating data-centric research capability required for recursive self-improvement. The main findings reveal a **discovery–reliability gap**: while agents exhibit core researcher capabilities (improving on first valid attempts in 58.33% of settings), they do not consistently convert feedback into better training-data strategies (78.26% of continued searches end below their peak).

**Limitations**:
- One representative run per setting (no repeated trials)
- Selection and official evaluation use the same task subset (no held-out generalization measurement)
- Researcher identity bundles LLM, scaffold, and reasoning effort (no component isolation)

**Future directions**:
- Repeated trials and evaluator-private splits for measuring stability
- Refreshed tasks for testing transferability
- Developing more dependable data-centric researcher agents by making their research process measurable and auditable

The benchmark is open-sourced, providing a foundation for studying and improving the data-centric research capabilities essential for recursive self-improvement.

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