Self-evolving agents improve future behavior from interaction experience, yet existing evaluations typically optimize under fixed execution conditions and do not test recovery after those conditions change. To address this gap, we introduce PACE-Bench (Physics Adaptation via Code Evolution), a simulator-grounded benchmark of 144 source-to-target adaptation pairs across six physics domains. Each pair links a source environment to a mutated target environment with the same goal and interface. A code-driven design that succeeds in the source fails in the target, where agents must iteratively adapt it into a working target design using diagnostic sandbox feedback within a limited attempt budget. We compare ten self-evolving methods from four paradigms. The benchmark remains far from saturated: Reflexion + Qwen3-14B succeeds on only 35.9% of full-benchmark pairs, while GPT-5.5 solves 66.7% of the Statics subset under the full budget. Together, these results show that simulator-grounded reflection is more reliable than unverified self-revision, while memory anchors agents to early designs and broad tree search explores without converging. Even revealing exact physical changes does not raise the performance ceiling, pointing to mechanism redesign rather than parameter inference as the central bottleneck. Data and code are available at https://github.com/thunlp/PACE-Bench.
Figures & tables
Figure 1: Existing self-evolving benchmarks test transfer or generalization, whereas PACE-Bench tests adaptation of an executable design after physical environment shift.
Benchmark
Feedback-Driven Improvement
Physical Simulation
Executable Design
Self-Evolution Evaluation
Adaptation After Env. Change
Self-evolving agent benchmarks
StreamBench Wu et al. (2024)
✓
×
×
✓
×
LifelongAgentBench Zheng et al. (2025a)
✓
×
×
✓
×
SE-Bench Yuan et al. (2026)
×
×
×
✓
×
SEA-Eval Jiang et al. (2026)
✓
×
×
✓
×
SkillLearnBench Zhong et al. (2026)
✓
×
×
✓
×
Table 1: Comparison of representative benchmarks for self-evolution, engineering design, and physical environments. The highlighted final column is the core capability evaluated by PACE-Bench ; the other columns describe its evaluation setting.
Figure 2: Overview of the three-phase dataset construction pipeline.
Figure 3: Overview of PACE-Bench . Left: the 36 tasks organized across six physics categories. Right: rendered snapshots of reference solutions succeeding on the source environments.
Qwen3-4B
Qwen3-8B
Qwen3-14B
Paradigm
Method
Pass@2
Score@2
Pass@2
Score@2
Pass@2
Score@2
Context
Vanilla
11.5 ( ↑ 0.0)
10.7 ( ↑ 0.0)
15.6 ( ↑ 0.0)
12.0 ( ↑ 0.0)
32.0 ( ↑ 0.0)
25.5 ( ↑ 0.0)
Reflexion
19.5 ( ↑ 8.0)
14.6 ( ↑ 3.9)
26.6 ( ↑ 11.0)
18.1 ( ↑ 6.1)
35.9 ( ↑ 3.9)
28.0 ( ↑ 2.5)
Self-Refine
6.2 ( ↓ 5.3)
5.5 ( ↓ 5.2)
3.1 ( ↓ 12.5)
3.7 ( ↓ 8.3)
7.1 ( ↓ 24.9)
8.0 ( ↓ 17.5)
Memory
ACE
15.5 ( ↑ 4.0)
13.3 ( ↑ 2.6)
19.5 ( ↑ 3.9)
14.9 ( ↑ 2.9)
25.0 ( ↓ 7.0)
19.6 ( ↓ 5.9)
ExpeL
11.5 ( ↑ 0.0)
10.5 ( ↓ 0.2)
13.2 ( ↓ 2.4)
10.1 ( ↓ 1.9)
15.6 ( ↓ 16.4)
13.0 ( ↓ 12.5)
Table 2: Main Results: Pass@2 (%) and Score@2 by Method and Model. Values in parentheses show Δ vs. Vanilla ( ↑ = improvement, ↓ = degradation).
Model
Pass@2 (%)
Score@2
Qwen3-4B
8.3
12.0
Qwen3-8B
33.3
21.8
Qwen3-14B
37.5
27.3
Qwen3-32B
37.5
28.4
DeepSeek-V4-Pro
45.8
48.7
GPT-5.5
66.7
78.1
Table 3: Vanilla performance on Statics subset under the full 20-attempt budget.
Model
Metric
Vanilla
Reflexion
Self-Refine
ACE
ExpeL
Reasoning Bank
ToT
Code Evolve
SEAL
RAGEN
TTT- Discover
Qwen3-4B
Score
24.8
23.7
11.9
23.9
21.5
21.8
27.4
13.4
23.3
13.5
14.2
Time
0.9h
0.8h
6.0h
1.3h
1.4h
0.8h
0.6h
1.8h
2.0h
5.5h
5.4h
S/Hr
27.5
29.6
2.0
18.4
15.4
27.2
45.7
7.5
11.6
2.5
2.6
Qwen3-8B
Score
25.5
22.1
15.0
25.7
22.6
25.0
23.2
8.9
28.0
14.2
14.7
Time
1.1h
1.5h
5.1h
1.3h
1.4h
1.0h
0.5h
2.2h
2.5h
5.8h
5.7h
S/Hr
23.2
14.7
2.9
19.8
16.1
25.0
46.4
4.1
11.2
2.4
2.6
Table 4: Cost-normalized results on the Kinematics subset under 20-attempt budget. Scores are fitted to the nearest 1/24 increment and shown to one decimal. S/Hr is computed from the fitted scores before display rounding.
Figure 4: Error type distribution by category (left) and method (right).
Qwen3-4B
Qwen3-8B
Qwen3-14B
Method
Global Sim
Trend (L − E)
Radicality
Global Sim
Trend (L − E)
Radicality
Global Sim
Trend (L − E)
Radicality
Vanilla
0.792
+0.112
0.208
0.780
+0.126
0.220
0.760
+0.114
0.240
Reflexion
0.772
+0.111
0.228
0.725
+0.117
0.275
0.720
+0.110
0.280
Self-Refine
0.672
+0.120
0.328
0.598
+0.122
0.402
0.597
+0.119
0.403
ACE
0.821
+0.145
0.179
0.795
+0.164
0.205
0.807
+0.163
0.193
ExpeL
0.840
+0.132
0.160
0.807
+0.152
0.193
0.794
+0.139
0.206
Table 5: Code Similarity by Method and Model (iterations ≥ 10). Trend (L − E) = mean similarity difference between late and early attempts; positive = increasing self-similarity. Bold denotes the highest value in each column.
Qwen3-4B
Qwen3-8B
Qwen3-14B
Method
CH
CE
Δ
CH
CE
Δ
CH
CE
Δ
Vanilla
1.6
10.0
+8.4
13.3
13.3
+0.0
17.0
9.8
−7.2
Reflexion
9.4
12.0
+2.6
17.9
13.2
−4.7
17.1
14.6
−2.5
ACE
6.0
12.0
+6.0
12.5
8.8
−3.7
7.3
10.4
+3.1
Table 6: Change-Hidden (CH) vs. Change-Exposed (CE) Pass@2 (%) pooled over Statics and Kinematics (approximately 48 environment pairs). CE discloses the changed variables and their exact new values.
Appendix figures & tables19 assets
Supplementary material from the paper’s appendix.
Appendix
Module
Role
environment.py
Physics and terrain configuration
evaluator.py
Success criteria and scoring logic
feedback.py
Diagnostic metrics
prompt.py
Task context C
stages.py
Mutation specs for E1−4
renderer.py
Simulation and GIF generation
Appendix
Table 7: Modules of each task in PACE-Bench .
Severity
Definition and example
Lv 3: Critical
Task unsolvable or evaluator broken (e.g., prompt constraints contradict the evaluator).
Lv 2: Moderate
Task solvable but prompt misleading (e.g., a stale visible-variable value).
Lv 1: Minor
Cosmetic issue (e.g., a renderer color mismatch or unused import).
Appendix
Table 8: Severity levels used during human verification.
Category
#Prompt Tokens
#Constraints
#Prim. APIs
Stage 1
Stage 2
Stage 3
Stage 4
Statics & Equilibrium
935
8
3
4
4
11
11
Kinematics & Linkages
835
7
9
3
4
7
9
Dynamics & Energy
894
12
9
1
2
5
8
Granular & Fluid Interaction
1,136
9
10
2
2
13
12
Cybernetics & Control
1,730
5
9
2
4
12
12
Exotic Physics
778
1
6
1
4
6
8
Appendix
Table 9: Dataset statistics by category (averaged over 6 tasks each). Stages 1–4 report average mutated physical parameters per stage, indicating progressive escalation in difficulty.
Full-benchmark statistic
Value
Pass/fail agreement between runs
86.6%
Median absolute score difference
0.0
Environment pairs with score difference ≤5
82.0%
Spearman ρ , run 1 vs. run 2 (4B / 8B / 14B)
0.667 / 0.881 / 0.976
Kinematics: two-run vs. three-run statistic
Value
Pair-level pass agreement
94.9%
Appendix
Table 10: Run-reliability analysis. The full-benchmark panel compares the two independent runs; the Kinematics panel compares statistics computed from two runs with those computed after adding a third run for five representative methods.
Figure 5: Pass@2 and Score@2 by model on Statics, Vanilla method, five-attempt budget.
Method
Qwen3-4B
Qwen3-8B
Qwen3-14B
Pass@2 w/o VLM
Pass@2 w/ VLM
Pass@2 w/o VLM
Pass@2 w/ VLM
Pass@2 w/o VLM
Pass@2 w/ VLM
Vanilla
0.0
18.2 ( +18.2 )
24.4
17.1 ( -7.3 )
40.9
18.2 ( -22.7 )
Reflexion
9.1
22.7 ( +13.6 )
42.9
23.8 ( -19.1 )
40.9
27.3 ( -13.6 )
ACE
4.5
13.6 ( +9.1 )
18.2
31.8 ( +13.6 )
13.6
22.7 ( +9.1 )
ExpeL
13.6
9.1 ( -4.5 )
14.3
42.9 ( +28.6 )
13.6
36.4 ( +22.8 )
ToT
13.6
9.1 ( -4.5 )
9.1
18.2 ( +9.1 )
4.5
0.0 ( -4.5 )
Appendix
Table 11: VLM Video Feedback Impact on Statics and Kinematics.
Model
Method
Catastrophic
Structural
Constraint
Numerical
Design
Stagnation
Exploration
Late
Budget
Collapse
Failure
Violation
Instability
Fixation
Convergence
Exhaustion
Qwen3-4B
Vanilla
0.0
+3.0
0.0
+3.0
+5.1
-8.1
+6.1
-4.5
-4.5
Reflexion
0.0
+1.8
0.0
-9.1
-4.1
-4.1
+24.7
+5.9
-15.0
ACE
0.0
+1.5
0.0
+11.0
-12.3
+15.8
-11.3
0.0
-4.8
ExpeL
0.0
+4.2
0.0
+9.7
-26.6
+4.2
+3.4
+5.0
0.0
ToT
0.0
+4.5
0.0
0.0
0.0
+18.9
-23.2
0.0
0.0
Appendix
Table 12: VLM Effect on Error Taxonomy: Δ error share when VLM video feedback is added. Positive = VLM increases this error type; negative = VLM reduces it.
Catastrophic
Structural
Constraint
Numerical
Design
Late
Budget
Model
Method
Collapse
Failure
Violation
Instability
Fixation
Stagnation
Exploration
Convergence
Exhaustion
Qwen3-4B
Vanilla
0.0
+3.0
0.0
-2.5
-11.6
-2.5
+22.7
-4.5
-4.5
Reflexion
0.0
+10.0
0.0
+5.0
+3.3
+3.3
-13.3
0.0
-8.3
ACE
0.0
+2.4
0.0
+6.3
-11.1
+5.6
-4.0
+5.6
-4.8
ExpeL
0.0
-0.8
0.0
+4.7
-6.6
-0.8
+3.4
0.0
0.0
ToT
0.0
+5.3
0.0
+5.3
0.0
+5.3
-15.8
0.0
0.0
Appendix
Table 13: CE Effect on Error Taxonomy: Δ error share when mutated variables are disclosed (CE minus CH). Positive = CE increases this error type; negative = CE reduces it. Statics only.
Figure 6: Pass@2@ k and Score@2@ k by model (all methods, all categories).
Method
1
2
3
4
5
6
7
8
9
10
Vanilla
0.255
0.468
0.536
0.843
0.518
0.493
0.778
0.793
0.553
0.943
ACE
0.185
0.870
0.842
0.762
0.772
0.895
0.814
1.000
0.670
0.828
Appendix
Table 14: Adjacent-attempt Jaccard code similarity for one Qwen3-14B Stage 4 case study. Each entry compares solutions on consecutive transitions.
Model
Pass@2 (%)
Score@2
Qwen3-4B
11.3
17.2
Qwen3-8B
12.8
16.8
Qwen3-14B
18.3
21.7
Appendix
Table 15: Vanilla from-scratch results by model, computed over eligible task–environment instances.
Target environment
Pass@2 (%)
Score@2
Source
32.3
30.8
Mutated-1
13.4
18.5
Mutated-2
10.9
16.6
Mutated-3
11.2
15.3
Mutated-4
6.4
11.6
Appendix
Table 16: Vanilla from-scratch results by target environment, computed over eligible task–environment instances.
Figure 7: Model × category Pass@2 heatmap (all methods aggregated).
Self-evolving agents improve over time by reflecting on past failures, but existing evaluation is limited in two ways: it measures only task scores, leaving reflection quality unknown, and it relies on agents' own episode runs, offering no mechanism to target specific failure patterns. We present BenchTrace, a benchmark for evaluating self-evolution ability in LLM agents. BenchTrace is built on a snapshot-reflection dataset of 1,821 annotated episodes spanning six diverse tasks, and comprises a Reflection Evaluation that probes failure identification through targeted QA tasks, and an Evolution Evaluation that tests whether past failure experience translates into avoidance behavior in a controlled self-evolution simulation. Building on BenchTrace, we propose failure avoidance rate (FAR), a new evaluation metric measuring the fraction of test cases in which the agent successfully avoids the target failure instance. Experiments with Qwen3-32B and GPT-4.1 reveal that both models fall below a 30% end-to-end pass rate on reflection evaluation, with diagnosis as the primary bottleneck. Evolution evaluation shows that self-evolution methods generally improve FAR over the non-evolving baseline, but agents forget early lessons as noise episodes accumulate, and agents fail to generalize their reflections beyond the specific context, causing negative transfer across task contexts. Our correlation analysis further reveals that only a fully correct reflection is strongly associated with higher FAR. BenchTrace exposes concrete limits of current self-evolution approaches and provides a controlled, model-agnostic framework for targeted evaluation.
Jiahao Huang, Fei Cheng, Junfeng Jiang +2
University of Tokyo · Kyoto University · National Institute of Informatics
Existing prompt-optimization techniques rely on local signals, causing poor generalization across tasks. In addition, they also rely on weak update mechanisms, such as full-prompt rewrites or unstructured merges, which cause knowledge loss and unstable adaptation. These limitations are magnified in research-coding workflows, which involve heterogeneous repositories and weak feedback, limiting abstraction and learning across tasks. We introduce Reflective Evolving Research Engineer (REVERE), a lightweight, self-adapting agent framework that learns from a Global Training Context, distills recurring cross-repository failure modes into reusable heuristics, and applies targeted, code-based edits to agent prompts. REVERE is evaluated across settings ranging from long-horizon to single-shot benchmarks, and improves over prior expert-crafted instructions by 4.50% on SUPER, 1.3% on ResearchCodeBench, and 4.89% on ScienceAgentBench. It does so at nearly 10x lower cost and 2.7x faster adaptation than existing prompt-optimization baselines, demonstrating that self-adapting agents with continual learning and global memory consolidation can meaningfully evolve their capabilities over time.
Agent self-evolution in long-horizon LLM systems is largely procedural: useful experience is not merely stored information, but reusable procedures for searching, debugging, and verification. Yet current evaluations do not isolate this form of transfer. Agent benchmarks test single-episode task solving; memory benchmarks target information retention rather than procedural reuse. We introduce EvoAgentBench, a benchmark for agent self-evolution via Ability-guided transfer across four agentic domains: web research, algorithmic reasoning, software engineering, and knowledge work. EvoAgentBench extracts trace-grounded Abilities from agent executions, canonicalizes them into operational units, and builds domain-specific Ability Graphs linking tasks that share procedural overlap. By design, every test task is backed by verified training-side Ability support. Across a 528/267 train/test split, two scaffolds, and three backbones, curated Ability content transfers reliably across model families, but no current automatic method sustains positive gain in all settings. EvoAgentBench shifts self-evolution evaluation from aggregate accuracy comparison to fine-grained diagnosis of experience encoding, routing, and uptake. The benchmark is publicly available at https://huggingface.co/datasets/EverMind-AI/EvoAgentBench.
Xingze Gao, Chuanrui Hu, Hongda Chen +9
1Anhui University · 2EverMind, Shanda Group · 3Southeast University