Runtime Reflexion (Error → Diagnose → Retry)

Context

Static skills freeze knowledge. Reflexion (Shinn et al. NeurIPS 2023) + Code Sandbox makes ML agents self-correct: 80%+ of runtime errors auto-fixable when errors are precisely classified. agy verified this as a P0 must-have for ML agents (MLE-bench Kaggle medal correlation).

The core insight: errors aren't random — they fall into ~12 categories, each with known fixes.

Guidance

Single Execution with Diagnosis

from framework.src.reflexion import CodeSandbox, ErrorAnalyzer, execute_with_analysis

sandbox = CodeSandbox(timeout_sec=30)
result, diagnosis = execute_with_analysis(generated_code, sandbox)

if not result.success:
    print(f"Error: {diagnosis.category.value}")
    print(f"Suggested fix: {diagnosis.suggested_fix}")
    print(f"Related skills: {diagnosis.related_skills}")
    # → "category=memory, fix=reduce batch_size, skills=[gpu-readiness-assessment]"

Self-Correction Loop

from framework.src.reflexion import ReflexionLoop, CodeSandbox

def my_llm_fix(prompt: str) -> str:
    """Call Claude/your LLM to fix code given the reflexion prompt"""
    return llm_client.messages.create(
        model="claude-sonnet-4-6",
        messages=[{"role": "user", "content": prompt}],
    ).content[0].text

loop = ReflexionLoop(
    sandbox=CodeSandbox(timeout_sec=60),
    llm_fix=my_llm_fix,
)
result = loop.run(initial_code, max_attempts=5)

if result.success:
    deploy(result.final_code)
else:
    log_to_vault(result.final_diagnosis)  # remember for next time

Error Categories (12)

Why This Matters

Without Reflexion: agent gets stuck on syntax error → user manually fixes → no learning. Repeat next competition.

With Reflexion: agent auto-fixes 80%+ errors → escalates to LLM with precise diagnosis → logs to vault for future prevention.

agy: "Reflexion + Sandbox is the only reliable deployment pattern for code-generation agents in 2025-2026."

When to Apply

When to Use

• Auto-generated Python code from LLM
• ML pipeline runs that may fail
• Kaggle competition automation
• Agent benchmarks (MLE-bench, AIDE)
• Any "agent gets stuck and gives up" pattern

When NOT to Use

• Single-shot queries (overkill)
• Production stable code (just monitor)
• When LLM fix is unavailable (record-only mode)

Notes

• Combine with sandbox isolation: never run untrusted code outside subprocess
• Set timeouts aggressively: 30-60s default; ML training needs more
• Log failures to vault: future prevention (memory-hierarchy-management)
• Track fix success rate: <50% means your prompts need improvement
• See also: multi-agent-roles (Critic uses Reflexion), self-evolving-skills

References

• Implementation: framework/src/reflexion/
• Research: Shinn et al. "Reflexion" (NeurIPS 2023), MLE-bench (OpenAI 2024)
• Pairing skill: multi-agent-roles (Continuity-Critic uses ErrorAnalyzer)