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abstract indexed · arXiv 2609.19607 · updated 2026-10-18

DeltaSelect: Affordable A/B Testing for Coding Agents

First page of DeltaSelect: Affordable A/B Testing for Coding Agents
From the original paper · arXiv 2609.19607Page 1. Select the image to read the PDF.

DeltaSelect replaces running full coding-agent benchmark suites during development with a fixed, budget-selected subset of tasks whose single-run results correlate with full-benchmark performance, mapping fractional verifier scores to a common scale via linear regression. It costs the one-time resampling analysis and harness alignment work, plus the risk that only a minority of tasks are reliable proxies (19.5% in the cited analysis), so the usable subset may be small. It can fail when the production harness diverges from the benchmark harness, when the task subset stops tracking full-benchmark performance as the agent changes, or when per-run variance makes baseline-versus-candidate differences statistically indistinguishable, as the paper's own score comparison (p=0.326) illustrates.

For solo builders

A possible application for this research area. Paper-specific feasibility still needs a full-paper review.

An agent looks good in demos, but you cannot tell which product tasks it fails.

What you would change

Use the study's evaluation idea to inspect a small set of tasks with human-checked answers.

Try the idea on your product

A proposed first test. Set your budget and success criteria before running it.

Use the study's evaluation idea to inspect a small set of tasks with human-checked answers.

Compare against

Your current evaluator and a manually reviewed reference set.

  1. Locate the paper's implementation and check its license, model support, data needs, and hardware requirements. Stop here if you cannot obtain the required artifacts.
  2. Save a small set of representative product tasks and expected outcomes. Keep evaluation tasks out of any training or tuning, and choose quality and cost limits before running.
  3. Run the baseline and the proposed change on identical inputs. Keep other settings fixed and repeat paired runs to expose variation.
  4. Save per-task outputs, failures, timings, and all usage costs. Review regressions before expanding the test.

What to measure

Agreement with human review, missed failures, false alarms, and evaluation cost per task.

When to keep it

Keep the change only if it meets your preselected quality and latency limits and improves the metric you care about after setup and operating costs. Otherwise retain the baseline. This is an exploration plan, not a validated recommendation.

Download test plan ↓

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Abstract-level screening only. Risks and infrastructure may not have been evaluated. This recommendation is not a reproduced result.
minimum test setup
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published evidence setup
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source-linked claims
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exposure checks
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Why it was shortlisted

The technical change, research area, and reason it entered the archive.

recommendation
test
research area
agent evaluation
technical change
Budget-constrained benchmark subset selection for agent A/B testing
published
2026-09-17

The method is open-source and directly targets cheap repeated comparisons on a constrained budget, but its validity is workload- and harness-specific, so the reader should validate correlation on their own tasks before relying on it for production decisions.

About the technical core

Equations have not been fetched yet.

When reading the methods, identify the rule, algorithm, or evaluation protocol that produces the claimed change. An equation is useful here only if it explains that mechanism.

Inspect the original paper

Claims and evidence

A claim is source-linked only when the PDF page and matching excerpt are available.

  1. claim 01Paperraft inference
    Read the brief interpretation

    DeltaSelect replaces running full coding-agent benchmark suites during development with a fixed, budget-selected subset of tasks whose single-run results correlate with full-benchmark performance, mapping fractional verifier scores to a common scale via linear regression. It costs the one-time resampling analysis and harness alignment work, plus the risk that only a minority of tasks are reliable proxies (19.5% in the cited analysis), so the usable subset may be small. It can fail when the production harness diverges from the benchmark harness, when the task subset stops tracking full-benchmark performance as the agent changes, or when per-run variance makes baseline-versus-candidate differences statistically indistinguishable, as the paper's own score comparison (p=0.326) illustrates.

    This is a Paperraft inference. It is not pinned to a verified PDF passage.

    Inspect the source
  2. claim 02Paperraft inference

    In a 13-evaluation case study the adopted agent version cost 58.1% less than the initial version (USD 1.75 vs 4.18, p=0.008) with a higher but not statistically significant calibrated score (42.36% vs 36.46%, p=0.326); total recorded evaluation cost was USD 27.86.

    This is a Paperraft inference. It is not pinned to a verified PDF passage.

    Inspect the source

Exposure map

Author findings, Paperraft interpretations, and the next check. Missing analysis never counts as evidence of safety.

quality

Still unknown

Which tasks improve, and which regress against the baseline?

compute and memory

Still unknown

What memory, hardware, and total compute does the complete method require?

latency

Still unknown

Are startup time, typical response time, and slow requests measured separately?

operations

Still unknown

What must be monitored, maintained, and rolled back?

software compatibility

Still unknown

Does the implementation support your model, runtime, and hardware?

security

Still unknown

What new data access, permissions, or trust boundaries does it introduce?

data and training

Still unknown

What data preparation or training is required, and is it included in the cost?

reproducibility

Still unknown

Are code, versions, inputs, and evaluation scripts available?

Continue the investigation

A reading guide for agent evaluation.

Editorial prompts, not findings from this paper or a validated test plan. Detailed analysis is still pending for the topics below.

What to inspect

Who grades the outputs? Inspect the rubric, disagreements, and whether the evaluator sees the method's identity.

Plan a fair comparison

Can you apply the same tasks and rubric to the baseline and candidate, then review disagreements by hand?

Questions for adoption

Are the results stable across prompts, languages, and task categories relevant to your product?

Read the paper with these questions

Inside the paper

Preview the first 3 pages of the original PDF. Click the stack to turn the page.

The downloadable skill includes SKILL.md and evidence.json, with recorded findings and unanswered checks. TRY-IT.md adds a product test plan and a blank results sheet.

A reading aid for your agent. Findings still need validation.

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Provisional research brief updated 2026-10-18. Paperraft has not reproduced this experiment.

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arXiv 2609.19607

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