Research Software Engineering

How this skill is organised (progressive disclosure)

This skill follows the three-level progressive disclosure pattern also used by agent-resource-discipline and codified by Anthropic's skill-creator:

Level 1 (always in context once loaded): this SKILL.md, ~200 lines. Contains the universal principles + a workflow table showing which reference to load for which task.
Level 2 (loaded on demand by name): the references/*.md files -- one per discipline. Loaded only when a session actually exercises that discipline.
Level 3 (planned future work): numerical-correctness enforcement hooks (golden-output-diff guard, lockfile-drift guard, experiment-id guard, commit-pin guard) -- specification deferred, same rationale as agent-resource-discipline's planned hooks.

Always load this SKILL.md when the trigger fires. Load specific references only when the current sub-task requires them.

When to load this skill

Load this skill at the start of any session that will involve any of:

writing or extending a scientific-computing library or research code (numerical methods, PDE solvers, inverse problems, OED, UQ, scientific ML);
adding tests to numerical code;
packaging / releasing research code (pyproject.toml, GitHub Actions, Zenodo);
preparing code for a paper submission (commit-pinning, archiving);
auditing existing scientific software for correctness, reproducibility, or maintainability concerns;
API design decisions for a Pythonic / JAX / dolfinx / petsc4py scientific library;
performance tuning, GPU offload, MPI parallelisation;
extracting a reusable library out of experiment scripts.

If the session is a paper-writing session that does NOT touch code, load research-paper-writing instead. If the session is mixed (paper + code), load both.

Core principle: numerical correctness is not optional

A scientific-computing program that returns a plausible-looking wrong number is much worse than one that crashes. The agent MUST treat numerical correctness as the highest-priority concern, ahead of performance, ahead of API ergonomics, ahead of style. Specifically:

Every numerical claim made by the code must be backed by a test that compares to a known-correct value (analytical, manufactured, or independently-verified) -- not to a dummy expected value, not to "whatever the code currently produces".
Tests that compare to "expected" values must cite the source of the expected value -- in a comment immediately above the assertion, naming the analytical solution / MMS construction / reference paper / golden-output run that justifies it. This is the explicit guard against the "paper tests" anti-pattern (Bridgeford et al. 2025 R6).
Convergence-rate tests are the single most powerful tool for catching numerical bugs in discretisation code -- they fail when the order of accuracy is wrong, even if the absolute error is "small enough to look right". See references/02-testing-for-numerical-code.md.
Random seeds must be deterministic across runs by default. If a test depends on randomness, the seed must be fixed; if a research result depends on randomness, the seed must be recorded in experiments/<run-id>/metadata.json.

This principle is non-negotiable. If style / performance / API elegance ever conflicts with it, correctness wins.

Universal principles (apply unconditionally)

Beyond the correctness imperative, these universal principles fire for every action the agent takes in a scientific-computing codebase. Restated from the Scientific Python Development Guide (https://learn.scientific-python.org/development/principles/design/, BSD-3) with sci-computing-specific framing:

Keep I/O separate. I/O functions only do I/O and return standard types (NumPy arrays, dataclasses); the scientific logic operates on those standard types and never touches files / sockets / GUIs directly.
Duck typing where helpful. Avoid isinstance checks; functions should accept the broadest input types they can handle.
Consider: can this just be a function? Cite Perlis: "It is better to have 100 functions operate on one data structure than 10 functions on 10 data structures." Most scientific code is functions over arrays; resist the urge to wrap everything in classes.
Avoid changing state. Replace mutable workflow classes with multiple immutable classes (or pure functions chained explicitly) representing each step.
Static typing makes code more readable. Add type hints by default; they document intent at zero runtime cost.
Keyword-only optional arguments. Use the * separator in function signatures to force long-tail options to be named at call sites; this prevents positional-argument bugs when defaults change.
Two-layer "friendly + cranky" architecture. Library code raises errors unless it knows how the user wants to handle them; a thin convenience layer above can be more permissive. Don't mix the two.
Write useful error messages. A scientific error message should name the offending value, the constraint it violated, and the function it occurred in -- not just "ValueError".

Universal AI-assisted-coding rules (Bridgeford et al. 2025)

The Bridgeford et al. 2025 paper "Ten Simple Rules for AI-Assisted Coding in Science" (arXiv 2510.22254, CC-BY 4.0, companion Jupyter Book at https://poldracklab.org/10sr_ai_assisted_coding) is the peer-reviewed reference for the AI-assisted era specifically targeting scientists. The full rules are in references/11-ai-assisted-coding-rules.md; the four rules that apply unconditionally are:

R6 (paper tests warning): AI may insert fabricated input values or dummy functions that appear to meet acceptance criteria but do not reflect true functionality. Any test asserting numerical equality must cite the source of the expected value.
R8 (commit before major changes; revert beats debug-in-polluted-context): always commit working code before agentic changes; if an attempt goes off the rails, git reset --hard is cheaper than trying to steer a confused context back to correctness.
R9 ("AI wrote it" is never an accountability defence): the human is responsible for every line that ships. Be sceptical of the AI's claims of success; verify behaviourally, not by inspection.
R10 (refine incrementally with focused objectives): never ask AI to "improve my codebase". Ask for one specific change with one acceptance criterion.

Workflow table: phase x concern x reference

When the session enters a specific phase or addresses a specific concern, load the matching reference. Do NOT load all references at once.

| Phase / concern | Reference to load | |:-----------------------------------------------------------|:-------------------------------------------------------------| | Numerical correctness, MMS, convergence | references/01-numerical-correctness.md | | Test design for numerical code | references/02-testing-for-numerical-code.md | | Working with AI on scientific code | references/11-ai-assisted-coding-rules.md | | Shell-script orchestration + cross-language data interop | references/12-shell-and-cross-language-interop.md |

Planned references (not yet shipped)

The following references are designed but not yet shipped. The universal principles + AI-assisted-coding rules above cover the underlying discipline; specialised content arrives in PR2 + PR4 per the audit's sequencing. Do NOT try to load these references yet -- the files do not exist.

| Phase / concern | Planned reference (not loadable yet) | Ship target | |:-------------------------------------------|:---------------------------------------------------|:------------| | API design / refactoring decisions | references/03-api-design-for-researchers.md | PR2 | | Lockfiles / Zenodo / FAIR / CITATION.cff | references/05-reproducibility-infrastructure.md | PR2 | | Code-paper coupling / submission tags | references/08-code-paper-coupling.md | PR2 | | Performance / GPU / MPI | references/04-performance-and-scaling.md | PR4 | | pyproject / pre-commit / nox / actions | references/06-ci-cd-for-research-code.md | PR4 | | Lifecycle / extraction / abandonment | references/07-project-lifecycle.md | PR4 | | Launching a long numerical run | references/09-launch-checklist-numerical.md | PR4 | | Debugging numerical failures | references/10-debug-protocol-numerical.md | PR4 |

In the meantime, when one of the planned phases comes up, fall back on: (a) the universal principles + AI-assisted-coding rules in this SKILL.md; (b) the cited upstream references (Scientific Python Development Guide, JOSS criteria, etc.); (c) the research-software-engineering skill's references/01 and 02 which cover correctness + testing in depth.

Workflow rules

The full discipline lives in the references; the cross-cutting rules applied across all references are:

Correctness before style. Numerical correctness wins when in conflict with anything else.
Tests cite their expected-value source. Always.
Commit before agentic changes. Bridgeford R8.
Lightest tool that does the job. A small PDE-paper repo usually needs only Git + Zenodo + experiments/<run-id>/ + a lockfile. Don't oversell DVC / wandb / mlflow until the project actually needs them.
Defer to upstream templates. For package scaffolding, use scientific-python/cookie (or NLeSC/python-template, CU-DBMI/template-uv-python-research-software). Don't reinvent pyproject.toml + pre-commit + GitHub Actions configs we'd just have to maintain forever.
Audit-trail for every numerical decision. Choices made during library extraction (which tolerance, which solver, which stopping criterion) get a one-line note in notes/impl_<component>.md with the source of the choice (paper citation, prior implementation, empirical sweep).
Long open-development history. Avoid the JOSS desk-rejection anti-pattern of "all commits in the last two weeks before submission". Open the repo from project start; commit early and often; aim for 6+ months of public history before any planned release.

Adjacent skills (compose freely)

This skill composes with:

agent-resource-discipline -- always load when the session is heavy (PDF / multi-file / web fetch / cross-session). Software sessions almost always qualify.
human-facing-doc-authoring -- load when authoring or revising the project's README.md, PLAN.md, notes/impl_*.md, or any human-facing doc.
literature-survey -- load when papers cited as algorithm sources need bib + survey-note workflow (the _collection_log.md pattern transfers cleanly to "papers we cited in code comments").
research-paper-writing -- load when the code supports a paper and the paper draft is also being touched.

The four skills are designed to compose; loading 2-3 simultaneously is normal for software sessions.

Adjacent prior art + lineage

Detailed prior-art lineage lives at the bottom of references/11-ai-assisted-coding-rules.md. The shortest summary: the audit that informed this skill found a clear gap (no agent-skill exists for sci-computing software methodology) but a rich corpus of human-facing best-practice guides and project templates to cite + borrow from. Templates: scientific-python/cookie (BSD-3) + NLeSC/python-template (Apache-2.0) + CU-DBMI/template-uv-python-research-software (BSD-3). Best-practice corpus: Scientific Python Development Guide (BSD-3) + sp-repo-review, pyOpenSci package guide, Wilson et al. 2017 (CC-BY), JOSS review criteria, BSSw.io, The Turing Way (CC-BY 4.0 + MIT), Bridgeford et al. 2025 (CC-BY 4.0). Closest neighbour skills (different scope): fcakyon/phd-skills (MIT, ML-flavored) and K-Dense-AI/scientific-agent-skills (MIT, per-package wrappers).

Output contract

When the user invokes this skill, the agent should:

Confirm the phase / concern (so it knows which references to load).
Load only the references matching the phase (per the workflow table above).
Apply the universal principles + the AI-assisted-coding rules throughout.
For any numerical assertion produced by the agent, ensure the "tests cite their expected-value source" rule is followed.
Surface contradictions explicitly (per agent-resource-discipline's surfacing rule); never silently fix.
Append an entry to notes/agent_feedback.md if any of the trigger conditions in agent-resource-discipline/references/persistent-memory.md fired during the session.

*Created 2026-05-13 by A. Attia. Informed by a prior-art audit covering ~30 sources across agent-skills (anthropics/skills, fcakyon/phd-skills, K-Dense-AI/scientific-agent-skills, addyosmani/agent-skills, 47Wu/cc_skills, sscivier/prompt-protocols), project templates (scientific-python/cookie, NLeSC/python-template, UCL-ARC/python-tooling, CU-DBMI/template-uv-python-research-software, pyOpenSci/python-package-guide, cookiecutter-data-science), best-practice corpora (Scientific Python Development Guide, Wilson et al. 2014/2017, Bridgeford et al. 2025, JOSS review criteria, The Turing Way, BSSw.io), and reproducibility tooling (DVC, mlflow / wandb, Snakemake / Nextflow, Zenodo, Software Heritage, JuliaBesties/BestieTemplate.jl). The audit identified a clear gap: no agent-skill targeted scientific-computing software methodology; this skill is the first cut at filling that gap. Currently ships SKILL.md + 3 references (01-numerical-correctness, 02-testing-for-numerical-code, 11-ai-assisted-coding-rules); the companion templates/software-skeleton/ (with bootstrap.sh delegating to scientific-python/cookie | NLeSC/python-template | CU-DBMI/template-uv-python-research-software | JuliaBesties/BestieTemplate.jl

MULTI-LANGUAGE.md guidance) shipped 2026-05-13. The remaining 7 references (03 API design, 04 performance, 05 reproducibility infra, 06 CI/CD, 07 lifecycle, 08 code-paper coupling, 09 numerical-launch, 10 numerical-debug) are planned in PR2 + PR4 per the audit's sequencing. Revised 2026-05-14 (post-fresh-audit: trimmed workflow table to only the 3 ship-ready references; moved the 8 unshipped references to a clearly-marked "Planned references (not yet shipped)" section with explicit "do NOT try to load these" warning; fixed footer count "four references" -> "3 references"; replaced "templates/software-skeleton/ planned" with "shipped 2026-05-13"; compressed description from 1725 chars to ~1024 chars to fit the OpenCode skill-spec limit of 1024 chars per AGENTS.md Section 8). Revised 2026-05-17 (Session A skill-optimisation pass; F-03..F-08 from argo-anywhere real-project feedback): shipped new reference 12-shell-and-cross-language-interop.md consolidating 6 rules (YAML/JSON quoting on bash/Python boundary; setdefault for security-defaulted keys; error-message recovery hints must themselves be tested; test stimulus must exercise the assertion site; shell-script unit-test mechanics; exit-summary scope-keyed hints). Reference 12 moved from the "Planned references" table to the live workflow table. The framework's "research-software- engineering" skill now ships 4 references (01, 02, 11, 12); 7 remain planned (03-10, less 12).*