AI Tech Inspire

From Vibe-Coding to Reproducible ML: Structure, LLMs, and Fast Experimentation

If you’ve ever “vibe-coded” an experiment and then sprinted toward a deadline, only to discover a lurking bug in the final hours, you’re in good company. At AI Tech Inspire, we’ve seen this pattern across labs and startups alike: fast iteration meets fragile scaffolding. The question isn’t whether to move fast; it’s how to build just enough structure so speed doesn’t silently corrupt results.

Key context

  • A Master’s student at ETH Zürich and a collaborator attempted a NeurIPS workshop paper.
  • They leaned heavily on LLMs for experiment code; multiple bugs led to unreliable data discovered near the deadline.
  • They worry about the negative impact if those bugs had slipped through.
  • Experience in big tech set expectations for high code quality, which felt heavy for small-scale research.
  • They’re looking for a workable balance between execution speed and reliability, plus guidance on LLM use and collaboration patterns.

Speed vs. reliability: define the middle ground

Production-grade rigor can be overkill for a short research sprint. But so is free-form hacking when conclusions need to be trusted. A practical middle ground is to aim for experiment velocity with guardrails: minimize ceremony while capturing reproducibility, sanity checks, and clear provenance.

“Move fast, keep receipts.”

In practice, that means prioritizing a small set of habits that pay for themselves quickly:

  • Single source of truth config (no magic numbers in code)
  • Deterministic seeding and a fixed evaluation harness
  • Automated run logging (metrics, hyperparams, commit hash)
  • Short, standardized smoke tests that run in minutes

These guardrails don’t block speed; they remove uncertainty, making iteration faster and bolder.

Where LLMs help (and when they hurt)

LLMs can accelerate boilerplate, refactors, and idea-to-skeleton translation. But they also fabricate APIs, miss edge cases, and introduce subtle data leaks. Treat the model like a bright junior engineer: great at drafts, never the final authority.

  • Use LLMs for: writing argparse/Hydra configs, data loader templates, test scaffolds, docstrings, vectorized refactors, code comments, visualization snippets.
  • Be cautious with: evaluation logic, statistical tests, data splitting, and anything affecting train/test boundaries.
  • Workflow idea: prompt the LLM to generate code plus a checklist of failure modes (e.g., “Where could leakage occur?”). Implement the code, then manually validate against its checklist.

Tools amplify this approach: if your stack is PyTorch or TensorFlow, and you’re pulling models from Hugging Face, ask the LLM to cite the specific function signatures and links it’s relying on. For generative work (say, Stable Diffusion), request cited configs and version info. And for GPU bits, require explicit notes about CUDA versions.

Minimum viable rigor: a checklist you can paste into your repo

  • Config first: Use --config files (e.g., yaml) for data paths, seeds, model hyperparams, and evaluation settings. Tools like Hydra or Sacred can help, but even a single config.yaml works.
  • Seeding and determinism: Set global seeds and pin framework determinism. Log the seed and any non-deterministic ops.
  • Baseline before bells: Always run a simple baseline (e.g., logistic regression or a small CNN) to ensure data and metrics are wired correctly.
  • Smoke tests: A 15-minute run that executes data loading, a few training steps, and evaluation on a tiny subset. Make this a pre-merge requirement.
  • Assertions everywhere: Assert tensor shapes, label ranges, and split ratios. Add checks for label leakage and duplicates.
  • Eval harness: One script/function that takes predictions + labels and returns metrics. Freeze it early. No per-experiment forks.
  • Artifact logging: Save config, commit hash, metrics, and checkpoints per run. Tools like MLflow or Weights & Biases help; a homegrown JSON log is fine.
  • Data versioning: If data shifts, tag it. Lightweight options include a dataset checksum file; heavier options include DVC.
  • Type checks and pre-commit: pre-commit hooks for formatting and linting; a light mypy pass catches many LLM-introduced mismatches.

A tiny template repo with train.py, eval.py, conf/, and tests/ will outperform ad hoc notebooks once multiple people and versions are involved. If you need distributed training or longer runs, capture the environment (e.g., conda env export or poetry.lock), and consider Docker.

Practical structure: from notebook to reproducible runs

Notebooks are great for exploration. But once a result looks promising, “graduate” it to a script with a config. A simple pattern:

  • python train.py conf=baseline.yaml
  • python eval.py run_id=2025-09-07-1337
  • python ablate.py conf=baseline.yaml override=model.dropout=0.0

Use a consistent naming scheme for runs, and tag them with the git commit. If you rely on GPT-assisted code, add its prompt and response as an artifact to the run so reviewers can audit intent.

Collaboration patterns that actually reduce bugs

  • Short PRs: Keep pull requests small and reviewable. Add a checklist at the top: “seed set,” “eval harness unchanged,” “smoke test passed.”
  • Experiment docs: A living EXPERIMENTS.md with a table: run_id, config, data_version, metric, notes. Link to artifacts.
  • Pair debugging: 30-minute pair sessions on data loading, metrics, and evaluation code pay off more than solo heroics on model tweaks.
  • Branch strategy: main is stable; exp/feature-x for new ideas; merge only after the smoke test and eval harness checks pass.
  • Review focus: Don’t review style bikesheds; review assumptions: “Are labels aligned?” “Any train/test contamination?” “Does the config reflect the paper table?”

For teams working across frameworks, keep the interface consistent: whether you’re in PyTorch or TensorFlow, ensure the same train()/evaluate() signatures and artifact layout. That avoids translation errors when swapping components.

Deadline mode: a fast pre-submission gauntlet

When the clock is ticking, prioritize checks with the highest bug-catch rate:

  • Re-run top results: Fresh environment, fresh seed. Confirm the same numbers within tolerance.
  • Hold-out sanity: Re-split the data (or use a different fold) and verify ordering doesn’t drive the result.
  • Metric cross-check: Duplicate metrics with an independent implementation (e.g., sklearn vs. custom).
  • Baseline resilience: Ensure the baseline’s relative rank is stable across seeds.
  • Leakage probes: Shuffle labels and confirm performance collapses to chance.
  • Reporting script: Auto-generate tables/plots from the artifacts, not from memory or ad hoc notebook cells.

If your pipeline touches GPUs, remember that kernel choices and mixed precision can induce subtle nondeterminism. Document the torch.backends/tf.config flags, driver versions, and CUDA details alongside runs.

Why this matters for developers and researchers

The difference between a result you can defend and one you can’t often comes down to a few habits, not months of platform engineering. Lightweight rigor compounds: fewer dead ends, tighter feedback loops, and confidence that an improvement is real—not a quirk of a random seed or a mislabeled split.

Engineers will appreciate the symmetry: it’s essentially “DevOps for experiments,” trimmed to fit the research pace. By turning configuration into a first-class artifact and using LLMs where they’re strongest, teams preserve velocity without gambling on validity.

Key takeaway: Treat structure as a speed enabler. The fastest teams are the ones that can trust their results.

Questions to sharpen your next sprint

  • What’s the smallest set of checks that would catch 80% of your historical bugs?
  • Which pieces of your pipeline are safe to auto-generate with an LLM—and which must be hand-audited?
  • Can every number in your results table be traced to a run ID, config, and commit?
  • If a collaborator reruns the top experiment on a fresh machine, does it reproduce within a reasonable tolerance?

None of this requires a massive tooling overhaul. Start with a smoke test, a single config file, and an evaluation harness you promise not to fork. Add run logging and a tiny EXPERIMENTS.md. Invite an LLM to draft the boring parts, and make it defend its choices. That’s the difference between vibe-coding and verifiable progress.

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