docs: fix conflicting lazy heavy import guidance in STYLEGUIDE.md (#759)

[chethanuk]

📋 Summary

STYLEGUIDE.md and lazy_heavy_imports.py recommend opposite import forms for lazy-loading
heavy dependencies. from data_designer.lazy_heavy_imports import pd, np is an attribute read
against the module's PEP-562 __getattr__ facade, so it fires while the consuming module is
still importing and pandas loads eagerly — the facade buys nothing. Only
import data_designer.lazy_heavy_imports as lazy + lazy.pd stays lazy, which is what the
module's own docstring already requires and what test_lazy_imports.py already asserts. This
aligns the guide to the form that actually works.

🔗 Related Issue

Fixes #759

🔄 Changes

• STYLEGUIDE.md: rewrite the four blocks that taught the from ... import pd, np form to use
  the import ... as lazy / lazy.pd form instead. Each example gains a call site and
  from __future__ import annotations so the snippets are runnable modules rather than
  illustrations that raise NameError if copy-pasted.
• scripts/benchmarks/benchmark_engine_v2.py: convert the tree's only remaining user of the
  banned form to the alias pattern.
• packages/data-designer/tests/test_lazy_imports.py: add
  test_scripts_avoid_from_lazy_heavy_imports_pattern, extending the existing
  packages/*/src/** guard to scripts/** — the gap that let the benchmark script drift.

🧪 Testing

• make test — test_lazy_imports.py: 1 failed, 4 passed before the fix (fails on
  benchmark_engine_v2.py); 5 passed after
• make lint / make format-check — all checks passed
• make test-interface — 1119 passed, 1 skipped, 1 pre-existing failure
  (test_import_performance, an environmental make perf-import timeout under machine load,
  reproduced identically on main with none of this branch's changes applied)
• Benchmark script re-run at a fixed seed, before and after conversion: identical
  dataset_hash

✅ Checklist

• Follows commit message conventions
• Commits are signed off (DCO) — squashed to one commit, git commit -s
• Architecture docs updated — N/A (docs/test/script only, no architecture change)

Note: issue #759 does not currently carry the triaged label; the upstream
linked-issue workflow may gate on that independent of this PR.

Fixes #759

[github-actions]

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I have read the DCO document and I hereby sign the DCO.

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1 out of 2 committers have signed the DCO.
✅ (nabinchha)[https://github.com/nabinchha]
❌ @chethanuk
_{You can retrigger this bot by commenting recheck in this Pull Request. Posted by the DCO Assistant Lite bot.}

[greptile-apps]

Confidence Score: 5/5

The PR appears safe to merge with no actionable correctness or repository-rule violations identified.

Summary

• Updates STYLEGUIDE.md examples to use import data_designer.lazy_heavy_imports as lazy.
• Converts benchmark NumPy and pandas accesses to the lazy module facade.
• Adds a regression test preventing the eager from-import pattern under scripts/**.

_{Reviews (2) · Last reviewed commit: "Merge branch 'main' into fix/issue-759-s..."}

[github-actions]

Issue #759 received the triaged label. The linked issue check is being re-evaluated.

[nabinchha]

Thanks for putting this together, @chethanuk!

Summary

This aligns STYLEGUIDE.md with the lazy facade's actual PEP 562 behavior, converts the remaining benchmark-script caller to the module-alias form, and extends the regression guard to scripts/**/*.py. The implementation matches the PR description and the resolution requested in issue #759.

Before merge, @chethanuk, please address the DCO Assistant request by following the bot's instructions to acknowledge the DCO, then comment recheck if the check does not rerun automatically.

Findings

No findings.

What Looks Good

• The revised examples show both deferred annotations and real lazy.<alias> call sites, so the recommended pattern is clear and directly usable.
• Updating the benchmark script alongside the documentation removes the known inconsistency rather than leaving an in-tree counterexample.
• The new script scan complements the existing runtime-source guard, and the focused lazy-import tests pass end to end.

Verdict

Ship it — the code changes are ready; merge remains pending the DCO acknowledgment requested above.

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This review was generated by an AI assistant.