CI Gates, Drift Control, and Review Surfaces¶

Page Maps¶

graph LR
  family["Reproducible Research"]
  program["Deep Dive Snakemake"]
  section["Scaling Workflows Interface Boundaries"]
  page["CI Gates, Drift Control, and Review Surfaces"]
  capstone["Capstone evidence"]

  family --> program --> section --> page
  page -.applies in.-> capstone

flowchart LR
  orient["Orient on the page map"] --> read["Read the main claim and examples"]
  read --> inspect["Inspect the related code, proof, or capstone surface"]
  inspect --> verify["Run or review the verification path"]
  verify --> apply["Apply the idea back to the module and capstone"]

Scaling does not stay safe because people intend to be careful.

It stays safe because the repository makes the risky boundaries visible early.

That is what CI gates and review surfaces are for.

A gate should defend a named contract¶

Weak gating culture says:

add more checks until the repository feels safer.

Strong gating culture says:

choose the smallest gate that proves one specific scaling boundary is still intact.

That difference matters. Otherwise the repository accumulates noisy checks without teaching what they protect.

What good scaling gates usually defend¶

In Module 04, gates are most useful when they protect things like:

the workflow still plans correctly
rule families remain visible and lint-clean
interface paths or schemas have not drifted silently
public contracts still parse and align
repository growth did not make the graph harder to review

These are scaling questions, not merely "did one command exit zero" questions.

A practical gate ladder¶

Useful gates often build on one another:

--lint for immediate design hygiene
dry-run for plan visibility
rule listing or rulegraph for surface visibility
targeted tests or verification for interface trust
stronger end-to-end proof routes when the change claims repository-level safety

The ladder matters because not every diff deserves the heaviest route first.

Drift control is part of the same story¶

As the repository grows, changes become harder to see by eye alone.

Drift surfaces help answer:

did code changes affect planned outputs
did parameter or interface changes alter what should rerun
did a public contract change even though the filenames look similar

Without drift evidence, scaling review becomes guesswork faster than most teams expect.

One healthy review pattern¶

flowchart TD
  diff["repository change"] --> lint["lint and dry-run"]
  lint --> surface["rulegraph or list-rules"]
  surface --> verify["targeted verification"]
  verify --> confirm["stronger proof route if claim expands"]

This is a scaling pattern because it keeps the repository reviewable as changes get wider.

What makes a review surface useful¶

A review surface is useful when it helps a human answer a precise question quickly.

Examples:

--list-rules helps review whether a split still exposes the expected rule families
--rulegraph helps review whether relationships stayed legible after modularization
a verification bundle helps review whether the publish contract still aligns

Those are stronger than "we ran CI and it passed" because they teach what passed.

Common failure modes¶

Failure mode	What it looks like	Better repair
gates are added without named ownership	CI becomes noisy but not more informative	tie each gate to one contract question
only end-to-end routes are trusted	small boundary failures are harder to localize	keep narrower review surfaces available
drift is noticed only after outputs look strange	interface changes arrive too late	add earlier drift or validation evidence
rule splits happen without a surface check	the repository gets bigger and less legible	review `--list-rules` or rulegraph deliberately
validation exists but no one knows what it protects	the gate feels bureaucratic	state the protected boundary in docs or review comments

The explanation a reviewer trusts¶

Strong explanation:

this gate exists because the workflow was split into new rule families; --list-rules and the rulegraph confirm the visible surface still matches the intended architecture, while verification checks the public contract only when the change reaches that boundary.

Weak explanation:

we added a few more CI checks because the repository is getting larger.

The strong version names the contract. The weak version names only anxiety.

End-of-page checkpoint¶

Before leaving this page, you should be able to:

explain why a gate should defend a named boundary
name one narrow review surface and one stronger proof route
describe how drift evidence supports scaling review
explain why CI success without boundary clarity is still weak governance