Review Checklists for Extension Safety¶

Page Maps¶

graph LR
  family["Python Programming"]
  program["Python Object-Oriented Programming"]
  section["Public Apis Extension Governance"]
  page["Review Checklists for Extension Safety"]
  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"]

This lesson exists because extension review often fails in a predictable way:

one reviewer checks signature shape
another checks version language
another worries about startup failure
nobody can tell whether the seam was actually reviewed well

Without a stable checklist, extension safety depends too much on memory and personality.

The point of this page is not to replace judgment. It is to make the same hard questions appear every time a seam changes.

Keep one seam visible¶

Use one concrete seam:

IncidentSink

That seam is narrow enough to be teachable and risky enough to make the checklist real.

If your checklist cannot help you review a seam this small, it will not save you on a larger one.

A useful checklist must go beyond type shape¶

A weak checklist reviews only:

names
methods
argument types

That is not enough.

An extension checklist must also cover:

whether the seam should be public at all
what authority boundaries it preserves
what registration or construction checks exist
what runtime failure behavior is expected
what compatibility promise is created
what docs, examples, and proof routes defend the story

Those are the real support obligations created by a public seam.

A seven-question extension-safety checklist¶

For IncidentSink, a strong short checklist is:

Is this seam public because of a real supported use case, or only because the host layout makes it easy to expose?
Does the seam grant capability only, rather than aggregate, repository, or runtime intimacy?
What explicit registration or construction checks reject malformed or incompatible implementations?
What happens if the sink is missing, slow, blocking, or raises at runtime?
What compatibility or deprecation promise is created by publishing this seam?
Which docs, examples, and import rules teach the supported usage path?
Which executable proof or review route would fail first if the seam drifted?

That checklist is short enough for repeated use and broad enough to catch the real governance risks.

Strong answers point to evidence¶

Good answers should point to evidence, not reassurance.

Examples:

one compatibility packet for sink behavior
one executable or smoke-tested facade example
one import-discipline review rule
one registration-validation path
one governance note recording why the seam is public

If a seam cannot answer the checklist with evidence, the support story is still thin.

Failure review belongs inside the checklist¶

Do not leave operational risk outside the review.

For the capstone seam, ask:

what happens if configuration is present but malformed?
what happens if a sink blocks longer than the host expects?
what happens if a sink raises after partial publication work?
what happens if a sink returns data the host should not trust?
what happens if the seam is still documented but no longer truly supported?

These are extension-safety questions, not later operations work.

Build a reusable review packet¶

A good checklist becomes stronger when paired with a tiny review packet:

seam description
supported use case
authority boundary note
failure-behavior note
compatibility promise
proof route

That packet makes the checklist reusable across maintainers and review cycles.

Worked review pass¶

A short review of IncidentSink might conclude:

the seam is justified because alternate sinks are a real supported need
the seam must receive already-shaped incident data and nothing with private authority
registration must reject malformed configuration before the workflow starts
runtime sink failure must not corrupt aggregate truth or duplicate visible work
facade examples and compatibility proof must teach the supported path consistently

That is a real governance result, not just a statement that the interface "looks clean."

Common failure modes¶

making the checklist so long that nobody reuses it
reviewing only type shape and missing ownership or failure behavior
asking questions with no evidence route attached
calling private-state access acceptable because the extension is "trusted"
forgetting that examples and docs define how consumers will actually use the seam

Review card¶

Use this compact review card during real changes:

Question	What a strong answer sounds like
should this seam be public at all?	one concrete supported use case
does it preserve authority boundaries?	capability without private-state intimacy
what rejects bad implementations early?	explicit registration or construction checks
what happens under runtime trouble?	failure behavior that preserves host truth
what support promise is created?	named compatibility and deprecation rule
what teaches the supported path?	facade docs and examples, not deep imports
what proof keeps it honest?	one executable or reviewable route

Capstone connection¶

Use this page to ask:

which seam needs this checklist first
which risk question is currently living only in reviewer memory
which proof route is still missing for the seam to pass review honestly
which failure behavior is still undocumented even though it affects support

That is how governance becomes repeatable instead of personality-driven.

Exit check¶

Leave this lesson only when you can do all of these:

explain why extension review must ask repeatable questions beyond protocol shape
draft a short checklist for one concrete capstone seam
identify one missing failure-mode question and one missing proof route in the current capstone review story