Add run_api_docs and enforce public-API docstrings by default in run_qa (2.0.0)

[ChrisRackauckas-Claude]

This draft PR should be ignored until reviewed by @ChrisRackauckas.

Motivation

A wave of near-identical PRs (SciML/SciMLSensitivity.jl#1537, SciML/DiffEqGPU.jl#472) added a hand-copied test/QA/public_api_docs.jl to individual SciML repos, each re-implementing the same check: every exported name has a docstring (and is rendered in the docs). This PR factors that into the shared harness and turns it on by default, so the fleet enforces public-API docstrings from a plain run_qa(MyPkg) and repos delete their bespoke files.

What's added

• public_api_names(pkg) — the sorted public API: exported names, plus public-declared names on Julia >= 1.11 (exported-only on the 1.10 LTS, so no per-repo if VERSION guards).
• run_api_docs(pkg; docstrings=true, rendered=false, docs_src, ignore, rendered_ignore, docstrings_broken, rendered_broken):
  • docstrings (on by default): every public name has a docstring. The lookup is Base.Docs.doc on the binding, so a name re-exported from a dependency counts as documented via that dependency — a repo isn't forced to redocument re-exports.
  • rendered (opt-in): every public name appears in a ```@docs block under docs_src (defaults to <pkgroot>/docs/src). An ```@autodocs block satisfies it wholesale.
  • ignore/rendered_ignore for exceptions; docstrings_broken/rendered_broken to mark the check @test_broken for a mid-migration repo (auto-flags an Unexpected Pass once fully documented).
• run_qa now runs api_docs by default (api_docs = true) via api_docs_kwargs. explicit_imports stays opt-in (its per-repo ignore-lists make default-on impractical).
• REPL added as a (stdlib) dep, imported for its load-time side effect: on Julia >= 1.11 the Base.Docs.doc(::Binding) methods live in REPL and are absent in a bare Pkg.test process. (The copied per-repo files only worked because the test env happened to load REPL transitively.)

Breaking change -> 2.0.0

Turning api_docs on by default changes the observable behavior of the pre-existing run_qa for every caller: a repo that upgrades and has undocumented public API will see its QA lane go red where it was green. Per SemVer that is a breaking change, so this is a major bump to 2.0.0 (not 1.9.0). Escape hatches: run_qa(MyPkg; api_docs = false), or api_docs_kwargs = (; ignore = (...)) / (; docstrings_broken = true).

Note: this deliberately reverses the opt-in stance explicit_imports uses. If you'd rather treat "stricter QA on a bump" as non-breaking and ship it as 1.9.0 (or keep api_docs opt-in), say so and I'll adjust.

Migration path for repos

A repo replaces its test/QA/public_api_docs.jl (and its runtests.jl include of it) with nothing extra — the check now rides along with run_qa:

run_qa(MyPackage; explicit_imports = true)          # docstring check included by default
# add api_docs_kwargs = (; rendered = true) to also require rendering in docs/src

Only 2 repos actually grew the bespoke file (SciMLSensitivity.jl, DiffEqGPU.jl); their migration PRs are a follow-up blocked on a 2.0.0 release.

Validation

• Pkg.test() green on Julia 1.11 (286 pass) and 1.10 (271 pass) locally — full output observed, not inferred.
• Runic.jl formatting applied to the changed src/test files.
• The suite includes a real, non-mocked assertion that SciMLTesting's own exported API is fully documented (run_api_docs(SciMLTesting) passes), so the check guards this package too.

🤖 Generated with Claude Code

https://claude.ai/code/session_01AedZ1o7uENECZRF7xUwUaS