test: three claims that were pinned by their shape and not by their answer

[sotashimozono]

Asked of the just-merged spec: is every behaviour actually checked? Three were not. Each was a
hasproperty or an isa Function — satisfied by an implementation that returns an empty result
for every input — and one of them was hiding a live defect.

reach_script answered :clean for a script that reaches a mark

const RESULT = simulate(model) is a script's work wearing a declaration's syntax, and it is how
the line that produces the figure is actually written. It was evaluated in the scratch module and
never analysed, so the thunk contained no call at all. The binding still has to be made — a later
struct may use it — so the value is computed at top level and the right-hand side is analysed as
well.

The test now runs three scripts: one that reaches a mark, one of the same shape that does not, and
the trivial one it had before.

A method-level mark had never been through a precompile cache

test/test_precompile.jl calls itself "the measurement that could kill the design", and it was
reading name, reason, since and tracking — a Symbol and three strings. It never read
sig, which is a Type in a const vector inside the cache image, and the fixture package
carried no mark on somebody else's generic, whose signature names typeof(Base.show) and a
type defined in the cached package.

MarkedPkg now carries one of each kind. The probe reads all three, with two controls that a mark
widened on its way through the cache would fail — Base.show is not experimental for anybody, and
the sibling show(::IO, ::Int) is not marked — and it runs reach across the package boundary
with a same-depth control. Both pass: the claim is now measured rather than assumed.

Cross-package propagation said reach isa Function

The spec admitted it needed a fixture package. It now asserts the claim is checked where that
package lives, and checks the module-boundary version it can reach on its own.

---

Renaming the precompilation testset while promoting it is what let the first two hide: the name
that said "a method mark survives precompilation" was the only record that it did not.

1005 assertions, green.

🤖 Generated with Claude Code

[github-actions]

📚 Docs preview: https://codes.sota-shimozono.com/ExperimentalAPI.jl/previews/PR15/

(updates on each push to this PR)

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

📢 Thoughts on this report? Let us know!