The screen's state machine had a seam and no matrix behind it. Every arm of
the `when` returns `Unit`, so an arm can render anything at all and still
compile -- a button offered where it cannot work, a state's own data never
reaching the node meant to show it, an affordance wired to the wrong
callback. The leaf tests cannot see any of that: they compose `FileCard`,
`AdvancedPicker` and the three pickers directly and never hold a
`ConversionState`.
The arm worth guarding most is `Ready`'s `enabled = validation.isValid`. The
Advanced picker deliberately lets an impossible container / codec pair be
selected, so that one expression is all that stands between an invalid spec
and a job that cannot succeed. `enabled = true` compiles, renders an
identical screen apart from one colour, and passed the whole suite before
this.
Callbacks are asserted over the complete log rather than one at a time, so a
case reads "this one fired and nothing else". A bare "the callback ran" check
stays green on an arm that fires the right callback for the wrong reason.
The routing chip needed a tag to be locatable at all: its text comes from the
finished job, so a text matcher would have to name a routing explanation the
screen does not own. That is the only production change here.
Not asserted, deliberately: `Failed`'s error colour, which Compose publishes
nowhere in the semantics tree; and the three absent `FileCard`s, which are
compile-guarded -- `Idle`, `Saved` and `Failed` carry no `input` -- so those
lines state the intent without being what enforces it.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
JMR-devandClaude Opus 5
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