feat(a11y): every widget describes itself, and an image can finally be named

[tannevaled]

Two gaps, found by auditing the accessibility layer rather than by hitting them.

An image could not be described

Image reported RoleImg with no name, and had no field to hold one. Its own doc comment said "Name is left for the host to fill in from context" — which A11y()'s by-value return makes impossible.

An image that cannot be described is the one thing accessibility exists to prevent. Image gains Alt; Thumbnail gains it too, falling back to the caption it already shows.

Twenty-one of 113 widgets said nothing at all

Worse than an imperfect role: CollectA11y silently skips a widget that does not implement Accessible, so a consumer could not tell "this has no semantics" from "nobody wrote its A11y()". The gap stayed invisible. All 113 now answer.

Layout and decoration answer RolePresentation. That is not filler — it is ARIA's own "look through me to the content inside", and it is now a stated position rather than an omission.

CollectA11y filters those out, so its callers see exactly what they saw before: the meaningful nodes, no structural furniture. The two existing tests asserting an HBox is skipped pass unchanged — which is the evidence this preserves the contract rather than reinterpreting it.

The rest carry real semantics:

widget	role	carries
Browser	document	the URL it is showing
PagingToolbar	toolbar	page 2 of 7
LoadMask	status	busy, only while it actually is
StatusIcon	status	its badge count
Window / WindowDecoration	dialog / banner	the title
Gantt	img	task count, matching the other charts

The guard

TestEveryWidgetIsAccessible parses the package, finds every struct embedding Base and every A11y() method, and fails naming any widget that describes itself as nothing. The gap cannot reopen quietly.

Verification

go test -race → 100.0% of statements, race-clean.

🤖 Generated with Claude Code