fix(csr,ui): deliver component outputs to parent bindings

An output only reaches a parent @binding when the component calls
output.<name>(). Two separate faults meant most of the library never got
there, and both failed silently at each end.

HTML lowercases attribute names, so a parent's @sizeChange registered under
"sizechange" while the component emitted "sizeChange". The lookup missed, fell
through to a DOM dispatch, and the binding was never invoked. That made all 17
camelCase outputs undeliverable -- DataTable.pageChange and .rowClick,
Map.markerClick, ChatBubble.messageClick, LayoutSplitter.sizeChange and the
rest. invokeComponentOutput now falls back to a case-insensitive lookup, and a
csr test fails without it.

Separately, 18 components dispatched hand-built CustomEvents rather than
calling output.*. A bubbling event on the component's own root never reaches a
binding, because parent handlers live in a registry only the output proxy
reads. Card, Footer, Breadcrumb, Accordion, alert, Badge, AnnouncementBar,
AvatarGroup, ToggleCount and InputNumber now emit properly; Marquee, Map,
Timeline, List and SearchBox additionally declare the outputs they were
already firing. Dispatches on window are left alone -- that is how Toaster,
Modal and DataTable signal across component boundaries.

Verified in a browser both ways before and after: an AnnouncementBar
dispatching its own bubbling "dismiss" never reached a page-level @dismiss,
and reached it immediately once it called output.dismiss().

This corrects the audit, which called the LayoutSplitter failure "narrow and
unexplained" and read 32 dead outputs as 16 components needing a rebuild.
"Outputs work elsewhere" was an assumption; the components that worked
happened to use lowercase names and output.*. The dead-output ratchet drops
from 32 to 22, and a new test forbids the raw-CustomEvent pattern outright.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

docs/ui-library-audit-2026-08-08.md

@@ -29,30 +29,58 @@ Two mistakes worth recording, because both nearly became wrong conclusions:
 - The semantic token spread sat _after_ the primary and secondary palette
   entries, so it would have overridden them. It now sits before.
 
+## Correction: outputs, and what was actually wrong
+
+The first version of this audit called the LayoutSplitter output failure
+"narrow and unexplained" and treated 32 dead outputs as 16 components needing a
+rebuild. Both were wrong, and the real cause was found by binding a page
+handler to a component in a browser and watching what arrived.
+
+**Two distinct faults were hiding behind one symptom.**
+
+_Emitting the wrong way._ An output only reaches a parent `@binding` when the
+component calls `output.<name>()`. The runtime resolves parent handlers from a
+registry that only `invokeComponentOutput` reads, so a component that builds
+its own `CustomEvent` — even a bubbling one, dispatched on its own root —
+emits into nothing. Eighteen components did exactly that, so their outputs were
+declared, documented, apparently fired, and never delivered. Converting them
+took ten dead outputs off the list and cost no new machinery.
+
+_Case._ HTML lowercases attribute names, so a parent's `@sizeChange` registers
+under `sizechange` while the component emits `sizeChange`. The lookup missed,
+fell through to a DOM dispatch, and the binding was never invoked — silently,
+with no error at either end. **All 17 camelCase outputs in the library were
+undeliverable**, including `DataTable.pageChange` and `DataTable.rowClick`,
+`Map.markerClick`, `ChatBubble.messageClick` and `LayoutSplitter.sizeChange`.
+The runtime now falls back to a case-insensitive lookup, and a test in
+`packages/csr` fails without that fallback.
+
+The lesson worth keeping: "outputs work elsewhere" was an assumption, not a
+measurement. The components that worked happened to use all-lowercase names and
+`output.*`; that coincidence made a framework-wide bug look like one broken
+component.
+
 ## Outstanding, with numbers
 
-**32 outputs across 16 components have no emitter of any kind.** This is the
-bug LayoutSplitter had: the component advertises an output, a caller binds to
-it, and nothing ever fires. Native event names are excluded — the runtime binds
-a DOM-listener fallback on component tags, so `click` and `input` do arrive.
+**22 outputs across 11 components have no emitter of any kind** (was 32 across
+16; see the correction above). The component advertises an output, a caller
+binds to it, and nothing ever fires. Native event names are excluded — the
+runtime binds a DOM-listener fallback on component tags, so `click` and `input`
+do arrive.
 
-| Component                            | Dead outputs                              |
-| ------------------------------------ | ----------------------------------------- |
-| FileUpload                           | upload, progress, success, cancel, remove |
-| ToastNotifications                   | add, dismiss, clear, action               |
-| AdvancedDatePicker                   | open, close, clear                        |
-| Card                                 | action, navigate, dismiss                 |
-| Accordion                            | open, close                               |
-| AdvancedRangeSlider                  | start, end                                |
-| Chart                                | dataPointClick, legendToggle              |
-| Confetti                             | start, complete                           |
-| TreeView                             | expand, collapse                          |
-| AnnouncementBar, Badge, Toast, alert | dismiss                                   |
-| AvatarGroup                          | overflow                                  |
-| CopyMarkup                           | success                                   |
-| Footer                               | action                                    |
+| Component           | Dead outputs                              |
+| ------------------- | ----------------------------------------- |
+| FileUpload          | upload, progress, success, cancel, remove |
+| ToastNotifications  | add, dismiss, clear, action               |
+| AdvancedDatePicker  | open, close, clear                        |
+| AdvancedRangeSlider | start, end                                |
+| Chart               | dataPointClick, legendToggle              |
+| Confetti            | start, complete                           |
+| TreeView            | expand, collapse                          |
+| Toast               | dismiss                                   |
+| CopyMarkup          | success                                   |
 
-A test pins this at 32 as a ceiling that only moves down.
+A test pins this at 22 as a ceiling that only moves down.
 
 **23 components are still on the `wire-next` scaffold pattern** — no style
 block, no functions, and for 19 of them an outputs block they never honour.
@@ -81,11 +109,6 @@ the busiest activity in the library.
 
 ## Known framework defects
 
-- **A component output is not delivered to a parent binding in at least one
-  case.** LayoutSplitter emits `sizeChange` and the component genuinely fires
-  the event, but `@sizeChange` on the tag is not invoked. Outputs work
-  elsewhere, so this is narrow and unexplained. Renaming away from the native
-  `resize` did not fix it, so the first hypothesis was wrong.
 - **A component tag nested inside another component slot is dropped**, leaving
   only its children.
 - **Component props and slot content render once** and do not track page state,