Fix Fetch dropping repeated form fields and leaking src into history

[titouanmathis]

Two faults in Fetch's URL resolution, both found while building a facet filter form. Targeting main (v1) deliberately: Fetch.ts is byte-identical on main and 2.x, so this patch applies to both, and v1 is what consumers are on today.

1. A repeated GET field only sent one value

get url() folded the form onto the base with url.searchParams.set(key, value) per entry. set replaces, so for a checkbox group — repeated names by design — only one value survived.

Measured in a browser before the fix, on a form with two boxes ticked:

FormData.getAll('project_category[]')      → ['portrait', 'still-life']
new URLSearchParams(new FormData(form))    → project_category[]=portrait&project_category[]=still-life
what Fetch requested                       → project_category[]=still-life

Ticking a second box changed nothing on screen, which is how it was noticed.

set was there for a reason the docblock states — a fixed query in src must be overridable by a live field — so append alone is not the fix: it would let the base's stale value through. The fold now deletes the base's values the first time it meets a name, then appends, which keeps the override and stops discarding the rest:

base ?genre=stale&section=keep, form genre=rock, genre=jazz	result
set (before)	genre=jazz&section=keep
append only	genre=stale&genre=rock&genre=jazz&section=keep
delete-once, then append	genre=rock&genre=jazz&section=keep

This also covers <select multiple>, which repeats a name without the [] suffix — so the fix cannot key on the name's shape.

2. History pushed the fetched URL, not the navigation

update() pushed the URL that was requested. With src set to a lighter endpoint, its parameters landed in the address bar and in every link a visitor copied.

src answers what to request. The new historyUrl getter answers what this navigation is: the element's own destination, folded with the same form data.

<a
  href="/projects/page/2?orderby=title"
  data-component="Fetch"
  data-option-history
  data-option-src="/projects/page/2?orderby=title&sections=listing">
  2
</a>

Requests the sections=listing URL, pushes /projects/page/2?orderby=title.

A URL passed explicitly to fetch(url) is still pushed as given — a caller that named a URL meant that URL — so fetch() now captures whether the URL came from the element or from the caller.

Nothing changes for an element without src, where the request URL and the destination are the same. update()'s signature is untouched, and a direct update() call still pushes the URL it was handed.

One consequence, documented rather than engineered around

A back or forward navigation re-fetches window.location.href, which is now the pushed URL rather than the src one. selector therefore has to match elements present in both responses. There is a tip about it in the docs.

Tests

packages/tests/Fetch/Fetch.spec.ts gains eight cases: repeated fields with and without brackets, repeated fields overriding a conflicting src query, historyUrl for links and for forms, historyUrl falling back to url, history pushing the destination rather than the src, and history pushing an explicitly passed URL.

<select multiple> is not among them, with a comment saying why: happy-dom puts only the first selected option into FormData, so the case cannot be expressed in this environment. The bracket-free coverage uses two same-named inputs instead, which makes the same point.

893 tests pass, npm run lint clean.

[github-actions]

Code Review

Risk: Medium — issues that should be addressed before merge.

Updates Fetch URL resolution to preserve repeated GET form values while replacing conflicting base parameters. Adds destination-based history resolution for element-triggered fetches and tests the new request and history behaviours.

1 issue found:

• issue — packages/ui/src/Fetch/Fetch.ts:348 — Clear request-specific history state after update

---

Review usage: 20,680 in (3,677 cached) / 705 out tokens — $0.0129 (openrouter/openai/gpt-5.6-luna, thinking: low)

Reviewed by @weareikko/code-review v0.9.5 for commit 7edbbdd.

[github-actions]

Export size

Bundled per export with peer dependencies left external, dynamic imports excluded and the output minified; sizes are gzipped.

@studiometa/ui

Export	Size (gzip)	Diff
FetchShopifyPartial	3.11 kB	+136 B (+4.5%)
FetchShopifySection	2.82 kB	+116 B (+4.2%)
(barrel)	30.88 kB	+114 B (+0.4%)
Fetch	2.56 kB	+114 B (+4.6%)
manifest	2.99 kB	-2 B (-0.1%)

Unchanged (128)

@studiometa/ui

Export	Size (gzip)	Diff
AbstractCarouselChild	542 B	–
AbstractCarouselComponent	219 B	–
AbstractFrameTrigger	1.11 kB	–
AbstractPrefetch	438 B	–
AbstractScrollAnimation	651 B	–
AbstractSliderChild	489 B	–
Accordion	1.11 kB	–
AccordionItem	995 B	–
Action	1.22 kB	–
AnchorNav	1018 B	–
AnchorNavLink	867 B	–
AnchorNavTarget	166 B	–
AnchorScrollTo	222 B	–
Carousel	2.89 kB	–
CarouselBtn	720 B	–
CarouselDrag	735 B	–
CarouselItem	786 B	–
CarouselWrapper	670 B	–
CircularMarquee	313 B	–
ClickOutside	219 B	–
Cursor	676 B	–
DataBind	3.97 kB	–
DataComputed	4.06 kB	–
DataEffect	4.04 kB	–
DataModel	4.07 kB	–
DataScope	1.4 kB	–
Dialog	1.79 kB	–
Disclosure	2.39 kB	–
DisclosureGroup	1.16 kB	–
Draggable	1.14 kB	–
Figure	1.07 kB	–
FigureShopify	1.35 kB	–
FigureTwicpics	1.6 kB	–
FigureVideo	1.27 kB	–
FigureVideoTwicpics	1.85 kB	–
Frame	2.51 kB	–
FrameAnchor	1.2 kB	–
FrameForm	1.32 kB	–
FrameLoader	788 B	–
FrameTarget	1.1 kB	–
FrameTriggerLoader	801 B	–
Hoverable	624 B	–
InView	204 B	–
InViewOnce	245 B	–
Indexable	1022 B	–
LargeText	499 B	–
LazyInclude	421 B	–
Menu	1.72 kB	–
MenuBtn	186 B	–
MenuList	1.28 kB	–
Modal	1.13 kB	–
ModalWithTransition	1.26 kB	–
Panel	1.52 kB	–
PrefetchWhenOver	485 B	–
PrefetchWhenVisible	510 B	–
ScrollAnimation	806 B	–
ScrollAnimationChild	979 B	–
ScrollAnimationChildWithEase	1.25 kB	–
ScrollAnimationParent	1.05 kB	–
ScrollAnimationTarget	898 B	–
ScrollAnimationTimeline	983 B	–
ScrollAnimationWithEase	1.08 kB	–
ScrollReveal	1005 B	–
Sentinel	175 B	–
Slider	2.28 kB	–
SliderBtn	745 B	–
SliderCount	549 B	–
SliderDots	1.15 kB	–
SliderDrag	348 B	–
SliderItem	574 B	–
SliderProgress	612 B	–
Sticky	929 B	–
Tabs	663 B	–
Target	125 B	–
Timer	589 B	–
TimerProgress	731 B	–
Toast	968 B	–
Toaster	1.3 kB	–
Track	1.61 kB	–
TrackContext	416 B	–
TrackShopify	1.71 kB	–
Transition	746 B	–
ViewTransition	658 B	–
animationScrollWithEase	438 B	–
autoload	3.04 kB	–
scheduler	324 B	–
types	20 B	–
viewTransition	325 B	–
withDeprecation	250 B	–
withIndex	986 B	–
withScrollAnimationDebug	1.63 kB	–
withTransition	717 B	–

@studiometa/ui-mapbox

Export	Size (gzip)	Diff
(barrel)	6.41 kB	–
AbstractMapboxControl	1.02 kB	–
AbstractMapboxMapChild	848 B	–
MAPBOX_CLUSTER_CONNECTED	143 B	–
MAPBOX_MAP_CONNECTED	128 B	–
MapboxCluster	2.13 kB	–
MapboxClusterItem	644 B	–
MapboxFullscreenControl	1.17 kB	–
MapboxGeocoder	1.21 kB	–
MapboxGeolocateControl	1.23 kB	–
MapboxImage	1.34 kB	–
MapboxImages	1.38 kB	–
MapboxLayer	1.36 kB	–
MapboxMap	723 B	–
MapboxMarker	1.11 kB	–
MapboxNavigationControl	1.21 kB	–
MapboxPopup	1.17 kB	–
MapboxSource	1.32 kB	–
StoreLocator	1.96 kB	–
autoload	681 B	–
dependencies	342 B	–
manifest	639 B	–
provideMapboxGeocoder	107 B	–
provideMapboxGl	104 B	–
resolveMapboxGeocoder	148 B	–
resolveMapboxGl	139 B	–

@studiometa/ui-motion

Export	Size (gzip)	Diff
(barrel)	2.7 kB	–
Motion	1.58 kB	–
MotionScrollTimeline	1.83 kB	–
MotionSequence	1.76 kB	–
MotionView	1010 B	–
autoload	363 B	–
dependencies	257 B	–
manifest	323 B	–
provideMotion	102 B	–
resolveMotion	115 B	–

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 87.85%. Comparing base (c939977) to head (7edbbdd).

Additional details and impacted files

@@             Coverage Diff              @@
##               main     #643      +/-   ##
============================================
+ Coverage     87.80%   87.85%   +0.05%     
  Complexity      145      145              
============================================
  Files           153      153              
  Lines          5443     5460      +17     
  Branches       1037     1040       +3     
============================================
+ Hits           4779     4797      +18     
+ Misses          580      579       -1     
  Partials         84       84              

Flag	Coverage Δ
unittests	87.85% <100.00%> (+0.05%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
packages/ui/src/Fetch/Fetch.ts	100.00% <100.00%> (+0.70%)	⬆️

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