RND-12706: measuring tabs fix

[BrettJephson]

We got stuck in a state of isMeasuring for the tabs which meant the ellipsis at start showed always.

This change:

1. fixes the issue with measurement
2. improves rendering of useSelect
3. adds an e2e test for dynamic tab measuring

[linear-code]

RND-12706

[changeset-bot]

🦋 Changeset detected

Latest commit: 4be36a1

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
gitbook	Patch

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[github-actions]

Summary of the deployments:

Version	URL	Status
Vercel	https://gitbook-v2-860ny3i1g-gitbook.vercel.app	✅
Cloudflare	https://23451a83-gitbook-open-v2-preview.gitbook.workers.dev	✅

Test content

Site	2v	2c
GitBook	https://gitbook-v2-860ny3i1g-gitbook.vercel.app/url/gitbook.com/docs	https://23451a83-gitbook-open-v2-preview.gitbook.workers.dev/url/gitbook.com/docs
E2E	https://gitbook-v2-860ny3i1g-gitbook.vercel.app/url/gitbook.gitbook.io/test-gitbook-open	https://23451a83-gitbook-open-v2-preview.gitbook.workers.dev/url/gitbook.gitbook.io/test-gitbook-open

[argos-ci]

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Build	Status	Details	Updated (UTC)
customers-v2-cloudflare (Inspect)	👍 Approved by Brett Jephson	7 changed, 4 ignored	Sep 7, 2026, 2:32 PM
customers-v2-vercel (Inspect)	👍 Approved by Brett Jephson	5 changed, 2 ignored	Sep 7, 2026, 2:30 PM
v2-cloudflare (Inspect)	👍 Approved by Brett Jephson	5 changed, 4 ignored	Sep 7, 2026, 2:34 PM
v2-vercel (Inspect)	👍 Approved by Brett Jephson	5 changed, 4 ignored	Sep 7, 2026, 2:32 PM

[github-actions]

Style invalidation on a large API reference

Elements restyled by opening one popup on the Snyk API reference. A share near or above 100% means the insertion restyles the whole document.

interaction	restyled	page	share	budget
openapi-select	5	10,786	0.0%	25%	✅
search	637	10,786	5.9%	125%	✅