Fix e2e tests that break when shard rebalancing changes their neighbors

[jorgefilipecosta]

Trunk's e2e suite has been red since #80314 landed, but not because that PR broke the editor: it added new e2e tests, and shard balancing is duration-based, so the suite's shards recomposed and two latent order-dependent specs started failing deterministically. This PR hardens both. The failing tests moved with each subsequent reshuffle — font-appearance-control.spec.js on Playwright shard 5 in the first two red runs, site-editor-inserter.spec.js on shard 7 after #79934 added more tests — which is the signature of order dependence rather than a product regression.

Font appearance control: the two tests read the block inspector but never open it, relying on the sidebar's default-visible state. Sidebar visibility is a persisted user preference: preferences are reset once per CI run in the global setup, then shared by every test in the shard, with writes flushed on a debounce. Any earlier test that leaves the sidebar hidden therefore starves these tests of an inspector, and the failure screenshots show exactly that: the Typography options click timing out with the sidebar closed. With a seeded isComplementaryAreaVisible: false preference the failure reproduces on trunk before #80314 too, and both development and production builds pass with a clean profile — the editor itself is fine. Fix: call editor.openDocumentSettingsSidebar() in beforeEach, like sibling specs do (a no-op when the sidebar is already open).

Site editor inserter: the InserterUtils tab locator used getByRole's default substring matching, so 'Patterns' also matches the My patterns pattern-category tab, which renders inside the Patterns panel whenever the site has user patterns — for example ones left behind by an earlier spec in the same run (deleteAllBlocks() also only runs once, in the global setup). The zoomed-out inserter opens straight to the Patterns tab, so expectActiveTab( 'Patterns' ) dies on a strict mode violation: with a user pattern present, the substring locator resolves to both tabs while the exact locator resolves to the one selected top-level tab. Fix: match tab names exactly.

Testing Instructions

1. npm run test:e2e -- test/e2e/specs/editor/various/font-appearance-control.spec.js test/e2e/specs/site-editor/site-editor-inserter.spec.js passes.
2. Font appearance, poisoned state: seed the closed sidebar an earlier test can leave behind — wp user meta update admin wp_persisted_preferences --format=json '{"core":{"isComplementaryAreaVisible":false},"_modified":"2026-08-03T00:00:00.000Z"}' — then drive the spec's steps manually (insert a paragraph, click Typography options): without this change the button never renders; with it the sidebar is opened explicitly. (Running the suite re-resets preferences in global setup, which is why mid-run state must be simulated.)
3. Inserter, poisoned state: create a user pattern (any reusable block), enter Zoom Out in the site editor and open the inserter: getByRole( 'tab', { name: 'Patterns' } ) now resolves to two tabs (Patterns, My patterns) which is the CI strict mode violation, while the exact-match locator used by this change resolves to the single selected tab.

AI usage disclosure: investigation and fixes drafted with AI assistance and reviewed by me.

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Co-authored-by: jorgefilipecosta <jorgefilipecosta@git.wordpress.org>

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