fix(web): remove the header theme-toggle icon flicker on first load#153
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The toggle gated its icon on a `mounted` state and rendered an empty placeholder until the client mounted, because next-themes keeps the theme in localStorage where the server can't read it — so the icon popped in a beat after first paint. The selected theme is now mirrored to a cookie, read in the root layout, and seeded into the toggle so SSR and hydration draw the same icon with no mount gate, no flicker, and no hydration mismatch. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
🦋 Changeset detectedLatest commit: a106c32 The changes in this PR will be included in the next version bump. This PR includes changesets to release 1 package
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Codecov Report✅ All modified and coverable lines are covered by tests. Additional details and impacted files@@ Coverage Diff @@
## main #153 +/- ##
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Coverage 84.29% 84.29%
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Files 70 70
Lines 1248 1248
Branches 293 293
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Hits 1052 1052
Misses 119 119
Partials 77 77
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What
Remove the header theme-toggle icon flicker on first load.
Why
The toggle gated its icon on a
mountedstate and rendered an empty placeholder until the client mounted. next-themes keeps the theme in localStorage, which the server can't read, so the icon could not be server-rendered and popped in a beat after first paint. This is the standard next-themes anti-mismatch pattern, traded for a flicker.How
The selected theme is mirrored into a cookie whenever it changes, read in the root layout (a server component) via
cookies(), and seeded into the toggle through a smallInitialThemeProvider. SSR and the first client render now draw the same icon, so the mount gate is gone: no flicker and no hydration mismatch. The cookie and localStorage are kept in sync, and a returning user whose cookie was absent converges once on mount.Impact
@flemo/webpatch. No library change.Test plan
pnpm --filter @flemo/web typecheck lint buildgreen.Rollback
Revert the squash merge.