The browser reads document.title back with its whitespace stripped and
collapsed, so a title with two spaces in a row, a tab or a space at the
edge never reads back as written. useDocumentTitle put its title back on
every <head> mutation whenever the two differed, and its own write was
such a mutation: an endless loop that froze the tab at full CPU, for
example on opening a message whose subject has two spaces in a row. It
now also accepts what the browser read back after its own write.
The tab title was "<context> - <app>", so two mailboxes open side by side
read the same in the tab strip and in the browser's session-restore list.
It is now "<context> - <account> - <app>", the order Gmail and Outlook Web
use: browsers cut a long title from the end, so the part that changes comes
first and the app name last. There is no setting for it; the account is what
tells the tabs apart.
The formatting, and the mail view's choice of context (composer, then
message, then mailbox), live in lib/tab-title.ts with tests. The mail view
sets its title through useDocumentTitle(), which other surfaces can use too.
Next renders the root layout's metadata <title> again on every client-side
navigation, after the surface has mounted; the hook puts its title back when
that happens. Only the surface that set the title last does so, so two
titles never fight.
Refs #1159
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
dealerweb
Linus Rath
Oğuz YılmazandClaude Opus 5.5