Add support for locale_behavior: "respect_accept_language"

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Ory Network Project

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Describe your problem

Currently, it seems like this mode is not supported, since there are no references to the "accept-language" header in the library.

In fact, it is not the key: project.default_locale which is used (as the name would perhaps suggest), but the intl.locale config key https://github.com/ory/elements/blob/795b1bda1f7236874fb7686f5fbf51237ff290a1/packages/elements-react/src/context/provider.tsx#L83.

Describe your ideal solution

I would expect the behaviour of the default OryProvider to interpret the "accept-language" header in "respect_accept_language" mode, and use that as the default application language, unless otherwise overridden in the config object.

I imagine that this would entail adding another function to "utils" which parses the header and possibly cross-references it with the project.enabled_locales array from config. Once this approach is approved, I'd be happy to open a PR.

Workarounds or alternatives

I was looking at using window.navigator.language as an alternative but this would mean that the config object would need to be rendered client-side.

Version

main 795b1bda1f7236874fb7686f5fbf51237ff290a1

Additional Context

No response

Start in packages/elements-react/src/context/provider.tsx around the intl.locale configuration and inspect the existing utils area for locale handling. Trace how the default OryProvider receives configuration, then define how accept-language should be parsed and matched against project.enabled_locales. Done means respect_accept_language selects that locale by default while an explicit config value still overrides it.