About this block

Locale Fallback Chain shows the order a locale resolves through when a string is missing. Three rows list the chain for French (Canada), each with a drag handle, its native name and tag, a coverage Progress bar, the translated count, and a role Badge reading Requested, Fallback, or Source. Below the list a resolution trace follows one key, checkout.summary.title, as it misses fr-CA, is served by fr-FR, and skips en-US, each step marked with a Miss, Served, or Skipped Badge and an icon.

The chain array is ordered and each row reads its position from the index, so reordering the array reorders the resolution. A traceBadge record maps each result to its label and variant, and the footer states the two rules that matter, reordering applies on the next publish and a key missing everywhere renders its key name in development.

When to use

Reach for this block on the locale settings page when a regional variant leans on a parent locale and the team needs to see exactly what a user gets for a missing string. Wire the chain to your resolution config and the trace to a real lookup so the served row is not a guess.

A natural flow around it on an Application Pro page:

Before

• Locale coverage matrix
• Translation progress card

After

• Translation table
• Settings shell

What you can display

One strong use is the fallback order for a regional variant. Other fallback chain shapes:

• Deep chain. A four or five locale chain when a dialect falls back through a region to a base language.
• Per key trace. The trace pinned to a single key the support team flagged as showing the wrong locale.
• Coverage gate view. The chain sorted by coverage so the weakest fallback in the order stands out.

Tip: read the trace top to bottom, the first Served row is exactly what a user sees, everything below it never runs.