Keep unsaved Scratch work when the locale changes

[jamiebenstead]

closes https://github.com/RaspberryPiFoundation/digital-editor-issues/issues/1804

• Don't reload the Scratch project when the locale changes, because the project's unsaved work only exists inside the Scratch iframe.
• Keep the Scratch iframe loaded and send it the new locale instead.
• The Scratch iframe switches language in place, the same way Scratch's own language menu does.

[Copilot]

Copilot review overview

🟡 Changes recommended

Locale updates can be lost during iframe startup and leave request metadata using the previous locale.

Review effort: Balanced
Findings: 2

Open (2)

• Refresh X-Project-Locale metadata when changing locale · New
• Preserve locale changes during frame startup · New

What changed in this PR

Keeps unsaved Scratch iframe work intact when changing locale.

Changes:

• Prevents Scratch project reloads on locale changes.
• Sends locale updates to the existing iframe.
• Applies locale changes through Scratch GUI state.

File	Description
src/​hooks/​useProject.js	Prevents matching Scratch projects from reloading.
src/​hooks/​useProject.test.jsx	Tests Scratch project preservation.
src/​components/​Editor/​Project/​ScratchContainer.jsx	Sends locale updates without changing iframe URL.
src/​components/​Editor/​Project/​ScratchContainer.test.jsx	Verifies in-place locale updates.
apps/​scratch-frame/​src/​ScratchIntegrationHOC.jsx	Handles locale update messages.
apps/​scratch-frame/​src/​ScratchIntegrationHOC.test.jsx	Tests Scratch locale selection.

---

💡 Add a code-review agent skill or configure MCP servers for context-aware, tailored reviews. Learn more in the docs.

[Copilot]

Copilot review overview

🟡 Changes recommended

New-project navigation can use a stale project locale, and in-place language changes leave the iframe document language outdated.

Review effort: Balanced
Findings: 1

Open (1)

• Update iframe document language after locale changes · New

Resolved since last review (2)

• Preserve locale changes during frame startup
• Refresh X-Project-Locale metadata when changing locale

Previously missed (1)

In code that hasn't changed since last review

Refresh initial locale when iframe project changes

src/​components/​Editor/​Project/​ScratchContainer.jsx:48

initialLocale is pinned for the entire ScratchContainer lifetime, but this component stays mounted when one Scratch project is replaced by another. If the user changes language on project A and then opens project B, iframeProjectIdentifier changes while this value remains A's original locale, so the new iframe loads B's wrong localized project copy even though its UI is switched to the latest language. Keep the locale pinned only while the iframe project identifier is unchanged, and refresh it when a genuinely new iframe project is loaded.

[cocomarine]

⭐