feat: surface editor crashes natively and offer a reload

[dcalhoun]

What?

A crashed editor left Gutenberg's own error fallback on screen, and the user had no way back other than closing the post. GutenbergKit now covers the editor with a native notice and offers to reload.

Why?

Fix the second half of CMM-2008. #638 and #640 stop the bridge failures; this makes the resulting state legible and recoverable.

Gutenberg's fallback is built for the desktop editor and neither of its actions helps on a phone:

• "Copy contents" reads the post through getEditedPostContent() at click time, but the boundary sits above EditorProvider, whose unmount runs setEditedPost( null, null ). It always copies an empty string.
• "Copy error" hands the user a stack trace.

GutenbergKit already owns the equivalent UI for the states either side of this one — displayError / EditorErrorView for load failures, progress and spinner views for loading. GutenbergView's own documentation states the contract: "This view manages its own loading UI internally… Consumers do not need to implement loading UI." A crash is the same kind of state, so it belongs here rather than being rebuilt in every host.

Native rather than web, specifically: the web fallback is rendered by a React tree that just crashed, and anything built there has to survive the same unmount that broke the copy button. The native layer is healthy by definition and, after #638/#640, knows authoritatively.

How?

• iOS — ContentUnavailableView covering the editor, matching displayError, plus a public reloadEditor().
• Android — the same, reusing EditorErrorView, which gains an optional action button. reloadEditor() clears didFireEditorLoaded so the reloaded editor re-announces itself, and returns to the spinner until it does.
• JS — drop canCopyContent, removing the button that never worked.

Reload restores content from the host's editorDidRequestLatestContent / LatestContentProvider, so work up to the host's last autosave survives. Readiness is restored only when onEditorLoaded arrives again, so bridge calls stay refused until the editor is genuinely usable.

The description makes no promise about saved work

The copy reads "Reload the editor to continue editing." and deliberately stops there.

Whether anything was persisted is entirely the host's business. WordPress-iOS mirrors content to Core Data about a second after typing stops; CustomPostEditorViewController and the comment editor have no mirror at all and read content only when the user saves. GutenbergKit cannot tell which it is embedded in, so it must not claim the work is safe — on the unmirrored hosts that would be false, and would encourage someone to close a post and lose the lot.

Hosts that do mirror content should override editorCrashedDescription (iOS) / gbk_editor_crashed_description (Android) to say so. Both are annotated with why.

Reload is user-initiated, not automatic

An automatic retry would recover transient crashes invisibly, but risks a loop when the crash comes from the post's own content, and silently discards anything since the last autosave. An explicit button keeps the user in control and matches how displayError already behaves. Worth revisiting if telemetry shows most crashes are transient.

Note for review

GutenbergViewTest drops manifest = Config.NONE and the module opts into isIncludeAndroidResources, because Robolectric needs the merged resources to construct the error view now that it reads a string resource. The pre-existing HttpServerAuthenticationTests failures are unrelated — they fail identically on clean trunk here (a local proxy returning 407).

Testing Instructions

Trip the boundary from the web inspector (iOS) or chrome://inspect (Android), on a post with at least one block:

const be = wp.data.select( 'core/block-editor' );
be.getBlockOrder = () => { throw new Error( 'repro' ); };
wp.data.dispatch( 'core/block-editor' ).updateSettings( {} );

1. Confirm the editor is covered by "The editor stopped working" with a Reload Editor button — not Gutenberg's "Copy contents / Copy error" notice.
2. Tap Reload Editor. The editor reloads and content up to the host's last autosave is intact.
3. Confirm editing works normally after the reload — typing, undo/redo, block insertion, save.
4. Without triggering a crash, confirm loading, load failures, and normal editing are unchanged.

Unit tests: ./android/gradlew -p ./android :Gutenberg:testDebugUnitTest --tests "org.wordpress.gutenberg.GutenbergViewTest"

Accessibility Testing Instructions

The crash view is standard ContentUnavailableView / TextView + Button content, so VoiceOver and TalkBack read the title, description, and button label, and the button is reachable by keyboard and switch control. Worth confirming the reload button is announced with its label and that focus moves into the notice when it appears.

Screenshots or screencast

To add — before/after of the crash state on both platforms.

🤖 Generated with Claude Code

https://claude.ai/code/session_01VuxMbKtUsaUF8nUVgKdxwK

[wpmobilebot]

XCFramework Build

This PR's XCFramework is available for testing. Add the following to your Package.swift:

.package(url: "https://github.com/wordpress-mobile/GutenbergKit", branch: "pr-build/642")

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