Write editor: add save/publish failure telemetry

[allilevine]

Proposed changes

Failed or stalled saves in the Write editor currently leave the Publish and Save buttons disabled with no error surfaced to the user and nothing recorded in Tracks, so the failures are invisible. This adds observability only — it does not change save behavior.

• savePost() is now a thin wrapper that reports throws during content preparation / tag resolution (today silent unhandled rejections) as wpcom_write_editor_save_failed with phase: "prepare", then re-throws so behavior is unchanged.
• The save-request catch fires the same event with phase: "save_request".
• A non-aborting 30s watchdog fires wpcom_write_editor_save_stalled for a request that never settles (e.g. one held open by a proxy, VPN, or ad blocker).
• Events carry error_code, HTTP error_status, a truncated error_message, and is_autosave / is_update / is_new_post to localize the root cause.

The behavioral fix (reset the saving flag on failure, add a request timeout, surface an error) is intentionally deferred to a follow-up so we can first confirm the actual failure mode from this data.

Related product discussion/links

• RSM-4323

Does this pull request change what data or activity we track or use?

Yes — it adds two new Tracks events for Write editor save diagnostics:

• wpcom_write_editor_save_failed — props: post_status, is_autosave, is_update, is_new_post, phase, error_code, error_status, error_message (truncated to 200 chars).
• wpcom_write_editor_save_stalled — props: post_status, is_autosave, is_update, is_new_post, elapsed_ms.

No post content or personally identifying information is recorded. The [Status] Needs Privacy Updates label should be applied.

Testing instructions

• Open the Write editor (wp-admin/admin.php?page=write), add a title and some body content.
• In DevTools, force a failing save: window.wp.apiFetch = () => Promise.reject( { code: 'rest_cannot_create', message: 'Simulated', data: { status: 503 } } );
• Clear the queue with window._tkq = [];, then click Publish.
• Confirm window._tkq contains a wpcom_write_editor_save_failed entry with phase: "save_request", error_code: "rest_cannot_create", error_status: 503. The existing error message and button re-enable behavior should be unchanged.
• For the prepare path: add a #tag line to the content and set window.wp.apiFetch = () => { throw new TypeError('boom'); }; — the event should fire with phase: "prepare".

[github-actions]

Are you an Automattician? Please test your changes on all WordPress.com environments to help mitigate accidental explosions.

• To test on WoA, go to the Plugins menu on a WoA dev site. Click on the "Upload" button and follow the upgrade flow to be able to upload, install, and activate the Jetpack Beta plugin. Once the plugin is active, go to Jetpack > Jetpack Beta, select your plugin (WordPress.com Site Helper), and enable the add/write-editor-save-failure-telemetry branch.
• To test on Simple, run the following command on your sandbox:

bin/jetpack-downloader test jetpack-mu-wpcom-plugin add/write-editor-save-failure-telemetry

Interested in more tips and information?

• In your local development environment, use the jetpack rsync command to sync your changes to a WoA dev blog.
• Read more about our development workflow here: PCYsg-eg0-p2
• Figure out when your changes will be shipped to customers here: PCYsg-eg5-p2

[github-actions]

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[jp-launch-control]

Code Coverage Summary

Coverage changed in 1 file.

File	Coverage	Δ%	Δ Uncovered
projects/packages/jetpack-mu-wpcom/src/features/write/view.js	0/6560 (0.00%)	0.00%	138 💔

Full summary · PHP report · JS report

_{Coverage check overridden by I don't care about code coverage for this PR Use this label to ignore the check for insufficient code coveage. .}