fix: Prevent draft autosave state loss and editor overwriting

[orrc]

What does this PR do?

Fixes a cluster of related draft/autosave bugs in the admin editor for revision-enabled content.

This started from a verified repro on a published post:

• Editing "Content" and waiting for autosave appeared to work locally
• However, the autosave PUT response returned stale content
• A redundant follow-up GET request also returned stale base-row data
• Any edits to "Excerpt" were overwritten immediately after autosave
• After page refresh, the rich text editor appeared to lose the saved draft content even though the draft revision had actually been updated

Root cause turned out to be three separate compounding issues:

1. packages/core

   • revision-backed autosave wrote the draft correctly, but the PUT response was built from the stale base content row instead of the active draft revision

2. packages/admin

   • autosave handling in the edit page was not safe for revision-backed content
   • initially this caused a redundant post-autosave GET
   • more importantly, an autosave response could overwrite newer local edits if the user kept typing while the request was in flight

3. packages/admin

   • PortableTextEditor treated its initial value as mount-only state
   • when parent state changed after mount (for example after draft load, reload, or reset), the live TipTap editor did not reconcile to that new value

What this PR changes:

• Returns the correct, draft-aware data from autosave responses for revision-backed content.
• Removes the redundant post-autosave GET call from the client (as the necessary data is in the autosave response).
• Only applies an autosave response back into edit-page queries when the local editor state still matches the snapshot that was sent.
• Reconciles post-mount external value changes into the rich-text editor.

Relates to #272, but extends beyond that admin-only reset loop to also fix the stale revision-backed autosave response, the redundant post-autosave refetch, and the in-flight autosave overwrite edge case.

Type of change

• Bug fix
• Feature (requires approved Discussion)
• Refactor (no behavior change)
• Documentation
• Performance improvement
• Tests
• Chore (dependencies, CI, tooling)

Checklist

• I have read CONTRIBUTING.md
• pnpm typecheck passes
• pnpm --silent lint:json | jq '.diagnostics | length' returns 0
• pnpm test passes (or targeted tests for my change)
• pnpm format has been run
• I have added/updated tests for my changes (if applicable)
• I have added a changeset (if this PR changes a published package)
• New features link to an approved Discussion: https://github.com/emdash-cms/emdash/discussions/...

AI-generated code disclosure

• This PR includes AI-generated code
  But with a lot of prior verification, including with Playwright, and a lot of discussion on the solution

[changeset-bot]

⚠️ No Changeset found

Latest commit: c3020e0

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[github-actions]

All contributors have signed the CLA ✍️ ✅
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[orrc]

I have read the CLA Document and I hereby sign the CLA

[github-actions]

Overlapping PRs

This PR modifies files that are also changed by other open PRs:

• feat(admin): add Lingui i18n infrastructure #234 (3 shared files)
• feat(admin): add Taxonomy Types management page #213 (3 shared files)
• Store CSS classes, make editor toolbar extensible #143 (4 shared files)

This may cause merge conflicts or duplicated work. A maintainer will coordinate.

[ascorbic]

Hey, could you resolve the conflicts and add a changeset?

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commit: c3020e0

[ascorbic]

Thanks for the thorough work here. Since this was opened, #302 has been merged, which fixes the admin-side form reset (replacing invalidateQueries with setQueryData cache patching). However, this PR contains two fixes that #302 doesn't address and that are still worth landing:

1. Server-side stale revision response – mergeDraftRevisionIntoItem in emdash-runtime.ts. The autosave PUT for revision-backed content was returning stale base-row data instead of draft revision data.
2. PortableText reconciliation – TipTap not updating when its value prop changes after mount.

Would you be up for extracting those into one or two smaller PRs? Both would be good to land, but the server-side fix in particular is self-contained and should be straightforward to land on its own.

[github-actions]

This PR has been inactive for 14 days. It will be closed automatically in 7 days if there is no further activity.

If you're still working on this, please push an update or leave a comment.

[emdashbot]

This is a well-targeted, sound bug-fix PR. The approach—fixing the server-side autosave response for revision-backed collections, eliminating the redundant post-autosave refetch, guarding against stale-response overwrites with a snapshot comparison, and making the rich-text editor reconcile post-mount value changes—is exactly what the three compounding issues call for.

I traced the full flow in ContentEditPage → ContentEditor → PortableTextEditor and in the runtime handleContentUpdate path. The server-side merge of draft revision data into the response item is done correctly and _rev remains valid because encodeRev only uses version and updatedAt, which are untouched. The client-side snapshot guard (currentDataRef.current === autosaveSnapshot) works because serializeEditorState returns a string and === compares primitive values. The cache update helper applyAutosaveResultToQueryCache updates both the content item and the draft revision query with matching keys, so the merged item memo stays consistent without a full invalidation. TipTap reconciliation uses a stable Portable-Text signature (stripping auto-generated _keys) to avoid false-positive setContent calls, and emitUpdate: false prevents onChange loops.

Tests cover all three fixes. I found no logic bugs, security issues, or regressions in the changed code.

The only remaining issue is a missing changeset. Both packages/core and packages/admin are published packages, and AGENTS.md requires a changeset for any behavior change in a published package. The PR checklist even leaves this box unchecked.

[emdashbot]

[needs fixing] This PR changes the behavior of the published emdash package (the autosave response now returns merged draft-revision data) and of @emdash-cms/admin (new autosave cache-updating logic and editor reconciliation). AGENTS.md requires a changeset for any published-package behavior change:

If your change affects a published package's behavior, add a changeset. Without one, the change won't trigger a package release.

Please add a changeset with pnpm changeset, edit it to cover both emdash (patch) and @emdash-cms/admin (patch), and describe the user-facing fixes.