fix: prevent table row drag from moving an extra adjacent row

[LimChaeJune]

Summary

Fixes a bug where dragging a single table row could move an extra adjacent row when the drop lands outside .bn-block-group (e.g. into the side menu gutter). Closes #2691.

Rationale

SideMenuView.dispatchSyntheticEvent re-dispatches drop events as synthetic so ProseMirror can handle drops that fall outside the editor bounds. Both SideMenuView and TableHandlesView listen for drop on pmView.root. SideMenuView's handlers already guard against the synthetic event, but TableHandlesView.dropHandler does not — so a single user gesture invokes dropHandler twice (once for the synthetic, once for the original). Between the two calls, ProseMirror commits the row move and refreshes state.block, causing the second call to drag the now-shifted neighbor along with the original target.

The fix clears state.draggingState once dropHandler has the values it needs, making the handler idempotent. This avoids leaking knowledge of SideMenuView's synthetic-event convention into TableHandlesView and protects against any future path that re-enters dropHandler for the same gesture.

Changes

• packages/core/src/extensions/TableHandles/TableHandles.ts: After destructuring draggingState from this.state, clear this.state.draggingState = undefined. The re-dispatched drop now short-circuits at the existing draggingState === undefined early return.
• tests/src/end-to-end/tables/tables.test.ts: Added a Playwright regression test that drags row 2 of a 5-row table onto the side-menu gutter (blockGroup.x - 50) and asserts the resulting row order.

Impact

• TableHandles row/column drag: Behavior unchanged for normal in-bounds drops. Out-of-bounds drops (side gutter, below table padding) now move only the dragged row instead of also dragging an adjacent one.
• dragEnd still sets draggingState = undefined, which is now a no-op after dropHandler ran but stays correct for drag cancellations that never reach dropHandler.

Testing

• Regression test: New Playwright test drags row 2 of a 5-row table onto the side-menu gutter and asserts the row order is ["R1", "R3", "R4", "R5", "R2"]. Fails without the fix with ["R1", "R4", "R5", "R2", "R3"] (the exact bug pattern from Table row drag moves two rows instead of one due to duplicate dropHandler invocation #2691). Passes on chromium and webkit; firefox is skipped following the existing dragdrop test convention.
• Manual: Verified the original repro in the BlockNote demo no longer triggers after the fix.

Screenshots/Video

Before

After

Checklist

• Code follows the project's coding standards.
• Unit tests covering the new feature have been added.
• All existing tests pass.
• The documentation has been updated to reflect the new feature

Additional Notes

the bug is intermittent in real use because it only triggers when the drop coordinate falls outside .bn-block-group. The regression test pins the drop to the side gutter to make this deterministic.

Summary by CodeRabbit

Bug Fixes

• Fixed table row drag-and-drop behavior to prevent unintended row movements during drag operations, ensuring only the selected row is repositioned as intended.
• Added regression test coverage to verify correct row drag behavior and confirm that only the intended row moves during drag operations.

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[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

Run ID: 5a124081-90ca-4dd7-a0c5-cf96e85a5346

📥 Commits

Reviewing files that changed from the base of the PR and between f6717b3 and 4cc161e.

📒 Files selected for processing (2)

• packages/core/src/extensions/TableHandles/TableHandles.ts
• tests/src/end-to-end/tables/tables.test.ts

---

📝 Walkthrough

Walkthrough

The PR fixes a bug where dragging a table row moved two rows instead of one. The dropHandler in TableHandles now clears draggingState early to prevent duplicate invocations from both synthetic and original drop events. A regression test verifies that only the dragged row moves.

Changes

Table Row Drag Fix

Layer / File(s)	Summary
State Clearing packages/core/src/extensions/TableHandles/TableHandles.ts	dropHandler now sets this.state.draggingState = undefined immediately after guard checks, before move logic executes, preventing duplicate handler invocations from re-dispatched synthetic drop events.
Regression Test tests/src/end-to-end/tables/tables.test.ts	New test "Row drag should move only the dragged row" (Firefox-skipped) replaces the editor with a 5-row × 1-column table, performs a row-handle drag-drop into the side-menu gutter, and asserts via DOM text that only the dragged row is repositioned (["R1", "R3", "R4", "R5", "R2"]).

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Suggested reviewers

• nperez0111

Poem

🐰 A row that danced with double boots,
Now settles in its proper spot—
One drag, one place, no phantom moves,
The test confirms what bugs have wrought! ✨

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title accurately describes the main fix: preventing duplicate row moves during table row drag operations.
Description check	✅ Passed	The PR description covers all required template sections with detailed rationale, changes, impact, testing, and screenshots demonstrating the fix.
Linked Issues check	✅ Passed	The PR directly addresses all coding requirements from issue #2691: preventing duplicate dropHandler invocations through idempotent handler design and adding a regression test.
Out of Scope Changes check	✅ Passed	All changes are directly scoped to fixing the duplicate row drag bug; no unrelated modifications were introduced.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

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commit: 4cc161e

[vercel]

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Project	Deployment	Actions	Updated (UTC)
blocknote	Ready	Preview	May 4, 2026 0:15am

[nperez0111]

Thanks for this @LimChaeJune this fixes the issue well!