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Slate v2 pathRef must invalidate on replace

docs/solutions/logic-errors/2026-04-08-slate-v2-pathref-must-invalidate-on-replace.md

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Slate v2 pathRef must invalidate on replace

Problem

pathRef was implemented on top of runtime IDs, which works well for moves and sibling shifts. But explicit snapshot replacement reuses path-based IDs, so the ref could silently point at unrelated replacement content.

Symptoms

  • a pathRef created for an old node still returned [0] after Editor.replace(...)
  • the behavior looked superficially stable while actually referring to a new node

What Didn't Work

  • tracking only runtimeId -> current path
  • assuming replace would naturally invalidate refs the same way move/remove do

Solution

Track a replace epoch in core and bind each pathRef to the epoch it was created in:

ts
const replaceEpoch = getCurrentReplaceEpoch(editor)

get current() {
  return detached || getCurrentReplaceEpoch(editor) !== replaceEpoch
    ? null
    : cloneNullablePath(getCurrentPathForRuntimeId(editor, runtimeId))
}

Increment the epoch only when an explicit snapshot replacement survives the transaction and publishes.

Why This Works

Moves and sibling shifts preserve logical node identity, so runtime IDs are the right anchor there. Explicit replace is a different boundary: the old document identity is gone. The replace epoch stops runtime-id reuse from masquerading as stable ref identity.

Prevention

  • treat replace as an identity reset, not just another tree mutation
  • when building ref helpers on runtime IDs, define the invalidation boundary up front
  • test ref behavior across move, remove, and replace, not just one of them