Slate v2 delete-text.ts Post-RC Stabilization Plan

Purpose

Stabilize and simplify delete-text.ts after RC recovery work.

This is a structure plan, not a semantics plan.

The goal is:

• keep current green behavior
• reduce local policy sprawl
• make future delete work less likely to reopen legacy recovery debt

Current Read

The file is functionally green and structurally ugly.

Current evidence already banked:

• pnpm --filter slate test
• SLATE_RUN_LEGACY_TRANSFORM_AUDIT=1 pnpm exec mocha --require ./config/babel/register.cjs ./packages/slate/test/legacy-transforms-fixtures.ts
• pnpm exec turbo build --filter=./packages/slate --filter=./packages/slate-history
• pnpm exec turbo typecheck --filter=./packages/slate --filter=./packages/slate-history
• pnpm lint:fix

Current reality:

• current slate suite is green
• legacy delete transform rows are green
• the file still mixes too many concerns in one routine:
  • target coercion
  • start/end delete edges
  • covered-node removal
  • cross-block merge policy
  • empty-structure cleanup
  • preserved empty-start restoration
  • final caret normalization

Non-Goals

This plan does not do any of these:

• widen or narrow the public delete API
• change legacy recovery scope
• redesign the transaction engine
• chase delete perf without evidence
• reopen already-closed delete semantics

Freeze Rule

Before any refactor step:

1. treat behavior as frozen
2. do not add new delete recovery
3. do not change proof expectations unless the runtime was already wrong

Lock set:

• pnpm --filter slate test
• legacy delete transform rows in legacy-transforms-fixtures.ts

Refactor Target Shape

Turn one large routine into one coordinator plus four private phases.

1. resolveDeleteTarget(...)

Own:

• point/range/path coercion
• collapsed-selection expansion
• void and elementReadOnly nudging
• hanging and unhang behavior

It should return one explicit internal object instead of mutating ad hoc locals.

2. removeDeleteContents(...)

Own:

• start-edge text removal
• covered-node collection and removal
• end-edge text removal

It should also return the minimal facts later phases need:

• surviving refs or points
• removed text
• whether interior element siblings were fully removed

3. reconcileDeleteStructure(...)

Own:

• cross-block merge behavior
• empty-artifact cleanup
• preserved empty-start block restoration
• optional adjacent text merge

This is where the policy split must become explicit:

• generic runtime cleanup
• legacy-compat recovery exceptions

4. resolveDeleteSelection(...)

Own:

• collapsed target choice
• caret normalization
• final set_selection

This is where forward/reverse inline spacer rules belong. They should not stay smeared across content-removal or structure-reconcile code.

Explicit Internal Control Object

Build one small internal plan object and pass it through the helpers.

Minimum fields:

• start
• end
• isSingleText
• isAcrossBlocks
• preserveEndBlock
• preserveEmptyStartBlockPath
• removedInteriorElementSiblingStructure
• startNonEditable
• endNonEditable

Rule:

• compute once
• pass forward
• stop recomputing the same meaning in multiple branches

Mandatory Helper Extractions

These should exist as private helpers, not repeated local policy blobs:

1. adjacent text merge predicate
2. empty-structure cleanup
3. preserved empty-start block restoration
4. “keep split text after fully removed interior element sibling” decision
5. final inline-boundary caret normalization

Compatibility Rule

Legacy recovery rules are allowed to survive, but they must be named as such.

Examples:

• shouldPreserveEmptyStartBlockForHangingRange(...)
• shouldKeepSplitTextAfterInteriorElementRemoval(...)

Bad shape:

• unnamed special cases hidden in branch order
• repeated if ladders that encode the same policy three times

Execution Order

Phase 0. Lock and Snapshot

• rerun the lock set
• record current green state

Phase 1. Extract the control object

• no behavior changes
• only move derived booleans and core paths into one named object

Phase 2. Extract target resolution

• move all coercion/nudge logic into resolveDeleteTarget(...)
• keep output byte-for-byte equivalent

Phase 3. Extract content removal

• move start-edge, interior-node, and end-edge removal into removeDeleteContents(...)
• keep refs and removed-text bookkeeping intact

Phase 4. Extract structure reconciliation

• move merge/cleanup/preserve logic into reconcileDeleteStructure(...)
• do not change any current cleanup decision until the helper boundary is proven

Phase 5. Extract selection resolution

• move final caret normalization and set_selection into resolveDeleteSelection(...)
• make the reverse/forward boundary cases readable and isolated

Phase 6. Trim duplicate policy

• remove repeated reinsertion and merge checks
• keep one authoritative place for each decision

Perf Rule

Do not optimize blindly.

After the structural refactor, measure only these three delete lanes:

1. interior element range delete
2. cross-block join delete
3. large hanging multi-block delete

Decision rule:

• if numbers stay flat, stop
• if numbers improve, bank it
• if numbers regress materially, revert or refine before keeping the refactor

Verification

Required after each meaningful phase:

• focused delete proof rows

Required at the end:

• pnpm exec turbo build --filter=./packages/slate --filter=./packages/slate-history
• pnpm exec turbo typecheck --filter=./packages/slate --filter=./packages/slate-history
• pnpm lint:fix
• pnpm --filter slate test
• SLATE_RUN_LEGACY_TRANSFORM_AUDIT=1 pnpm exec mocha --require ./config/babel/register.cjs ./packages/slate/test/legacy-transforms-fixtures.ts

Stop Conditions

Stop the refactor immediately if any of these happens:

• current slate suite reopens
• legacy delete rows reopen
• a helper extraction forces new public semantics
• the file starts getting longer instead of simpler

Success Criteria

This plan is complete when:

1. behavior is still green
2. delete-text.ts is split into named local phases
3. duplicated delete policy is reduced
4. compatibility rules are explicit instead of hidden
5. the three delete perf lanes do not regress materially

Blunt Read

This should be done after RC, not before.

The current file is ugly but green. That is acceptable for RC.

This plan exists so the team does not confuse “green” with “finished”.