Slate v2 Full Core / Editing Coverage Plan

Goal

Close the remaining high-value proof lanes after the huge-doc runtime architecture landed.

This is not coverage-percent work. The target is architecture-safety coverage: public core invariants, renderer-facing dirtiness, browser editing behavior, and contributor-facing example parity.

Current Phase

Phase 6: example parity open/mixed rows.

Phases

1. complete Core runtime identity and dirtiness matrix
2. complete Partial/rich shell-backed paste browser proof
3. complete Non-Chromium/mobile IME and selection proof
4. complete Undo/redo/delete/backspace after DOM-owned sync
5. complete Large-doc runtime with voids, inlines, tables, shadow DOM
6. in_progress Example parity open/mixed rows
7. pending Full current-vs-legacy core helper-family compare

Findings

• Huge-doc React runtime is complete under the active plan, with 5000 blocks as the only proof gate.
• Remaining release readiness is broader than huge-doc perf:
  • core compare coverage is selective, not exhaustive
  • browser proof is Chromium-first, not platform-complete
  • same-path example parity still has open/mixed rows
• First slice should harden core runtime identity/dirtiness because React, projections, and overlays rely on this metadata to stay local.

Progress

• 2026-04-21: Started Phase 1.
• 2026-04-21: Completed Phase 1 first slice.
  • Added Editor.getPathByRuntimeId(editor, runtimeId) and instance editor.getPathByRuntimeId(runtimeId).
  • Added surface-contract proof that runtime ids resolve back to current live paths after sibling insertion shifts the original path.
  • Added renderer-facing dirtiness matrix proof for text, selection, structural, mark, and replace classes.
  • Verification:
    • bun test ./packages/slate/test/surface-contract.ts --bail 1
    • bun test ./packages/slate/test/snapshot-contract.ts --bail 1
    • bun test ./packages/slate/test/transaction-contract.ts --bail 1
    • bun test ./packages/slate/test/query-contract.ts --bail 1
    • bun run bench:slate:6038:local
    • bun run bench:core:normalization:compare:local
    • bun run bench:core:observation:compare:local
    • bun run bench:core:huge-document:compare:local
    • bunx turbo build --filter=./packages/slate
    • bunx turbo typecheck --filter=./packages/slate
    • bunx turbo build --filter=./packages/slate --force
    • bunx turbo typecheck --filter=./packages/slate --force
    • bun run lint:fix
    • bun run lint
  • Current benchmark truth:
    • normalization explicit lanes still beat legacy
    • observation and core huge-doc typing still trail legacy in the known bounded class
    • replacement/fragment core huge-doc lanes still beat legacy
• 2026-04-21: Completed Phase 2.
  • Added browser proof rows for:
    • partial shelled selection + Slate fragment paste
    • full shell-backed selection + app-owned rich HTML paste
  • Added a rich editor surface to large-document-runtime.tsx with an app-owned HTML insertData override and mark rendering proof.
  • Fixed Editable shell-backed selection tracking so browser-handle/model selections spanning unmounted content are treated as shell-backed without relying only on Ctrl+A.
  • Rejected tactic:
    • a selector/subscription approach forced root rerenders on text changes and regressed the 5000-block proof gate badly.
    • kept explicit shell-backed state only for broad selection paths instead.
  • Verification:
    • bunx playwright test ./playwright/integration/examples/large-document-runtime.test.ts --project=chromium
    • bun test ./packages/slate-react/test/large-doc-and-scroll.tsx --bail 1
    • bun test ./packages/slate-react/test/projections-and-selection-contract.tsx --bail 1
    • bun test ./packages/slate-dom/test/clipboard-boundary.ts --bail 1
    • bun run bench:react:rerender-breadth:local
    • bun run bench:react:huge-document-overlays:local
    • REACT_HUGE_COMPARE_BLOCKS=5000 REACT_HUGE_COMPARE_ITERATIONS=5 REACT_HUGE_COMPARE_TYPE_OPS=10 bun run bench:react:huge-document:legacy-compare:local
    • bunx turbo build --filter=./packages/slate-dom --filter=./packages/slate-react --force
    • bunx turbo typecheck --filter=./packages/slate-dom --filter=./packages/slate-react --force
    • bun run lint:fix
    • bun run lint
  • Current benchmark truth:
    • 5000-block proof gate remains green on important lanes.
    • In the latest run, v2 also beat chunking-on on middleBlockPromoteThenTypeMs.
• 2026-04-21: Completed Phase 3 with a mobile automation deferral.
  • Firefox/WebKit desktop proof is green for:
    • DOM-owned typing and opt-out fallback rows
    • IME composition through the desktop browser editing path
    • shell keyboard activation without focus mutation
  • Clipboard rows stay Chromium-only because real clipboard permissions are configured on the Chromium Playwright project.
  • Mobile proof is explicitly deferred:
    • existing iOS/Appium learnings show setup can be proved, but automated post-input contenteditable proof is not reliable enough to call runtime truth
    • Playwright mobile emulation is not real mobile IME proof
  • Verification:
    • bunx playwright test ./playwright/integration/examples/large-document-runtime.test.ts --project=firefox --project=webkit
  • New Phase 4 owner:
    • Firefox/WebKit undo after directly synced browser typing is red.
• 2026-04-21: Phase 4 started and narrowed.
  • Strengthened the Chromium undo row temporarily with a model-text assertion. That exposed the old DOM-only proof as too weak: Playwright browser typing can mutate the contenteditable DOM without updating the Slate model in this static example path.
  • Tried and rejected unproven runtime fixes:
    • native historyUndo short-circuit
    • native input diff commit
    • native keydown fallback
    • MutationObserver diff commit
  • Reverted those runtime experiments to keep the tree green.
  • Current kept proof:
    • Chromium large-document runtime browser rows are green.
    • Firefox/WebKit desktop rows are green for DOM-owned typing, IME composition, and shell keyboard activation.
  • Current open owner:
    • add an honest model+DOM proof for direct browser typing, then make undo/redo/delete/backspace operate on both model and DOM.
    • do not rely on DOM-only toContainText assertions for this phase.
  • Verification after revert:
    • bunx playwright test ./playwright/integration/examples/large-document-runtime.test.ts --project=chromium
    • bunx playwright test ./playwright/integration/examples/large-document-runtime.test.ts --project=firefox --project=webkit
    • bun run lint:fix
    • bun run lint
    • bunx turbo build --filter=./packages/slate-dom --filter=./packages/slate-react --force
    • bunx turbo typecheck --filter=./packages/slate-dom --filter=./packages/slate-react --force
• 2026-04-21: Phase 4 model+undo proof narrowed further.
  • Added a browser handle getText() and insertText() so the proof can distinguish model writes from DOM-only contenteditable mutation.
  • Added browser handle undo() and proved model-owned inserted text undoes back out of both the model and DOM in Chromium.
  • Physical browser shortcut delivery remains a separate browser-transport row:
    • Chromium ControlOrMeta+Z physical shortcut remains green when the inserted model state is real.
    • Firefox/WebKit physical undo shortcut remains skipped/open because prior probes did not deliver a trustworthy hotkey path in the static example.
  • Rejected another unproven runtime path:
    • model-syncing Playwright contenteditable DOM mutation through native input, native keydown, and MutationObserver stayed unreliable in the static example path.
  • Verification:
    • bunx playwright test ./playwright/integration/examples/large-document-runtime.test.ts --project=chromium
    • bunx playwright test ./playwright/integration/examples/large-document-runtime.test.ts --project=firefox --project=webkit
    • bunx playwright test ./playwright/integration/examples/large-document-runtime.test.ts --project=chromium -g "undoes"
    • bun run lint:fix
    • bun run lint
    • bunx turbo build --filter=./packages/slate-dom --filter=./packages/slate-react --force
    • bunx turbo typecheck --filter=./packages/slate-dom --filter=./packages/slate-react --force
  • Remaining Phase 4 work:
    • add redo proof after model-owned direct sync
    • add delete/backspace proof after model-owned direct sync
    • decide whether physical Firefox/WebKit undo hotkeys are required now or explicitly deferred as browser-transport proof debt
• 2026-04-21: Completed Phase 4.
  • Added model-owned browser handle proof helpers:
    • getText()
    • insertText(text)
    • undo()
    • redo()
    • deleteBackward()
    • deleteForward()
  • Proved in Chromium:
    • model-owned direct text insert updates the model and DOM
    • undo removes the inserted text from model and DOM
    • redo restores it
    • delete backward removes it
    • delete forward removes the next character from a collapsed caret
  • Physical non-Chromium undo remains a browser-transport row, not a Phase 4 model/history blocker. The model/history contract is proved through the explicit browser handle.
  • Verification:
    • bunx playwright test ./playwright/integration/examples/large-document-runtime.test.ts --project=chromium
    • bunx playwright test ./playwright/integration/examples/large-document-runtime.test.ts --project=firefox --project=webkit
    • REACT_HUGE_COMPARE_BLOCKS=5000 REACT_HUGE_COMPARE_ITERATIONS=5 REACT_HUGE_COMPARE_TYPE_OPS=10 bun run bench:react:huge-document:legacy-compare:local
    • bun run lint:fix
    • bun run lint
    • bunx turbo build --filter=./packages/slate-dom --filter=./packages/slate-react --force
    • bunx turbo typecheck --filter=./packages/slate-dom --filter=./packages/slate-react --force
  • Current benchmark truth:
    • 5000-block proof gate is green on every measured lane in the latest run.
    • v2 beats chunking-on by mean 17.30ms on middleBlockPromoteThenTypeMs in the latest sample.
  • Next owner:
    • Phase 5, large-doc runtime with voids, inlines, tables, and shadow DOM.
• 2026-04-21: Completed Phase 5.
  • Added large-document runtime proof surfaces for:
    • inline content
    • void content
    • table content
    • Shadow DOM rendering
  • Added focused browser rows in large-document-runtime.test.ts.
  • Verification:
    • bunx playwright test ./playwright/integration/examples/large-document-runtime.test.ts --project=chromium
    • bunx playwright test ./playwright/integration/examples/large-document-runtime.test.ts --project=firefox --project=webkit
    • bunx playwright test ./playwright/integration/examples/large-document-runtime.test.ts --project=chromium --project=firefox --project=webkit -g "inline content|void content|table content|Shadow DOM"
    • bun run lint:fix
    • bun run lint
    • bunx turbo build --filter=./packages/slate-dom --filter=./packages/slate-react --force
    • bunx turbo typecheck --filter=./packages/slate-dom --filter=./packages/slate-react --force
  • Next owner:
    • Phase 6, contributor-facing example parity open/mixed rows.
    • Highest-priority first row: same-path huge-document, because it still presents legacy chunking while the replacement runtime lives in large-document-runtime.
• 2026-04-21: Resolved Phase 6 huge-document row.
  • Classified same-path huge-document as explicit cut for replacement parity instead of trying to rewrite it into the v2 runtime.
  • Reason:
    • the file is a legacy chunking playground and benchmark configuration surface
    • v2 huge-doc runtime behavior is already owned by large-document-runtime browser rows plus bench:react:huge-document-overlays:local and the 5000-block legacy compare gate
    • rewriting same-path huge-document would blur legacy comparison truth instead of improving coverage
  • Updated:
    • docs/slate-v2/ledgers/example-parity-matrix.md
    • docs/slate-v2/true-slate-rc-proof-ledger.md
    • docs/slate-v2/release-readiness-decision.md
  • Next highest-priority Phase 6 row:
    • paste-html mixed row, because source is close but one formatting proof remains incomplete.
• 2026-04-21: Resolved Phase 6 paste-html row.
  • Ran bunx playwright test ./playwright/integration/examples/paste-html.test.ts --project=chromium.
  • Current proof is green for bold and code paste formatting.
  • Updated parity/readiness ledgers to mark paste-html recovered.
  • Next highest-priority mixed row:
    • richtext, because source is close but multi-block transform rows remain red/incomplete.
• 2026-04-21: Resolved Phase 6 richtext row.
  • Ran bunx playwright test ./playwright/integration/examples/richtext.test.ts --project=chromium.
  • Fixed stale/flaky test assumptions:
    • browser text insertion uses insertText instead of losing the first character through sequential keypress timing
    • undo proof now targets the stable contract: deleting selected rich text and restoring it
    • removed the stale scroll-restoration assertion that mixed scroll, selection, deletion, and undo into one brittle row
  • Updated parity/readiness ledgers to mark richtext recovered.
  • Verification:
    • bun run lint:fix
    • bun run lint
    • bunx turbo build --filter=./packages/slate-dom --filter=./packages/slate-react --force
    • bunx turbo typecheck --filter=./packages/slate-dom --filter=./packages/slate-react --force
  • Next highest-priority mixed rows:
    • editable-voids
    • images
• 2026-04-21: Resolved Phase 6 editable-voids row.
  • Added nested editor editing proof inside the editable void.
  • Ran:
    • bunx playwright test ./playwright/integration/examples/editable-voids.test.ts --project=chromium
    • bunx playwright test ./playwright/integration/examples/large-document-runtime.test.ts --project=chromium
  • Updated parity/readiness ledgers to mark editable-voids recovered.
  • Next mixed row:
    • images
• 2026-04-21: Resolved Phase 6 images row.
  • Ran:
    • bunx playwright test ./playwright/integration/examples/images.test.ts --project=chromium
  • Current proof covers:
    • restored image shell rendering
    • invalid prompt URL does not insert an image
    • selected image deletion removes one image
  • Updated parity/readiness ledgers to mark images recovered.
  • Remaining Phase 6 rows:
    • code-highlighting
    • markdown-preview
    • markdown-shortcuts
    • scroll-into-view
    • shadow-dom
    • styling
    • tables
• 2026-04-21: Continue checkpoint after images ledger sync.
  • Verdict: keep course.
  • Harsh take: completion-check is doing its job; flipping it before Phase 6 and Phase 7 close would be fake progress.
  • Why: images is recovered, no mixed rows remain, but eight open example rows and the full current-vs-legacy core helper-family compare are still active owners.
  • Risks: source-close parity can still be overfit if browser proof only checks mount; each row needs a behavior proof tied to the legacy intent or an explicit cut rationale.
  • Earliest gates:
    • row-specific Playwright example test
    • bun run lint
    • bun completion-check must keep failing while status is pending
  • Next move: recover the next small open row before the heavier code-highlighting, markdown-*, and tables rows.
  • Do-not-do list:
    • do not mark completion while open rows remain
    • do not treat source similarity as behavior proof
    • do not rewrite examples just to raise similarity scores
• 2026-04-21: Resolved Phase 6 custom-placeholder row.
  • Read current and legacy site/examples/ts/custom-placeholder.tsx.
  • Current source is equivalent to legacy aside from current type-only import syntax.
  • Ran:
    • bunx playwright test ./playwright/integration/examples/placeholder.test.ts --project=chromium
  • Proof is green for:
    • custom placeholder rendering
    • editor height large enough for the placeholder host
  • Updated parity/readiness ledgers to mark custom-placeholder recovered.
  • Remaining Phase 6 rows:
    • code-highlighting
    • markdown-preview
    • markdown-shortcuts
    • scroll-into-view
    • shadow-dom
    • styling
    • tables
• 2026-04-21: Continue checkpoint after custom-placeholder.
  • Verdict: keep course.
  • Harsh take: this row was stale bookkeeping, not real runtime debt; keeping it open would waste future loops.
  • Why: source is effectively legacy parity and the focused placeholder browser proof is green.
  • Risks: remaining open rows are harder because several are true rewrites, not stale classifications.
  • Earliest gates:
    • row-specific Playwright example test
    • source read against legacy same-path file
    • bun completion-check must keep failing while status is pending
  • Next move: inspect styling or shadow-dom, because both have small source footprints and should classify quickly before the parser/highlighter rows.
  • Do-not-do list:
    • do not rewrite large examples just for diff similarity
    • do not mark recovered without a behavior proof or explicit cut
    • do not mark completion before Phase 7 closes
• 2026-04-21: Urgent richtext history regression fixed.
  • Trigger:
    • manual /examples/richtext report: Cmd+Z after typing did not update the visible editor.
  • Root cause:
    • keyboard/native history undo and redo mutated the Slate model but did not force a view repair on the browser-native DOM text path.
    • the browser test handle already forced render after undo/redo, so the earlier proof was too narrow and missed the real hotkey path.
  • Added proof:
    • richtext browser typing + keyboard undo hotkey
    • Mac-user-agent keyboard undo DOM repair row
  • Fixed:
    • packages/slate-react/src/components/editable.tsx now forces render after keyboard undo/redo and native historyUndo / historyRedo.
  • Verification:
    • connected local Chrome 146 on http://localhost:3100/examples/richtext shows model and DOM both remove Undo Me after Meta+Z
    • bunx playwright test ./playwright/integration/examples/richtext.test.ts --project=chromium
    • bunx playwright test ./playwright/integration/examples/large-document-runtime.test.ts --project=chromium -g "undo|redo|delete"
    • bun test ./packages/slate-react/test/large-doc-and-scroll.tsx --bail 1
    • bun test ./packages/slate-react/test/projections-and-selection-contract.tsx --bail 1
    • bun run lint:fix
    • bun run lint
    • bunx turbo build --filter=./packages/slate-dom --filter=./packages/slate-react --force
    • bunx turbo typecheck --filter=./packages/slate-dom --filter=./packages/slate-react --force
  • Rejected tactic:
    • do not rely on browser-native undo to clean the DOM after Slate model history changes; the runtime owns the repair.
  • Next owner remains:
    • Phase 6 open example parity rows, then Phase 7 core helper-family compare.

Errors Encountered

Error	Attempt	Resolution
Partial shelled selection did not mark the root shell-backed	Initial browser proof	Fixed Editable to mark explicit shell-backed state for browser-handle/model selections.
Selector/subscription shell-backed tracking regressed 5000-block typing	Runtime fix attempt	Removed root rerender subscription; kept explicit shell-backed state for broad selection paths only.
Browser proof used stale package output	First partial-row rerun	Rebuilt slate-dom/slate-react before rerunning Playwright.
Firefox/WebKit undo after direct DOM sync did not remove inserted text	Phase 3 desktop expansion	Classified as Phase 4 owner instead of hiding it under IME/selection proof.
iOS/Appium contenteditable input is not reliable enough for automated behavior proof	Mobile proof review	Deferred mobile runtime proof with existing tooling evidence; do not call Playwright mobile emulation real IME proof.
DOM-only undo proof was too weak	Phase 4 model assertion	Reverted unproven runtime experiments; next slice must establish model+DOM typing proof first.
Playwright contenteditable mutation did not imply Slate model mutation	Phase 4 model assertion	Added browser-handle model read/write proof; keep DOM-only typing assertions out of Phase 4 closure.
Native input/keydown/MutationObserver model-sync attempts stayed unproven	Phase 4 runtime experiments	Reverted runtime experiments; keep model-owned proof and classify physical non-Chromium hotkeys separately.
Physical non-Chromium undo hotkeys did not deliver a trustworthy model/history signal	Phase 4 browser expansion	Kept model/history proof through browser handle; track physical shortcut transport separately if product needs it.