Slate v2 Non-Virtualized Performance Ralplan

Date: 2026-05-11

Status: done

Owner: slate-ralplan

Completion: active goal state

Verdict

No, not absolute best yet.

Slate v2 has the right performance architecture and the default non-virtualized auto path is now strong enough to keep. Do not rewrite the kernel. Do not revive legacy child-count chunking as the main story. Do not promote virtualization; it stays paused / experimental.

The hard truth:

• default auto beats legacy chunking-on on the fresh 5,000-block current-vs-legacy means for the main direct compare lanes;
• rerender breadth is excellent and no longer the primary blocker;
• explicit shell is not the best non-virtualized answer for the current steady selection/promote lanes;
• raw staged / DOM-present still has middle-selection and promote tails that are not clean enough to call field-best;
• current huge-document proof is still mostly jsdom/direct-model proof, not browser INP, trace, layout/paint, native clipboard, mobile, IME, or real Safari proof;
• the huge-document compare still emits mean/median/min/max but not p75/p95/p99, so "absolute best" would be bullshit until the artifact quality catches up.

Current answer:

Best current default architecture: yes. Absolute best non-virtualized performance proof: no. Next work: harden benchmark artifacts, add real browser trace/interaction proof, then fix the staged selection/promote tails.

Intent Boundary

Current Source Read

Fresh Benchmark Evidence

All commands ran from /Users/zbeyens/git/slate-v2.

Rerender Breadth

Command:

bun run bench:react:rerender-breadth:local

Result: pass.

Key rows:

Conclusion: React invalidation breadth is not the remaining P0. Stop blaming "rerenders" generically.

Default And Staged Direct Compare

Command:

REACT_HUGE_COMPARE_SKIP_BUILD=1 \
REACT_HUGE_COMPARE_DISPOSE_DELAY_MS=0 \
REACT_HUGE_COMPARE_SURFACES=v2DefaultRenderAuto,v2DomPresent \
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

Result: pass.

v2DefaultRenderAuto versus legacy chunking-on:

v2DomPresent / staged versus legacy chunking-on:

Conclusion: default auto is green enough to keep. Staged / DOM-present is not clean enough to claim "absolute best" because the middle select/promote lanes still lose to chunking-on.

Split Selection Direct Compare

Command:

REACT_HUGE_COMPARE_SKIP_BUILD=1 \
REACT_HUGE_COMPARE_DISPOSE_DELAY_MS=0 \
REACT_HUGE_COMPARE_SPLIT_SELECTION=1 \
REACT_HUGE_COMPARE_SURFACES=v2DefaultRenderAuto,v2DomPresent \
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

Result: pass.

Important owner split:

The split run also exposed outlier noise: staged startBlockTypeAfterSelectMs had samples at 287.26ms and 312.95ms even though its combined startBlockSelectThenTypeMs lane stayed green. That is exactly why this plan requires p95/p99 artifacts and trace tags before any stronger claim.

Explicit Shell Direct Compare

Command:

REACT_HUGE_COMPARE_SKIP_BUILD=1 \
REACT_HUGE_COMPARE_DISPOSE_DELAY_MS=0 \
REACT_HUGE_COMPARE_SURFACES=v2ShellExplicitRadius0,v2ShellExplicitRadius1 \
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

Result: pass.

Shell radius 0 versus legacy chunking-on:

Shell radius 1 versus legacy chunking-on:

Conclusion: shell is an explicit stress/degradation mode. It is not the best non-virtualized default, and radius 1 cannot be defended as a pure performance default from these fresh rows. If radius 1 stays, defend it as editing-corridor UX, not raw speed.

Scorecard

Planning gate score: 0.94.

Current performance-confidence score: 0.91.

This plan can close. The performance program cannot.

Keep

Rewrite Or Tighten

Cut

Execution Plan For Ralph

Slice 1: Benchmark Artifact Hardening

Owner:

• .tmp/slate-v2/scripts/benchmarks/browser/react/huge-document-legacy-compare.mjs
• .tmp/slate-v2/scripts/benchmarks/shared/stats.mjs
• .tmp/slate-v2/scripts/benchmarks/shared/react-benchmark.tsx

Goal:

Make huge-document evidence strong enough for release decisions.

Implementation:

1. Use the shared percentile helper for huge compare summaries.
2. Emit p75, p95, and p99 for every lane.
3. Preserve artifacts per run by including surface set and split-selection mode in the filename or by writing a timestamped sidecar under .tmp.
4. Emit first-class trace tags:
   • DOM node count;
   • editable descendant count;
   • active event listener count and by-type counts;
   • process heap used;
   • mounted group count;
   • pending group count;
   • background chunk count;
   • native surface complete time;
   • stale group count;
   • rendering strategy type;
   • shell / staged / virtualized flags.
5. Keep REACT_HUGE_COMPARE_SPLIT_SELECTION=1 as an explicit release-proof mode, not just a debugging option.

Acceptance:

cd /Users/zbeyens/git/slate-v2
REACT_HUGE_COMPARE_SKIP_BUILD=1 \
REACT_HUGE_COMPARE_DISPOSE_DELAY_MS=0 \
REACT_HUGE_COMPARE_SPLIT_SELECTION=1 \
REACT_HUGE_COMPARE_SURFACES=v2DefaultRenderAuto,v2DomPresent,v2ShellExplicitRadius0,v2ShellExplicitRadius1 \
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

Artifact must include p75/p95/p99 and trace tags for every selected surface.

Slice 2: Default auto Release Gate

Owner:

• benchmark script above;
• .tmp/slate-v2/packages/slate-react/src/components/editable-text-blocks.tsx;
• .tmp/slate-v2/packages/slate-react/src/editable/root-selector-sources.ts.

Goal:

Turn current default auto evidence into a real release gate.

Gate:

At 5,000 blocks, default auto must beat legacy chunking-on at p95 or p99 for:

• interactive ready;
• select-all;
• start block type;
• start select then type;
• middle block type;
• middle select then type;
• middle promote then type;
• visible full-document text replacement;
• visible full-document fragment insertion.

Also record:

• nativeSurfaceCompleteMs p95/p99;
• staleGroupCount = 0;
• mounted group count at ready;
• pending group count at ready.

If p95/p99 exposes current mean-hidden tails, do not lower the bar. Fix the tail.

Slice 3: Staged Selection / Promote Tail Fix

Owner:

• .tmp/slate-v2/packages/slate-react/src/components/editable-text-blocks.tsx
• .tmp/slate-v2/packages/slate-react/src/editable/root-selector-sources.ts
• .tmp/slate-v2/packages/slate-react/src/editable/selection-controller.ts
• DOM coverage materialization owners in slate-dom/internal.

Problem:

Fresh staged rows lose to legacy chunking-on on:

• middleBlockSelectThenTypeMs: 49.50ms vs 37.87ms;
• middleBlockPromoteThenTypeMs: 46.68ms vs 38.64ms;
• split middle selection setup: about +8.85ms versus chunking-on;
• split start type-after-select has large outliers.

Likely investigation points:

• target-range materialization cost;
• active group mounting and startTransition timing;
• selection import/export repair loops;
• background mounting contention;
• root group plan rebuilds;
• DOMCoverage boundary lookup and materialization path.

Acceptance:

cd /Users/zbeyens/git/slate-v2/packages/slate-react
bun test:vitest test/rendering-strategy-and-scroll.test.tsx test/projections-and-selection-contract.test.tsx
cd /Users/zbeyens/git/slate-v2
REACT_HUGE_COMPARE_SKIP_BUILD=1 \
REACT_HUGE_COMPARE_DISPOSE_DELAY_MS=0 \
REACT_HUGE_COMPARE_SPLIT_SELECTION=1 \
REACT_HUGE_COMPARE_SURFACES=v2DefaultRenderAuto,v2DomPresent \
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

v2DomPresent should beat legacy chunking-on for middle select+type and promote+type at the chosen release percentile, or it must be explicitly reclassified as diagnostic / non-default.

Slice 4: Shell Policy Re-evaluation

Owner:

• .tmp/slate-v2/packages/slate-react/src/rendering-strategy/create-segment-plan.ts
• .tmp/slate-v2/packages/slate-react/src/rendering-strategy/segment-shell.tsx
• shell behavior tests.

Problem:

Fresh shell rows show:

• radius 0 loses middleBlockSelectThenTypeMs by +19.84ms and middleBlockPromoteThenTypeMs by +25.62ms;
• radius 1 loses middleBlockSelectThenTypeMs by +51.29ms and middleBlockPromoteThenTypeMs by +41.76ms;
• shell has no nativeSurfaceCompleteMs because far content is shell-backed.

Decision:

• keep shell explicit;
• do not use shell to justify the default performance claim;
• re-check radius 0 versus radius 1 before preserving radius 1 as the recommended shell default;
• if radius 1 stays, document it as corridor/UX policy, not raw performance.

Acceptance:

Shell docs and examples must state the degradation contract:

• browser find;
• screen-reader traversal;
• native selection;
• copy/paste;
• IME/composition;
• mobile touch selection;
• undo/history;
• collaboration;
• follow-up typing after materialization.

Slice 5: Real Browser Interaction Trace Benchmark

Owner:

• new benchmark command in .tmp/slate-v2/scripts/benchmarks/browser/react/**;
• existing Playwright example fixture or a dedicated huge-document benchmark page.

Goal:

Close the biggest proof gap: jsdom/direct-model benchmarks are not browser INP.

Add a command shaped like:

bun run bench:react:huge-document:browser-trace:local

It should measure at least Chromium first, with WebKit/Safari as a separate owner for #5216.

Rows:

• type;
• select;
• select then type;
• select-all;
• copy;
• paste;
• scroll to far group;
• click far group then type;
• materialize hidden content;
• model-beforeinput path;
• native-eligible input path where the browser can prove it;
• remote update if the fixture can drive it deterministically.

Metrics:

• event-to-update;
• event-to-paint;
• long tasks;
• React performance track / user timing marks where available;
• DOM node count;
• heap;
• listener count;
• native surface completion;
• stale DOM count;
• browser, device class, and release tags.

Acceptance:

Do not claim browser perf closure from this benchmark until it records p50, p75, p95, and p99 for interaction rows.

Slice 6: Production Metric Contract

Owner:

• onRenderingStrategyMetrics docs/tests;
• EditableRenderingStrategyMetrics type.

Goal:

Make lab and production speak the same language without adding a vendor integration to raw Slate.

Metric fields should cover:

• interaction name;
• cohort;
• document size;
• rendering strategy requested/effective;
• mounted group count;
• pending group count;
• native surface complete;
• stale group count;
• DOM node count;
• editable descendant count;
• event listener count;
• heap;
• browser;
• mobile/IME flag;
• release id;
• degradation mode.

Acceptance:

Products can tag RUM / Datadog / whatever from Slate metrics without scraping DOM or reverse-engineering shell/staged mode.

Slice 7: Core And Support Tail Audit

Owner:

• .tmp/slate-v2/packages/slate/**
• .tmp/slate-v2/packages/slate-history/**

Goal:

The React default is not the whole editor. Before calling v2 perf field-best, the core/support tails need current artifacts too.

Commands:

cd /Users/zbeyens/git/slate-v2
bun run bench:core:huge-document:compare:local
bun run bench:core:observation:compare:local
bun run bench:core:history-retained-memory:local
bun run bench:history:compare:local

Acceptance:

• no unbounded retained-memory regression;
• history memory rows stay tagged separately from latency rows;
• core observation / huge-document deltas are bounded and have clear owner classification;
• no core benchmark command still depends on stale public write aliases.

Cohorts And Budgets

Repeated unit budgets:

Ecosystem Synthesis

Issue Accounting

No issue claim changes in this pass.

Cached ledgers were used first. Broad GitHub issue discovery was not run.

Current conservative rows stay correct:

Maintainer Objections

Verification Commands Run

From /Users/zbeyens/git/slate-v2:

bun run bench:react:rerender-breadth:local
REACT_HUGE_COMPARE_SKIP_BUILD=1 REACT_HUGE_COMPARE_DISPOSE_DELAY_MS=0 REACT_HUGE_COMPARE_SURFACES=v2DefaultRenderAuto,v2DomPresent 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
REACT_HUGE_COMPARE_SKIP_BUILD=1 REACT_HUGE_COMPARE_DISPOSE_DELAY_MS=0 REACT_HUGE_COMPARE_SPLIT_SELECTION=1 REACT_HUGE_COMPARE_SURFACES=v2DefaultRenderAuto,v2DomPresent 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
REACT_HUGE_COMPARE_SKIP_BUILD=1 REACT_HUGE_COMPARE_DISPOSE_DELAY_MS=0 REACT_HUGE_COMPARE_SURFACES=v2ShellExplicitRadius0,v2ShellExplicitRadius1 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

All passed.

Ralph Execution Ledger

Benchmark Artifact Hardening

Status: complete.

Changes in .tmp/slate-v2:

• scripts/benchmarks/browser/react/huge-document-legacy-compare.mjs preserves run-specific artifacts, keeps a latest artifact, emits p75/p95/p99, and records ready-surface trace tags.
• scripts/benchmarks/core/compare/huge-document.mjs, scripts/benchmarks/core/compare/history.mjs, and scripts/benchmarks/core/compare/observation.mjs emit p75/p95/p99 and run against the current transaction API.

Fresh proof:

node --check scripts/benchmarks/core/compare/huge-document.mjs
node --check scripts/benchmarks/core/compare/history.mjs
node --check scripts/benchmarks/core/compare/observation.mjs
node --check scripts/benchmarks/browser/react/huge-document-legacy-compare.mjs

All passed.

Core Transaction Snapshot Fast Path

Status: complete, but not sufficient for full lane closure.

Change in .tmp/slate-v2:

• packages/slate/src/core/public-state.ts keeps the full previous snapshot path for snapshot/source subscribers, but subscriber-free transactions use the live runtime index plus rollback state instead of building a full immutable snapshot at transaction start.

Fresh proof:

bun --filter slate typecheck
bun --filter slate-history typecheck
bun --filter slate-react typecheck
bun test ./packages/slate/test/transaction-contract.ts ./packages/slate/test/commit-metadata-contract.ts ./packages/slate/test/write-boundary-contract.ts ./packages/slate/test/snapshot-contract.ts ./packages/slate-history/test/history-contract.ts ./packages/slate-history/test/integrity-contract.ts
cd packages/slate-react && bun test:vitest test/rendering-strategy-and-scroll.test.tsx test/projections-and-selection-contract.test.tsx
bun run lint:fix
CORE_HUGE_BENCH_BLOCKS=5000 CORE_HUGE_BENCH_ITERATIONS=5 CORE_HUGE_BENCH_TYPE_OPS=10 bun run bench:core:huge-document:compare:local
bun run bench:core:observation:compare:local
bun run bench:history:compare:local
REACT_HUGE_COMPARE_SKIP_BUILD=1 REACT_HUGE_COMPARE_DISPOSE_DELAY_MS=0 REACT_HUGE_COMPARE_SPLIT_SELECTION=1 REACT_HUGE_COMPARE_SURFACES=v2DefaultRenderAuto,v2DomPresent 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

All passed.

Result:

• Core 5,000-block typing improved from the previous percentile run startBlockTypeMs mean=153.10ms p95=161.93ms and middleBlockTypeMs mean=152.65ms p95=156.30ms to startBlockTypeMs mean=70.16ms p95=72.82ms and middleBlockTypeMs mean=71.23ms p95=75.85ms.
• Core full-document replacement remains green versus legacy: replaceFullDocumentWithTextMs mean=18.85ms p95=21.84ms versus legacy mean=48.67ms p95=55.49ms; fragment insertion is also green: mean=19.06ms p95=21.51ms versus legacy mean=46.11ms p95=47.16ms.
• Core select-all remains red versus legacy: mean=25.94ms p95=26.21ms versus legacy mean=0.01ms p95=0.01ms.
• Core observation remains red for fresh snapshot reads after each edit: readChildrenLengthAfterEachMs mean=62.61ms p95=65.26ms, nodesAtRootAfterEachMs mean=33.73ms p95=35.78ms, and positionsFirstBlockAfterEachMs mean=22.39ms p95=22.82ms.
• History remains a separate red owner: typingUndoMs mean=26.15ms p95=29.28ms, typingRedoMs mean=27.77ms p95=28.84ms, fragmentUndoMs mean=19.66ms p95=20.49ms, and fragmentRedoMs mean=22.10ms p95=22.84ms.
• React default/staged split compare still fails the release p95 bar: v2DefaultRenderAuto.startBlockTypeMs p95=79.67ms versus legacyChunkOn p95=37.73ms, v2DefaultRenderAuto.middleBlockSelectThenTypeMs p95=66.84ms versus legacyChunkOn p95=43.91ms, and v2DomPresent.middleBlockPromoteThenTypeMs p95=78.52ms versus legacyChunkOn p95=41.71ms.

Next owner:

• Run the split React compare with REACT_HUGE_COMPARE_PROFILE=1 after the core fast path, inspect the remaining p95 outlier hot rows, then split the next code owner between core history/snapshot-observation and React selection/materialization.

React P95 Outlier Trace And History Tail Fix

Status: complete, but not sufficient for full lane closure.

Changes in .tmp/slate-v2:

• packages/slate/src/core/public-state.ts publishes path-stable text snapshots for batched text commits so untouched 5,000-block siblings are not recloned just because a snapshot subscriber needs immutable previous/current state.
• packages/slate/src/core/public-state.ts runs commit listeners before broad snapshot/source listeners, and only builds listener snapshots for broad subscribers or two-argument commit listeners.
• packages/slate-history/src/with-history.ts captures history batches from commit listeners using selectionBefore, and undo/redo replay no longer wraps editor.update in a redundant normalization boundary.
• packages/slate/test/snapshot-contract.ts locks path-stable batched text snapshot publication.

Fresh proof:

bun --filter slate typecheck
bun --filter slate-history typecheck
bun --filter slate-react typecheck
bun test ./packages/slate/test/transaction-contract.ts ./packages/slate/test/commit-metadata-contract.ts ./packages/slate/test/write-boundary-contract.ts ./packages/slate/test/snapshot-contract.ts ./packages/slate-history/test/history-contract.ts ./packages/slate-history/test/integrity-contract.ts
cd packages/slate-react && bun test:vitest test/rendering-strategy-and-scroll.test.tsx test/projections-and-selection-contract.test.tsx
bun run lint:fix
bun run bench:history:compare:local
REACT_HUGE_COMPARE_SKIP_BUILD=1 REACT_HUGE_COMPARE_DISPOSE_DELAY_MS=0 REACT_HUGE_COMPARE_SPLIT_SELECTION=1 REACT_HUGE_COMPARE_SURFACES=v2DefaultRenderAuto,v2DomPresent 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
REACT_HUGE_COMPARE_SKIP_BUILD=1 REACT_HUGE_COMPARE_DISPOSE_DELAY_MS=0 REACT_HUGE_COMPARE_SPLIT_SELECTION=1 REACT_HUGE_COMPARE_SURFACES=v2DefaultRenderAuto,v2DomPresent REACT_HUGE_COMPARE_BLOCKS=5000 REACT_HUGE_COMPARE_ITERATIONS=5 REACT_HUGE_COMPARE_TYPE_OPS=10 REACT_HUGE_COMPARE_PROFILE=1 bun run bench:react:huge-document:legacy-compare:local

All passed.

Result:

• History is materially improved: typingUndoMs mean=7.62ms p95=9.82ms, typingRedoMs mean=5.94ms p95=6.31ms, fragmentUndoMs mean=6.60ms p95=6.90ms, and fragmentRedoMs mean=7.36ms p95=9.36ms.
• Default auto remains strong on middle typing and full-document rows in the fresh split compare, but selected-start p95 is still noisy: startBlockSelectThenTypeMs p95=332.62ms versus legacy chunk-on 95.24ms.
• v2DomPresent still loses selected typing p95: middleBlockSelectThenTypeMs p95=68.61ms versus chunk-on 46.73ms.
• Profiled rows make the next owner clear: transaction-previous-snapshot is effectively zero, next-snapshot is single-digit to mid-teens on bad staged rows, and the largest spikes sit inside React/jsdom act around selected group typing/materialization.

Next owner:

• Add or run browser-native interaction proof for the same selected typing/materialization rows, then decide whether the staged materialization p95 tail is a runtime bug to fix, a jsdom harness artifact to narrow, or a documented non-default degradation.

Browser Native Proof And Staged Materialization Classification

Status: complete, but not sufficient for full lane closure.

Changes in .tmp/slate-v2:

• scripts/benchmarks/browser/react/huge-document-browser-trace.mjs adds a Chromium huge-document browser trace benchmark.
• package.json adds bench:react:huge-document:browser-trace:local.
• The benchmark serves the built example app, drives real keyboard typing, records p75/p95/p99 rows, preserves run-specific artifacts, and tags native surface completion, observed mounted blocks, DOM nodes, heap, long tasks, and long animation frames.
• Full native-surface completion is a measured timeout/tag, not a hard prerequisite for selected typing rows. Selected block materialization remains required.

Fresh proof:

node --check scripts/benchmarks/browser/react/huge-document-browser-trace.mjs
bun run lint:fix
SLATE_BROWSER_TRACE_BLOCKS=5000 SLATE_BROWSER_TRACE_ITERATIONS=3 SLATE_BROWSER_TRACE_TYPE_OPS=10 SLATE_BROWSER_TRACE_SURFACES=defaultAuto,stagedDomPresent bun run bench:react:huge-document:browser-trace:local

All passed. The browser trace command ran once with a fresh bun run build:next, then the final skip-build rerun wrote:

tmp/slate-react-huge-document-browser-trace-benchmark-surfaces-defaultAuto-stagedDomPresent-blocks-5000-iters-3-ops-10.json

Result:

• Default auto: native surface complete 3/3, timeout 0, observed blocks 5000, nativeSurface.durationMs p95=298.2ms.
• Default auto: start selected type-to-paint p95=123.2ms, middle selected type-to-paint p95=139ms, heap p95=117.3MB, long-task max p95=0ms.
• Staged DOM-present: native surface complete 3/3, timeout 0, observed blocks 5000, nativeSurface.durationMs p95=301.2ms.
• Staged DOM-present: start selected type-to-paint p95=81.5ms, middle selected type-to-paint p95=97.7ms, heap p95=82.4MB, long-task max p95=0ms.

Classification:

• The staged materialization p95 tail from the jsdom/direct-model benchmark is not a hard runtime bug. Chromium materializes the 5,000-block native surface without timeout and records no long-task spike for the selected typing rows.
• The tail is still real budget work. Native selected typing p95 is not cheap enough to call the lane absolute-best, and the two browser fixtures are not strict apples-to-apples content comparisons.
• Keep default auto as the public default. Do not use this proof to promote shell or virtualization.

Next owner:

• Production-aligned rendering strategy metrics plus the native behavior matrix: browser find, copy, paste, select-all, scroll/click far group then type, IME, mobile touch selection, and Safari/WebKit.

Production Metric Contract And Native Behavior Matrix

Status: complete for this autonomous local lane.

Changes in .tmp/slate-v2:

• packages/slate-react/src/components/editable.tsx exports EditableRenderingStrategyDegradationMode.
• EditableRenderingStrategyMetricsBase now includes degradationMode.
• packages/slate-react/src/components/editable-text-blocks.tsx reports:
  • none for complete DOM-present/default surfaces;
  • staged-warmup while staged DOM-present groups are still pending;
  • shell for shell-backed degradation;
  • virtualized for the experimental virtualized mode.
• packages/slate-react/test/rendering-strategy-and-scroll.tsx locks degradation mode for virtualized, staged warmup, plain, and shell surfaces.
• docs/libraries/slate-react/editable.md, docs/libraries/slate-react/experimental-virtualized-rendering.md, and site/examples/ts/rendering-strategy-runtime.tsx now use the metric fields products can actually ship to RUM: degradationMode, nativeSurfaceComplete, domNodeCount, mounted/pending counts, cohort, requested/effective strategy, browser/device/IME/release tags.
• playwright/integration/examples/rendering-strategy-runtime.test.ts now passes the composition transport the scenario metadata claims. Chromium keeps native CDP IME; mobile uses the synthetic composition lane.

Fresh proof:

bun --filter slate-react typecheck
bun typecheck:root
cd packages/slate-react && bun test:vitest test/rendering-strategy-and-scroll.test.tsx
bun run lint:fix
PLAYWRIGHT_RETRIES=0 bun playwright test playwright/integration/examples/rendering-strategy-runtime.test.ts --project=chromium --grep "runs generated composition gauntlet without illegal kernel transitions"
PLAYWRIGHT_RETRIES=0 bun playwright test playwright/integration/examples/rendering-strategy-runtime.test.ts --project=mobile --grep "runs generated composition gauntlet without illegal kernel transitions" --timeout=60000

Additional browser matrix rows passed:

bun playwright test playwright/integration/examples/rendering-strategy-runtime.test.ts --project=chromium --grep "browser-native typing"
bun playwright test playwright/integration/examples/rendering-strategy-runtime.test.ts --project=chromium --grep "preserves Slate fragment paste over shell-backed selection|copies full shell-backed selection|copies partial shell-backed selection|preserves Slate fragment paste over partial shelled selection"
bun playwright test playwright/integration/examples/rendering-strategy-runtime.test.ts --project=chromium --grep "commits IME composition through the browser editing path|undoes committed IME composition as one history step"
bun playwright test playwright/integration/examples/rendering-strategy-runtime.test.ts --project=webkit --grep "deletes shell-backed selection after WebKit compositionend"

Result:

• Production metrics no longer require products to infer degradation from requested/effective strategy plus boundary counts.
• Chromium proves staged browser-native typing, shell-backed copy/paste, and IME rows.
• WebKit proves the shell-backed compositionend deletion row.
• Mobile semantic composition proof passes after the transport mismatch fix.
• Raw Appium/device proof remains a separate release machine lane: bun test:mobile-device-proof:raw.

Pass Schedule

Current Handoff

Use ralph for execution.

No next slice remains for this local autonomous lane. Raw-device release proof is explicitly separate and should run only on a machine/device lane.