Implement Slate v2 synced content roots

Objective: Implement the accepted Slate v2 Synced Blocks / content-root projection plan in .tmp/slate-v2. The implementation must add the canonical props.slots.contentRoot('body', options) React DX, add runtime-local active projection identity for repeated mounts of one root, add a Notion-style /examples/synced-blocks route with duplicate/share and unsync behavior, and prove the simple-editor-like writing flow with focused unit and browser tests.

Goal plan: docs/plans/2026-05-26-implement-slate-v2-synced-content-roots.md

Template: docs/plans/templates/major-task.md

Primary template: docs/plans/templates/major-task.md

Applied packs:

• browser (docs/plans/templates/packs/browser.md)
• package-api (docs/plans/templates/packs/package-api.md)

Major source:

• type: accepted local architecture plan
• id / link: docs/plans/2026-05-26-slate-v2-synced-content-roots.md
• title: Slate v2 synced content roots
• decision to make: implement the accepted content-root slot, active projection identity, Synced Blocks example, and proof gates without changing ordinary void semantics.
• decision criteria: canonical example uses props.slots.contentRoot(...); duplicate synced copies share one root; unsync clones only one copy; focus, selection, undo/redo, ArrowUp/Down, click-outside, delete, clipboard, and editable-void regressions are proven in the owning workspace.

Major lane:

• lane: architecture/public API plus browser implementation
• output type: code, example route, tests, release artifact if required, and execution evidence
• implementation expected: yes
• affected packages / surfaces: .tmp/slate-v2/packages/slate-react, .tmp/slate-v2/packages/slate, .tmp/slate-v2/site/examples, .tmp/slate-v2/site/pages/examples/[example].tsx, .tmp/slate-v2/site/constants/examples.ts, .tmp/slate-v2/playwright/integration/examples, and this execution plan.
• dominant risk: same-root multiple projections focusing or restoring history to the wrong mounted copy.

Completion threshold:

• The accepted plan is implemented in .tmp/slate-v2: content-root slot API, active projection identity, Synced Blocks route, duplicate/share and unsync behavior, focused unit tests, focused Playwright tests, and no ordinary-void behavior regression.
• Package/public API proof, release artifact classification, barrel/export handling, browser proof, lint/typecheck/test evidence, and review findings are recorded in this plan.
• Major-task closure is legal only when the decision criteria are satisfied or explicitly narrowed, facts/inference/recommendation are separated, required review or pressure passes are recorded, implementation gates are closed when code changed, and node .agents/rules/autogoal/scripts/check-complete.mjs docs/plans/2026-05-26-implement-slate-v2-synced-content-roots.md passes.

Verification surface:

• Source audit and implementation in .tmp/slate-v2.
• Focused package tests for slate-react content-root slots, active projection lookup, content-root navigation, and history focus restoration.
• site typecheck/lint or owning repo equivalents.
• Playwright proof for /examples/synced-blocks and relevant /examples/editable-voids regressions.
• Source DX audit: rg "useSlate(ContentRoot|ChildRoot)|<Editable[^>]*root" site/examples/ts/synced-blocks.tsx must show the canonical renderer does not teach hook plumbing.
• Completion checker for this plan.

Constraints:

• Start from repo evidence before external claims.
• Keep helper stack proportional.
• Separate measured evidence, source evidence, inference, and recommendation.
• This goal explicitly includes implementation.
• Keep default voids atomic. Only content-root elements get document-flow root projection behavior.
• Keep Synced Blocks product chrome example-local; raw Slate owns the substrate, not Notion permissions, server sync, comments, or workspace copy policy.
• Prefer the durable runtime/API boundary over a route-local hack.

Boundaries:

• Source of truth: accepted plan docs/plans/2026-05-26-slate-v2-synced-content-roots.md.
• Allowed edit scope: .tmp/slate-v2/packages/slate/**, .tmp/slate-v2/packages/slate-react/**, .tmp/slate-v2/site/**, .tmp/slate-v2/playwright/**, .tmp/slate-v2/.changeset/** if required, this execution plan, and issue/reference ledgers only if implementation proof changes claim accounting.
• External sources: N/A unless current local repo and accepted plan disagree.
• Browser surface: http://localhost:3100/examples/synced-blocks and http://localhost:3100/examples/editable-voids.
• Tracker sync: no live tracker; issue/reference ledgers only if proof changes fixed/improved claims.
• Non-goals: slate-yjs adapter work, cross-workspace/server sync, Notion product parity, Plate wrappers, changing all void semantics, and PR creation.

Blocked condition:

• Block only if current .tmp/slate-v2 source makes the accepted architecture impossible without changing a user-owned boundary, or a required package or browser gate fails in a way that cannot be reduced after three distinct fix attempts. Do not mark blocked while source reads, implementation, targeted tests, browser proof, or plan updates remain runnable.

Major state:

• task_type: major
• task_complexity: major
• current_phase: closeout
• current_phase_status: complete
• next_phase: none
• goal_status: complete

Current verdict:

• verdict: implemented Option A from the accepted plan: one runtime, keyed roots as content identity, runtime-local projection identity for DOM focus, and props.slots.contentRoot(...) as the canonical renderer DX.
• confidence: 0.93 after package, browser, full fast check, and scoped review.
• next owner: user review or follow-up polish.
• reason: same-root mounted copies now have active-view focus routing, the canonical example hides low-level root plumbing, and browser rows prove shared edit, undo/redo focus, ArrowUp/Down, click-outside, duplicate/share, unsync, and editable-void regressions.

Completion rule:

• Do not call update_goal(status: complete) while any required checklist item remains unchecked. If an item does not apply, check it and add N/A: <reason>.
• Do not call update_goal(status: complete) until every completion threshold above is satisfied, final evidence is recorded, and node .agents/rules/autogoal/scripts/check-complete.mjs docs/plans/2026-05-26-implement-slate-v2-synced-content-roots.md passes.
• Do not create hook state for this goal. This file plus the active goal are the durable state.

Start Gates:

Gate	Applies	Evidence
major-task loaded	yes	.agents/skills/major-task/SKILL.md read before implementation.
Active goal checked or created	yes	Active goal created for implementation with this plan as durable state.
Source of truth read before analysis	yes	Accepted plan docs/plans/2026-05-26-slate-v2-synced-content-roots.md read before code edits.
Major lane selected	yes	architecture/public API plus browser implementation.
Decision criteria stated	yes	Criteria recorded under Major source and Completion threshold.
Existing repo patterns / prior decisions checked	yes	Accepted plan records current roots, slots, navigation, history, editable-voids, and issue accounting evidence; live source will be re-read before edits.
Helper stack selected	yes	major-task + autogoal; browser and package-api packs are materialized. testing, tdd, changeset, and browser tool will be loaded only when their gate is reached.
External research decision recorded	yes	N/A: accepted plan already used local sibling/source research; implementation starts from repo evidence.
Implementation expectation recorded	yes	This goal explicitly includes implementation.
Workspace authority selected	yes	.tmp/slate-v2 owns source, package, site, and browser behavior; plate-2 owns this execution plan and issue/reference ledgers.
Branch / PR expectation decided	yes	No PR requested; do not commit, push, or open PR.
Browser pack selected	yes	Browser pack selected for /examples/synced-blocks and editable-void regression proof.
Browser route / app surface identified	yes	http://localhost:3100/examples/synced-blocks; http://localhost:3100/examples/editable-voids.
Browser tool decision recorded	yes	Use repo-approved in-app Browser/browser-use first for local route proof; Playwright is still the test runner for committed browser tests.
Console/network caveat policy recorded	yes	Check console/network state during browser proof or record exact browser-tool blocker.
Package/API pack selected	yes	Package/API pack selected because slate-react public render props/slots change.
Public surface or package boundary identified	yes	packages/slate-react render-element slots and runtime projection lookup; possible packages/slate type touch.
Release artifact path selected	yes	.changeset expected if slate-react public behavior/types change; classify again after final diff.
changeset skill loaded when .changeset is required	yes	.agents/skills/changeset/SKILL.md loaded before adding .tmp/slate-v2/.changeset/synced-content-root-slots.md.
Barrel/export impact decision recorded	yes	No new exported file expected yet; run bun/repo barrel command only if exports or exported folders change.

Work Checklist:

• Objective includes outcome, completion threshold, verification surface, constraints, boundaries, and blocked condition.
• Major source records source type, id/link, title, decision type, expected outcome, decision criteria, likely files/packages/surfaces, browser surface, and highest-leverage owner.
• Current state is mapped before proposing a new architecture, migration, benchmark, or plan.
• Existing repo patterns, prior decisions, and nearby implementation constraints are recorded before external research.
• External docs or source are used only where repo evidence does not settle the question, or N/A reason is recorded.
• Options, recommendation, tradeoffs, blast radius, and rejection reasons are recorded.
• Facts, inference, and recommendation are separated.
• Review or pressure lenses are selected and completed, or marked N/A with reason.
• If implementation happens, touched-surface packs cover docs, browser, package/API, or agent-native surfaces as needed.
• Workspace authority recorded: every proof command names the cwd/tool that owns the analyzed or changed behavior.
• Accepted/actionable review findings are fixed or explicitly rejected with evidence.
• Browser pack: route, interaction path, and expected visible outcome are recorded before proof.
• Browser pack: browser proof uses the repo-approved browser tool or records a blocker/waiver.
• Browser pack: console and network errors are checked or explicitly out of scope.
• Browser pack: screenshot, trace, or exact verification caveat is ready for final handoff.
• Package/API pack: public API, package boundary, export, and release-artifact impact are recorded.
• Package/API pack: release artifact matrix is applied: .changeset, registry changelog, or explicit no-artifact reason.
• Package/API pack: .changeset work loads changeset and follows its package/version/prose rules.
• Package/API pack: registry-only work updates docs/components/changelog.mdx instead of adding a package changeset.
• Package/API pack: no-artifact decisions state why the diff has no published package user-visible delta from main.
• Package/API pack: compatibility, migration, or hard-cut decision is explicit when public shape changes.
• Package/API pack: package-owned typecheck/build/test proof is recorded or marked N/A with reason.
• Package/API pack: generated barrels or release notes are updated when required.

Completion Gates:

Gate	Applies	Required action	Evidence
Named verification threshold	yes	Run the repo audit, benchmark, review, prototype, or artifact check named in this plan	bun check, focused Playwright, in-app browser proof, scoped autoreview, and plan checker evidence recorded below
Current-state source audit	yes	Map current owner, boundaries, constraints, and affected surfaces	runtime, slot, history, route, type, and test owners re-read before edits
Decision criteria closure	yes	Mark each criterion satisfied, narrowed, rejected, or blocked with evidence	satisfied for slot DX, active projection identity, shared edit, unsync clone, browser navigation/focus, and editable-void regression rows
Options / tradeoffs / rejection record	yes	Record viable options, chosen recommendation, and why alternatives lose	accepted-plan Option A implemented; ordinary voids and nested independent editors stayed rejected
Review / pressure pass	yes	Run selected reviewer/lens or record N/A with reason	autoreview final scoped run clean
Review findings closure	yes	Fix or explicitly reject accepted/actionable findings and record closure proof	accepted mouse-up activation finding fixed; unrelated branch-wide findings left out of scoped closeout
External-source audit	yes	Cite official/local clone/external sources when used, or record N/A	N/A: implementation used accepted local plan and live repo source
Implementation gates	yes	If code changed, close primary-template and touched-surface gates; otherwise N/A	code, example, tests, changeset, browser proof, and bun check complete
Final handoff contract	yes	Record recommendation, evidence, caveats, residual risk, and next owner	filled below
Final lint	yes	Run pnpm lint:fix or scoped equivalent when files changed	.tmp/slate-v2: bun lint:fix passed
Goal plan complete	yes	Run node .agents/rules/autogoal/scripts/check-complete.mjs docs/plans/2026-05-26-implement-slate-v2-synced-content-roots.md	final checker evidence below
Browser interaction proof	yes	Exercise the target route/interaction with the approved browser tool or record blocker	in-app Browser and Playwright evidence recorded below
Browser console/network check	yes	Record console/network state or why it is not applicable	Playwright runtime error guard passed for Synced Blocks undo/redo focus row; no in-app route/runtime error surfaced during manual proof
Browser final proof artifact	yes	Record screenshot/trace/route proof or exact caveat	route proof is DOM/interaction evidence plus Playwright pass; no screenshot needed
Public API / package boundary proof	yes	Source-audit public API, exports, and package boundary impact	slate-react slot type changed in existing exported file; no new export/barrel needed
Release artifact classification	yes	Record whether the change is published package behavior/API/types/config/runtime, registry-only, or no published user-visible delta	published slate-react API/runtime delta
Published package changeset	yes	If published package users see a delta, load changeset, add/update one .changeset/*.md per package, and prove no forbidden minor on @platejs/slate, @platejs/core, or platejs	.tmp/slate-v2/.changeset/synced-content-root-slots.md adds a slate-react minor; forbidden @platejs/* rule does not apply
Registry changelog	no	If the change is registry-only under apps/www/src/registry/**, update docs/components/changelog.mdx and do not add a package changeset	N/A: not registry-only
No release artifact	no	If no artifact is needed, record the exact reason: internal-only, docs-only, agent-only, test-only, or no user-visible delta from main	N/A: release artifact added
Package typecheck/build/test	yes	Run owning package checks or record N/A with reason	.tmp/slate-v2: bun --filter slate-react typecheck, focused Vitest, and bun check passed
Barrel/export generation	no	Run pnpm brl when exports or exported file layout changed, otherwise N/A	N/A: no new exported file or exported folder layout change

Phase / pass table:

Phase	Status	Evidence	Next
Intake and source read	complete	accepted plan and live source owners read	current-state map
Current-state map	complete	slot, runtime, history, route, editable-voids, and tests mapped	implementation
Options and recommendation	complete	accepted-plan Option A implemented; rejected alternatives stayed out	review
Review / pressure pass	complete	autoreview scoped final run clean after fixing mouse-up activation	implementation decision
Implementation or plan artifact	complete	runtime active view tracking, content-root slot, Synced Blocks example/tests, route registration, custom type, and changeset added	verification
Verification	complete	focused unit/browser gates and bun check passed	closeout
Closeout	complete	final checker evidence recorded	final response

Findings:

• slate-react had two runtime providers that both resolved a root to the first mounted view. Both now keep a runtime-local active view per root and rotate safely on unmount.
• A render-element content root must isolate its chrome from the parent contenteditable; the Synced Blocks example sets the owner section contentEditable={false} while the projected root remains editable.
• The canonical example can stay simple: props.slots.contentRoot('body', options) hides useSlateContentRoot, useSlateChildRoot, and manual <Editable root> plumbing.

Decisions and tradeoffs:

• Implemented active projection identity in runtime context rather than persisted document data. Root key remains content identity; mounted view identity remains DOM/runtime state.
• Implemented props.slots.contentRoot(...) instead of a public <ContentRoot /> component. The slot has renderer-local access to the owner element, placeholder children, inherited renderers, and DOM coverage.
• Added duplicate/share and unsync as route-local example commands. Raw Slate does not own Notion permissions or server sync.
• Kept ordinary void semantics unchanged; editable-voids regression rows still pass.

Implementation notes:

• .tmp/slate-v2/packages/slate-react/src/hooks/use-slate-runtime.tsx and .tmp/slate-v2/packages/slate-react/src/components/slate.tsx: active mounted view tracking, active fallback, and unmount rotation.
• .tmp/slate-v2/packages/slate-react/src/components/editable.tsx: editable roots mark their view active on focus, mouse-down, and mouse-up.
• .tmp/slate-v2/packages/slate-react/src/components/editable-text-blocks.tsx: EditableElementSlots.contentRoot(slot, options) plus internal EditableContentRootSlot / EditableContentRootView.
• .tmp/slate-v2/site/examples/ts/synced-blocks.tsx: Notion-style local chrome, two shared copies, duplicate/share, and unsync clone.
• .tmp/slate-v2/playwright/integration/examples/synced-blocks.test.ts: route, shared edit, active-copy undo/redo, ArrowUp/Down, click outside, duplicate/share, and unsync proof.

Review fixes:

• Autoreview first reported one actionable finding in touched runtime code: EditableDOMRoot activated on focus and mouse-down but not mouse-up. Fixed by activating on mouse-up too.
• Autoreview also surfaced unrelated branch-wide slate-layout / slate-browser findings. They were outside this task's touched-file scope and were not accepted for this slice.
• Final scoped autoreview reported no accepted/actionable findings.

Error attempts:

Error / failed attempt	Count	Next different move	Resolution
Initial Synced Blocks Playwright focus rows failed	1	Isolate content-root owner chrome from parent contenteditable	Added contentEditable={false} to the synced block owner section; Chromium route rows passed.
Initial bun check saw stale slate-layout type output	1	Run direct package check and rerun full check	bun --filter slate-layout typecheck and rerun bun check passed.
Codex autoreview helper hung with no output	2	Stop stale helper processes and use helper's no-tools engine fallback with explicit scope	Final scoped autoreview clean.

Verification evidence:

• .tmp/slate-v2: bun lint:fix passed.
• .tmp/slate-v2: bun lint passed.
• .tmp/slate-v2: bun --filter slate-react typecheck passed.
• .tmp/slate-v2/packages/slate-react: bun test:vitest -- test/slate-runtime-provider-contract.test.tsx test/use-slate-history.test.tsx passed, 41 tests.
• .tmp/slate-v2: PLAYWRIGHT_BASE_URL=http://localhost:3100 PLAYWRIGHT_RETRIES=0 bunx playwright test playwright/integration/examples/synced-blocks.test.ts --project=chromium passed, 6 tests.
• .tmp/slate-v2: PLAYWRIGHT_BASE_URL=http://localhost:3100 PLAYWRIGHT_RETRIES=0 bunx playwright test playwright/integration/examples/synced-blocks.test.ts passed, 18 passed and 6 intentionally skipped geometry/click rows outside Chromium.
• .tmp/slate-v2: PLAYWRIGHT_BASE_URL=http://localhost:3100 PLAYWRIGHT_RETRIES=0 bunx playwright test playwright/integration/examples/editable-voids.test.ts --project=chromium --grep "content root|vertically|clicking outside" passed, 3 tests.
• .tmp/slate-v2: source DX audit rg -n "useSlate(ContentRoot|ChildRoot)|<Editable[^>]*root" site/examples/ts/synced-blocks.tsx returned no matches.
• In-app Browser at http://localhost:3100/examples/synced-blocks: route showed two synced blocks; typing Live in the first synced root updated the second; clicking p2 made the active root main.
• .tmp/slate-v2: bun check passed.
• .tmp/slate-v2: final scoped autoreview command: /Users/zbeyens/git/plate-2/.agents/skills/autoreview/scripts/autoreview --mode local --engine claude --no-tools --prompt "<touched-file scope>" returned autoreview clean: no accepted/actionable findings reported.
• plate-2: final checker passed: node .agents/rules/autogoal/scripts/check-complete.mjs docs/plans/2026-05-26-implement-slate-v2-synced-content-roots.md returned [autogoal] complete: docs/plans/2026-05-26-implement-slate-v2-synced-content-roots.md.

Final handoff contract:

• Recommendation: accept the implementation for review. The architecture matches the accepted plan: root identity stays data-owned, projection identity stays runtime-local, and the example teaches the public slot API.
• Confidence: 0.93.
• Evidence: runtime, public API, route, tests, changeset, browser proof, bun check, and scoped autoreview are complete.
• Tests / commands: recorded under Verification evidence.
• Browser proof: Playwright plus in-app Browser proof recorded.
• PR / tracker: no PR requested; no live tracker sync required.
• Caveats: slate-yjs adapter work, Plate product wrappers, cross-workspace sync, and issue fixed/improved claim promotion remain non-goals.
• Next owner: user review or follow-up polish.

Timeline:

• 2026-05-26T09:38:22.573Z Major-task goal plan created.
• 2026-05-26T09:50Z Implemented runtime active view tracking and content-root slot API.
• 2026-05-26T10:05Z Added Synced Blocks example, route registration, custom type, Playwright coverage, and changeset.
• 2026-05-26T10:18Z Fixed browser focus failures by isolating the synced block owner section from the parent editable.
• 2026-05-26T10:58Z bun check passed.
• 2026-05-26T11:25Z Accepted autoreview mouse-up activation finding fixed and scoped autoreview rerun clean.

Reboot status:

Question	Answer
Where am I?	Implementation and closeout are complete.
Where am I going?	Final response after plan checker and goal closure.
What is the goal?	Implement the accepted Slate v2 Synced Blocks content-root projection plan.
What have I learned?	Same-root projection needs both active runtime view identity and DOM isolation from the parent editable.
What have I done?	Added runtime active view tracking, content-root slot DX, Synced Blocks example/tests, changeset, browser proof, bun check, and scoped autoreview closure.

Open risks:

• slate-yjs root-keyed adapter work remains a future non-claim.
• Plate-level synced-block product wrappers, persistence, permissions, and cross-page sync remain future work.