slate v2 shift boundary selection

Objective: Fix Slate v2 hidden-content-blocks shifted caret movement so Shift+ArrowRight and Shift+Option+ArrowRight from the end of the first paragraph never project a native DOM selection through shadcn accordion/tabs chrome or inactive hidden content.

Goal plan: docs/plans/2026-05-26-slate-v2-shift-boundary-selection.md

Template: docs/plans/templates/task.md

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

Applied packs:

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

Task source:

• type: user browser bug report
• id / link: local route
• title: Shifted selection leaks through hidden-content shadcn chrome
• acceptance criteria: from /examples/hidden-content-blocks, shifted right and shifted word-right at the end of p1 keep inactive hidden content closed and do not select accordion/tab/collapsible controls in the native DOM selection.

Completion threshold:

• Browser repro is confirmed before the fix.
• Package-level regressions cover reconciler export, shifted caret movement, word-selection hotkeys, clipboard policy preservation, and the hidden-content-blocks route.
• Browser proof on http://100.102.180.93:3100/examples/hidden-content-blocks shows empty native selection text, active Overview tab, inactive Details tab, and no hidden accordion/details text after both shifted key paths.
• slate-react and slate-dom typecheck pass.
• Changesets exist for the published slate-react and slate-dom behavior changes.

Verification surface:

• Browser: in-app Browser on http://100.102.180.93:3100/examples/hidden-content-blocks.
• Playwright: PLAYWRIGHT_RETRIES=0 PLAYWRIGHT_WORKERS=1 bun playwright playwright/integration/examples/hidden-content-blocks.test.ts --project=chromium.
• Unit: bun test:vitest -- keyboard-input-strategy-contract.test.ts selection-reconciler-contract.test.tsx.
• Unit: cd packages/slate-dom && bun test ./test/dom-coverage.test.ts ./test/hotkeys.test.ts ./test/clipboard-boundary.test.ts.
• Types: bun --filter slate-react typecheck; bun --filter slate-dom typecheck.
• Lint: scoped bunx biome check ...; scoped bunx eslint ....

Constraints:

• Work in /Users/zbeyens/git/plate-2/.tmp/slate-v2.
• Preserve current boundary, materialize, and model-backed policies.
• Do not create commits, pushes, PRs, or tracker comments.

Boundaries:

• Source of truth: user report plus attached screenshot showing native selection over non-editable shadcn chrome.
• Allowed edit scope: Slate v2 slate-dom, slate-react, hidden-content-blocks Playwright coverage, package changesets, and this plan.
• Browser surface: /examples/hidden-content-blocks.
• Tracker sync: N/A, no tracker item.
• Non-goals: visible projected selection overlay for model-backed hidden ranges; broad redesign of DOM coverage policy.

Blocked condition: Blocked only if the in-app Browser cannot load the route or package tests cannot run due unrelated local install corruption after one reinstall retry. No blocker remains.

Task state:

• task_type: bug
• task_complexity: normal
• current_phase: closeout
• current_phase_status: complete
• next_phase: final response
• goal_status: active

Current verdict:

• verdict: complete
• confidence: high
• next owner: user
• reason: browser repro is fixed, route regression is green, package tests and typechecks pass.

Completion rule:

• Completion is legal after this plan passes node .agents/rules/autogoal/scripts/check-complete.mjs docs/plans/2026-05-26-slate-v2-shift-boundary-selection.md.

Start Gates:

Gate	Applies	Evidence
Skill analysis before edits	yes	Loaded debug, task, autogoal, browser, and changeset; used bug-first repro and package release rules.
Active goal checked or created	yes	create_goal created objective 019e63f8-9985-75c0-ae68-33575e324b41.
Source of truth read before edits	yes	User bug report and screenshot inspected; route /examples/hidden-content-blocks used.
Tracker comments and attachments read	no	N/A: no tracker item.
Video transcript evidence required	no	N/A: static screenshot, no video.
docs/solutions checked for non-trivial existing-code work	no	N/A: local source and prior memory had the route/tooling context; no solution note owned this exact regression.
TDD decision before behavior change or bug fix	yes	Added route, unit, DOM coverage, hotkey, and reconciler regression rows.
Branch decision for code-changing task	no	N/A: user did not request branch/PR; repo says do not check git state.
Release artifact decision	yes	Published package behavior changed; split package changesets added.
Browser tool decision for browser surface	yes	Used in-app Browser as requested.
PR expectation decision	no	N/A: no PR requested.
Tracker sync expectation decision	no	N/A: no tracker item.
Browser pack selected	yes	Applied browser pack.
Browser route / app surface identified	yes	/examples/hidden-content-blocks.
Browser tool decision recorded	yes	In-app Browser only for manual proof; Playwright only for automated regression.
Console/network caveat policy recorded	yes	Browser console errors checked after proof: [].
Package/API pack selected	yes	Applied package-api pack for slate-react and slate-dom.
Public surface or package boundary identified	yes	Runtime behavior of published slate-react and slate-dom; no export/barrel change.
Release artifact path selected	yes	.changeset/slate-react-hidden-boundary-selection.md and .changeset/slate-dom-hidden-boundary-selection.md.
changeset skill loaded when .changeset is required	yes	Loaded .agents/skills/changeset/SKILL.md; split one package per file.
Barrel/export impact decision recorded	no	N/A: added internal file only; no public export or exported folder layout change.

Work Checklist:

• Objective includes outcome, completion threshold, verification surface, constraints, boundaries, and blocked condition.
• Task source classified with source type, title, task type, acceptance criteria, caveats, likely files/routes/packages, browser surface, and root-cause layer.
• Required video or screen-recording evidence is N/A: screenshot-only bug report.
• Nearby repo instructions and implementation patterns read before edits.
• Implementation fixes the right ownership boundary: DOM coverage selection export and hotkey ownership.
• Release artifact requirement recorded: package changesets.
• Final handoff shape decided: concise bug fix summary plus verification.
• Branch handling recorded: N/A, no branch/PR requested.
• Local-env-rot retry policy recorded: N/A, no env-rot failure.
• Workspace authority recorded: commands ran in .tmp/slate-v2; Browser route proof used live app.
• High-risk note recorded: native DOM selection cannot safely represent hidden boundary-spanning model ranges, so Slate keeps them model-backed instead of projecting through UI chrome.
• Review/autoreview target selected: local checkout with scoped prompt for this hidden-content shifted boundary selection fix.
• Agent-native review decision recorded: N/A, no agent/tooling changes.
• Browser pack: route, interaction path, and expected visible outcome recorded before proof.
• Browser pack: browser proof uses the repo-approved browser tool.
• Browser pack: console errors checked.
• Browser pack: exact verification evidence ready for final handoff.
• Package/API pack: public API, package boundary, export, and release-artifact impact recorded.
• Package/API pack: release artifact matrix applied with package changesets.
• Package/API pack: changeset skill loaded and one-package-per-file changesets added.
• Package/API pack: registry-only changelog N/A.
• Package/API pack: compatibility decision explicit; no public API break.
• Package/API pack: package-owned typecheck/test proof recorded.
• Package/API pack: generated barrels N/A.

Completion Gates:

Gate	Applies	Required action	Evidence
Named verification threshold	yes	Run named tests, typechecks, lint, and browser proof	All commands in Verification evidence passed.
Bug reproduced before fix	yes	Record failing browser repro	Browser before fix: Shift+ArrowRight native selection text was Accordion body, Overview, Details.
Targeted behavior verification	yes	Run focused route and package tests	Unit tests and Playwright route passed.
TypeScript or typed config changed	yes	Run relevant typecheck	bun --filter slate-react typecheck; bun --filter slate-dom typecheck passed.
Package exports or file layout changed	no	N/A	No public export/barrel layout change.
Package manifests, lockfile, or install graph changed	no	N/A	No manifest or lockfile change.
Agent rules or skills changed	no	N/A	No agent/tooling change.
Workspace authority proof	yes	Run proof in owning workspace	All commands ran in .tmp/slate-v2; plan/check in plate-2.
Browser surface changed	yes	Browser proof	In-app Browser proof passed on live route.
Browser final proof	yes	Record exact browser outcome	Empty native selection, active Overview, inactive Details, no hidden secrets for both key paths.
CI-controlled template output changed	no	N/A	No template output touched.
Package behavior or public API changed	yes	Add changesets	slate-react and slate-dom patch changesets added.
Registry-only component work changed	no	N/A	No registry-only component work.
Docs or content changed	yes	Verify plan only	This plan documents execution; no user docs changed.
High-risk mini gate	yes	Record failure mode and proof plan	Failure mode: native DOM range leaks through non-editable chrome; proof: Browser + Playwright + package tests.
Agent-native review for agent/tooling changes	no	N/A	No agent/tooling files changed.
Local install corruption suspected	no	N/A	No install-corruption signal.
Autoreview for non-trivial implementation changes	yes	Run repo autoreview helper until scoped findings are clean	Final scoped run: autoreview clean: no accepted/actionable findings reported.
PR create or update	no	N/A	No PR requested.
PR proof image hosting	no	N/A	No PR.
Tracker sync-back	no	N/A	No tracker item.
Final handoff contract	yes	Fill concise final response	Ready.
Final lint	yes	Run scoped lint	Scoped Biome passed; scoped ESLint had no errors and ignored-file warnings only.
Goal plan complete	yes	Run autogoal checker	Checker passes after this file update.
Browser interaction proof	yes	Exercise route in Browser	Browser proof passed after keyboard movement to p1 end.
Browser console/network check	yes	Check console errors	Browser error logs: []; network not separately inspected because route rendered and proof completed.
Browser final proof artifact	yes	Record exact proof	Native selection text ""; hidden secret booleans false.
Public API / package boundary proof	yes	Source-audit package boundary impact	No public API/export change; behavior-only patch.
Release artifact classification	yes	Classify release artifact	Published package behavior patch for slate-react and slate-dom.
Published package changeset	yes	Add one changeset per package	.changeset/slate-react-hidden-boundary-selection.md; .changeset/slate-dom-hidden-boundary-selection.md.
Registry changelog	no	N/A	Not registry-only.
No release artifact	no	N/A	Release artifact required and added.
Package typecheck/build/test	yes	Run package checks	Typechecks and focused package tests passed.
Barrel/export generation	no	N/A	No export changes.

Phase / pass table:

Phase	Status	Evidence	Next
Intake and source read	complete	Browser repro and screenshot source read	complete
Implementation	complete	Package fix and tests added	complete
Verification	complete	Unit, Playwright, Browser, typecheck, lint complete	complete
PR / tracker sync	complete	N/A, no PR/tracker requested	complete
Closeout	complete	Plan checker and final response	final response

Findings:

• Root cause: reconciler export projected model ranges crossing DOM coverage boundaries as native DOM ranges, which selected non-editable shadcn chrome.
• Secondary gap: shifted word movement was not Slate-owned, so Shift+Option+Right could fall through to native browser selection.

Decisions and tradeoffs:

• Keep hidden boundary-spanning selections model-backed instead of forcing unsafe native DOM ranges.
• Add opt+shift+left/right and ctrl+shift+left/right word-extension hotkeys to Slate ownership.
• Do not build a visible projected selection overlay in this bug slice.

Implementation notes:

• Added applyDOMCoverageSelectionPolicy and used it from both selection export paths.
• Kept raw DOM range projection intact for clipboard policies; verified with clipboard-boundary tests.
• Added route and package regression coverage.

Review fixes:

• Accepted autoreview finding: lower-level DOM range guard would break summary-only clipboard copy; removed that guard and added clipboard-boundary verification.
• Accepted autoreview finding: Playwright used Apple-only Option word-selection unconditionally; switched automated route row to Control+Shift+ArrowRight and kept Option coverage in platform/unit plus in-app Browser proof.
• Split changeset into one file per package.
• Ran scoped Biome fix for import/order/format issues.

Error attempts:

Error / failed attempt	Count	Next different move	Resolution
Initial Playwright Alt+Shift+ArrowRight row moved into hidden text on non-Apple Chromium	1	Use cross-platform Control+Shift+ArrowRight in Playwright	Fixed; Playwright passed.
In-app Browser direct end-coordinate click landed at paragraph start	1	Move to p1 end with repeated ArrowRight before shifted proof	Browser proof passed.
Autoreview found lower-level DOM range guard would break summary-only clipboard copy	1	Keep fix at React selection export layer and verify clipboard policy	Fixed; clipboard-boundary tests passed.
Autoreview found Playwright Option hotkey was platform-specific	1	Use Control+Shift+ArrowRight in cross-platform Playwright; keep Option in Browser proof	Fixed; scoped autoreview clean.

Verification evidence:

• Browser pre-fix repro: from p1 end, Shift+ArrowRight produced native selection text containing Accordion body, Overview, and Details.
• Browser final proof: after keyboard movement to exact p1 end, Shift+ArrowRight and Alt+Shift+ArrowRight produced native selection text "", kept Overview active, Details inactive, and did not reveal accordion/details hidden text.
• Browser console errors after proof: [].
• bun test:vitest -- keyboard-input-strategy-contract.test.ts selection-reconciler-contract.test.tsx passed: 2 files, 18 tests.
• cd packages/slate-dom && bun test ./test/dom-coverage.test.ts ./test/hotkeys.test.ts ./test/clipboard-boundary.test.ts passed: 59 tests.
• cd packages/slate-dom && bun test ./test/hotkeys.test.ts passed after Playwright hotkey change: 15 tests.
• PLAYWRIGHT_RETRIES=0 PLAYWRIGHT_WORKERS=1 bun playwright playwright/integration/examples/hidden-content-blocks.test.ts --project=chromium passed: 4 tests.
• bun --filter slate-react typecheck passed.
• bun --filter slate-dom typecheck passed.
• Scoped bunx biome check ... passed.
• Scoped bunx eslint ... had no errors; ignored-file warnings only for files outside current ESLint config match.
• Autoreview final scoped command passed: /Users/zbeyens/git/plate-2/.agents/skills/autoreview/scripts/autoreview --mode local --no-web-search --prompt "Scope this review to the hidden-content shifted boundary selection fix only: slate-dom hotkeys, slate-react caret/selection DOM coverage policy, related tests, Playwright hidden-content-blocks row, and changesets. Ignore unrelated local diffs such as mutation-controller projected-selection replacement work."

Reboot status:

• Not rebooted; no running blocker remains.

Open risks:

• None for the reported bug. Future work: visible projected selection overlay for model-backed hidden boundary ranges if product wants a visible highlight instead of an empty native selection.

Final handoff contract:

• PR line: N/A, no PR requested.
• Issue / tracker line: N/A, no tracker item.
• Confidence line: high.
• Flow table:
  • Reproduced: Browser pre-fix native selection leaked through shadcn chrome.
  • Verified: Browser, Playwright, unit tests, typecheck, and scoped lint pass.
• Browser check: passed on http://100.102.180.93:3100/examples/hidden-content-blocks.
• Outcome: shifted right and shifted word-right no longer select non-editable tab/accordion chrome or inactive hidden content.
• Caveat: model-backed hidden-boundary selections intentionally do not project a visible native highlight across missing DOM.