chore: upgrade TypeScript 6, Vitest 4, tsdown 0.21, Turbo 2.10 (#322)

[thedavidweng]

Issue

Implements #322 (parent #318).

Stacking note — please read

This PR depends on #370 (Vite 8 migration) and #369 (React 19 alignment). Vitest 4 peers vite: ^6 || ^7 || ^8, so it requires the Vite 8 base. This branch is based on main and includes the React 19 + Vite 8 commits from #369 and #370. The TypeScript/Vitest/tsdown/Turbo–specific changes are the last 2 commits.

For review, please focus on these files (this PR only):

• package.json (root typescript, vitest, turbo lines)
• packages/core/package.json (tsdown, typescript, @types/node lines)
• packages/cli/package.json (tsdown, typescript, @types/node lines)
• apps/web/package.json (@types/node line)
• packages/core/tsdown.config.ts
• packages/cli/tsdown.config.ts
• packages/core/tsconfig.json (removed deprecated baseUrl for TS 6)
• .changeset/typescript-vitest-tsdown-turbo.md

Once #369 and #370 merge, I will rebase this branch onto main and the diff will shrink to only the TS/Vitest/tsdown/Turbo changes.

Exact scope

Upgrade repository build/test/typecheck tooling only:

• TypeScript
• @types/node
• Vitest
• tsdown
• Turbo

No React/Vite/Biome/Oxlint/runtime library upgrades in this PR.

Versions before → after

Package	Before	After
typescript (core/cli)	^5.9.3	^6.0.3
typescript (web)	^6.0.3	^6.0.3 (aligned)
typescript (root)	(none)	6.0.3
@types/node (core/cli)	^22.19.17	^22.19.21
@types/node (web)	^25.6.0	^22.19.21 (aligned to Node 22 contract)
vitest	^2.1.9	^4.1.10
tsdown	^0.9.9	^0.21.10
turbo	^2.9.18	^2.10.5

Why the old state was a problem

• Split TypeScript generations (5.x in core/cli vs 6.x on web) hid compatibility issues
• Vitest 2 still pulled Vite 5 into the test graph after the Vite 8 migration
• tsdown 0.9 lagged the Rolldown generation used by Vite 8
• Larger future migration gaps

Why these versions were chosen

TypeScript 6.0.3 (not 7)

TypeScript 7.0.2 is the latest stable, but it is not adopted here:

Candidate	Blocker
tsdown@0.22.8 (peers include typescript@^7)	engines.node is ^22.18.0 || >=24.11.0, incompatible with the repo's Node >=22.13.0 contract from #317
tsdown@0.21.10 (Node >=20.19.0, OK for 22.13+)	peers are typescript: ^5 || ^6 only — no TypeScript 7

Selected: TypeScript 6.0.3 (newest common stable supported by tsdown 0.21.10 + the Node 22.13+ contract).

Follow-up trigger: adopt TypeScript 7 when either (a) tsdown ≥0.22 lowers Node engines to include 22.13+, or (b) the repo intentionally raises engines to match tsdown 0.22+.

Other selections

• Vitest 4.1.10: latest stable; peers vite: ^6 \|\| ^7 \|\| ^8 — resolves the Vitest→Vite 5 leftover
• tsdown 0.21.10: newest stable compatible with Node 22.13+
• Turbo 2.10.5: latest stable
• @types/node 22.19.21: matches published engines.node >=22.13.0

Breaking changes reviewed

• Vitest 2→4: config still valid; 306 tests pass unchanged (no silent snapshot updates)
• tsdown 0.9→0.21: default output became .mjs/.d.mts; set fixedExtension: false to preserve .js/.d.ts export paths
• Deprecated external → deps.neverBundle
• Build target node18 → node22 (matches package engines)
• Removed deprecated baseUrl from packages/core/tsconfig.json (TS 6 deprecates it; moduleResolution: bundler resolves paths without it)

Source changes required (this PR only)

• packages/core/tsdown.config.ts / packages/cli/tsdown.config.ts
• packages/core/tsconfig.json (remove deprecated baseUrl)
• Workspace package.json version bumps + lockfile
• Changeset for core + cli

Tests added or changed

None required; existing suite green on Vitest 4 (306 tests).

Benchmark results

Same machine, Node 24.18.0, pnpm 10.17.0. Warm-up + 5 measured runs; medians.

Metric	Before	After	Change
pnpm typecheck warm	427 ms	387 ms	−40 ms
pnpm test	2138 ms	1859 ms	−279 ms
core package build	1582 ms	1652 ms	+70 ms
CLI package build	462 ms	488 ms	+26 ms
full monorepo build cold (turbo --force)	16736 ms	15766 ms	−970 ms
packed core size	275447 B	274869 B	−578 B
packed CLI size	54366 B	54374 B	+8 B

Manual validation

On Node 24.18.0 with pnpm 10.17.0 (current main toolchain, plus the React 19 + Vite 8 base):

pnpm install
pnpm format:check / lint / typecheck / test (306 passed) / build  # pass
pnpm --filter @open-slide/core|cli pack                            # pass

Known limitations

• TypeScript 7 blocked as documented above
• tsdown 0.22+ blocked by Node engines vs chore: adopt Node.js 24 for development and support maintained LTS runtimes #317 contract
• Includes React 19 + Vite 8 commits from feat!: align core, demo, and CLI template on React 19 (#319) #369/feat!: migrate runtime to Vite 8 and native Rolldown optimizer options (#320) #370 (stacking artifact); will rebase onto main after those merge

Prohibited workarounds

Confirmed not used: --force, --legacy-peer-deps, overrides/resolutions, patch-package, prereleases, blanket suppressions, silent snapshot churn, unrelated features.

Summary by CodeRabbit

• Breaking Changes

  • React 19 is now required for the core package, CLI, and generated workspaces.
  • Generated workspaces are upgraded to Vite 8 with native optimizer configuration.

• Improvements

  • Updated build and testing tooling, including TypeScript 6, Vitest 4, tsdown, and related upgrades.
  • Improved TypeScript typings for nullable React refs across navigation/overlay components.
  • Enhanced MDX image rendering and virtual import optimization behavior.

[vercel]

@thedavidweng is attempting to deploy a commit to the open-slide Team on Vercel.

A member of the Team first needs to authorize it.

[coderabbitai]

Walkthrough

The PR aligns the monorepo with React 19, Vite 8, TypeScript 6, Vitest 4, and tsdown 0.21; migrates virtual-module optimization to Rolldown; updates Node 22 builds; and widens several React ref types to allow null.

Changes

Toolchain and runtime alignment

Layer / File(s)	Summary
Runtime and build toolchain versions .changeset/*, apps/demo/package.json, apps/web/package.json, package.json, packages/cli/package.json, packages/cli/template/package.json, packages/core/package.json	Release notes and workspace dependencies are updated for React 19, Vite 8, TypeScript 6, Vitest 4, tsdown 0.21, and aligned Node type versions.
Node 22 build configuration packages/cli/tsdown.config.ts, packages/core/tsdown.config.ts, packages/core/tsconfig.json	CLI and core builds target Node 22, configure fixed extensions, use deps.neverBundle, and remove the core baseUrl setting.
Rolldown virtual-module externalization packages/core/src/vite/config.ts, packages/core/src/vite/config.test.ts	Vite optimization now uses a Rolldown plugin to externalize virtual:open-slide/*, with tests covering matching and unrelated module IDs.
React runtime and nullable ref contracts apps/web/components/mdx.tsx, packages/core/src/app/...	MDX image props are normalized before rendering, and navigation, viewport, and inspector refs accept nullable RefObject values.

Estimated code review effort: 3 (Moderate) | ~25 minutes

Sequence Diagram(s)

sequenceDiagram
  participant ViteConfig
  participant Rolldown
  participant VirtualModuleResolver
  ViteConfig->>Rolldown: configure optimizeDeps.rolldownOptions
  Rolldown->>VirtualModuleResolver: resolveId virtual:open-slide/*
  VirtualModuleResolver-->>Rolldown: mark matching module external

Loading

Possibly related issues

• Issue 322 — Covers the TypeScript, Vitest, and tsdown upgrades represented by this PR.

Possibly related PRs

• 1weiho/open-slide#344 — Overlaps on the React/Vite upgrades, nullable refs, and virtual-module optimization.
• 1weiho/open-slide#369 — Touches the same React 19 alignment and nullable ref contract changes.
• 1weiho/open-slide#370 — Directly overlaps with the Vite 8 Rolldown optimizer migration and its tests.

Suggested reviewers: 1weiho

Poem

I hopped through React’s fresh green leaves,
While Rolldown tuned the build with ease.
Nullable refs now gently land,
TypeScript tools march paw in hand.
A carrot toast to versions new! 🐇

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly reflects the main tooling upgrades, including TypeScript 6, Vitest 4, and tsdown 0.21.

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[coderabbitai]

Actionable comments posted: 2

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In @.changeset/vite-8-migration.md:
- Line 6: Update the changeset description to a short, direct, present-tense
statement describing the user-facing Vite 8 and native Rolldown optimizer
migration.

In `@packages/cli/template/package.json`:
- Around line 14-20: Revert the dependency changes in the CLI template manifest
and leave packages/cli/template/package.json untouched. If the dependency update
is required, apply it at the appropriate source outside the excluded template
manifest, preserving the path restriction for template package.json and
open-slide.config.ts files.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro Plus

Run ID: 117649f2-9285-4508-8bec-17ea7f269add

📥 Commits

Reviewing files that changed from the base of the PR and between c408ba0 and cae47a2.

⛔ Files ignored due to path filters (1)

• pnpm-lock.yaml is excluded by !**/pnpm-lock.yaml

📒 Files selected for processing (19)

• .changeset/react-19-alignment.md
• .changeset/typescript-vitest-tsdown-turbo.md
• .changeset/vite-8-migration.md
• apps/demo/package.json
• apps/web/components/mdx.tsx
• apps/web/package.json
• package.json
• packages/cli/package.json
• packages/cli/template/package.json
• packages/cli/tsdown.config.ts
• packages/core/package.json
• packages/core/src/app/components/inspector/inspect-overlay.tsx
• packages/core/src/app/lib/use-click-page-navigation.ts
• packages/core/src/app/lib/use-wheel-page-navigation.ts
• packages/core/src/app/routes/slide.tsx
• packages/core/src/vite/config.test.ts
• packages/core/src/vite/config.ts
• packages/core/tsconfig.json
• packages/core/tsdown.config.ts

💤 Files with no reviewable changes (1)

• packages/core/tsconfig.json

[thedavidweng]

Addressed CodeRabbit review:

Fixed: Tightened the vite-8-migration.md changeset description to be shorter and more direct.

Template package.json (not reverted): Same rationale as #369/#370 — the template must align with React 19 + Vite 8 to avoid dual React copies in generated projects. The path restriction applies to slide-authoring agents, not framework-level dependency upgrades.