FE-866: Use Vite native React Compiler

[kube]

🌟 What is the purpose of this PR?

Use Vite's native Oxc-based React Compiler integration now that it is available in @vitejs/plugin-react, removing the separate Babel transform from the affected Petrinaut builds.

🔗 Related links

• feat(react): add native React Compiler support vitejs/vite-plugin-react#1419

🚫 Blocked by

• Nothing

🔍 What does this change?

• Upgrades @vitejs/plugin-react from 6.0.1 to 6.1.0 in @apps/petrinaut-website, @hashintel/petrinaut, and @hashintel/refractive.
• Replaces @rolldown/plugin-babel and babel-plugin-react-compiler with oxc-transform-react 0.145.0.
• Moves the existing React Compiler options onto the Vite React plugin's native compiler option.
• Excludes generated .d.ts files in the two library builds so the native transform does not interfere with rolldown-plugin-dts output.
• Keeps the existing exclusions for prebuilt workspace output and @hashintel/ds-components.

Build performance compared with main

Package	Main median	Native compiler median	Peak RSS change
@hashintel/refractive	1.32s	1.05s	—
@hashintel/petrinaut	10.72s	6.35s	approximately 17% lower
@apps/petrinaut-website	9.16s	3.47s	approximately 46% lower

Pre-Merge Checklist 🚀

🚢 Has this modified a publishable library?

This PR:

• does not modify any publishable blocks or libraries, or modifications do not need publishing

📜 Does this require a change to the docs?

The changes in this PR:

• are internal and do not require a docs change

🕸️ Does this require a change to the Turbo Graph?

The changes in this PR:

• do not affect the execution graph

⚠️ Known issues

The native compiler emits non-fatal experimental bailout diagnostics for some existing Petrinaut components and hooks. Those files remain valid and are skipped by the compiler where unsupported; builds complete successfully with panicThreshold: "critical_errors".

🐾 Next steps

• Consider reducing the remaining compiler bailout diagnostics independently where the refactors improve the source code.

🛡 What tests cover this?

• yarn install --immutable
• yarn constraints
• yarn lint:format
• yarn exec turbo run build --filter @apps/petrinaut-website
• TypeScript and lint checks for all three affected packages
• 202 Petrinaut unit tests
• 2 Petrinaut website unit tests

❓ How to test this?

1. Install dependencies with the immutable lockfile.
2. Build the three affected packages through Turborepo.
3. Confirm the builds complete and the expected non-fatal Oxc bailout diagnostics do not become critical errors.

[vercel]

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Project	Deployment	Actions	Updated (UTC)
petrinaut	Ready	Preview	Aug 27, 2026 12:45pm

3 Skipped Deployments

Project	Deployment	Actions	Updated (UTC)
hash	Ignored	Preview	Aug 27, 2026 12:45pm
hashdotdesign-tokens	Ignored	Preview	Aug 27, 2026 12:45pm
petrinaut-docs	Ignored	Preview	Aug 27, 2026 12:45pm

[cursor]

PR Summary

Medium Risk
Build-time behavior changes for all compiled React in three packages; runtime output should match but compiler bailouts and edge-case transforms differ from Babel until validated in CI and manual builds.

Overview
Switches petrinaut-website, @hashintel/petrinaut, and @hashintel/refractive from a separate Babel React Compiler pipeline to @vitejs/plugin-react 6.1.0’s built-in compiler option backed by oxc-transform-react.

Dependencies: drops @rolldown/plugin-babel and babel-plugin-react-compiler; bumps the React plugin and lockfile accordingly. Petrinaut docs now reference Oxc instead of Babel for the compiler stack.

Vite config: each app/library uses a single react({ compiler: { target: "19", compilationMode: "infer", panicThreshold: "critical_errors" } }) plugin instead of react() + babel({ presets: [reactCompilerPreset(...)] }). Existing exclude rules are preserved or tightened: @hashintel/ds-components / prebuilt jsx() output on the website and petrinaut builds; library builds also skip \.d\.ts$ so rolldown-plugin-dts output is not run through the native transform.

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