SRE-415: Fix vercel not building

[TimDiekmann]

🌟 What is the purpose of this PR?

Remove the sourcing of Cargo environment variables in the Vercel build script, as it's no longer needed with mise handling environment setup.

🔗 Related links

• https://linear.app/hash/issue/H-3212/clean-up-env-files (internal)
• https://linear.app/hash/issue/H-3213/use-consistent-naming-schema-for-environment-variables (internal)
• https://linear.app/hash/issue/H-4202/sort-out-which-environment-variables-are-defined-where (internal)

🔍 What does this change?

• Removes source "$HOME/.cargo/env" from the Vercel build script
• Adds a reference to H-3212 in the environment variable cleanup comments

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

🛡 What tests cover this?

• Vercel build process will validate this change works correctly

❓ How to test this?

1. Checkout the branch
2. Verify the Vercel build completes successfully without the Cargo environment sourcing

[vercel]

The latest updates on your projects. Learn more about Vercel for GitHub.

2 Skipped Deployments

Project	Deployment	Actions	Updated (UTC)
hashdotdesign	Ignored	Preview	Feb 1, 2026 0:03am
hashdotdesign-tokens	Ignored	Preview	Feb 1, 2026 0:03am

[cursor]

PR Summary

Low Risk
Build-script-only change removing Cargo env sourcing; primary risk is Vercel builds failing if Rust tooling was implicitly required.

Overview
Removes source "$HOME/.cargo/env" from apps/hash-frontend/vercel-build.sh, relying solely on mise to set up the build environment for Vercel.

Adds an additional internal issue link to the existing .env cleanup comments.

^{Written by Cursor Bugbot for commit 66a0436. This will update automatically on new commits. Configure here.}

[TimDiekmann]

• BE-359: Refactor entity embedding generation to use entity IDs instead of full entities #8345
• BE-310: Protect sensitive properties from enumeration attacks #8332
• SRE-415: Fix vercel not building #8342 👈 (View in Graphite)
• main

This stack of pull requests is managed by Graphite. Learn more about stacking.

[augmentcode]

🤖 Augment PR Summary

Summary: Stops sourcing $HOME/.cargo/env during Vercel builds now that mise handles environment setup.

Changes: Removes the Cargo env sourcing step and adds a reference to H-3212 for ongoing environment variable cleanup.

_{🤖 Was this summary useful? React with 👍 or 👎}

[augmentcode]

Review completed. No suggestions at this time.

Comment augment review to trigger a new review at any time.