Document Rust requirement for macOS development setup

[tzahari]

Proposed change

The macOS setup instructions list the Homebrew packages needed for local development, but script/setup can fail if no Rust toolchain is installed: several Python dependencies of Home Assistant (such as cryptography, orjson, and pydantic-core) contain Rust extensions, and pip needs rustc/cargo to build them from source whenever no prebuilt wheel is available for the current Python version and platform.

This adds a short note to the "Developing on macOS" section explaining when Rust is needed and how to install it via Homebrew.

Type of change

• Document existing features within Home Assistant
• Document new or changing features which there is an existing pull request elsewhere
• Spelling or grammatical corrections, or rewording for improved clarity
• Changes to the backend of this documentation
• Remove stale or deprecated documentation

Checklist

• I have read and followed the documentation guidelines.
• The documentation follows the Home Assistant documentation standards.

🤖 Generated with Claude Code

Summary by CodeRabbit

• Documentation
  • Updated macOS development setup instructions to include an extra Rust installation step.
  • Clarified what to do if setup fails because rustc or cargo are missing.
  • Added guidance for installing Rust with Homebrew when required by native dependency builds.

[coderabbitai]

📝 Walkthrough

Walkthrough

This PR adds documentation to development_environment.mdx explaining that some Home Assistant Python dependencies compile native Rust extensions from source, and instructs macOS users to install Rust via Homebrew if script/setup fails due to missing rustc/cargo.

Changes

Documentation update

Layer / File(s)	Summary
Add Rust setup instructions docs/development_environment.mdx	Adds macOS instructions explaining when Rust is required to build Python dependencies from source and how to install Rust via Homebrew if script/setup fails.

Estimated code review effort: 1 (Trivial) | ~2 minutes

Estimated code review effort

1 (Trivial) | ~2 minutes

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly summarizes the main change: documenting the Rust requirement for macOS development setup.
Description check	✅ Passed	The description covers the proposed change, type of change, and checklist, with only the optional additional information section omitted.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
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.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands.}

[coderabbitai]

🧹 Nitpick comments (1)

docs/development_environment.mdx (1)

169-169: 📐 Maintainability & Code Quality | 🔵 Trivial | 💤 Low value

Front the goal before the conditional clause.

The instructional sentence places the action ("install Rust as well") after the condition. Per path instructions, front the goal.

✏️ Suggested rewording

-Some Python dependencies of Home Assistant, such as `cryptography` and `orjson`, contain extensions written in Rust. If no prebuilt wheel is available for your Python version and platform, pip builds them from source, which requires a [Rust toolchain](https://www.rust-lang.org/tools/install). If the `script/setup` script below fails because `rustc` or `cargo` is missing, install Rust as well:
+Some Python dependencies of Home Assistant, such as `cryptography` and `orjson`, contain extensions written in Rust. If no prebuilt wheel is available for your Python version and platform, pip builds them from source, which requires a [Rust toolchain](https://www.rust-lang.org/tools/install). Install Rust as well if the `script/setup` script below fails because `rustc` or `cargo` is missing:

As per path instructions, "In step-by-step instructions, if in doubt what to front, front the 'goal' before the location phrase in the instructional sentence."

🤖 Prompt for 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.

In `@docs/development_environment.mdx` at line 169, Reword the instructional
sentence in the documentation so the goal comes first: place “install Rust as
well” before the conditional clause about `script/setup` failing due to missing
`rustc` or `cargo`. Keep the rest of the sentence structure intact and preserve
the references to `script/setup`, `rustc`, and `cargo` so the guidance reads as
a fronted goal followed by the condition.

Source: Path instructions

🤖 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.

Nitpick comments:
In `@docs/development_environment.mdx`:
- Line 169: Reword the instructional sentence in the documentation so the goal
comes first: place “install Rust as well” before the conditional clause about
`script/setup` failing due to missing `rustc` or `cargo`. Keep the rest of the
sentence structure intact and preserve the references to `script/setup`,
`rustc`, and `cargo` so the guidance reads as a fronted goal followed by the
condition.

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

Run ID: ab629aa9-4ca1-42cb-bb0c-12345e8c2ec2

📥 Commits

Reviewing files that changed from the base of the PR and between 151f4d9 and 4f48d12.

📒 Files selected for processing (1)

• docs/development_environment.mdx