[R2] Fix custom header middleware examples

[rdimaio]

Summary

Fixes the R2 AWS SDK for JavaScript v3 examples by narrowing middleware requests to Smithy HttpRequest objects and updating their header maps directly.

Current Smithy middleware types define args.request as unknown and require callers to guard it as an HTTP request before modification. The original RequestInit cast produced strict TypeScript errors because RequestInit.headers may be undefined and its HeadersInit type cannot be indexed by header name.

The corrected examples compile under strict TypeScript with the current AWS SDK. Runtime testing with a stub request handler also confirmed that both custom headers reach the serialized S3 request.

Documentation checklist

• The change adheres to the documentation style guide.

[cloudflare-docs-bot]

Review

🚨 2 critical, ⚠️ 1 warning found in commit 92abc82.

👉 Fix in your agent 👈

Fix the following review findings in PR #32596 (https://github.com/cloudflare/cloudflare-docs/pull/32596).

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---

## Code Review

### Critical (2)

#### CR-ecff8637db23 · Incorrect module import
- **File:** `src/content/docs/r2/examples/aws/custom-header.mdx` line 49
- **Issue:** The example imports `HttpRequest` from `@smithy/core/protocols`, but the runtime `HttpRequest` class (and its `isInstance` method) is exported from `@smithy/protocol-http`. This subpath does not exist in `@smithy/core`, so users copying the snippet will get a module-resolution or build error.
- **Fix:** Change this import to `import { HttpRequest } from "@smithy/protocol-http";`. The same correction is needed at line 132.

#### CR-72622b8fb770 · Incorrect module import
- **File:** `src/content/docs/r2/examples/aws/custom-header.mdx` line 132
- **Issue:** This TypeScript snippet repeats the same incorrect import at line 49: `HttpRequest` is not exported from `@smithy/core/protocols`.
- **Fix:** Change this import to `import { HttpRequest } from "@smithy/protocol-http";`.

---

## Style Guide Review

### Warnings (1)

#### SG-45b5e0f0ae5d · Internal links should use root-relative paths
- **File:** `src/content/docs/r2/examples/aws/custom-header.mdx` line 138
- **Issue:** Comment includes the full internal URL `https://developers.cloudflare.com/r2/api/tokens`.
- **Fix:** Use a root-relative path with a trailing slash: `/r2/api/tokens/`.

Code Review

This code review is in beta and may not always be helpful — use your judgment.

Critical (2)

File	Issue
r2/examples/aws/custom-header.mdx line 49	Incorrect module import — The example imports HttpRequest from @smithy/core/protocols, but the runtime HttpRequest class (and its isInstance method) is exported from @smithy/protocol-http. This subpath does not exist in @smithy/core, so users copying the snippet will get a module-resolution or build error. Fix: Change this import to import { HttpRequest } from "@smithy/protocol-http";. The same correction is needed at line 132.
r2/examples/aws/custom-header.mdx line 132	Incorrect module import — This TypeScript snippet repeats the same incorrect import at line 49: HttpRequest is not exported from @smithy/core/protocols. Fix: Change this import to import { HttpRequest } from "@smithy/protocol-http";.

Conventions

_{No convention issues found.}

Style Guide Review

Warnings (1)

File	Issue
r2/examples/aws/custom-header.mdx line 138	Internal links should use root-relative paths — Comment includes the full internal URL https://developers.cloudflare.com/r2/api/tokens. Fix: Use a root-relative path with a trailing slash: /r2/api/tokens/.

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