In Cloudflare Workers, Request.headers is immutable per the Fetch API spec.
headersContextFromRequest was storing the original request.headers reference
directly in HeadersContext, so when applyMiddlewareRequestHeaders later called
ctx.headers.set() (to propagate middleware-modified headers like x-request-url
into the server component context), Workers threw:
TypeError: Can't modify immutable headers.
Fix by wrapping with new Headers(request.headers), which creates an independent
mutable copy while preserving all header values.
harris.dev
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