Bug: Hyphen in dynamic route slug causes regex syntax error

[tsuyuni]

Problem Description

When using OpenNext for Cloudflare, dynamic routes containing hyphens in the slug (e.g., [...better-auth]) are not properly escaped when converted to regular expressions, causing the following error:

Uncaught SyntaxError: Invalid regular expression: /^/(?:)?api/auth/[...better-auth](?:/)?$/: Range out of order in character class

Steps to Reproduce

1. Create a Next.js application with the following route structure:

   src/app/api/auth/[...better-auth]/route.ts
   

2. Build with OpenNext Cloudflare:

   opennextjs-cloudflare build

3. Deploy to Cloudflare Workers - the above error occurs during runtime

Root Cause

In regular expressions, hyphens within character classes [] are treated as range operators (e.g., [a-z]). When [...better-auth] is converted to a regex pattern, the hyphen is not properly escaped within the character class, causing a "Range out of order" error because . and a don't form a valid range.

Expected Behavior

The hyphen should be properly escaped in the generated regex:

/^/(?:)?api/auth/[...better\-auth](?:/)?$/

Or the hyphen should be placed at the beginning or end of the character class:

/^/(?:)?api/auth/[-...betterauth](?:/)?$/

Current Workaround

Use slug names without hyphens:

src/app/api/auth/[...auth]/route.ts

Environment

• Next.js: 15.3.4
• @opennextjs/cloudflare: ^1.4.0
• Node.js: v18+
• Cloudflare Workers

Impact

This prevents using popular authentication libraries like Better Auth that use hyphened route names by convention ([...better-auth]).

[vicb]

Could you please attach a repro (link to a GH repository).
I can not reproduce locally