[bug] Prefixing dynamic path segments on redirects breaks typedRoutes, generating static routes instead of dynamic routes

[davbrito]

Link to the code that reproduces this issue

https://codesandbox.io/p/devbox/next-issue-dynamic-path-redirect-types-4kxlpc

To Reproduce

1. Add the following redirects in your next.config.js:

typedRoutes: true, // ensure typed routes enabled
redirects() {
  return [
    {
      source: "/c:id",
      destination: "/dashboard/customers/:id",
      permanent: true,
    },
    {
      source: "/p:id",
      destination: "/dashboard/products/:id",
      permanent: true,
    },
  ];
},

2. Run next typegen and notice the produced route lists:

3. Observe that routes prefixed with a dynamic path segment (e.g., /a/m:id, /a/p:id) are generated as static routes instead of dynamic routes in the type generation result.

Current vs. Expected behavior

Current behavior:

• When dynamic path segments are prefixed in redirect source paths (such as "/a/m:id"), typedRoutes generates these as static routes (e.g., "/a/m[id]") rather than dynamic routes with appropriate parameter typing.

Expected behavior:

• Dynamic segments in redirect sources should cause typedRoutes to generate those paths as dynamic routes with params.

Provide environment information

Operating System:
  Platform: linux
  Arch: x64
  Version: #1 SMP PREEMPT_DYNAMIC Sun Aug  6 20:05:33 UTC 2023
  Available memory (MB): 4102
  Available CPU cores: 2
Binaries:
  Node: 20.12.1
  npm: 10.5.0
  Yarn: N/A
  pnpm: 10.24.0
Relevant Packages:
  next: 16.0.7 // Latest available version is detected (16.0.7).
  eslint-config-next: N/A
  react: 19.2.1
  react-dom: 19.2.1
  typescript: 5.9.3
Next.js Config:
  output: N/A

Which area(s) are affected? (Select all that apply)

Dynamic Routes, Redirects

Which stage(s) are affected? (Select all that apply)

next dev (local), next build (local)

Additional context

No response