I ran across this while building a SPA with 11ty and in these cases netlify redirects not working is really annoying.

I also created a small reproduction of the issue here: https://github.com/Snapstromegon/netlify-eleventy-dev.

This is a small, but annoying bug (and I don't know if netlify dev not working too is on this, or netlify-cli's side to fix). There is a workaround for static builds though, when you use netlify dev:

Add these two scripts to your package.json:

{
    "build:watch": "npx @11ty/eleventy --watch",
    "dev": "npx netlify-cli dev"
}

Add this to your netlify.toml

[dev]
  framework = "#static"
  autoLaunch = false
  command = "npm run build:watch"

This does not work for stuff that requires the use of the dev server like auto reloading, but it solves the base issue as a workaround.

Btw: The redirect parser is now located here: https://github.com/netlify/build/tree/main/packages/redirect-parser