add a flag

would be useful to have a flag to indicate that a path has been rewritten. maybe `ctx.rewrite = true` or similar. would you accept a PR?

Read the repository's URL rewriting middleware entry point to understand how rewritten paths are handled and whether rewrite state is already tracked. Clarify the expected flag semantics, then add coverage showing when the flag is set and run the existing test suite.

Written by the indexing model from the issue text.