path-types

# Path Types Apply this guidance when defining new types. Change existing code only when explicitly requested, and keep edits minimal and proportional. Treat these rules as the target state of an ongoing migration; if compliance is difficult, ask the user how to proceed. - In app-server protocol types, use `LegacyAppPathString` for backwards compatibility during the URI migration. At the protocol boundary, convert it to `PathUri` and use `PathUri` internally. For host-local logic, such as some config values, use `AbsolutePathBuf` or `PathBuf` instead. - In exec-server protocol types, use `PathUri`. Internally, use `PathUri` or `AbsolutePathBuf` as appropriate. - In dependencies shared by both servers, use `PathUri` or separate APIs that decouple their use cases. - Tool call arguments that the model is expected to generate should be deserialized as regular `String`s with feature-specific path handling code. ## Migration requirements Keep these requirements in mind while migrating code to conform with the above guidelines: * existing app-server clients keep sending and receiving legacy native-path strings * app-server can retain and manipulate foreign-platform path URIs * exec-server APIs use file:// URIs * local-only operation must not change model-visible text * model tool arguments may contain raw relative or absolute paths for any OS * path reasoning must work before the related environment has come online * URIs cannot explicitly encode the executor’s path c...