path-uri: remove legacy path deserialization (#29158)

## Why

I'd originally added `PathUri` legacy path deserialization thinking we'd
want it for having `PathUri` in public app-server APIs. Since then we've
added `LegacyAppPathString` to handle the messy conversions that we need
for backcompat. It's confusing for `PathUri` to support deserializing
legacy paths when we don't yet want to actually expose app-server
callers or rollout storage to the new URI format.

Stacked on top of #29472 to avoid breaking compatibility in case those
types ended up stored somewhere for someone.

## What changed

- Parse deserialized `PathUri` values exclusively as valid `file:` URIs.
- Replace legacy acceptance coverage with rejection coverage for
top-level filesystem paths and sandbox working directories.
- Serialize CWDs in hand-built exec-server process requests as `PathUri`
values.

codex-rs/exec-server/README.md

@@ -340,9 +340,9 @@ Params:
 
 ## Filesystem RPCs
 
-Filesystem methods use canonical `file:` URIs and return JSON-RPC errors for
-invalid or unavailable paths. For compatibility, requests also accept native
-absolute path strings and normalize them to `file:` URIs:
+Filesystem methods require valid `file:` URI strings and return JSON-RPC errors
+for invalid or unavailable paths. Native absolute path strings are rejected;
+callers must convert them to `file:` URIs before sending requests:
 
 - `fs/readFile`
 - `fs/open`, `fs/readBlock`, and `fs/close` (internal transport for

codex-rs/exec-server/src/protocol.rs

@@ -591,38 +591,33 @@ mod tests {
     }
 
     #[test]
-    fn filesystem_protocol_accepts_legacy_absolute_paths_and_serializes_path_uris() {
-        let legacy_path = std::env::current_dir()
+    fn filesystem_protocol_rejects_native_absolute_paths() {
+        let native_path = std::env::current_dir()
             .expect("current directory")
-            .join("legacy-file.txt");
-        let legacy_cwd = std::env::current_dir().expect("current directory");
-        let native_sandbox = FileSystemSandboxContext::from_permission_profile_with_cwd(
-            PermissionProfile::default(),
-            PathUri::from_host_native_path(&legacy_cwd).expect("cwd URI"),
-        );
-        let mut legacy_sandbox =
-            serde_json::to_value(&native_sandbox).expect("sandbox should serialize");
-        legacy_sandbox["cwd"] = serde_json::json!(legacy_cwd.to_string_lossy());
-        let params: FsReadFileParams = serde_json::from_value(serde_json::json!({
-            "path": legacy_path.to_string_lossy(),
-            "sandbox": legacy_sandbox,
-        }))
-        .expect("legacy absolute path should deserialize");
-        let expected_sandbox = native_sandbox;
-        let expected = FsReadFileParams {
-            path: PathUri::from_host_native_path(legacy_path).expect("path URI"),
-            sandbox: Some(expected_sandbox.clone()),
-        };
+            .join("native-file.txt");
+        let native_cwd = std::env::current_dir().expect("current directory");
 
-        assert_eq!(params, expected);
-        assert_eq!(
-            serde_json::to_value(params).expect("params should serialize"),
-            serde_json::json!({
-                "path": expected.path.to_string(),
-                "sandbox": serde_json::to_value(expected_sandbox)
-                    .expect("sandbox should serialize"),
-            })
+        serde_json::from_value::<FsReadFileParams>(serde_json::json!({
+            "path": native_path.to_string_lossy(),
+            "sandbox": null,
+        }))
+        .expect_err("native absolute path should not deserialize as a URI");
+
+        let sandbox = FileSystemSandboxContext::from_permission_profile_with_cwd(
+            PermissionProfile::default(),
+            PathUri::from_host_native_path(&native_cwd).expect("cwd URI"),
         );
+        let mut native_path_sandbox =
+            serde_json::to_value(sandbox).expect("sandbox should serialize");
+        native_path_sandbox["cwd"] = serde_json::json!(native_cwd.to_string_lossy());
+
+        serde_json::from_value::<FsReadFileParams>(serde_json::json!({
+            "path": PathUri::from_host_native_path(native_path)
+                .expect("path URI")
+                .to_string(),
+            "sandbox": native_path_sandbox,
+        }))
+        .expect_err("native absolute sandbox cwd should not deserialize as a URI");
     }
 
     #[test]

codex-rs/exec-server/tests/process.rs

@@ -12,6 +12,7 @@ use codex_exec_server::ReadResponse;
 use codex_exec_server::TerminateResponse;
 use codex_exec_server::WriteResponse;
 use codex_exec_server::WriteStatus;
+use codex_utils_path_uri::PathUri;
 use common::exec_server::exec_server;
 use pretty_assertions::assert_eq;
 
@@ -46,7 +47,7 @@ async fn exec_server_starts_process_over_websocket() -> anyhow::Result<()> {
             serde_json::json!({
                 "processId": "proc-1",
                 "argv": ["true"],
-                "cwd": std::env::current_dir()?,
+                "cwd": PathUri::from_host_native_path(std::env::current_dir()?)?,
                 "env": {},
                 "tty": false,
                 "pipeStdin": false,
@@ -113,7 +114,7 @@ async fn exec_server_defaults_omitted_pipe_stdin_to_closed_stdin() -> anyhow::Re
                     "-c",
                     "sleep 0.3; if IFS= read -r line; then printf 'read:%s\\n' \"$line\"; else printf 'eof\\n'; fi"
                 ],
-                "cwd": std::env::current_dir()?,
+                "cwd": PathUri::from_host_native_path(std::env::current_dir()?)?,
                 "env": {},
                 "tty": false,
                 "arg0": null
@@ -207,7 +208,7 @@ async fn exec_server_dedupes_retried_process_write_ids() -> anyhow::Result<()> {
                     "-c",
                     "IFS= read -r first; printf 'line:%s\\n' \"$first\"; IFS= read -r second; printf 'line:%s\\n' \"$second\""
                 ],
-                "cwd": std::env::current_dir()?,
+                "cwd": PathUri::from_host_native_path(std::env::current_dir()?)?,
                 "env": {},
                 "tty": false,
                 "pipeStdin": true,
@@ -341,7 +342,7 @@ async fn exec_server_resumes_detached_session_without_killing_processes() -> any
             serde_json::json!({
                 "processId": "proc-resume",
                 "argv": ["/bin/sh", "-c", "sleep 5"],
-                "cwd": std::env::current_dir()?,
+                "cwd": PathUri::from_host_native_path(std::env::current_dir()?)?,
                 "env": {},
                 "tty": false,
                 "pipeStdin": false,

codex-rs/utils/path-uri/src/lib.rs

@@ -45,13 +45,9 @@ const BAD_PATH_URI_PREFIX: &str = "file:///%00/bad/path/";
 /// are not resolved.
 ///
 /// Serde represents a `PathUri` as its canonical URI string. Deserialization
-/// also accepts an absolute native path for compatibility with fields that
-/// previously used [`AbsolutePathBuf`]; relative paths are rejected. Valid
-/// `file:` strings round-trip through their canonical URL form, including
-/// encoded non-UTF-8 path bytes, but conversion to a native path remains
-/// host-dependent as described by [RFC 8089].
+/// accepts only valid `file:` URI strings. These strings round-trip through
+/// their canonical URL form, including encoded non-UTF-8 path bytes.
 ///
-/// [RFC 8089]: https://www.rfc-editor.org/rfc/rfc8089.html
 /// [VS Code resources]: https://github.com/microsoft/vscode/blob/main/src/vs/base/common/resources.ts
 #[derive(Clone, Debug, PartialEq, Eq, Hash, TS)]
 #[ts(type = "string")]
@@ -478,30 +474,7 @@ impl<'de> Deserialize<'de> for PathUri {
         D: Deserializer<'de>,
     {
         let value = String::deserialize(deserializer)?;
-        let unsupported_scheme = match Url::parse(&value) {
-            Ok(url) => match Self::try_from(url) {
-                Ok(uri) => return Ok(uri),
-                // `Url` parses a Windows drive prefix such as `C:\` as the
-                // scheme `c`. Give any unsupported URI one chance to satisfy
-                // the native absolute-path invariant before reporting it.
-                Err(error @ PathUriParseError::UnsupportedScheme(_)) => Some(error),
-                Err(error) => return Err(serde::de::Error::custom(error)),
-            },
-            Err(url::ParseError::RelativeUrlWithoutBase) => None,
-            Err(error) => {
-                return Err(serde::de::Error::custom(PathUriParseError::InvalidUri(
-                    error,
-                )));
-            }
-        };
-
-        let path = AbsolutePathBuf::from_absolute_path_checked(value).map_err(|path_error| {
-            serde::de::Error::custom(
-                unsupported_scheme
-                    .map_or_else(|| path_error.to_string(), |error| error.to_string()),
-            )
-        })?;
-        Ok(Self::from_abs_path(&path))
+        Self::parse(&value).map_err(serde::de::Error::custom)
     }
 }
 

codex-rs/utils/path-uri/src/tests.rs

@@ -1,5 +1,4 @@
 use super::*;
-use codex_utils_absolute_path::AbsolutePathBufGuard;
 use pretty_assertions::assert_eq;
 #[cfg(windows)]
 use std::ffi::OsString;
@@ -418,14 +417,14 @@ fn path_uri_serializes_as_a_string() {
 }
 
 #[test]
-fn path_uri_deserializes_legacy_absolute_paths() {
+fn path_uri_rejects_native_absolute_paths_during_deserialization() {
     let path = AbsolutePathBuf::current_dir()
         .expect("current directory")
         .join("workspace/src");
     let json = serde_json::to_string(&path).expect("absolute path should serialize");
-    let uri: PathUri = serde_json::from_str(&json).expect("legacy absolute path should parse");
 
-    assert_eq!(uri, PathUri::from_abs_path(&path));
+    serde_json::from_str::<PathUri>(&json)
+        .expect_err("native absolute path should not deserialize as a URI");
 }
 
 #[test]
@@ -437,13 +436,11 @@ fn path_uri_rejects_relative_native_paths() {
 }
 
 #[test]
-fn path_uri_rejects_legacy_relative_paths_with_absolute_path_guard() {
-    let base = AbsolutePathBuf::current_dir().expect("current directory");
-    let _guard = AbsolutePathBufGuard::new(base.as_path());
+fn path_uri_rejects_relative_strings_during_deserialization() {
     let error = serde_json::from_str::<PathUri>(r#""src/lib.rs""#)
-        .expect_err("legacy relative path should be rejected");
+        .expect_err("relative path should be rejected");
 
-    assert!(error.to_string().contains("path is not absolute"));
+    assert!(error.to_string().contains("relative URL without a base"));
 }
 
 #[test]