permissions: remove cwd special path (#19841)

## Why

The experimental `PermissionProfile` API had both `:cwd` and
`:project_roots` special filesystem paths, which made the permission
root ambiguous. This PR removes the unstable `current_working_directory`
special path before the permissions API is stabilized, so callers use
`:project_roots` for symbolic project-root access.

## What changed

- Removes `FileSystemSpecialPath::CurrentWorkingDirectory` from protocol
and app-server protocol models, plus regenerated app-server
JSON/TypeScript schemas.
- Replaces internal `:cwd` permission entries with `:project_roots`
entries.
- Keeps the existing cwd-update behavior for legacy-shaped
workspace-write profiles, while removing the deleted
`CurrentWorkingDirectory` case from that compatibility path.
- Keeps `PermissionProfile::workspace_write()` as the reusable symbolic
workspace-write helper, with docs noting that `:project_roots` entries
resolve at enforcement time.
- Updates app-server docs/examples and approval UI labeling to stop
advertising `:cwd` as a permission token.

## Compatibility

Persisted rollout items may contain the old
`{"kind":"current_working_directory"}` tag from earlier experimental
`permissionProfile` snapshots. This PR keeps that tag as a
deserialize-only alias for `ProjectRoots { subpath: None }`, while
continuing to serialize only the new `project_roots` tag.

## Follow-up

This PR intentionally does not introduce an explicit project-root set on
`SessionConfiguration` or runtime sandbox resolution. Today, the
resolver still uses the active cwd as the single implicit project root.
A follow-up should model project roots separately from tool cwd so
`:project_roots` entries can resolve against the configured project
roots, and resolve to no entries when there are no project roots.

## Verification

- `cargo test -p codex-protocol permissions:: --lib`
- `cargo test -p codex-app-server-protocol`
- `cargo test -p codex-sandboxing -p codex-exec-server --lib`
- `cargo test -p codex-core session_configuration_apply_ --lib`
- `cargo test -p codex-app-server
command_exec_permission_profile_project_roots_use_command_cwd --test
all`
- `cargo test -p codex-tui
thread_read_session_state_does_not_reuse_primary_permission_profile
--lib`
- `cargo test -p codex-tui
preset_matching_accepts_workspace_write_with_extra_roots --lib`
- `cargo test -p codex-config --lib`

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

@@ -117,9 +117,7 @@ pub(crate) fn file_system_policy_has_cwd_dependent_entries(
         .any(|entry| match &entry.path {
             FileSystemPath::GlobPattern { pattern } => !Path::new(pattern).is_absolute(),
             FileSystemPath::Special {
-                value:
-                    FileSystemSpecialPath::CurrentWorkingDirectory
-                    | FileSystemSpecialPath::ProjectRoots { .. },
+                value: FileSystemSpecialPath::ProjectRoots { .. },
             } => true,
             FileSystemPath::Path { .. } | FileSystemPath::Special { .. } => false,
         })

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

@@ -118,7 +118,7 @@ fn sandbox_cwd(sandbox: &FileSystemSandboxContext) -> Result<AbsolutePathBuf, JS
     let file_system_policy = sandbox.permissions.file_system_sandbox_policy();
     if file_system_policy_has_cwd_dependent_entries(&file_system_policy) {
         return Err(invalid_request(
-            "file system sandbox context with cwd-relative permissions requires cwd".to_string(),
+            "file system sandbox context with dynamic permissions requires cwd".to_string(),
         ));
     }
 
@@ -467,7 +467,7 @@ mod tests {
         let cwd = AbsolutePathBuf::from_absolute_path(std::env::temp_dir().as_path())
             .expect("absolute cwd");
         let policy = restricted_policy(vec![special_entry(
-            FileSystemSpecialPath::CurrentWorkingDirectory,
+            FileSystemSpecialPath::project_roots(/*subpath*/ None),
             FileSystemAccessMode::Write,
         )]);
         let sandbox_context = sandbox_context_with_cwd(&policy, cwd.clone());
@@ -479,7 +479,7 @@ mod tests {
     fn sandbox_cwd_rejects_cwd_dependent_profile_without_context_cwd() {
         let policy = FileSystemSandboxPolicy::restricted(vec![FileSystemSandboxEntry {
             path: FileSystemPath::Special {
-                value: FileSystemSpecialPath::CurrentWorkingDirectory,
+                value: FileSystemSpecialPath::project_roots(/*subpath*/ None),
             },
             access: FileSystemAccessMode::Write,
         }]);
@@ -491,7 +491,7 @@ mod tests {
 
         assert_eq!(
             err.message,
-            "file system sandbox context with cwd-relative permissions requires cwd"
+            "file system sandbox context with dynamic permissions requires cwd"
         );
     }
 

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

@@ -252,7 +252,7 @@ mod tests {
     fn remote_sandbox_context_preserves_required_cwd() {
         let policy = FileSystemSandboxPolicy::restricted(vec![FileSystemSandboxEntry {
             path: FileSystemPath::Special {
-                value: FileSystemSpecialPath::CurrentWorkingDirectory,
+                value: FileSystemSpecialPath::project_roots(/*subpath*/ None),
             },
             access: FileSystemAccessMode::Write,
         }]);