permissions: centralize legacy sandbox projection (#19734)

## Why

The remaining migration work still needs `SandboxPolicy` at a few
compatibility boundaries, but those projections should come from one
canonical path. Keeping ad hoc legacy projections scattered through
app-server, CLI, and config code makes it easy for behavior to drift as
`PermissionProfile` gains fidelity that the legacy enum cannot
represent.

## What Changed

- Adds `Permissions::legacy_sandbox_policy(cwd)` and
`Config::legacy_sandbox_policy()` as the compatibility projection from
the canonical `PermissionProfile`.
- Adds `Permissions::can_set_legacy_sandbox_policy()` so legacy inputs
are checked after they are converted into profile semantics.
- Updates app-server command handling, Windows sandbox setup, session
configuration, and sandbox summaries to use the centralized projection
helper.
- Leaves `SandboxPolicy` in place only for boundary inputs/outputs that
still speak the legacy abstraction.

## Verification

- `cargo check -p codex-config -p codex-core -p codex-sandboxing -p
codex-app-server -p codex-cli -p codex-tui`
- `cargo test -p codex-tui
permissions_selection_history_snapshot_full_access_to_default --
--nocapture`
- `cargo test -p codex-tui
permissions_selection_sends_approvals_reviewer_in_override_turn_context
-- --nocapture`
- `bazel test //codex-rs/tui:tui-unit-tests-bin
--test_arg=permissions_selection_history_snapshot_full_access_to_default
--test_output=errors`
- `bazel test //codex-rs/tui:tui-unit-tests-bin
--test_arg=permissions_selection_sends_approvals_reviewer_in_override_turn_context
--test_output=errors`


---
[//]: # (BEGIN SAPLING FOOTER)
Stack created with [Sapling](https://sapling-scm.com). Best reviewed
with [ReviewStack](https://reviewstack.dev/openai/codex/pull/19734).
* #19737
* #19736
* #19735
* __->__ #19734

codex-rs/tui/src/app/config_persistence.rs

@@ -300,9 +300,11 @@ impl App {
                 .set_approval_policy(self.config.permissions.approval_policy.value());
         }
         if sandbox_policy_override.is_some()
-            && let Err(err) = self
-                .chat_widget
-                .set_sandbox_policy(self.config.permissions.sandbox_policy.get().clone())
+            && let Err(err) = self.chat_widget.set_sandbox_policy(
+                self.config
+                    .permissions
+                    .legacy_sandbox_policy(self.config.cwd.as_path()),
+            )
         {
             tracing::error!(
                 error = %err,
@@ -312,8 +314,11 @@ impl App {
                 .add_error_message(format!("Failed to enable Auto-review: {err}"));
         }
         if sandbox_policy_override.is_some() {
-            self.runtime_sandbox_policy_override =
-                Some(self.config.permissions.sandbox_policy.get().clone());
+            self.runtime_sandbox_policy_override = Some(
+                self.config
+                    .permissions
+                    .legacy_sandbox_policy(self.config.cwd.as_path()),
+            );
         }
 
         if approval_policy_override.is_some()

codex-rs/tui/src/app/event_dispatch.rs

@@ -834,7 +834,10 @@ impl App {
                             /*hint*/ None,
                         ));
 
-                    let policy = self.config.permissions.sandbox_policy.get().clone();
+                    let policy = self
+                        .config
+                        .permissions
+                        .legacy_sandbox_policy(self.config.cwd.as_path());
                     let policy_cwd = self.config.cwd.clone();
                     let command_cwd = self.config.cwd.clone();
                     let env_map: std::collections::HashMap<String, String> =
@@ -1245,8 +1248,11 @@ impl App {
                         .add_error_message(format!("Failed to set sandbox policy: {err}"));
                     return Ok(AppRunControl::Continue);
                 }
-                self.runtime_sandbox_policy_override =
-                    Some(self.config.permissions.sandbox_policy.get().clone());
+                self.runtime_sandbox_policy_override = Some(
+                    self.config
+                        .permissions
+                        .legacy_sandbox_policy(self.config.cwd.as_path()),
+                );
                 self.sync_active_thread_permission_settings_to_cached_session()
                     .await;
 
@@ -1269,7 +1275,10 @@ impl App {
                             std::env::vars().collect();
                         let tx = self.app_event_tx.clone();
                         let logs_base_dir = self.config.codex_home.clone();
-                        let sandbox_policy = self.config.permissions.sandbox_policy.get().clone();
+                        let sandbox_policy = self
+                            .config
+                            .permissions
+                            .legacy_sandbox_policy(self.config.cwd.as_path());
                         Self::spawn_world_writable_scan(
                             cwd,
                             env_map,

codex-rs/tui/src/app/thread_session_state.rs

@@ -12,7 +12,10 @@ impl App {
 
         let approval_policy = self.config.permissions.approval_policy.value();
         let approvals_reviewer = self.config.approvals_reviewer;
-        let sandbox_policy = self.config.permissions.sandbox_policy.get().clone();
+        let sandbox_policy = self
+            .config
+            .permissions
+            .legacy_sandbox_policy(self.config.cwd.as_path());
         let permission_profile = Some(
             self.chat_widget
                 .config_ref()
@@ -45,7 +48,10 @@ impl App {
         thread_id: ThreadId,
         thread: &Thread,
     ) -> ThreadSessionState {
-        let sandbox_policy = self.config.permissions.sandbox_policy.get().clone();
+        let sandbox_policy = self
+            .config
+            .permissions
+            .legacy_sandbox_policy(self.config.cwd.as_path());
         let mut session = self
             .primary_session_configured
             .clone()
@@ -185,8 +191,10 @@ mod tests {
         app.chat_widget
             .set_sandbox_policy(expected_sandbox_policy.clone())
             .expect("set widget sandbox policy");
-        app.config.permissions.sandbox_policy =
-            codex_config::Constrained::allow_any(expected_sandbox_policy.clone());
+        app.config
+            .permissions
+            .set_legacy_sandbox_policy(expected_sandbox_policy.clone(), app.config.cwd.as_path())
+            .expect("set app sandbox policy");
 
         app.sync_active_thread_permission_settings_to_cached_session()
             .await;