add a slash command to grant sandbox read access to inaccessible directories (#11512)

There is an edge case where a directory is not readable by the sandbox.
In practice, we've seen very little of it, but it can happen so this
slash command unlocks users when it does.

Future idea is to make this a tool that the agent knows about so it can
be more integrated.

codex-rs/tui/src/slash_command.rs

@@ -17,6 +17,8 @@ pub enum SlashCommand {
     Permissions,
     #[strum(serialize = "setup-default-sandbox")]
     ElevateSandbox,
+    #[strum(serialize = "sandbox-add-read-dir")]
+    SandboxReadRoot,
     Experimental,
     Skills,
     Review,
@@ -84,7 +86,10 @@ impl SlashCommand {
             SlashCommand::Agent => "switch the active agent thread",
             SlashCommand::Approvals => "choose what Codex is allowed to do",
             SlashCommand::Permissions => "choose what Codex is allowed to do",
-            SlashCommand::ElevateSandbox => "set up default agent sandbox",
+            SlashCommand::ElevateSandbox => "set up elevated agent sandbox",
+            SlashCommand::SandboxReadRoot => {
+                "let sandbox read a directory: /sandbox-add-read-dir <absolute_path>"
+            }
             SlashCommand::Experimental => "toggle experimental features",
             SlashCommand::Mcp => "list configured MCP tools",
             SlashCommand::Apps => "manage apps",
@@ -104,7 +109,10 @@ impl SlashCommand {
     pub fn supports_inline_args(self) -> bool {
         matches!(
             self,
-            SlashCommand::Review | SlashCommand::Rename | SlashCommand::Plan
+            SlashCommand::Review
+                | SlashCommand::Rename
+                | SlashCommand::Plan
+                | SlashCommand::SandboxReadRoot
         )
     }
 
@@ -122,6 +130,7 @@ impl SlashCommand {
             | SlashCommand::Approvals
             | SlashCommand::Permissions
             | SlashCommand::ElevateSandbox
+            | SlashCommand::SandboxReadRoot
             | SlashCommand::Experimental
             | SlashCommand::Review
             | SlashCommand::Plan
@@ -151,6 +160,7 @@ impl SlashCommand {
 
     fn is_visible(self) -> bool {
         match self {
+            SlashCommand::SandboxReadRoot => cfg!(target_os = "windows"),
             SlashCommand::Rollout | SlashCommand::TestApproval => cfg!(debug_assertions),
             _ => true,
         }