Added model summary and risk assessment for commands that violate sandbox policy (#5536)

This PR adds support for a model-based summary and risk assessment for
commands that violate the sandbox policy and require user approval. This
aids the user in evaluating whether the command should be approved.

The feature works by taking a failed command and passing it back to the
model and asking it to summarize the command, give it a risk level (low,
medium, high) and a risk category (e.g. "data deletion" or "data
exfiltration"). It uses a new conversation thread so the context in the
existing thread doesn't influence the answer. If the call to the model
fails or takes longer than 5 seconds, it falls back to the current
behavior.

For now, this is an experimental feature and is gated by a config key
`experimental_sandbox_command_assessment`.

Here is a screen shot of the approval prompt showing the risk assessment
and summary.

<img width="723" height="282" alt="image"
src="https://github.com/user-attachments/assets/4597dd7c-d5a0-4e9f-9d13-414bd082fd6b"
/>

codex-rs/core/src/codex.rs

@@ -88,6 +88,7 @@ use crate::protocol::Op;
 use crate::protocol::RateLimitSnapshot;
 use crate::protocol::ReviewDecision;
 use crate::protocol::ReviewOutputEvent;
+use crate::protocol::SandboxCommandAssessment;
 use crate::protocol::SandboxPolicy;
 use crate::protocol::SessionConfiguredEvent;
 use crate::protocol::StreamErrorEvent;
@@ -755,6 +756,32 @@ impl Session {
         }
     }
 
+    pub(crate) async fn assess_sandbox_command(
+        &self,
+        turn_context: &TurnContext,
+        call_id: &str,
+        command: &[String],
+        failure_message: Option<&str>,
+    ) -> Option<SandboxCommandAssessment> {
+        let config = turn_context.client.config();
+        let provider = turn_context.client.provider().clone();
+        let auth_manager = Arc::clone(&self.services.auth_manager);
+        let otel = self.services.otel_event_manager.clone();
+        crate::sandboxing::assessment::assess_command(
+            config,
+            provider,
+            auth_manager,
+            &otel,
+            self.conversation_id,
+            call_id,
+            command,
+            &turn_context.sandbox_policy,
+            &turn_context.cwd,
+            failure_message,
+        )
+        .await
+    }
+
     /// Emit an exec approval request event and await the user's decision.
     ///
     /// The request is keyed by `sub_id`/`call_id` so matching responses are delivered
@@ -767,6 +794,7 @@ impl Session {
         command: Vec<String>,
         cwd: PathBuf,
         reason: Option<String>,
+        risk: Option<SandboxCommandAssessment>,
     ) -> ReviewDecision {
         let sub_id = turn_context.sub_id.clone();
         // Add the tx_approve callback to the map before sending the request.
@@ -792,6 +820,7 @@ impl Session {
             command,
             cwd,
             reason,
+            risk,
             parsed_cmd,
         });
         self.send_event(turn_context, event).await;