feat(core) RequestRule (#9489)

## Summary
Instead of trying to derive the prefix_rule for a command mechanically,
let's let the model decide for us.

## Testing
- [x] tested locally

codex-rs/core/src/tools/handlers/shell.rs

@@ -6,6 +6,7 @@ use std::sync::Arc;
 use crate::codex::TurnContext;
 use crate::exec::ExecParams;
 use crate::exec_env::create_env;
+use crate::exec_policy::ExecApprovalRequest;
 use crate::function_tool::FunctionCallError;
 use crate::is_safe_command::is_known_safe_command;
 use crate::protocol::ExecCommandSource;
@@ -28,16 +29,27 @@ pub struct ShellHandler;
 
 pub struct ShellCommandHandler;
 
+struct RunExecLikeArgs {
+    tool_name: String,
+    exec_params: ExecParams,
+    prefix_rule: Option<Vec<String>>,
+    session: Arc<crate::codex::Session>,
+    turn: Arc<TurnContext>,
+    tracker: crate::tools::context::SharedTurnDiffTracker,
+    call_id: String,
+    freeform: bool,
+}
+
 impl ShellHandler {
-    fn to_exec_params(params: ShellToolCallParams, turn_context: &TurnContext) -> ExecParams {
+    fn to_exec_params(params: &ShellToolCallParams, turn_context: &TurnContext) -> ExecParams {
         ExecParams {
-            command: params.command,
+            command: params.command.clone(),
             cwd: turn_context.resolve_path(params.workdir.clone()),
             expiration: params.timeout_ms.into(),
             env: create_env(&turn_context.shell_environment_policy),
             sandbox_permissions: params.sandbox_permissions.unwrap_or_default(),
             windows_sandbox_level: turn_context.windows_sandbox_level,
-            justification: params.justification,
+            justification: params.justification.clone(),
             arg0: None,
         }
     }
@@ -50,7 +62,7 @@ impl ShellCommandHandler {
     }
 
     fn to_exec_params(
-        params: ShellCommandToolCallParams,
+        params: &ShellCommandToolCallParams,
         session: &crate::codex::Session,
         turn_context: &TurnContext,
     ) -> ExecParams {
@@ -64,7 +76,7 @@ impl ShellCommandHandler {
             env: create_env(&turn_context.shell_environment_policy),
             sandbox_permissions: params.sandbox_permissions.unwrap_or_default(),
             windows_sandbox_level: turn_context.windows_sandbox_level,
-            justification: params.justification,
+            justification: params.justification.clone(),
             arg0: None,
         }
     }
@@ -108,29 +120,32 @@ impl ToolHandler for ShellHandler {
         match payload {
             ToolPayload::Function { arguments } => {
                 let params: ShellToolCallParams = parse_arguments(&arguments)?;
-                let exec_params = Self::to_exec_params(params, turn.as_ref());
-                Self::run_exec_like(
-                    tool_name.as_str(),
+                let prefix_rule = params.prefix_rule.clone();
+                let exec_params = Self::to_exec_params(&params, turn.as_ref());
+                Self::run_exec_like(RunExecLikeArgs {
+                    tool_name: tool_name.clone(),
                     exec_params,
+                    prefix_rule,
                     session,
                     turn,
                     tracker,
                     call_id,
-                    false,
-                )
+                    freeform: false,
+                })
                 .await
             }
             ToolPayload::LocalShell { params } => {
-                let exec_params = Self::to_exec_params(params, turn.as_ref());
-                Self::run_exec_like(
-                    tool_name.as_str(),
+                let exec_params = Self::to_exec_params(&params, turn.as_ref());
+                Self::run_exec_like(RunExecLikeArgs {
+                    tool_name: tool_name.clone(),
                     exec_params,
+                    prefix_rule: None,
                     session,
                     turn,
                     tracker,
                     call_id,
-                    false,
-                )
+                    freeform: false,
+                })
                 .await
             }
             _ => Err(FunctionCallError::RespondToModel(format!(
@@ -181,30 +196,43 @@ impl ToolHandler for ShellCommandHandler {
         };
 
         let params: ShellCommandToolCallParams = parse_arguments(&arguments)?;
-        let exec_params = Self::to_exec_params(params, session.as_ref(), turn.as_ref());
-        ShellHandler::run_exec_like(
-            tool_name.as_str(),
+        let prefix_rule = params.prefix_rule.clone();
+        let exec_params = Self::to_exec_params(&params, session.as_ref(), turn.as_ref());
+        ShellHandler::run_exec_like(RunExecLikeArgs {
+            tool_name,
             exec_params,
+            prefix_rule,
             session,
             turn,
             tracker,
             call_id,
-            true,
-        )
+            freeform: true,
+        })
         .await
     }
 }
 
 impl ShellHandler {
-    async fn run_exec_like(
-        tool_name: &str,
-        exec_params: ExecParams,
-        session: Arc<crate::codex::Session>,
-        turn: Arc<TurnContext>,
-        tracker: crate::tools::context::SharedTurnDiffTracker,
-        call_id: String,
-        freeform: bool,
-    ) -> Result<ToolOutput, FunctionCallError> {
+    async fn run_exec_like(args: RunExecLikeArgs) -> Result<ToolOutput, FunctionCallError> {
+        let RunExecLikeArgs {
+            tool_name,
+            exec_params,
+            prefix_rule,
+            session,
+            turn,
+            tracker,
+            call_id,
+            freeform,
+        } = args;
+
+        let features = session.features();
+        let request_rule_enabled = features.enabled(crate::features::Feature::RequestRule);
+        let prefix_rule = if request_rule_enabled {
+            prefix_rule
+        } else {
+            None
+        };
+
         // Approval policy guard for explicit escalation in non-OnRequest modes.
         if exec_params
             .sandbox_permissions
@@ -214,9 +242,9 @@ impl ShellHandler {
                 codex_protocol::protocol::AskForApproval::OnRequest
             )
         {
+            let approval_policy = turn.approval_policy;
             return Err(FunctionCallError::RespondToModel(format!(
-                "approval policy is {policy:?}; reject command — you should not ask for escalated permissions if the approval policy is {policy:?}",
-                policy = turn.approval_policy
+                "approval policy is {approval_policy:?}; reject command — you should not ask for escalated permissions if the approval policy is {approval_policy:?}"
             )));
         }
 
@@ -229,7 +257,7 @@ impl ShellHandler {
             turn.as_ref(),
             Some(&tracker),
             &call_id,
-            tool_name,
+            tool_name.as_str(),
         )
         .await?
         {
@@ -246,17 +274,17 @@ impl ShellHandler {
         let event_ctx = ToolEventCtx::new(session.as_ref(), turn.as_ref(), &call_id, None);
         emitter.begin(event_ctx).await;
 
-        let features = session.features();
         let exec_approval_requirement = session
             .services
             .exec_policy
-            .create_exec_approval_requirement_for_command(
-                &features,
-                &exec_params.command,
-                turn.approval_policy,
-                &turn.sandbox_policy,
-                exec_params.sandbox_permissions,
-            )
+            .create_exec_approval_requirement_for_command(ExecApprovalRequest {
+                features: &features,
+                command: &exec_params.command,
+                approval_policy: turn.approval_policy,
+                sandbox_policy: &turn.sandbox_policy,
+                sandbox_permissions: exec_params.sandbox_permissions,
+                prefix_rule,
+            })
             .await;
 
         let req = ShellRequest {
@@ -274,7 +302,7 @@ impl ShellHandler {
             session: session.as_ref(),
             turn: turn.as_ref(),
             call_id: call_id.clone(),
-            tool_name: tool_name.to_string(),
+            tool_name,
         };
         let out = orchestrator
             .run(&mut runtime, &req, &tool_ctx, &turn, turn.approval_policy)
@@ -377,10 +405,11 @@ mod tests {
             login,
             timeout_ms,
             sandbox_permissions: Some(sandbox_permissions),
+            prefix_rule: None,
             justification: justification.clone(),
         };
 
-        let exec_params = ShellCommandHandler::to_exec_params(params, &session, &turn_context);
+        let exec_params = ShellCommandHandler::to_exec_params(&params, &session, &turn_context);
 
         // ExecParams cannot derive Eq due to the CancellationToken field, so we manually compare the fields.
         assert_eq!(exec_params.command, expected_command);

codex-rs/core/src/tools/handlers/unified_exec.rs

@@ -43,6 +43,8 @@ struct ExecCommandArgs {
     sandbox_permissions: SandboxPermissions,
     #[serde(default)]
     justification: Option<String>,
+    #[serde(default)]
+    prefix_rule: Option<Vec<String>>,
 }
 
 #[derive(Debug, Deserialize)]
@@ -135,19 +137,28 @@ impl ToolHandler for UnifiedExecHandler {
                     max_output_tokens,
                     sandbox_permissions,
                     justification,
+                    prefix_rule,
                     ..
                 } = args;
 
+                let features = session.features();
+                let request_rule_enabled = features.enabled(crate::features::Feature::RequestRule);
+                let prefix_rule = if request_rule_enabled {
+                    prefix_rule
+                } else {
+                    None
+                };
+
                 if sandbox_permissions.requires_escalated_permissions()
                     && !matches!(
                         context.turn.approval_policy,
                         codex_protocol::protocol::AskForApproval::OnRequest
                     )
                 {
+                    let approval_policy = context.turn.approval_policy;
                     manager.release_process_id(&process_id).await;
                     return Err(FunctionCallError::RespondToModel(format!(
-                        "approval policy is {policy:?}; reject command — you cannot ask for escalated permissions if the approval policy is {policy:?}",
-                        policy = context.turn.approval_policy
+                        "approval policy is {approval_policy:?}; reject command — you cannot ask for escalated permissions if the approval policy is {approval_policy:?}"
                     )));
                 }
 
@@ -183,6 +194,7 @@ impl ToolHandler for UnifiedExecHandler {
                             tty,
                             sandbox_permissions,
                             justification,
+                            prefix_rule,
                         },
                         &context,
                     )

codex-rs/core/src/tools/router.rs

@@ -114,6 +114,7 @@ impl ToolRouter {
                             workdir: exec.working_directory,
                             timeout_ms: exec.timeout_ms,
                             sandbox_permissions: Some(SandboxPermissions::UseDefault),
+                            prefix_rule: None,
                             justification: None,
                         };
                         Ok(Some(ToolCall {

codex-rs/core/src/tools/spec.rs

@@ -30,6 +30,7 @@ pub(crate) struct ToolsConfig {
     pub web_search_mode: Option<WebSearchMode>,
     pub collab_tools: bool,
     pub collaboration_modes_tools: bool,
+    pub request_rule_enabled: bool,
     pub experimental_supported_tools: Vec<String>,
 }
 
@@ -49,6 +50,7 @@ impl ToolsConfig {
         let include_apply_patch_tool = features.enabled(Feature::ApplyPatchFreeform);
         let include_collab_tools = features.enabled(Feature::Collab);
         let include_collaboration_modes_tools = features.enabled(Feature::CollaborationModes);
+        let request_rule_enabled = features.enabled(Feature::RequestRule);
 
         let shell_type = if !features.enabled(Feature::ShellTool) {
             ConfigShellToolType::Disabled
@@ -81,6 +83,7 @@ impl ToolsConfig {
             web_search_mode: *web_search_mode,
             collab_tools: include_collab_tools,
             collaboration_modes_tools: include_collaboration_modes_tools,
+            request_rule_enabled,
             experimental_supported_tools: model_info.experimental_supported_tools.clone(),
         }
     }
@@ -142,8 +145,50 @@ impl From<JsonSchema> for AdditionalProperties {
     }
 }
 
-fn create_exec_command_tool() -> ToolSpec {
-    let properties = BTreeMap::from([
+fn create_approval_parameters(include_prefix_rule: bool) -> BTreeMap<String, JsonSchema> {
+    let mut properties = BTreeMap::from([
+        (
+            "sandbox_permissions".to_string(),
+            JsonSchema::String {
+                description: Some(
+                    "Sandbox permissions for the command. Set to \"require_escalated\" to request running without sandbox restrictions; defaults to \"use_default\"."
+                        .to_string(),
+                ),
+            },
+        ),
+        (
+            "justification".to_string(),
+            JsonSchema::String {
+                description: Some(
+                    r#"Only set if sandbox_permissions is \"require_escalated\". 
+                    Request approval from the user to run this command outside the sandbox. 
+                    Phrased as a simple question that summarizes the purpose of the 
+                    command as it relates to the task at hand - e.g. 'Do you want to 
+                    fetch and pull the latest version of this git branch?'"#
+                    .to_string(),
+                ),
+            },
+        ),
+    ]);
+
+    if include_prefix_rule {
+        properties.insert(
+            "prefix_rule".to_string(),
+            JsonSchema::Array {
+                items: Box::new(JsonSchema::String { description: None }),
+                description: Some(
+                    r#"Only specify when sandbox_permissions is `require_escalated`. 
+                    Suggest a prefix command pattern that will allow you to fulfill similar requests from the user in the future.
+                    Should be a short but reasonable prefix, e.g. [\"git\", \"pull\"] or [\"uv\", \"run\"] or [\"pytest\"]."#.to_string(),
+                ),
+            });
+    }
+
+    properties
+}
+
+fn create_exec_command_tool(include_prefix_rule: bool) -> ToolSpec {
+    let mut properties = BTreeMap::from([
         (
             "cmd".to_string(),
             JsonSchema::String {
@@ -199,25 +244,8 @@ fn create_exec_command_tool() -> ToolSpec {
                 ),
             },
         ),
-        (
-            "sandbox_permissions".to_string(),
-            JsonSchema::String {
-                description: Some(
-                    "Sandbox permissions for the command. Set to \"require_escalated\" to request running without sandbox restrictions; defaults to \"use_default\"."
-                        .to_string(),
-                ),
-            },
-        ),
-        (
-            "justification".to_string(),
-            JsonSchema::String {
-                description: Some(
-                    "Only set if sandbox_permissions is \"require_escalated\". 1-sentence explanation of why we want to run this command."
-                        .to_string(),
-                ),
-            },
-        ),
     ]);
+    properties.extend(create_approval_parameters(include_prefix_rule));
 
     ToolSpec::Function(ResponsesApiTool {
         name: "exec_command".to_string(),
@@ -280,8 +308,8 @@ fn create_write_stdin_tool() -> ToolSpec {
     })
 }
 
-fn create_shell_tool() -> ToolSpec {
-    let properties = BTreeMap::from([
+fn create_shell_tool(include_prefix_rule: bool) -> ToolSpec {
+    let mut properties = BTreeMap::from([
         (
             "command".to_string(),
             JsonSchema::Array {
@@ -301,19 +329,8 @@ fn create_shell_tool() -> ToolSpec {
                 description: Some("The timeout for the command in milliseconds".to_string()),
             },
         ),
-        (
-            "sandbox_permissions".to_string(),
-            JsonSchema::String {
-                description: Some("Sandbox permissions for the command. Set to \"require_escalated\" to request running without sandbox restrictions; defaults to \"use_default\".".to_string()),
-            },
-        ),
-        (
-            "justification".to_string(),
-            JsonSchema::String {
-                description: Some("Only set if sandbox_permissions is \"require_escalated\". 1-sentence explanation of why we want to run this command.".to_string()),
-            },
-        ),
     ]);
+    properties.extend(create_approval_parameters(include_prefix_rule));
 
     let description  = if cfg!(windows) {
         r#"Runs a Powershell command (Windows) and returns its output. Arguments to `shell` will be passed to CreateProcessW(). Most commands should be prefixed with ["powershell.exe", "-Command"].
@@ -344,8 +361,8 @@ Examples of valid command strings:
     })
 }
 
-fn create_shell_command_tool() -> ToolSpec {
-    let properties = BTreeMap::from([
+fn create_shell_command_tool(include_prefix_rule: bool) -> ToolSpec {
+    let mut properties = BTreeMap::from([
         (
             "command".to_string(),
             JsonSchema::String {
@@ -375,19 +392,8 @@ fn create_shell_command_tool() -> ToolSpec {
                 description: Some("The timeout for the command in milliseconds".to_string()),
             },
         ),
-        (
-            "sandbox_permissions".to_string(),
-            JsonSchema::String {
-                description: Some("Sandbox permissions for the command. Set to \"require_escalated\" to request running without sandbox restrictions; defaults to \"use_default\".".to_string()),
-            },
-        ),
-        (
-            "justification".to_string(),
-            JsonSchema::String {
-                description: Some("Only set if sandbox_permissions is \"require_escalated\". 1-sentence explanation of why we want to run this command.".to_string()),
-            },
-        ),
     ]);
+    properties.extend(create_approval_parameters(include_prefix_rule));
 
     let description = if cfg!(windows) {
         r#"Runs a Powershell command (Windows) and returns its output.
@@ -1292,13 +1298,13 @@ pub(crate) fn build_specs(
 
     match &config.shell_type {
         ConfigShellToolType::Default => {
-            builder.push_spec(create_shell_tool());
+            builder.push_spec(create_shell_tool(config.request_rule_enabled));
         }
         ConfigShellToolType::Local => {
             builder.push_spec(ToolSpec::LocalShell {});
         }
         ConfigShellToolType::UnifiedExec => {
-            builder.push_spec(create_exec_command_tool());
+            builder.push_spec(create_exec_command_tool(config.request_rule_enabled));
             builder.push_spec(create_write_stdin_tool());
             builder.register_handler("exec_command", unified_exec_handler.clone());
             builder.register_handler("write_stdin", unified_exec_handler);
@@ -1307,7 +1313,7 @@ pub(crate) fn build_specs(
             // Do nothing.
         }
         ConfigShellToolType::ShellCommand => {
-            builder.push_spec(create_shell_command_tool());
+            builder.push_spec(create_shell_command_tool(config.request_rule_enabled));
         }
     }
 
@@ -1579,7 +1585,7 @@ mod tests {
         // Build expected from the same helpers used by the builder.
         let mut expected: BTreeMap<String, ToolSpec> = BTreeMap::from([]);
         for spec in [
-            create_exec_command_tool(),
+            create_exec_command_tool(false),
             create_write_stdin_tool(),
             create_list_mcp_resources_tool(),
             create_list_mcp_resource_templates_tool(),
@@ -2413,7 +2419,7 @@ mod tests {
 
     #[test]
     fn test_shell_tool() {
-        let tool = super::create_shell_tool();
+        let tool = super::create_shell_tool(false);
         let ToolSpec::Function(ResponsesApiTool {
             description, name, ..
         }) = &tool
@@ -2443,7 +2449,7 @@ Examples of valid command strings:
 
     #[test]
     fn test_shell_command_tool() {
-        let tool = super::create_shell_command_tool();
+        let tool = super::create_shell_command_tool(false);
         let ToolSpec::Function(ResponsesApiTool {
             description, name, ..
         }) = &tool